2024 |
Unraveling the Mechanisms of Zirconium Metal–Organic Frameworks-Based Mixed-Matrix Membranes Preventing Polysulfide Shuttling Article de journal Wenqing Lu; Zhenfeng Pang; Aran Lamaire; Fu Liu; Shan Dai; Moisés L. Pinto; Rezan Demir-Cakan; Kong Ooi Tan; Veronique Van Speybroeck; Vanessa Pimenta; Christian Serre Small Science, 2024. @article{Lu2024, title = {Unraveling the Mechanisms of Zirconium Metal\textendashOrganic Frameworks-Based Mixed-Matrix Membranes Preventing Polysulfide Shuttling}, author = {Wenqing Lu and Zhenfeng Pang and Aran Lamaire and Fu Liu and Shan Dai and Mois\'{e}s L. Pinto and Rezan Demir-Cakan and Kong Ooi Tan and Veronique Van Speybroeck and Vanessa Pimenta and Christian Serre}, url = {https://onlinelibrary.wiley.com/doi/10.1002/smsc.202300339}, doi = {10.1002/smsc.202300339}, year = {2024}, date = {2024-05-02}, journal = {Small Science}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2023 |
Efficient 18.8 T MAS-DNP NMR reveals hidden side chains in amyloid fibrils Article de journal Alons Lends; Nicolas Birlirakis; Xinyi Cai; Asen Daskalov; Jayakrishna Shenoy; Muhammed Bilal; Mélanie Berbon; Fabien Ferrage; Yangping Liu; Antoine Loquet; Kong Ooi Tan Journal of Biomolecular NMR, 77 , 2023. @article{Lends2023, title = {Efficient 18.8 T MAS-DNP NMR reveals hidden side chains in amyloid fibrils}, author = {Alons Lends and Nicolas Birlirakis and Xinyi Cai and Asen Daskalov and Jayakrishna Shenoy and Muhammed Bilal and M\'{e}lanie Berbon and Fabien Ferrage and Yangping Liu and Antoine Loquet and Kong Ooi Tan}, url = {https://link.springer.com/article/10.1007/s10858-023-00416-5}, doi = {10.1007/s10858-023-00416-5}, year = {2023}, date = {2023-06-08}, journal = {Journal of Biomolecular NMR}, volume = {77}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
In-house fabrication of 1.3 to 7 mm MAS drive caps using desktop 3D printers Article de journal Cyriaque Amerein; Utsab Banerjee; Zhenfeng Pang; Wenqing Lu; Vanessa Pimenta; Kong Ooi Tan Journal of Magnetic Resonance, 2023. @article{Amerein2023, title = {In-house fabrication of 1.3 to 7 mm MAS drive caps using desktop 3D printers}, author = {Cyriaque Amerein and Utsab Banerjee and Zhenfeng Pang and Wenqing Lu and Vanessa Pimenta and Kong Ooi Tan }, url = {https://www.chimie.ens.fr/wp-content/uploads/2023/02/1-s2.0-S1090780723000265-main.pdf}, doi = {10.1016/j.jmr.2023.107391}, year = {2023}, date = {2023-02-06}, journal = {Journal of Magnetic Resonance}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2022 |
Drug Screening of Achiral Molecules by Long-Lived States in NMR Article de journal A. Sonnefeld; A. Razanahoera; P. Pelupessy; G Bodenhausen; K. Sheberstov Science Advances, 2022. @article{Sonnefeld2022b, title = {Drug Screening of Achiral Molecules by Long-Lived States in NMR}, author = {A. Sonnefeld and A. Razanahoera and P. Pelupessy and G Bodenhausen and K. Sheberstov}, url = {https://www.science.org/doi/10.1126/sciadv.ade2113}, year = {2022}, date = {2022-12-02}, journal = {Science Advances}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Polychromatic Excitation of Delocalized Long-Lived Proton Spin States in Aliphatic Chains. Article de journal A.Sonnefeld; G Bodenhausen; K. Sheberstov Phys. Rev. Letters, 2022. @article{A.Sonnefeld2022, title = {Polychromatic Excitation of Delocalized Long-Lived Proton Spin States in Aliphatic Chains.}, author = {A.Sonnefeld and G Bodenhausen and K. Sheberstov }, url = {https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.129.183203}, doi = {10.1103/PhysRevLett.129.183203}, year = {2022}, date = {2022-10-28}, journal = {Phys. Rev. Letters}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Room-Temperature Quantitative Quantum Sensing of Lithium Ions with a Radical-Embedded Metal–Organic Framework Article de journal Lei Sun; Luming Yang; Jin-Hu Dou; Jian Li; Grigorii Skorupskii; Michael Mardini; Kong Ooi Tan; Tianyang Chen; Chenyue Sun; Julius J. Oppenheim; Robert G. Griffin; Mircea Dincă; Tijana Rajh J. Am. Chem. Soc., 144 , p. 19008−19016, 2022. @article{Sun2022, title = {Room-Temperature Quantitative Quantum Sensing of Lithium Ions with a Radical-Embedded Metal\textendashOrganic Framework}, author = {Lei Sun and Luming Yang and Jin-Hu Dou and Jian Li and Grigorii Skorupskii and Michael Mardini and Kong Ooi Tan and Tianyang Chen and Chenyue Sun and Julius J. Oppenheim and Robert G. Griffin and Mircea Dinc\u{a} and Tijana Rajh}, url = {https://pubs.acs.org/doi/pdf/10.1021/jacs.2c07692}, doi = {10.1021/jacs.2c07692}, year = {2022}, date = {2022-10-06}, journal = { J. Am. Chem. Soc.}, volume = {144}, pages = {19008−19016}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Observing Nearby Nuclei on Paramagnetic Trityls and MOFs via DNP and Electron Decoupling Article de journal Kong Ooi Tan; Luming Yang; Michael Mardini; Choon Boon Cheong; Benoit Driesschaert; Mircea Dincă; Robert Guy Griffin Chemistry – A European Journal, 2022. @article{https://doi.org/10.1002/chem.202202556, title = {Observing Nearby Nuclei on Paramagnetic Trityls and MOFs via DNP and Electron Decoupling}, author = {Kong Ooi Tan and Luming Yang and Michael Mardini and Choon Boon Cheong and Benoit Driesschaert and Mircea Dinc\u{a} and Robert Guy Griffin}, url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/chem.202202556}, doi = {https://doi.org/10.1002/chem.202202556}, year = {2022}, date = {2022-09-11}, journal = {Chemistry \textendash A European Journal}, abstract = {Dynamic nuclear polarization (DNP) is an NMR sensitivity enhancement technique that mediates polarization transfer from unpaired electrons to NMR-active nuclei. Despite its success in elucidating important structural information on biological and inorganic materials, the detailed polarization-transfer pathway\textemdashfrom the electrons to the nearby and then the bulk solvent nuclei, and finally to the molecules of interest\textemdashremains unclear. In particular, the nuclei in the paramagnetic polarizing agent play significant roles in relaying the enhanced NMR polarizations to more remote nuclei. Despite their importance, the direct NMR observation of these nuclei is challenging because of poor sensitivity. Here, we show that a combined DNP and electron decoupling approach can enable direct NMR detection of these nuclei. We achieved an ~80% improvement in NMR intensity via electron decoupling at 0.35 T and 80 K on trityl radicals. Moreover, we recorded a DNP enhancement factor of 𝜀 ~ 90 and ~11% higher NMR intensity using electron decoupling on paramagnetic metal-organic framework, magnesium hexaoxytriphenylene (MgHOTP MOF).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dynamic nuclear polarization (DNP) is an NMR sensitivity enhancement technique that mediates polarization transfer from unpaired electrons to NMR-active nuclei. Despite its success in elucidating important structural information on biological and inorganic materials, the detailed polarization-transfer pathway—from the electrons to the nearby and then the bulk solvent nuclei, and finally to the molecules of interest—remains unclear. In particular, the nuclei in the paramagnetic polarizing agent play significant roles in relaying the enhanced NMR polarizations to more remote nuclei. Despite their importance, the direct NMR observation of these nuclei is challenging because of poor sensitivity. Here, we show that a combined DNP and electron decoupling approach can enable direct NMR detection of these nuclei. We achieved an ~80% improvement in NMR intensity via electron decoupling at 0.35 T and 80 K on trityl radicals. Moreover, we recorded a DNP enhancement factor of 𝜀 ~ 90 and ~11% higher NMR intensity using electron decoupling on paramagnetic metal-organic framework, magnesium hexaoxytriphenylene (MgHOTP MOF). |
Designing broadband pulsed dynamic nuclear polarization sequences in static solids Article de journal Nino Wili; Anders Bodholt Nielsen; Laura Alicia Völker; Lukas Schreder; Niels Chr. Nielsen; Gunnar Jeschke; Kong Ooi Tan Science Advances, 8 , 2022. @article{Wili2022, title = {Designing broadband pulsed dynamic nuclear polarization sequences in static solids}, author = {Nino Wili and Anders Bodholt Nielsen and Laura Alicia V\"{o}lker and Lukas Schreder and Niels Chr. Nielsen and Gunnar Jeschke and Kong Ooi Tan}, url = {https://www.science.org/doi/10.1126/sciadv.abq0536}, doi = {DOI: 10.1126/sciadv.abq0536}, year = {2022}, date = {2022-07-15}, journal = {Science Advances}, volume = {8}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
A unified description for polarization-transfer mechanisms in magnetic resonance in static solids: Cross polarization and DNP Article de journal Zhenfeng Pang; Sheetal Jain; Chen Yang; Xueqian Kong; Kong Ooi Tan The Journal of Chemical Physics, 156 (24), p. 244109, 2022. @article{2022Pang, title = {A unified description for polarization-transfer mechanisms in magnetic resonance in static solids: Cross polarization and DNP}, author = {Zhenfeng Pang and Sheetal Jain and Chen Yang and Xueqian Kong and Kong Ooi Tan }, url = {https://aip.scitation.org/doi/abs/10.1063/5.0092265}, doi = {10.1063/5.0092265}, year = {2022}, date = {2022-06-24}, journal = {The Journal of Chemical Physics}, volume = {156}, number = {24}, pages = {244109}, abstract = {Polarization transfers are crucial building blocks in magnetic resonance experiments, i.e., they can be used to polarize insensitive nuclei and correlate nuclear spins in multidimensional nuclear magnetic resonance (NMR) spectroscopy. The polarization can be transferred either across different nuclear spin species or from electron spins to the relatively low-polarized nuclear spins. The former route occurring in solid-state NMR can be performed via cross polarization (CP), while the latter route is known as dynamic nuclear polarization (DNP). Despite having different operating conditions, we opinionate that both mechanisms are theoretically similar processes in ideal conditions, i.e., the electron is merely another spin-1/2 particle with a much higher gyromagnetic ratio. Here, we show that the CP and DNP processes can be described using a unified theory based on average Hamiltonian theory combined with fictitious operators. The intuitive and unified approach has allowed new insights into the cross-effect DNP mechanism, leading to better design of DNP polarizing agents and extending the applications beyond just hyperpolarization. We explore the possibility of exploiting theoretically predicted DNP transients for electron\textendashnucleus distance measurements\textemdashsuch as routine dipolar-recoupling experiments in solid-state NMR. }, keywords = {}, pubstate = {published}, tppubtype = {article} } Polarization transfers are crucial building blocks in magnetic resonance experiments, i.e., they can be used to polarize insensitive nuclei and correlate nuclear spins in multidimensional nuclear magnetic resonance (NMR) spectroscopy. The polarization can be transferred either across different nuclear spin species or from electron spins to the relatively low-polarized nuclear spins. The former route occurring in solid-state NMR can be performed via cross polarization (CP), while the latter route is known as dynamic nuclear polarization (DNP). Despite having different operating conditions, we opinionate that both mechanisms are theoretically similar processes in ideal conditions, i.e., the electron is merely another spin-1/2 particle with a much higher gyromagnetic ratio. Here, we show that the CP and DNP processes can be described using a unified theory based on average Hamiltonian theory combined with fictitious operators. The intuitive and unified approach has allowed new insights into the cross-effect DNP mechanism, leading to better design of DNP polarizing agents and extending the applications beyond just hyperpolarization. We explore the possibility of exploiting theoretically predicted DNP transients for electron–nucleus distance measurements—such as routine dipolar-recoupling experiments in solid-state NMR. |
Integrated, Stretched, and Adiabatic Solid Effects Article de journal Yifan Quan; Jakob Steiner; Yifu Ouyang; Kong Ooi Tan; W. Thomas Wenckebach; Patrick Hautle; Robert G. Griffin J. Phys. Chem. Lett, 13 , p. 5751, 2022. @article{Quan2022, title = {Integrated, Stretched, and Adiabatic Solid Effects}, author = {Yifan Quan and Jakob Steiner and Yifu Ouyang and Kong Ooi Tan and W. Thomas Wenckebach and Patrick Hautle and Robert G. Griffin }, url = {https://pubs.acs.org/doi/abs/10.1021/acs.jpclett.2c01147}, doi = {10.1021/acs.jpclett.2c01147}, year = {2022}, date = {2022-06-17}, journal = {J. Phys. Chem. Lett}, volume = {13}, pages = {5751}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Observation of a Four-Spin Solid Effect Article de journal Kong Ooi Tan; Robert G. Griffin J. Chem. Phys., 2022. @article{Tan2022FSSE, title = {Observation of a Four-Spin Solid Effect}, author = {Kong Ooi Tan and Robert G. Griffin }, url = {https://aip.scitation.org/doi/abs/10.1063/5.0091663}, doi = {10.1063/5.0091663}, year = {2022}, date = {2022-04-12}, journal = {J. Chem. Phys.}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2021 |
Overhauser Dynamic Nuclear Polarization with Selectively Deuterated BDPA Radicals Article de journal Léo Delage-Laurin; Ravi Shankar Palani; Natalie Golota; Michael Mardini; Yifu Ouyang; Kong Ooi Tan; Timothy M. Swager; Robert G. Griffin J. Am. Chem. Soc., 143 (48), p. 20281–20290, 2021. @article{Tan2021OE, title = {Overhauser Dynamic Nuclear Polarization with Selectively Deuterated BDPA Radicals}, author = {L\'{e}o Delage-Laurin and Ravi Shankar Palani and Natalie Golota and Michael Mardini and Yifu Ouyang and Kong Ooi Tan and Timothy M. Swager and Robert G. Griffin}, url = {https://pubs.acs.org/doi/abs/10.1021/jacs.1c09406}, doi = {10.1021/jacs.1c09406}, year = {2021}, date = {2021-11-23}, journal = {J. Am. Chem. Soc.}, volume = {143}, number = {48}, pages = {20281\textendash20290}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
DNPSOUP: A simulation software package for dynamic nuclear polarization Article de journal Chen Yang; Kong Ooi Tan; R G Griffin Journal of Magnetic Resonance, p. 107107, 2021, ISSN: 1090-7807. @article{YANG2021107107, title = {DNPSOUP: A simulation software package for dynamic nuclear polarization}, author = {Chen Yang and Kong Ooi Tan and R G Griffin}, url = {https://www.sciencedirect.com/science/article/pii/S1090780721001968}, doi = {https://doi.org/10.1016/j.jmr.2021.107107}, issn = {1090-7807}, year = {2021}, date = {2021-01-01}, journal = {Journal of Magnetic Resonance}, pages = {107107}, abstract = {Dynamic Nuclear Polarization Simulation Optimized with a Unified Propagator (DNPSOUP) is an open-source numerical software program that models spin dynamics for dynamic nuclear polarization (DNP). The software package utilizes a direct numerical approach using the inhomogeneous master equation to treat the time evolution of spin density operator under coherent Hamiltonians and stochastic relaxation effects. Here we present the details of the theory behind the software, starting from the master equation, and arriving at characteristic operators for any section of density operator time-evolution. We then provide an overview of the DNPSOUP software architecture. The efficacy of the program is demonstrated by simulating DNP field profiles on small spin systems exploiting both continuous wave and time-domain DNP mechanisms. Examples include Zeeman field profiles for the solid effect, Overhauser effect, and cross effect, and microwave field profiles for NOVEL, off-resonance NOVEL, the integrated solid effect, the stretched solid effect, and TOP-DNP. The software should facilitate a better understanding of the DNP process, aid in the design of optimized DNP polarizing agents, and allow us to examine new pulsed DNP methods at conditions that are not currently experimentally accessible, especially at high magnetic fields with high-power microwave pulses.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dynamic Nuclear Polarization Simulation Optimized with a Unified Propagator (DNPSOUP) is an open-source numerical software program that models spin dynamics for dynamic nuclear polarization (DNP). The software package utilizes a direct numerical approach using the inhomogeneous master equation to treat the time evolution of spin density operator under coherent Hamiltonians and stochastic relaxation effects. Here we present the details of the theory behind the software, starting from the master equation, and arriving at characteristic operators for any section of density operator time-evolution. We then provide an overview of the DNPSOUP software architecture. The efficacy of the program is demonstrated by simulating DNP field profiles on small spin systems exploiting both continuous wave and time-domain DNP mechanisms. Examples include Zeeman field profiles for the solid effect, Overhauser effect, and cross effect, and microwave field profiles for NOVEL, off-resonance NOVEL, the integrated solid effect, the stretched solid effect, and TOP-DNP. The software should facilitate a better understanding of the DNP process, aid in the design of optimized DNP polarizing agents, and allow us to examine new pulsed DNP methods at conditions that are not currently experimentally accessible, especially at high magnetic fields with high-power microwave pulses. |
Time domain DNP at 1.2 T Article de journal T V Can; Kong Ooi Tan; C Yang; R T Weber; R G Griffin Journal of Magnetic Resonance, 329 , p. 107012, 2021, ISSN: 1090-7807. @article{CAN2021107012, title = {Time domain DNP at 1.2 T}, author = {T V Can and Kong Ooi Tan and C Yang and R T Weber and R G Griffin}, url = {https://www.sciencedirect.com/science/article/pii/S1090780721001014}, doi = {https://doi.org/10.1016/j.jmr.2021.107012}, issn = {1090-7807}, year = {2021}, date = {2021-01-01}, journal = {Journal of Magnetic Resonance}, volume = {329}, pages = {107012}, abstract = {We present the results of an experimental pulsed DNP study at 1.2 T (33.5 GHz/51 MHz electron and 1H Larmor frequencies, respectively). The results include a comparison of constant-amplitude NOVEL (CA-NOVEL), ramped-amplitude NOVEL (RA-NOVEL) and the frequency-swept integrated solid effect (FS-ISE) experiments all of which were performed at the NOVEL matching condition, ω1S=ω0I, where ω1S is the electron Rabi frequency andω0I the proton Larmor frequency. To the best of our knowledge, this is the first pulsed DNP study carried out at field higher than X-band (0.35 T) using the NOVEL condition. A combination of high microwave power (∼150 W) and a microwave cavity with a high Q (∼500) allowed us to satisfy the NOVEL matching condition. We also observed stretched solid effect (S2E) contributions in the Zeeman field profiles when chirped pulses are applied. Furthermore, the high quality factor of the cavity limits the concentration of the radical to ∼5 mM and generates a hysteresis in the FS-ISE experiments. Nevertheless, we observe very high DNP enhancements that are comparable to the results at X-band. These promising outcomes suggest the importance of further studies at even higher fields that delineate the instrumentation and methods required for time domain DNP.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present the results of an experimental pulsed DNP study at 1.2 T (33.5 GHz/51 MHz electron and 1H Larmor frequencies, respectively). The results include a comparison of constant-amplitude NOVEL (CA-NOVEL), ramped-amplitude NOVEL (RA-NOVEL) and the frequency-swept integrated solid effect (FS-ISE) experiments all of which were performed at the NOVEL matching condition, ω1S=ω0I, where ω1S is the electron Rabi frequency andω0I the proton Larmor frequency. To the best of our knowledge, this is the first pulsed DNP study carried out at field higher than X-band (0.35 T) using the NOVEL condition. A combination of high microwave power (∼150 W) and a microwave cavity with a high Q (∼500) allowed us to satisfy the NOVEL matching condition. We also observed stretched solid effect (S2E) contributions in the Zeeman field profiles when chirped pulses are applied. Furthermore, the high quality factor of the cavity limits the concentration of the radical to ∼5 mM and generates a hysteresis in the FS-ISE experiments. Nevertheless, we observe very high DNP enhancements that are comparable to the results at X-band. These promising outcomes suggest the importance of further studies at even higher fields that delineate the instrumentation and methods required for time domain DNP. |
2020 |
Spin Thermometry: A Straightforward Measure of Millikelvin Deuterium Spin Temperatures Achieved by Dynamic Nuclear Polarization Article de journal Behdad Aghelnejad; Sina Marhabaie; Mathieu Baudin; Geoffrey Bodenhausen; Diego Carnevale The Journal of Physical Chemistry Letters, 11 (9), p. 3219–3225, 2020, ISSN: 1948-7185. @article{Aghelnejad2020, title = {Spin Thermometry: A Straightforward Measure of Millikelvin Deuterium Spin Temperatures Achieved by Dynamic Nuclear Polarization}, author = {Behdad Aghelnejad and Sina Marhabaie and Mathieu Baudin and Geoffrey Bodenhausen and Diego Carnevale}, url = {https://pubs.acs.org/doi/10.1021/acs.jpclett.0c00713}, doi = {10.1021/acs.jpclett.0c00713}, issn = {1948-7185}, year = {2020}, date = {2020-05-01}, journal = {The Journal of Physical Chemistry Letters}, volume = {11}, number = {9}, pages = {3219--3225}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Self‐Assembly of DNA and RNA Building Blocks Explored by Nitrogen‐14 NMR Crystallography: Structure and Dynamics Article de journal Diego Carnevale; Marcel Hollenstein; Geoffrey Bodenhausen ChemPhysChem, 21 (10), p. 1044–1051, 2020, ISSN: 1439-4235. @article{Carnevale2020, title = {Self‐Assembly of DNA and RNA Building Blocks Explored by Nitrogen‐14 NMR Crystallography: Structure and Dynamics}, author = {Diego Carnevale and Marcel Hollenstein and Geoffrey Bodenhausen}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/cphc.201901214}, doi = {10.1002/cphc.201901214}, issn = {1439-4235}, year = {2020}, date = {2020-05-01}, journal = {ChemPhysChem}, volume = {21}, number = {10}, pages = {1044--1051}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Adiabatic Solid Effect Article de journal Kong Ooi Tan; Ralph T Weber; Thach Van Can; Robert G Griffin The Journal of Physical Chemistry Letters, 11 (9), p. 3416–3421, 2020, ISSN: 1948-7185. @article{Tan2020, title = {Adiabatic Solid Effect}, author = {Kong Ooi Tan and Ralph T Weber and Thach Van Can and Robert G Griffin}, url = {https://pubs.acs.org/doi/10.1021/acs.jpclett.0c00654}, doi = {10.1021/acs.jpclett.0c00654}, issn = {1948-7185}, year = {2020}, date = {2020-05-01}, journal = {The Journal of Physical Chemistry Letters}, volume = {11}, number = {9}, pages = {3416--3421}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Theoretical and computational framework for the analysis of the relaxation properties of arbitrary spin systems. Application to high-resolution relaxometry Article de journal Nicolas Bolik-Coulon; Pavel Kadeřávek; Philippe Pelupessy; Jean-Nicolas Dumez; Fabien Ferrage; Samuel F Cousin Journal of Magnetic Resonance, 313 , p. 106718, 2020, ISSN: 10907807. @article{Bolik-Coulon2020b, title = {Theoretical and computational framework for the analysis of the relaxation properties of arbitrary spin systems. Application to high-resolution relaxometry}, author = {Nicolas Bolik-Coulon and Pavel Kade\v{r}\'{a}vek and Philippe Pelupessy and Jean-Nicolas Dumez and Fabien Ferrage and Samuel F Cousin}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1090780720300367}, doi = {10.1016/j.jmr.2020.106718}, issn = {10907807}, year = {2020}, date = {2020-04-01}, journal = {Journal of Magnetic Resonance}, volume = {313}, pages = {106718}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Theoretical and computational framework for the analysis of the relaxation properties of arbitrary spin systems. Application to high-resolution relaxometry Article de journal N Bolik-Coulon; P Kadeřávek; P Pelupessy; J-N Dumez; F Ferrage; S F Cousin Journal of Magnetic Resonance, 313 , p. 106718, 2020. @article{Bolik-Coulon2020, title = {Theoretical and computational framework for the analysis of the relaxation properties of arbitrary spin systems. Application to high-resolution relaxometry}, author = {N Bolik-Coulon and P Kade\v{r}\'{a}vek and P Pelupessy and J-N Dumez and F Ferrage and S F Cousin}, doi = {10.1016/j.jmr.2020.106718}, year = {2020}, date = {2020-03-16}, journal = {Journal of Magnetic Resonance}, volume = {313}, pages = {106718}, abstract = {A wide variety of nuclear magnetic resonance experiments rely on the prediction and analysis of relax- ation processes. Recently, innovative approaches have been introduced where the sample travels through a broad range of magnetic fields in the course of the experiment, such as dissolution dynamic nuclear polarization or high-resolution relaxometry. Understanding the relaxation properties of nuclear spin systems over orders of magnitude of magnetic fields is essential to rationalize the results of these exper- iments. For example, during a high-resolution relaxometry experiment, the absence of control of nuclear spin relaxation pathways during the sample transfers and relaxation delays leads to systematic devia- tions of polarization decays from an ideal mono-exponential decay with the pure longitudinal relaxation rate. These deviations have to be taken into account to describe quantitatively the dynamics of the sys- tem. Here, we present computational tools to (1) calculate analytical expressions of relaxation rates for a broad variety of spin systems and (2) use these analytical expressions to correct the deviations arising in high-resolution relaxometry experiments. These tools lead to a better understanding of nuclear spin relaxation, which is required to improve the sensitivity of many pulse sequences, and to better charac- terize motions in macromolecules.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A wide variety of nuclear magnetic resonance experiments rely on the prediction and analysis of relax- ation processes. Recently, innovative approaches have been introduced where the sample travels through a broad range of magnetic fields in the course of the experiment, such as dissolution dynamic nuclear polarization or high-resolution relaxometry. Understanding the relaxation properties of nuclear spin systems over orders of magnitude of magnetic fields is essential to rationalize the results of these exper- iments. For example, during a high-resolution relaxometry experiment, the absence of control of nuclear spin relaxation pathways during the sample transfers and relaxation delays leads to systematic devia- tions of polarization decays from an ideal mono-exponential decay with the pure longitudinal relaxation rate. These deviations have to be taken into account to describe quantitatively the dynamics of the sys- tem. Here, we present computational tools to (1) calculate analytical expressions of relaxation rates for a broad variety of spin systems and (2) use these analytical expressions to correct the deviations arising in high-resolution relaxometry experiments. These tools lead to a better understanding of nuclear spin relaxation, which is required to improve the sensitivity of many pulse sequences, and to better charac- terize motions in macromolecules. |
Sensitivity-enhanced three-dimensional and carbon-detected two-dimensional NMR of proteins using hyperpolarized water Article de journal Gregory L Olsen; Or Szekely; Borja Mateos; Pavel Kadeřávek; Fabien Ferrage; Robert Konrat; Roberta Pierattelli; Isabella C Felli; Geoffrey Bodenhausen; Dennis Kurzbach; Lucio Frydman Journal of Biomolecular NMR, 74 (2-3), p. 161–171, 2020, ISSN: 0925-2738. @article{Olsen2020, title = {Sensitivity-enhanced three-dimensional and carbon-detected two-dimensional NMR of proteins using hyperpolarized water}, author = {Gregory L Olsen and Or Szekely and Borja Mateos and Pavel Kade\v{r}\'{a}vek and Fabien Ferrage and Robert Konrat and Roberta Pierattelli and Isabella C Felli and Geoffrey Bodenhausen and Dennis Kurzbach and Lucio Frydman}, url = {http://link.springer.com/10.1007/s10858-020-00301-5}, doi = {10.1007/s10858-020-00301-5}, issn = {0925-2738}, year = {2020}, date = {2020-03-01}, journal = {Journal of Biomolecular NMR}, volume = {74}, number = {2-3}, pages = {161--171}, abstract = {Signal enhancements of up to two orders of magnitude in protein NMR can be achieved by employing HDO as a vector to introduce hyperpolarization into folded or intrinsically disordered proteins. In this approach, hyperpolarized HDO produced by dissolution-dynamic nuclear polarization (D-DNP) is mixed with a protein solution waiting in a high-field NMR spectrometer, whereupon amide proton exchange and nuclear Overhauser effects (NOE) transfer hyperpolarization to the protein and enable acquisition of a signal-enhanced high-resolution spectrum. To date, the use of this strategy has been limited to 1D and 1 H- 15 N 2D correlation experiments. Here we introduce 2D 13 C-detected D-DNP, to reduce exchange-induced broadening and other relaxation penalties that can adversely affect proton-detected D-DNP experiments. We also introduce hyperpolarized 3D spectroscopy, opening the possibility of D-DNP studies of larger proteins and IDPs, where assignment and residue-specific investigation may be impeded by spectral crowding. The signal enhancements obtained depend in particular on the rates of chemical and magnetic exchange of the observed residues, thus resulting in non-uniform ‘hyperpolarization-selective' signal enhancements. The resulting spectral sparsity, however, makes it possible to resolve and monitor individual amino acids in IDPs of over 200 residues at acquisition times of just over a minute. We apply the proposed experiments to two model systems: the compactly folded protein ubiquitin, and the intrinsically disordered protein (IDP) osteopontin (OPN).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Signal enhancements of up to two orders of magnitude in protein NMR can be achieved by employing HDO as a vector to introduce hyperpolarization into folded or intrinsically disordered proteins. In this approach, hyperpolarized HDO produced by dissolution-dynamic nuclear polarization (D-DNP) is mixed with a protein solution waiting in a high-field NMR spectrometer, whereupon amide proton exchange and nuclear Overhauser effects (NOE) transfer hyperpolarization to the protein and enable acquisition of a signal-enhanced high-resolution spectrum. To date, the use of this strategy has been limited to 1D and 1 H- 15 N 2D correlation experiments. Here we introduce 2D 13 C-detected D-DNP, to reduce exchange-induced broadening and other relaxation penalties that can adversely affect proton-detected D-DNP experiments. We also introduce hyperpolarized 3D spectroscopy, opening the possibility of D-DNP studies of larger proteins and IDPs, where assignment and residue-specific investigation may be impeded by spectral crowding. The signal enhancements obtained depend in particular on the rates of chemical and magnetic exchange of the observed residues, thus resulting in non-uniform ‘hyperpolarization-selective' signal enhancements. The resulting spectral sparsity, however, makes it possible to resolve and monitor individual amino acids in IDPs of over 200 residues at acquisition times of just over a minute. We apply the proposed experiments to two model systems: the compactly folded protein ubiquitin, and the intrinsically disordered protein (IDP) osteopontin (OPN). |
Boosting the resolution of low‐field 15N relaxation experiments on intrinsically disordered proteins with triple‐resonance NMR Article de journal Z Jasenáková; V Zapletal; P Padrta; M Zachrdla; N Bolik-Coulon; T Marquardsen; J-M Tyburn; L Zidek; F Ferrage Journal of Biomolecular NMR, 74 , p. 139, 2020. @article{Jasen\'{a}kov\'{a}2020, title = {Boosting the resolution of low‐field 15N relaxation experiments on intrinsically disordered proteins with triple‐resonance NMR}, author = {Z Jasen\'{a}kov\'{a} and V Zapletal and P Padrta and M Zachrdla and N Bolik-Coulon and T Marquardsen and J-M Tyburn and L Zidek and F Ferrage }, doi = {10.1007/s10858-019-00298-6}, year = {2020}, date = {2020-01-20}, journal = {Journal of Biomolecular NMR}, volume = {74}, pages = {139}, abstract = {Improving our understanding of nanosecond motions in disordered proteins requires the enhanced sampling of the spectral density function obtained from relaxation at low magnetic fields. High-resolution relaxometry and two-field NMR meas- urements of relaxation have, so far, only been based on the recording of one- or two-dimensional spectra, which provide insufficient resolution for challenging disordered proteins. Here, we introduce a 3D-HNCO-based two-field NMR experi- ment for measurements of protein backbone 15N amide longitudinal relaxation rates. The experiment provides accurate longitudinal relaxation rates at low field (0.33 T in our case) preserving the resolution and sensitivity typical for high-field NMR spectroscopy. Radiofrequency pulses applied on six different radiofrequency channels are used to manipulate the spin system at both fields. The experiment was demonstrated on the C-terminal domain of ???? subunit of RNA polymerase from Bacillus subtilis, a protein with highly repetitive amino-acid sequence and very low dispersion of backbone chemical shifts.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Improving our understanding of nanosecond motions in disordered proteins requires the enhanced sampling of the spectral density function obtained from relaxation at low magnetic fields. High-resolution relaxometry and two-field NMR meas- urements of relaxation have, so far, only been based on the recording of one- or two-dimensional spectra, which provide insufficient resolution for challenging disordered proteins. Here, we introduce a 3D-HNCO-based two-field NMR experi- ment for measurements of protein backbone 15N amide longitudinal relaxation rates. The experiment provides accurate longitudinal relaxation rates at low field (0.33 T in our case) preserving the resolution and sensitivity typical for high-field NMR spectroscopy. Radiofrequency pulses applied on six different radiofrequency channels are used to manipulate the spin system at both fields. The experiment was demonstrated on the C-terminal domain of ???? subunit of RNA polymerase from Bacillus subtilis, a protein with highly repetitive amino-acid sequence and very low dispersion of backbone chemical shifts. |
An easy-to-implement combinatorial approach involving an activity-based assay for the discovery of a peptidyl copper complex mimicking superoxide dismutase Article de journal Amandine Vincent; Jennifer Rodon Fores; Elodie Tauziet; Elodie Quévrain; Ágnes Dancs; Amandine Conte-Daban; Anne-Sophie Bernard; Philippe Pelupessy; Koudedja Coulibaly; Philippe Seksik; Christelle Hureau; Katalin Selmeczi; Clotilde Policar; Nicolas Delsuc Chem. Commun., 56 , p. 399-402, 2020. @article{C9CC07920C, title = {An easy-to-implement combinatorial approach involving an activity-based assay for the discovery of a peptidyl copper complex mimicking superoxide dismutase}, author = {Amandine Vincent and Jennifer Rodon Fores and Elodie Tauziet and Elodie Qu\'{e}vrain and \'{A}gnes Dancs and Amandine Conte-Daban and Anne-Sophie Bernard and Philippe Pelupessy and Koudedja Coulibaly and Philippe Seksik and Christelle Hureau and Katalin Selmeczi and Clotilde Policar and Nicolas Delsuc}, url = {http://dx.doi.org/10.1039/C9CC07920C}, doi = {10.1039/C9CC07920C}, year = {2020}, date = {2020-01-01}, journal = {Chem. Commun.}, volume = {56}, pages = {399-402}, publisher = {The Royal Society of Chemistry}, abstract = {A combinatorial approach using a one-bead-one-compound method and a screening based on a SOD-activity assay was set up for the discovery of an efficient peptidyl copper complex. The complex exhibited good stability constants, suitable redox potentials and excellent intrinsic activity. This complex was further assayed in cells for its antioxidant properties and showed beneficial effects when cells were subjected to oxidative stress.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A combinatorial approach using a one-bead-one-compound method and a screening based on a SOD-activity assay was set up for the discovery of an efficient peptidyl copper complex. The complex exhibited good stability constants, suitable redox potentials and excellent intrinsic activity. This complex was further assayed in cells for its antioxidant properties and showed beneficial effects when cells were subjected to oxidative stress. |
2019 |
Protein Dynamics from Accurate Low-Field Site-Specific Longitudinal and Transverse Nuclear Spin Relaxation Article de journal P Kadeřávek; N Bolik-Coulon; S F Cousin; T Marquardsen; J-M Tyburn; J-N Dumez; F Ferrage The Journal of Physical Chemistry Letters, 10 , p. 5917, 2019. @article{Kade\v{r}\'{a}vek2019, title = {Protein Dynamics from Accurate Low-Field Site-Specific Longitudinal and Transverse Nuclear Spin Relaxation}, author = {P Kade\v{r}\'{a}vek and N Bolik-Coulon and S F Cousin and T Marquardsen and J-M Tyburn and J-N Dumez and F Ferrage}, url = {https://pubs.acs.org/doi/10.1021/acs.jpclett.9b02233}, doi = {10.1021/acs.jpclett.9b02233}, year = {2019}, date = {2019-09-11}, journal = {The Journal of Physical Chemistry Letters}, volume = {10}, pages = {5917}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Pulsed Dynamic Nuclear Polarization incollection Kong Ooi Tan; Sudheer Jawla; Richard J Temkin; Robert G Griffin eMagRes, p. 339–352, 2019, ISBN: 9780470034590. @incollection{Tan2019d, title = {Pulsed Dynamic Nuclear Polarization}, author = {Kong Ooi Tan and Sudheer Jawla and Richard J Temkin and Robert G Griffin}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/9780470034590.emrstm1551 https://doi.org/10.1002/9780470034590.emrstm1551}, doi = {10.1002/9780470034590.emrstm1551}, isbn = {9780470034590}, year = {2019}, date = {2019-09-01}, booktitle = {eMagRes}, pages = {339--352}, series = {Major Reference Works}, abstract = {Abstract In the last two decades continuous-wave (CW) microwave irradiation obtained from gyrotron microwave sources has been utilized extensively in the development and applications of new experimental approaches to high frequency dynamic nuclear polarization (DNP). Despite the abundant successes of this approach, it is well established experimentally and understood theoretically that at higher magnetic fields, where the resolution of the NMR spectra is optimal, the enhancement factors in CW DNP experiments decrease. Potentially this issue can be mitigated by using time domain or pulsed DNP techniques, which theoretically have field-independent enhancement factors. In this contribution, we discuss the pulsed DNP experiments that have been developed to date, along with the theory and the applicability of the sequences. As we will see pulsed techniques are fundamentally different from the CW-DNP methodology and require a different array of instrumentation, spin physics, and radicals. Hence, in addition to the underlying theory, we discuss the specifications of the microwave sources, DNP probes, and optimal radicals for pulsed DNP. The review ends with a summary of the current and future applications of pulsed DNP and conjectures as to the development of the pulsed methods for experiments at increasingly higher magnetic fields.}, keywords = {}, pubstate = {published}, tppubtype = {incollection} } Abstract In the last two decades continuous-wave (CW) microwave irradiation obtained from gyrotron microwave sources has been utilized extensively in the development and applications of new experimental approaches to high frequency dynamic nuclear polarization (DNP). Despite the abundant successes of this approach, it is well established experimentally and understood theoretically that at higher magnetic fields, where the resolution of the NMR spectra is optimal, the enhancement factors in CW DNP experiments decrease. Potentially this issue can be mitigated by using time domain or pulsed DNP techniques, which theoretically have field-independent enhancement factors. In this contribution, we discuss the pulsed DNP experiments that have been developed to date, along with the theory and the applicability of the sequences. As we will see pulsed techniques are fundamentally different from the CW-DNP methodology and require a different array of instrumentation, spin physics, and radicals. Hence, in addition to the underlying theory, we discuss the specifications of the microwave sources, DNP probes, and optimal radicals for pulsed DNP. The review ends with a summary of the current and future applications of pulsed DNP and conjectures as to the development of the pulsed methods for experiments at increasingly higher magnetic fields. |
Three-spin solid effect and the spin diffusion barrier in amorphous solids Article de journal Kong Ooi Tan; Michael Mardini; Chen Yang; Jan Henrik Ardenkjær-Larsen; Robert Guy Griffin Science Advances, 5 (7), p. eaax2743, 2019, ISSN: 2375-2548. @article{Tan2019a, title = {Three-spin solid effect and the spin diffusion barrier in amorphous solids}, author = {Kong Ooi Tan and Michael Mardini and Chen Yang and Jan Henrik Ardenkj{\ae}r-Larsen and Robert Guy Griffin}, url = {http://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aax2743 http://doi.org/10.1126/sciadv.aax2743 https://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aax2743}, doi = {10.1126/sciadv.aax2743}, issn = {2375-2548}, year = {2019}, date = {2019-07-01}, journal = {Science Advances}, volume = {5}, number = {7}, pages = {eaax2743}, abstract = {Dynamic nuclear polarization (DNP) has evolved as the method of choice to enhance NMR signal intensities and to address a variety of otherwise inaccessible chemical, biological and physical questions. Despite its success, there is no detailed understanding of how the large electron polarization is transferred to the surrounding nuclei or where these nuclei are located relative to the polarizing agent. To address these questions we perform an analysis of the three-spin solid effect, and show that it is exquisitely sensitive to the electron-nuclear distances. We exploit this feature and determine that the size of the spin diffusion barrier surrounding the trityl radical in a glassy glycerol\textendashwater matrix is <6 r{A}, and that the protons involved in the initial transfer step are on the trityl molecule. 1 H ENDOR experiments indicate that polarization is then transferred in a second step to glycerol molecules in intimate contact with the trityl.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dynamic nuclear polarization (DNP) has evolved as the method of choice to enhance NMR signal intensities and to address a variety of otherwise inaccessible chemical, biological and physical questions. Despite its success, there is no detailed understanding of how the large electron polarization is transferred to the surrounding nuclei or where these nuclei are located relative to the polarizing agent. To address these questions we perform an analysis of the three-spin solid effect, and show that it is exquisitely sensitive to the electron-nuclear distances. We exploit this feature and determine that the size of the spin diffusion barrier surrounding the trityl radical in a glassy glycerol–water matrix is <6 Å, and that the protons involved in the initial transfer step are on the trityl molecule. 1 H ENDOR experiments indicate that polarization is then transferred in a second step to glycerol molecules in intimate contact with the trityl. |
Experimental characterization of the dynamics of IDPs and IDRs by NMR Livre N Bolik-Coulon; G Bouvignies; L Carlier; F Ferrage 2019, ISBN: 9780128163481. @book{Bolik-Coulon2019b, title = {Experimental characterization of the dynamics of IDPs and IDRs by NMR}, author = {N Bolik-Coulon and G Bouvignies and L Carlier and F Ferrage}, editor = {N Salvi}, url = {http://www.sciencedirect.com/science/article/pii/B978012816348100003X}, doi = {10.1016/B978-0-12-816348-1.00003-X}, isbn = {9780128163481}, year = {2019}, date = {2019-07-01}, series = {Intrinsically Disordered Proteins}, keywords = {}, pubstate = {published}, tppubtype = {book} } |
Understanding the methyl-TROSY effect over a wide range of magnetic fields Article de journal N Bolik-Coulon; S F Cousin; P Kadeřávek; J-N Dumez; F Ferrage The Journal of Chemical Physics, 150 , p. 224202, 2019. @article{Bolik-Coulon2019, title = {Understanding the methyl-TROSY effect over a wide range of magnetic fields}, author = {N Bolik-Coulon and S F Cousin and P Kade\v{r}\'{a}vek and J-N Dumez and F Ferrage}, url = {https://aip.scitation.org/doi/10.1063/1.5095757}, doi = {10.1063/1.5095757}, year = {2019}, date = {2019-06-14}, journal = {The Journal of Chemical Physics}, volume = {150}, pages = {224202}, abstract = {The use of relaxation interference in the methyl Transverse Relaxation-Optimized SpectroscopY (TROSY) experiment has opened new avenues for the study of large proteins and protein assemblies in nuclear magnetic resonance. So far, the theoretical description of the methyl- TROSY experiment has been limited to the slow-tumbling approximation, which is correct for large proteins on high-field spectrometers. In a recent paper, favorable relaxation interference was observed in the methyl groups of a small protein at a magnetic field as low as 0.33 T, well outside the slow-tumbling regime. Here, we present a model to describe relaxation interference in methyl groups over a broad range of magnetic fields, not limited to the slow-tumbling regime. We predict that the type of multiple-quantum transition that shows favorable relaxation properties change with the magnetic field. Under the condition of fast methyl-group rotation, methyl-TROSY experiments can be recorded over the entire range of magnetic fields from a fraction of 1 T up to 100 T.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The use of relaxation interference in the methyl Transverse Relaxation-Optimized SpectroscopY (TROSY) experiment has opened new avenues for the study of large proteins and protein assemblies in nuclear magnetic resonance. So far, the theoretical description of the methyl- TROSY experiment has been limited to the slow-tumbling approximation, which is correct for large proteins on high-field spectrometers. In a recent paper, favorable relaxation interference was observed in the methyl groups of a small protein at a magnetic field as low as 0.33 T, well outside the slow-tumbling regime. Here, we present a model to describe relaxation interference in methyl groups over a broad range of magnetic fields, not limited to the slow-tumbling regime. We predict that the type of multiple-quantum transition that shows favorable relaxation properties change with the magnetic field. Under the condition of fast methyl-group rotation, methyl-TROSY experiments can be recorded over the entire range of magnetic fields from a fraction of 1 T up to 100 T. |
Proton Relaxometry of Long-Lived Spin Order Article de journal A S Kiryutin; M S Panov; A V Yurkovskaya; K L Ivanov; G Bodenhausen ChemPhysChem, 2019. @article{Kiryutin:2019, title = {Proton Relaxometry of Long-Lived Spin Order}, author = {A S Kiryutin and M S Panov and A V Yurkovskaya and K L Ivanov and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85061255935&doi=10.1002%2fcphc.201800960&partnerID=40&md5=8d1dd2f78c5385054ce05e31ef314334}, doi = {10.1002/cphc.201800960}, year = {2019}, date = {2019-01-01}, journal = {ChemPhysChem}, abstract = {A study of long-lived spin order in chlorothiophene carboxylates at both high and low magnetic fields is presented. Careful sample preparation (removal of dissolved oxygen in solution, chelating of paramagnetic impurities, reduction of convection) allows one to obtain very long-lived singlet order of the two coupled protons in chlorothiophene derivatives, having lifetimes of about 130 s in D 2 O and 240 s in deuterated methanol, which are much longer than the T 1 -relaxation times (18 and 30 s, respectively, at a field B 0 = 9.4 T). In protonated solvents the relaxation times become shorter, but the lifetime is still substantially longer than T 1 . In addition, long-lived coherences are shown to have lifetimes as long as 30 s. Thiophene derivatives can be used as molecular tags to study slow transport, slow dynamics and slow chemical processes, as has been shown in recent years. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } A study of long-lived spin order in chlorothiophene carboxylates at both high and low magnetic fields is presented. Careful sample preparation (removal of dissolved oxygen in solution, chelating of paramagnetic impurities, reduction of convection) allows one to obtain very long-lived singlet order of the two coupled protons in chlorothiophene derivatives, having lifetimes of about 130 s in D 2 O and 240 s in deuterated methanol, which are much longer than the T 1 -relaxation times (18 and 30 s, respectively, at a field B 0 = 9.4 T). In protonated solvents the relaxation times become shorter, but the lifetime is still substantially longer than T 1 . In addition, long-lived coherences are shown to have lifetimes as long as 30 s. Thiophene derivatives can be used as molecular tags to study slow transport, slow dynamics and slow chemical processes, as has been shown in recent years. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
A Low-Temperature Broadband NMR Probe for Multinuclear Cross-Polarization Article de journal Behdad Aghelnejad; Geoffrey Bodenhausen; Sina Marhabaie ChemPhysChem, 20 (21), p. 2830–2835, 2019, ISSN: 14397641. @article{Aghelnejad2019, title = {A Low-Temperature Broadband NMR Probe for Multinuclear Cross-Polarization}, author = {Behdad Aghelnejad and Geoffrey Bodenhausen and Sina Marhabaie}, doi = {10.1002/cphc.201900723}, issn = {14397641}, year = {2019}, date = {2019-01-01}, journal = {ChemPhysChem}, volume = {20}, number = {21}, pages = {2830--2835}, abstract = {Dissolution dynamic nuclear polarization (D-DNP) probes are usually designed for one or at most two specific nuclei. Investigation of multiple nuclei usually requires manufacturing a number of costly probes. In addition, changing the probe is a time-consuming process since a system that works at low temperature (usually between 1.2 and 4.2 K) must be warmed up, thus increasing the risks of contamination. Here, an efficient apparatus is described for D-DNP designed not only for microwave-enhanced direct observation of a wide range of nuclei S such as 1H, 13C, 2H, 23Na, and 17O, but also for cross-polarization (CP) from I=1H to such S nuclei. Unlike most conventional designs, the tuning and matching circuits are partly immersed in superfluid helium at temperatures down to 1.2 K. Intense radio-frequency (RF) fields with amplitudes on the order of 50 kHz or better can be applied simultaneously to both nuclei I and S using RF amplifiers with powers on the order of 90 and 80 W, respectively, without significant losses of liquid helium. The system can operate at temperatures over a wide range between 1.2 and 300 K.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dissolution dynamic nuclear polarization (D-DNP) probes are usually designed for one or at most two specific nuclei. Investigation of multiple nuclei usually requires manufacturing a number of costly probes. In addition, changing the probe is a time-consuming process since a system that works at low temperature (usually between 1.2 and 4.2 K) must be warmed up, thus increasing the risks of contamination. Here, an efficient apparatus is described for D-DNP designed not only for microwave-enhanced direct observation of a wide range of nuclei S such as 1H, 13C, 2H, 23Na, and 17O, but also for cross-polarization (CP) from I=1H to such S nuclei. Unlike most conventional designs, the tuning and matching circuits are partly immersed in superfluid helium at temperatures down to 1.2 K. Intense radio-frequency (RF) fields with amplitudes on the order of 50 kHz or better can be applied simultaneously to both nuclei I and S using RF amplifiers with powers on the order of 90 and 80 W, respectively, without significant losses of liquid helium. The system can operate at temperatures over a wide range between 1.2 and 300 K. |
Long-Lived States in Hyperpolarized Deuterated Methyl Groups Reveal Weak Binding of Small Molecules to Proteins Article de journal Thomas Kress; Astrid Walrant; Geoffrey Bodenhausen; Dennis Kurzbach The Journal of Physical Chemistry Letters, (i), p. 1523–1529, 2019, ISSN: 1948-7185. @article{Kress2019, title = {Long-Lived States in Hyperpolarized Deuterated Methyl Groups Reveal Weak Binding of Small Molecules to Proteins}, author = {Thomas Kress and Astrid Walrant and Geoffrey Bodenhausen and Dennis Kurzbach}, url = {http://pubs.acs.org/doi/10.1021/acs.jpclett.9b00149}, doi = {10.1021/acs.jpclett.9b00149}, issn = {1948-7185}, year = {2019}, date = {2019-01-01}, journal = {The Journal of Physical Chemistry Letters}, number = {i}, pages = {1523--1529}, abstract = {We introduce a method for the detection of weak interactions of small molecules such as metabolites or medicaments that contain deuterated methyl groups with proteins in solution. The technique relies on long-lived imbalances of spin state populations, which are generated by dissolution dynamic nuclear polarization (D-DNP) and feature lifetimes that depend on the frequency of internal rotation of deuterated methyl groups. We demonstrate the technique for interactions between deuterated dimethyl sulfoxide (DMSO-d 6) and bovine serum albumin (BSA) or trypsin, where the methyl group rotation is slowed down upon protein binding, which causes a marked reduction in the lifetime of the population imbalances. D euterated drugs have gained ample attention in the recent past as deuteration of selected moieties in established medicaments can lead to improved pharmacoki-netic properties. 1 Because C−D bonds (D = 2 H) are more stable than C−H bonds with respect to enzymatic degradation, deuterated drugs may feature a prolonged half-life time in the body, 2 which allows one to reduce their dosage and attenuate side effects. 3,4 From an analytical viewpoint, deuteration of drugs offers novel possibilities for nuclear magnetic resonance (NMR) spectroscopy. NMR is a key method to investigate interactions of both drugs and target proteins. Complementary to methods such as isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) that provide global thermodynamic and kinetic parameters about drug/target systems, solution-state NMR can localize drug binding sites and characterize their dynamics at atomic resolution. In addition, the affinity of drugs or their metabolites for macromolecules such as proteins 5 can be studied by a wealth of NMR techniques that exploit, for example, contrasts in T 2 or T 1$rho$ as well as relaxation rates of long-lived states or long-lived coherences upon binding. 6,7 Alternatively, differences in signal intensities can be observed upon selective saturation of one of the binding partners, known as saturation transfer difference (STD) spectroscopy, 8,9 or of the solvent, known as water-LOGSY. 10,11 In the past years, dissolution dynamic nuclear polarization (D-DNP) has also become increasingly popular as a tool for drug screening and ligand binding studies. For example, Lerche et al. have demonstrated how to use carbon-13 signal losses to identify the binding of small ligands to macromolecular hosts; 12 Hilty and co-workers have shown how to employ relaxation dispersion techniques in combination with 13 C and 19 F detection, 13,14 while Wilson and co-workers used changes in longitudinal 13 C relaxation upon ligand binding in magnetic resonance imaging. 15 To expand NMR and D-DNP to deuterated drugs and metabolites, we expand the NMR toolbox by monitoring effects on long-lived nuclear spin states (LLS) in deuterated methyl groups (CD 3). The relaxation rates R LLS = 1/T LLS of these LLS are sensitive to the frequency of internal CD 3 rotation, thus enabling one to identify interactions between target proteins and drugs or metabolites containing deuterated methyl groups. LLS involving two or more deuterons have been described as imbalances between populations of nuclear spin states of different symmetry. 16 If the internal methyl group rotation is fast, the flow of populations between different symmetry manifolds is forbidden to first order, so that population imbalances have a prolonged lifetime compared to spin−lattice relaxation times. Different kinds of LLS have been reported in CH 2 and CH 3 groups by Dumez, Levitt, Jannin, and co-workers 17−19 and in CD 2 and CD 3 groups by Kurzbach et al. 20 and by Jhajharia et al. 21 In deuterated methyl groups, LLS return to equilibrium populations with rates that depend on (i) the correlation time}, keywords = {}, pubstate = {published}, tppubtype = {article} } We introduce a method for the detection of weak interactions of small molecules such as metabolites or medicaments that contain deuterated methyl groups with proteins in solution. The technique relies on long-lived imbalances of spin state populations, which are generated by dissolution dynamic nuclear polarization (D-DNP) and feature lifetimes that depend on the frequency of internal rotation of deuterated methyl groups. We demonstrate the technique for interactions between deuterated dimethyl sulfoxide (DMSO-d 6) and bovine serum albumin (BSA) or trypsin, where the methyl group rotation is slowed down upon protein binding, which causes a marked reduction in the lifetime of the population imbalances. D euterated drugs have gained ample attention in the recent past as deuteration of selected moieties in established medicaments can lead to improved pharmacoki-netic properties. 1 Because C−D bonds (D = 2 H) are more stable than C−H bonds with respect to enzymatic degradation, deuterated drugs may feature a prolonged half-life time in the body, 2 which allows one to reduce their dosage and attenuate side effects. 3,4 From an analytical viewpoint, deuteration of drugs offers novel possibilities for nuclear magnetic resonance (NMR) spectroscopy. NMR is a key method to investigate interactions of both drugs and target proteins. Complementary to methods such as isothermal titration calorimetry (ITC) and surface plasmon resonance (SPR) that provide global thermodynamic and kinetic parameters about drug/target systems, solution-state NMR can localize drug binding sites and characterize their dynamics at atomic resolution. In addition, the affinity of drugs or their metabolites for macromolecules such as proteins 5 can be studied by a wealth of NMR techniques that exploit, for example, contrasts in T 2 or T 1$rho$ as well as relaxation rates of long-lived states or long-lived coherences upon binding. 6,7 Alternatively, differences in signal intensities can be observed upon selective saturation of one of the binding partners, known as saturation transfer difference (STD) spectroscopy, 8,9 or of the solvent, known as water-LOGSY. 10,11 In the past years, dissolution dynamic nuclear polarization (D-DNP) has also become increasingly popular as a tool for drug screening and ligand binding studies. For example, Lerche et al. have demonstrated how to use carbon-13 signal losses to identify the binding of small ligands to macromolecular hosts; 12 Hilty and co-workers have shown how to employ relaxation dispersion techniques in combination with 13 C and 19 F detection, 13,14 while Wilson and co-workers used changes in longitudinal 13 C relaxation upon ligand binding in magnetic resonance imaging. 15 To expand NMR and D-DNP to deuterated drugs and metabolites, we expand the NMR toolbox by monitoring effects on long-lived nuclear spin states (LLS) in deuterated methyl groups (CD 3). The relaxation rates R LLS = 1/T LLS of these LLS are sensitive to the frequency of internal CD 3 rotation, thus enabling one to identify interactions between target proteins and drugs or metabolites containing deuterated methyl groups. LLS involving two or more deuterons have been described as imbalances between populations of nuclear spin states of different symmetry. 16 If the internal methyl group rotation is fast, the flow of populations between different symmetry manifolds is forbidden to first order, so that population imbalances have a prolonged lifetime compared to spin−lattice relaxation times. Different kinds of LLS have been reported in CH 2 and CH 3 groups by Dumez, Levitt, Jannin, and co-workers 17−19 and in CD 2 and CD 3 groups by Kurzbach et al. 20 and by Jhajharia et al. 21 In deuterated methyl groups, LLS return to equilibrium populations with rates that depend on (i) the correlation time |
Time-optimized pulsed dynamic nuclear polarization Article de journal Kong Ooi Tan; Chen Yang; Ralph T Weber; Guinevere Mathies; Robert G Griffin Science Advances, 5 (1), p. eaav6909, 2019, ISSN: 2375-2548. @article{Kong_Ooi_Tan52857775, title = {Time-optimized pulsed dynamic nuclear polarization}, author = {Kong Ooi Tan and Chen Yang and Ralph T Weber and Guinevere Mathies and Robert G Griffin}, url = {http://doi.org/10.1126/sciadv.aav6909 http://advances.sciencemag.org/ http://advances.sciencemag.org/lookup/doi/10.1126/sciadv.aav6909}, doi = {10.1126/sciadv.aav6909}, issn = {2375-2548}, year = {2019}, date = {2019-01-01}, journal = {Science Advances}, volume = {5}, number = {1}, pages = {eaav6909}, abstract = {Pulsed dynamic nuclear polarization (DNP) techniques can accomplish electron-nuclear polarization transfer efficiently with an enhancement factor that is independent of the Zeeman field. However, they often require large Rabi frequencies and, therefore, high-power microwave irradiation. Here, we propose a new low-power DNP sequence for static samples that is composed of a train of microwave pulses of length $tau$ p spaced with delays d . A particularly robust DNP condition using a period $tau$ m = $tau$ p + d set to $sim$1.25 times the Larmor period $tau$ Larmor is investigated which is a time-optimized pulsed DNP sequence (TOP-DNP). At 0.35 T, we obtained an enhancement of $sim$200 using TOP-DNP compared to $sim$172 with nuclear spin orientation via electron spin locking (NOVEL), a commonly used pulsed DNP sequence, while using only $sim$7% microwave power required for NOVEL. Experimental data and simulations at higher fields suggest a field-independent enhancement factor, as predicted by the effective Hamiltonian.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Pulsed dynamic nuclear polarization (DNP) techniques can accomplish electron-nuclear polarization transfer efficiently with an enhancement factor that is independent of the Zeeman field. However, they often require large Rabi frequencies and, therefore, high-power microwave irradiation. Here, we propose a new low-power DNP sequence for static samples that is composed of a train of microwave pulses of length $tau$ p spaced with delays d . A particularly robust DNP condition using a period $tau$ m = $tau$ p + d set to $sim$1.25 times the Larmor period $tau$ Larmor is investigated which is a time-optimized pulsed DNP sequence (TOP-DNP). At 0.35 T, we obtained an enhancement of $sim$200 using TOP-DNP compared to $sim$172 with nuclear spin orientation via electron spin locking (NOVEL), a commonly used pulsed DNP sequence, while using only $sim$7% microwave power required for NOVEL. Experimental data and simulations at higher fields suggest a field-independent enhancement factor, as predicted by the effective Hamiltonian. |
2018 |
Dipolar Couplings in Solid Polypeptides Probed by 14N NMR Spectroscopy Article de journal Diego Carnevale; Benoit Grosjean; Geoffrey Bodenhausen Communications Chemistry, 1 (1), p. 73, 2018, ISSN: 2399-3669. @article{Carnevale:2018, title = {Dipolar Couplings in Solid Polypeptides Probed by 14N NMR Spectroscopy}, author = {Diego Carnevale and Benoit Grosjean and Geoffrey Bodenhausen}, doi = {10.1038/s42004-018-0072-5}, issn = {2399-3669}, year = {2018}, date = {2018-11-01}, journal = {Communications Chemistry}, volume = {1}, number = {1}, pages = {73}, abstract = {The acquisition of 14N NMR spectra in solid samples is challenging due to quadrupolar couplings with magnitudes up to several MHz. This nucleus is nonetheless important as it is involved in the formation of essential secondary structures in biological systems. Here we report the structural study of the atomic environment of amide functions in polypeptides using magic-angle spinning NMR spectroscopy of the ubiquitous 14N isotope. The cyclic undecapeptide cyclosporin, in which only four hydrogen atoms are directly bound to nitrogen atoms, is chosen for illustration. Structural details of different environments can be revealed without resorting to isotopic enrichment. The network of inter- and intra-residue dipolar couplings between amide 14N nuclei and nearby protons can be probed and mapped out up to a tunable cutoff distance. Density functional theory calculations of NMR quadrupolar interaction tensors agree well with the experimental evidence and allow the unambiguous assignment of all four non-methylated NH nitrogen sites and neighboring proton nuclei.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The acquisition of 14N NMR spectra in solid samples is challenging due to quadrupolar couplings with magnitudes up to several MHz. This nucleus is nonetheless important as it is involved in the formation of essential secondary structures in biological systems. Here we report the structural study of the atomic environment of amide functions in polypeptides using magic-angle spinning NMR spectroscopy of the ubiquitous 14N isotope. The cyclic undecapeptide cyclosporin, in which only four hydrogen atoms are directly bound to nitrogen atoms, is chosen for illustration. Structural details of different environments can be revealed without resorting to isotopic enrichment. The network of inter- and intra-residue dipolar couplings between amide 14N nuclei and nearby protons can be probed and mapped out up to a tunable cutoff distance. Density functional theory calculations of NMR quadrupolar interaction tensors agree well with the experimental evidence and allow the unambiguous assignment of all four non-methylated NH nitrogen sites and neighboring proton nuclei. |
Efficient low-power TOBSY sequences for fast MAS Article de journal Kong Ooi Tan; Vipin Agarwal; Nils-Alexander Lakomek; Susanne Penzel; Beat H Meier; Matthias Ernst Solid State Nuclear Magnetic Resonance, 89 (October), p. 27–34, 2018, ISSN: 09262040. @article{Tan2017, title = {Efficient low-power TOBSY sequences for fast MAS}, author = {Kong Ooi Tan and Vipin Agarwal and Nils-Alexander Lakomek and Susanne Penzel and Beat H Meier and Matthias Ernst}, url = {http://linkinghub.elsevier.com/retrieve/pii/S0926204017301339 https://linkinghub.elsevier.com/retrieve/pii/S0926204017301339}, doi = {10.1016/j.ssnmr.2017.11.003}, issn = {09262040}, year = {2018}, date = {2018-02-01}, journal = {Solid State Nuclear Magnetic Resonance}, volume = {89}, number = {October}, pages = {27--34}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Advances in single-scan time-encoding magnetic resonance imaging Article de journal S Marhabaie; G Bodenhausen; P Pelupessy Scientific Reports, 8 (1), 2018. @article{Marhabaie:2018, title = {Advances in single-scan time-encoding magnetic resonance imaging}, author = {S Marhabaie and G Bodenhausen and P Pelupessy}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050354134&doi=10.1038%2fs41598-018-28460-4&partnerID=40&md5=66743e40da2eab9d12c99d04739febbb}, doi = {10.1038/s41598-018-28460-4}, year = {2018}, date = {2018-01-01}, journal = {Scientific Reports}, volume = {8}, number = {1}, abstract = {Time-encoding MRI is a single-scan method that uses traditional k-encoding only in one direction. In the orthogonal "time-encoding" direction, a string of echoes appears in an order that depends on the position of the corresponding spin packets. In one variant of time-encoding, this is achieved by using a series of selective pulses and appropriate gradients in both k-encoding and time-encoding directions. Although time-encoding offers some advantages over traditional single-scan Fourier methods such as echo planar imaging (EPI), the original time-encoding sequence also has some drawbacks that limit its applications. In this work, we show how one can improve several aspects of the original time-encoding sequence. By using an additional gradient pulse one can change the order in which the echoes appear, leading to identical echo times for all echoes, and hence to a uniform signal attenuation due to transverse relaxation and a reduction in average signal attenuation due to diffusion. By rearranging positive and negative gradients one can reduce the switching rate of the gradients. Furthermore, we show how one can implement time-encoding sequences in an interleaved fashion in order to reduce signal attenuation due to transverse relaxation and diffusion, while increasing the spatial resolution. © 2018 The Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Time-encoding MRI is a single-scan method that uses traditional k-encoding only in one direction. In the orthogonal "time-encoding" direction, a string of echoes appears in an order that depends on the position of the corresponding spin packets. In one variant of time-encoding, this is achieved by using a series of selective pulses and appropriate gradients in both k-encoding and time-encoding directions. Although time-encoding offers some advantages over traditional single-scan Fourier methods such as echo planar imaging (EPI), the original time-encoding sequence also has some drawbacks that limit its applications. In this work, we show how one can improve several aspects of the original time-encoding sequence. By using an additional gradient pulse one can change the order in which the echoes appear, leading to identical echo times for all echoes, and hence to a uniform signal attenuation due to transverse relaxation and a reduction in average signal attenuation due to diffusion. By rearranging positive and negative gradients one can reduce the switching rate of the gradients. Furthermore, we show how one can implement time-encoding sequences in an interleaved fashion in order to reduce signal attenuation due to transverse relaxation and diffusion, while increasing the spatial resolution. © 2018 The Author(s). |
A cryogen-consumption-free system for dynamic nuclear polarization at 9.4 Ŧ Article de journal M Baudin; B Vuichoud; A Bornet; G Bodenhausen; S Jannin Journal of Magnetic Resonance, 294 , p. 115–121, 2018. @article{Baudin:2018, title = {A cryogen-consumption-free system for dynamic nuclear polarization at 9.4 {T}}, author = {M Baudin and B Vuichoud and A Bornet and G Bodenhausen and S Jannin}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85050138503&doi=10.1016%2fj.jmr.2018.07.001&partnerID=40&md5=23b88ad7e5428b32bf2a6ec5a10b8c8e}, doi = {10.1016/j.jmr.2018.07.001}, year = {2018}, date = {2018-01-01}, journal = {Journal of Magnetic Resonance}, volume = {294}, pages = {115--121}, abstract = {A novel system for dissolution dynamic nuclear polarization based on a cost-effective “cryogen-free” magnet that can generate fields up to 9.4 T with a sample space that can reach temperatures below 1.4 K in a continuous and stable manner. Polarization levels up to P(1H) = 60 ± 5% can be reached with TEMPOL in about 20 min, and P(13C) = 50 ± 5% can be achieved using adiabatic cross polarization. © 2018 Elsevier Inc.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A novel system for dissolution dynamic nuclear polarization based on a cost-effective “cryogen-free” magnet that can generate fields up to 9.4 T with a sample space that can reach temperatures below 1.4 K in a continuous and stable manner. Polarization levels up to P(1H) = 60 ± 5% can be reached with TEMPOL in about 20 min, and P(13C) = 50 ± 5% can be achieved using adiabatic cross polarization. © 2018 Elsevier Inc. |
Generating para-water from para-hydrogen: A Gedankenexperiment Article de journal K L Ivanov; G Bodenhausen Journal of Magnetic Resonance, 292 , p. 48–52, 2018. @article{Ivanov:2018a, title = {Generating para-water from para-hydrogen: A Gedankenexperiment}, author = {K L Ivanov and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85047271001&doi=10.1016%2fj.jmr.2018.05.003&partnerID=40&md5=13bd4dd743d83d7bb3ddc9f9f8dd7abc}, doi = {10.1016/j.jmr.2018.05.003}, year = {2018}, date = {2018-01-01}, journal = {Journal of Magnetic Resonance}, volume = {292}, pages = {48--52}, abstract = {A novel conceptual approach is described that is based on the transfer of hyperpolarization from para-hydrogen in view of generating a population imbalance between the two spin isomers of H2O. The approach is analogous to SABRE (Signal Amplification By Reversible Exchange) and makes use of the transfer of spin order from para-hydrogen to H2O in a hypothetical organometallic complex. The spin order transfer is expected to be most efficient at avoided level crossings. The highest achievable enrichment levels of para- and ortho-water are discussed. © 2018 Elsevier Inc.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A novel conceptual approach is described that is based on the transfer of hyperpolarization from para-hydrogen in view of generating a population imbalance between the two spin isomers of H2O. The approach is analogous to SABRE (Signal Amplification By Reversible Exchange) and makes use of the transfer of spin order from para-hydrogen to H2O in a hypothetical organometallic complex. The spin order transfer is expected to be most efficient at avoided level crossings. The highest achievable enrichment levels of para- and ortho-water are discussed. © 2018 Elsevier Inc. |
Targeting the Pentose Phosphate Pathway: Characterization of a New 6PGL Inhibitor Article de journal A T Tran; A Sadet; P Calligari; P Lopes; J Ouazzani; M Sollogoub; E Miclet; D Abergel Biophysical Journal, 115 (11), p. 2114–2126, 2018. @article{Tran:2018, title = {Targeting the Pentose Phosphate Pathway: Characterization of a New 6PGL Inhibitor}, author = {A T Tran and A Sadet and P Calligari and P Lopes and J Ouazzani and M Sollogoub and E Miclet and D Abergel}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056789414&doi=10.1016%2fj.bpj.2018.10.027&partnerID=40&md5=83791c30edf0ef19f0e0bf85e2d86d61}, doi = {10.1016/j.bpj.2018.10.027}, year = {2018}, date = {2018-01-01}, journal = {Biophysical Journal}, volume = {115}, number = {11}, pages = {2114--2126}, abstract = {Human African trypanosomiasis, or sleeping sickness, is a lethal disease caused by the protozoan parasite Trypanosoma brucei. However, although many efforts have been made to understand the biochemistry of this parasite, drug development has led to treatments that are of limited efficiency and of great toxicity. To develop new drugs, new targets must be identified, and among the several metabolic processes of trypanosomes that have been proposed as drug targets, carbohydrate metabolism (glycolysis and the pentose phosphate pathway (PPP)) appears as a promising one. As far as the PPP is concerned, a limited number of studies are related to the glucose-6-phosphate dehydrogenase. In this work, we have focused on the activity of the second PPP enzyme (6-phospho-gluconolactonase (6PGL)) that transforms 6-phosphogluconolactone into 6-phosphogluconic acid. A lactam analog of the natural substrate has been synthesized, and binding of the ligand to 6PGL has been investigated by NMR titration. The ability of this ligand to inhibit 6PGL has also been demonstrated using ultraviolet experiments, and protein-inhibitor interactions have been investigated through docking calculations and molecular dynamics simulations. In addition, a marginal inhibition of the third enzyme of the PPP (6-phosphogluconate dehydrogenase) was also demonstrated. Our results thus open new prospects for targeting T. brucei. © 2018 Biophysical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } Human African trypanosomiasis, or sleeping sickness, is a lethal disease caused by the protozoan parasite Trypanosoma brucei. However, although many efforts have been made to understand the biochemistry of this parasite, drug development has led to treatments that are of limited efficiency and of great toxicity. To develop new drugs, new targets must be identified, and among the several metabolic processes of trypanosomes that have been proposed as drug targets, carbohydrate metabolism (glycolysis and the pentose phosphate pathway (PPP)) appears as a promising one. As far as the PPP is concerned, a limited number of studies are related to the glucose-6-phosphate dehydrogenase. In this work, we have focused on the activity of the second PPP enzyme (6-phospho-gluconolactonase (6PGL)) that transforms 6-phosphogluconolactone into 6-phosphogluconic acid. A lactam analog of the natural substrate has been synthesized, and binding of the ligand to 6PGL has been investigated by NMR titration. The ability of this ligand to inhibit 6PGL has also been demonstrated using ultraviolet experiments, and protein-inhibitor interactions have been investigated through docking calculations and molecular dynamics simulations. In addition, a marginal inhibition of the third enzyme of the PPP (6-phosphogluconate dehydrogenase) was also demonstrated. Our results thus open new prospects for targeting T. brucei. © 2018 Biophysical Society |
Classical Polarizable Force Field to Study Hydrated Charged Clays and Zeolites Article de journal S Tesson; W Louisfrema; M Salanne; A Boutin; E Ferrage; B Rotenberg; V Marry Journal of Physical Chemistry C, 122 (43), p. 24690–24704, 2018. @article{Tesson:2018, title = {Classical Polarizable Force Field to Study Hydrated Charged Clays and Zeolites}, author = {S Tesson and W Louisfrema and M Salanne and A Boutin and E Ferrage and B Rotenberg and V Marry}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85056108305&doi=10.1021%2facs.jpcc.8b06230&partnerID=40&md5=7039754c45487a2d939680ec685cf6d0}, doi = {10.1021/acs.jpcc.8b06230}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry C}, volume = {122}, number = {43}, pages = {24690--24704}, abstract = {Following our previous works on dry clays, we extend the classical polarizable ion model (PIM) to hydrated dioctahedral clays by considering Na-, Cs-, Ca-, and Sr-montmorillonites in the mono- and bihydrated states. The parameters of the force field are determined by optimizing the atomic forces and dipoles on density functional theory calculations. The simulation results are compared with results obtained with CLAYFF force field and validated in comparison with the experiment. The X-ray diffraction patterns calculated from classical molecular dynamics simulations performed with the PIM force field are in very good agreement with experiments. We also demonstrate the transferability of PIM force field to other aluminosilicates: here, a faujasite-type zeolite compensated with Na+ with a significant improvement in cation locations compared to nonpolarizable force fields. © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Following our previous works on dry clays, we extend the classical polarizable ion model (PIM) to hydrated dioctahedral clays by considering Na-, Cs-, Ca-, and Sr-montmorillonites in the mono- and bihydrated states. The parameters of the force field are determined by optimizing the atomic forces and dipoles on density functional theory calculations. The simulation results are compared with results obtained with CLAYFF force field and validated in comparison with the experiment. The X-ray diffraction patterns calculated from classical molecular dynamics simulations performed with the PIM force field are in very good agreement with experiments. We also demonstrate the transferability of PIM force field to other aluminosilicates: here, a faujasite-type zeolite compensated with Na+ with a significant improvement in cation locations compared to nonpolarizable force fields. © 2018 American Chemical Society. |
Metal-free class Ie ribonucleotide reductase from pathogens initiates catalysis with a tyrosine-derived dihydroxyphenylalanine radical Article de journal Elizabeth J Blaesi; Gavin M Palowitch; Kai Hu; Amelia J Kim; Hannah R Rose; Rahul Alapati; Marshall G Lougee; Hee Jong Kim; Alexander T Taguchi; Kong Ooi Tan; others Proceedings of the National Academy of Sciences, 115 (40), p. 10022–10027, 2018. @article{blaesi2018metal, title = {Metal-free class Ie ribonucleotide reductase from pathogens initiates catalysis with a tyrosine-derived dihydroxyphenylalanine radical}, author = {Elizabeth J Blaesi and Gavin M Palowitch and Kai Hu and Amelia J Kim and Hannah R Rose and Rahul Alapati and Marshall G Lougee and Hee Jong Kim and Alexander T Taguchi and Kong Ooi Tan and others}, year = {2018}, date = {2018-01-01}, journal = {Proceedings of the National Academy of Sciences}, volume = {115}, number = {40}, pages = {10022\textendash10027}, publisher = {National Academy of Sciences}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
High-Resolution NMR of Folded Proteins in Hyperpolarized Physiological Solvents Article de journal P Kadeřávek; F Ferrage; G Bodenhausen; D Kurzbach Chemistry - A European Journal, 24 (51), p. 13418–13423, 2018. @article{Kaderavek:2018, title = {High-Resolution NMR of Folded Proteins in Hyperpolarized Physiological Solvents}, author = {P Kade\v{r}\'{a}vek and F Ferrage and G Bodenhausen and D Kurzbach}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053232886&doi=10.1002%2fchem.201802885&partnerID=40&md5=65d2aa185f12361021010b6644e8938c}, doi = {10.1002/chem.201802885}, year = {2018}, date = {2018-01-01}, journal = {Chemistry - A European Journal}, volume = {24}, number = {51}, pages = {13418--13423}, abstract = {Hyperpolarized 2D exchange spectroscopy (HYPEX) to obtain high-resolution nuclear magnetic resonance (NMR) spectra of folded proteins under near-physiological conditions is reported. The technique is based on hyperpolarized water, which is prepared by dissolution dynamic nuclear polarization and mixed in situ in an NMR spectrometer with a protein in a physiological saline buffer at body temperature. Rapid exchange of labile protons with the hyperpolarized solvent, combined with cross-relaxation effects (NOEs), leads to boosted signal intensities for many amide 1H\textendash15N correlations in the protein ubiquitin. As the introduction of hyperpolarization to the target protein is mediated via the solvent, the method is applicable to a broad spectrum of target molecules. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Hyperpolarized 2D exchange spectroscopy (HYPEX) to obtain high-resolution nuclear magnetic resonance (NMR) spectra of folded proteins under near-physiological conditions is reported. The technique is based on hyperpolarized water, which is prepared by dissolution dynamic nuclear polarization and mixed in situ in an NMR spectrometer with a protein in a physiological saline buffer at body temperature. Rapid exchange of labile protons with the hyperpolarized solvent, combined with cross-relaxation effects (NOEs), leads to boosted signal intensities for many amide 1H–15N correlations in the protein ubiquitin. As the introduction of hyperpolarization to the target protein is mediated via the solvent, the method is applicable to a broad spectrum of target molecules. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Time-Resolved Protein Side-Chain Motions Unraveled by High-Resolution Relaxometry and Molecular Dynamics Simulations Article de journal S F Cousin; P Kadeřávek; N Bolik-Coulon; Y Gu; C Charlier; L Carlier; L Bruschweiler-Li; T Marquardsen; J -M Tyburn; R Brüschweiler; F Ferrage Journal of the American Chemical Society, 140 (41), p. 13456–13465, 2018. @article{Cousin:2018, title = {Time-Resolved Protein Side-Chain Motions Unraveled by High-Resolution Relaxometry and Molecular Dynamics Simulations}, author = {S F Cousin and P Kade\v{r}\'{a}vek and N Bolik-Coulon and Y Gu and C Charlier and L Carlier and L Bruschweiler-Li and T Marquardsen and J -M Tyburn and R Br\"{u}schweiler and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054139114&doi=10.1021%2fjacs.8b09107&partnerID=40&md5=e619ef5070ec06092676f682c2c6cd3d}, doi = {10.1021/jacs.8b09107}, year = {2018}, date = {2018-01-01}, journal = {Journal of the American Chemical Society}, volume = {140}, number = {41}, pages = {13456--13465}, abstract = {Motions of proteins are essential for the performance of their functions. Aliphatic protein side chains and their motions play critical roles in protein interactions: for recognition and binding of partner molecules at the surface or serving as an entropy reservoir within the hydrophobic core. Here, we present a new NMR method based on high-resolution relaxometry and high-field relaxation to determine quantitatively both motional amplitudes and time scales of methyl-bearing side chains in the picosecond-to-nanosecond range. We detect a wide variety of motions in isoleucine side chains in the protein ubiquitin. We unambiguously identify slow motions in the low nanosecond range, which, in conjunction with molecular dynamics computer simulations, could be assigned to transitions between rotamers. Our approach provides unmatched detailed insight into the motions of aliphatic side chains in proteins and provides a better understanding of the nature and functional role of protein side-chain motions. © Copyright 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Motions of proteins are essential for the performance of their functions. Aliphatic protein side chains and their motions play critical roles in protein interactions: for recognition and binding of partner molecules at the surface or serving as an entropy reservoir within the hydrophobic core. Here, we present a new NMR method based on high-resolution relaxometry and high-field relaxation to determine quantitatively both motional amplitudes and time scales of methyl-bearing side chains in the picosecond-to-nanosecond range. We detect a wide variety of motions in isoleucine side chains in the protein ubiquitin. We unambiguously identify slow motions in the low nanosecond range, which, in conjunction with molecular dynamics computer simulations, could be assigned to transitions between rotamers. Our approach provides unmatched detailed insight into the motions of aliphatic side chains in proteins and provides a better understanding of the nature and functional role of protein side-chain motions. © Copyright 2018 American Chemical Society. |
Analysis of NMR Spin-Relaxation Data Using an Inverse Gaussian Distribution Function Article de journal A Hsu; F Ferrage; A G Palmer III Biophysical Journal, 115 (12), p. 2301–2309, 2018. @article{Hsu:2018, title = {Analysis of NMR Spin-Relaxation Data Using an Inverse Gaussian Distribution Function}, author = {A Hsu and F Ferrage and A G Palmer III}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057226262&doi=10.1016%2fj.bpj.2018.10.030&partnerID=40&md5=eab8de988f2c698fae81d4860dcddc7b}, doi = {10.1016/j.bpj.2018.10.030}, year = {2018}, date = {2018-01-01}, journal = {Biophysical Journal}, volume = {115}, number = {12}, pages = {2301--2309}, abstract = {Spin relaxation in solution-state NMR spectroscopy is a powerful approach to explore the conformational dynamics of biological macromolecules. Probability distribution functions for overall or internal correlation times have been used previously to model spectral density functions central to spin-relaxation theory. Applications to biological macromolecules rely on transverse relaxation rate constants, and when studying nanosecond timescale motions, sampling at ultralow frequencies is often necessary. Consequently, appropriate distribution functions necessitate spectral density functions that are accurate and convergent as frequencies approach zero. In this work, the inverse Gaussian probability distribution function is derived from general properties of spectral density functions at low and high frequencies for macromolecules in solution, using the principle of maximal entropy. This normalized distribution function is first used to calculate the correlation function, followed by the spectral density function. The resulting model-free spectral density functions are finite at a frequency of zero and can be used to describe distributions of either overall or internal correlation times using the model-free ansatz. To validate the approach, 15N spin-relaxation data for the bZip transcription factor domain of the Saccharomyces cerevisiae protein GCN4, in the absence of cognate DNA, were analyzed using the inverse Gaussian probability distribution for intramolecular correlation times. The results extend previous models for the conformational dynamics of the intrinsically disordered, DNA-binding region of the bZip transcription factor domain. © 2018 Biophysical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } Spin relaxation in solution-state NMR spectroscopy is a powerful approach to explore the conformational dynamics of biological macromolecules. Probability distribution functions for overall or internal correlation times have been used previously to model spectral density functions central to spin-relaxation theory. Applications to biological macromolecules rely on transverse relaxation rate constants, and when studying nanosecond timescale motions, sampling at ultralow frequencies is often necessary. Consequently, appropriate distribution functions necessitate spectral density functions that are accurate and convergent as frequencies approach zero. In this work, the inverse Gaussian probability distribution function is derived from general properties of spectral density functions at low and high frequencies for macromolecules in solution, using the principle of maximal entropy. This normalized distribution function is first used to calculate the correlation function, followed by the spectral density function. The resulting model-free spectral density functions are finite at a frequency of zero and can be used to describe distributions of either overall or internal correlation times using the model-free ansatz. To validate the approach, 15N spin-relaxation data for the bZip transcription factor domain of the Saccharomyces cerevisiae protein GCN4, in the absence of cognate DNA, were analyzed using the inverse Gaussian probability distribution for intramolecular correlation times. The results extend previous models for the conformational dynamics of the intrinsically disordered, DNA-binding region of the bZip transcription factor domain. © 2018 Biophysical Society |
Measuring Solvent Hydrogen Exchange Rates by Multifrequency Excitation 15N CEST: Application to Protein Phase Separation Article de journal T Yuwen; A Bah; J P Brady; F Ferrage; G Bouvignies; L E Kay Journal of Physical Chemistry B, 122 (49), p. 11206–11217, 2018. @article{Yuwen:2018, title = {Measuring Solvent Hydrogen Exchange Rates by Multifrequency Excitation 15N CEST: Application to Protein Phase Separation}, author = {T Yuwen and A Bah and J P Brady and F Ferrage and G Bouvignies and L E Kay}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85053865280&doi=10.1021%2facs.jpcb.8b06820&partnerID=40&md5=a061f9c2e15482bd5d837067aeb2551b}, doi = {10.1021/acs.jpcb.8b06820}, year = {2018}, date = {2018-01-01}, journal = {Journal of Physical Chemistry B}, volume = {122}, number = {49}, pages = {11206--11217}, abstract = {Solvent exchange rates provide important information about the structural and dynamical properties of biomolecules. A large number of NMR experiments have been developed to measure such rates in proteins, the great majority of which quantify the buildup of signals from backbone amides after initial perturbation of water magnetization. Here we present a different approach that circumvents the main limitations that result from these classical hydrogen exchange NMR experiments. Building on recent developments that enable rapid recording of chemical exchange saturation transfer (CEST) pseudo-3D data sets, we describe a 15N-based CEST scheme for measurement of solvent exchange in proteins that exploits the one-bond 15N deuterium isotope shift. The utility of the approach is verified with an application to a 236 residue intrinsically disordered protein domain under conditions where it phase separates and a second application involving a mutated form of the domain that does not phase separate, establishing very similar hydrogen exchange rates for both samples. The methodology is well suited for studies of hydrogen exchange in any 15N-labeled biomolecule. A discussion of the merits of the CEST experiment in relation to the popular CLEANEX-PM scheme is presented. © 2018 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Solvent exchange rates provide important information about the structural and dynamical properties of biomolecules. A large number of NMR experiments have been developed to measure such rates in proteins, the great majority of which quantify the buildup of signals from backbone amides after initial perturbation of water magnetization. Here we present a different approach that circumvents the main limitations that result from these classical hydrogen exchange NMR experiments. Building on recent developments that enable rapid recording of chemical exchange saturation transfer (CEST) pseudo-3D data sets, we describe a 15N-based CEST scheme for measurement of solvent exchange in proteins that exploits the one-bond 15N deuterium isotope shift. The utility of the approach is verified with an application to a 236 residue intrinsically disordered protein domain under conditions where it phase separates and a second application involving a mutated form of the domain that does not phase separate, establishing very similar hydrogen exchange rates for both samples. The methodology is well suited for studies of hydrogen exchange in any 15N-labeled biomolecule. A discussion of the merits of the CEST experiment in relation to the popular CLEANEX-PM scheme is presented. © 2018 American Chemical Society. |
Field-cycling long-lived-state NMR of 15N2 spin pairs Dépubli S J Elliott; P Kadeřávek; L J Brown; M Sabba; S Glöggler; D J O'Leary; R C D Brown; F Ferrage; M H Levitt 2018. @unpublished{Elliott:2018, title = {Field-cycling long-lived-state NMR of 15N2 spin pairs}, author = {S J Elliott and P Kade\v{r}\'{a}vek and L J Brown and M Sabba and S Gl\"{o}ggler and D J O'Leary and R C D Brown and F Ferrage and M H Levitt}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85057325562&doi=10.1080%2f00268976.2018.1543906&partnerID=40&md5=a5d60a6318b7852a1a83f6b3909deb2a}, doi = {10.1080/00268976.2018.1543906}, year = {2018}, date = {2018-01-01}, abstract = {A range of nuclear magnetic resonance spectroscopy and imaging applications are limited by the short lifetimes of magnetisation in solution. Long-lived states, which are slowly relaxing configurations of nuclear spins, have been shown to alleviate this limitation. Long-lived states have decay lifetimes TLLS significantly exceeding the longitudinal relaxation time T1, in some cases by an order of magnitude. Here we present an experimental case of a long-lived state for a 15N labelled molecular system in solution. We observe a strongly biexponential decay for the long-lived state, with the lifetime of the slowly relaxing component exceeding 40 minutes, ∼21 times longer than the spin-lattice relaxation time T1. The lifetime of the long-lived state was revealed by using a dedicated two-field NMR spectrometer capable of fast sample shuttling between high and low magnetic fields, and the application of a resonant radiofrequency field at low magnetic field. The relaxation characteristics of the long-lived state are examined. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.}, keywords = {}, pubstate = {published}, tppubtype = {unpublished} } A range of nuclear magnetic resonance spectroscopy and imaging applications are limited by the short lifetimes of magnetisation in solution. Long-lived states, which are slowly relaxing configurations of nuclear spins, have been shown to alleviate this limitation. Long-lived states have decay lifetimes TLLS significantly exceeding the longitudinal relaxation time T1, in some cases by an order of magnitude. Here we present an experimental case of a long-lived state for a 15N labelled molecular system in solution. We observe a strongly biexponential decay for the long-lived state, with the lifetime of the slowly relaxing component exceeding 40 minutes, ∼21 times longer than the spin-lattice relaxation time T1. The lifetime of the long-lived state was revealed by using a dedicated two-field NMR spectrometer capable of fast sample shuttling between high and low magnetic fields, and the application of a resonant radiofrequency field at low magnetic field. The relaxation characteristics of the long-lived state are examined. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group. |
Determination of protein ps-ns motions by high-resolution relaxometry Livre S F Cousin; P Kadeřávek; N Bolik-Coulon; F Ferrage 2018. @book{Cousin:2018a, title = {Determination of protein ps-ns motions by high-resolution relaxometry}, author = {S F Cousin and P Kade\v{r}\'{a}vek and N Bolik-Coulon and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034820210&doi=10.1007%2f978-1-4939-7386-6_9&partnerID=40&md5=acb0426074b113adef7f6c89e86d7340}, doi = {10.1007/978-1-4939-7386-6_9}, year = {2018}, date = {2018-01-01}, volume = {1688}, series = {Methods in Molecular Biology}, abstract = {Many of the functions of biomacromolecules can be rationalized by the characterization of their conformational energy landscapes: the structures of the dominant states, transitions between states and motions within states. Nuclear magnetic resonance (NMR) spectroscopy is the technique of choice to study internal motions in proteins. The determination of motions on picosecond to nanosecond timescales requires the measurement of nuclear spin relaxation rates at multiple magnetic fields. High sensitivity and resolution are obtained only at high magnetic fields, so that, until recently, site-specific relaxation rates in biomolecules were only measured over a narrow range of high magnetic fields. This limitation was particularly striking for the quantification of motions on nanosecond timescales, close to the correlation time for overall rotational diffusion. High-resolution relaxometry is an emerging technique to investigate picosecond\textemdashnanosecond motions of proteins. This approach uses a high-field NMR spectrometer equipped with a sample shuttle device, which allows for the measurement of the relaxation rate constants at low magnetic fields, while preserving the sensitivity and resolution of a high-field NMR spectrometer. The combined analysis of high-resolution relaxometry and standard high-field relaxation data provides a more accurate description of the dynamics of proteins, in particular in the nanosecond range. The purpose of this chapter is to describe how to perform high-resolution relaxometry experiments and how to analyze the rates measured with this technique. © 2018, Springer Science+Business Media LLC.}, keywords = {}, pubstate = {published}, tppubtype = {book} } Many of the functions of biomacromolecules can be rationalized by the characterization of their conformational energy landscapes: the structures of the dominant states, transitions between states and motions within states. Nuclear magnetic resonance (NMR) spectroscopy is the technique of choice to study internal motions in proteins. The determination of motions on picosecond to nanosecond timescales requires the measurement of nuclear spin relaxation rates at multiple magnetic fields. High sensitivity and resolution are obtained only at high magnetic fields, so that, until recently, site-specific relaxation rates in biomolecules were only measured over a narrow range of high magnetic fields. This limitation was particularly striking for the quantification of motions on nanosecond timescales, close to the correlation time for overall rotational diffusion. High-resolution relaxometry is an emerging technique to investigate picosecond—nanosecond motions of proteins. This approach uses a high-field NMR spectrometer equipped with a sample shuttle device, which allows for the measurement of the relaxation rate constants at low magnetic fields, while preserving the sensitivity and resolution of a high-field NMR spectrometer. The combined analysis of high-resolution relaxometry and standard high-field relaxation data provides a more accurate description of the dynamics of proteins, in particular in the nanosecond range. The purpose of this chapter is to describe how to perform high-resolution relaxometry experiments and how to analyze the rates measured with this technique. © 2018, Springer Science+Business Media LLC. |
Tailored Microstructured Hyperpolarizing Matrices for Optimal Magnetic Resonance Imaging Article de journal M Cavaillès; A Bornet; X Jaurand; B Vuichoud; D Baudouin; M Baudin; L Veyre; G Bodenhausen; J -N Dumez; S Jannin; C Copéret; C Thieuleux Angewandte Chemie - International Edition, 57 (25), p. 7453–7457, 2018. @article{Cavailles:2018, title = {Tailored Microstructured Hyperpolarizing Matrices for Optimal Magnetic Resonance Imaging}, author = {M Cavaill\`{e}s and A Bornet and X Jaurand and B Vuichoud and D Baudouin and M Baudin and L Veyre and G Bodenhausen and J -N Dumez and S Jannin and C Cop\'{e}ret and C Thieuleux}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85043712475&doi=10.1002%2fanie.201801009&partnerID=40&md5=02311ccf4fb362f7f0464f308dc298d6}, doi = {10.1002/anie.201801009}, year = {2018}, date = {2018-01-01}, journal = {Angewandte Chemie - International Edition}, volume = {57}, number = {25}, pages = {7453--7457}, abstract = {Tailoring the physical features and the porous network architecture of silica-based hyperpolarizing solids containing TEMPO radicals, known as HYPSO (hybrid polarizing solids), enabled unprecedented performance of dissolution dynamic nuclear polarization (d-DNP). High polarization values up to P(1H)=99 % were reached for samples impregnated with a mixture of H2O/D2O and loaded in a 6.7 T polarizer at temperatures around 1.2 K. These HYPSO materials combine the best performance of homogeneous DNP formulations with the advantages of solid polarizing matrices, which provide hyperpolarized solutions free of any\textemdashpotentially toxic\textemdashadditives (radicals and glass-forming agents). The hyperpolarized solutions can be expelled from the porous solids, filtered, and rapidly transferred either to a nuclear magnetic resonance (NMR) spectrometer or to a magnetic resonance imaging (MRI) system. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Tailoring the physical features and the porous network architecture of silica-based hyperpolarizing solids containing TEMPO radicals, known as HYPSO (hybrid polarizing solids), enabled unprecedented performance of dissolution dynamic nuclear polarization (d-DNP). High polarization values up to P(1H)=99 % were reached for samples impregnated with a mixture of H2O/D2O and loaded in a 6.7 T polarizer at temperatures around 1.2 K. These HYPSO materials combine the best performance of homogeneous DNP formulations with the advantages of solid polarizing matrices, which provide hyperpolarized solutions free of any—potentially toxic—additives (radicals and glass-forming agents). The hyperpolarized solutions can be expelled from the porous solids, filtered, and rapidly transferred either to a nuclear magnetic resonance (NMR) spectrometer or to a magnetic resonance imaging (MRI) system. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Sisyphus desperately seeking publisher Article de journal A Molinié; G Bodenhausen Journal of Biosciences, 43 (1), p. 9–14, 2018. @article{Molinie:2018, title = {Sisyphus desperately seeking publisher}, author = {A Molini\'{e} and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85039744523&doi=10.1007%2fs12038-017-9725-2&partnerID=40&md5=5f5d22ce94bbba411fe394ed9325d889}, doi = {10.1007/s12038-017-9725-2}, year = {2018}, date = {2018-01-01}, journal = {Journal of Biosciences}, volume = {43}, number = {1}, pages = {9--14}, abstract = {As a punishment for his trickery, King Sisyphus was made to endlessly roll a huge boulder up a steep hill. The maddening nature of the punishment was reserved for King Sisyphus due to his hubristic belief that his cleverness surpassed that of Zeus himself. Today’s scientists also pay a heavy price for their hubris and narcissism. They try to trick the editors of a few ‘top’ journals by peppering their papers with glitter and ‘bling-bling’, making overblown promises, and giving minimal credit to their predecessors. The editors wield their Olympian authority by making today’s scientists endlessly push their weighty boulders up steep hills. By bowing to this implacable ritual, we scientists confer undue power to a handful of popular but irresponsible journals. © 2017, Indian Academy of Sciences.}, keywords = {}, pubstate = {published}, tppubtype = {article} } As a punishment for his trickery, King Sisyphus was made to endlessly roll a huge boulder up a steep hill. The maddening nature of the punishment was reserved for King Sisyphus due to his hubristic belief that his cleverness surpassed that of Zeus himself. Today’s scientists also pay a heavy price for their hubris and narcissism. They try to trick the editors of a few ‘top’ journals by peppering their papers with glitter and ‘bling-bling’, making overblown promises, and giving minimal credit to their predecessors. The editors wield their Olympian authority by making today’s scientists endlessly push their weighty boulders up steep hills. By bowing to this implacable ritual, we scientists confer undue power to a handful of popular but irresponsible journals. © 2017, Indian Academy of Sciences. |
Sample Ripening through Nanophase Separation Influences the Performance of Dynamic Nuclear Polarization Article de journal E M M Weber; G Sicoli; H Vezin; G Frébourg; D Abergel; G Bodenhausen; D Kurzbach Angewandte Chemie - International Edition, 57 (18), p. 5171–5175, 2018. @article{Weber:2018, title = {Sample Ripening through Nanophase Separation Influences the Performance of Dynamic Nuclear Polarization}, author = {E M M Weber and G Sicoli and H Vezin and G Fr\'{e}bourg and D Abergel and G Bodenhausen and D Kurzbach}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044241782&doi=10.1002%2fanie.201800493&partnerID=40&md5=43bb50812719cf82c566fb0b1e75d97a}, doi = {10.1002/anie.201800493}, year = {2018}, date = {2018-01-01}, journal = {Angewandte Chemie - International Edition}, volume = {57}, number = {18}, pages = {5171--5175}, abstract = {Mixtures of water and glycerol provide popular matrices for low-temperature spectroscopy of vitrified samples. However, they involve counterintuitive physicochemical properties, such as spontaneous nanoscopic phase separations (NPS) in solutions that appear macroscopically homogeneous. We demonstrate that such phenomena can substantially influence the efficiency of dynamic nuclear polarization (DNP) by factors up to 20 % by causing fluctuations in local concentrations of polarization agents (radicals). Thus, a spontaneous NPS of water/glycerol mixtures that takes place on time scales on the order of 30\textendash60 min results in a confinement of polarization agents in nanoscopic water-rich vesicles, which in return affects the DNP. Such effects were found for three common polarization agents, TEMPOL, AMUPol and Trityl. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Mixtures of water and glycerol provide popular matrices for low-temperature spectroscopy of vitrified samples. However, they involve counterintuitive physicochemical properties, such as spontaneous nanoscopic phase separations (NPS) in solutions that appear macroscopically homogeneous. We demonstrate that such phenomena can substantially influence the efficiency of dynamic nuclear polarization (DNP) by factors up to 20 % by causing fluctuations in local concentrations of polarization agents (radicals). Thus, a spontaneous NPS of water/glycerol mixtures that takes place on time scales on the order of 30–60 min results in a confinement of polarization agents in nanoscopic water-rich vesicles, which in return affects the DNP. Such effects were found for three common polarization agents, TEMPOL, AMUPol and Trityl. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Relaxation of long-lived modes in NMR of deuterated methyl groups Article de journal K L Ivanov; T Kress; M Baudin; D Guarin; D Abergel; G Bodenhausen; D Kurzbach Journal of Chemical Physics, 149 (5), 2018. @article{Ivanov:2018, title = {Relaxation of long-lived modes in NMR of deuterated methyl groups}, author = {K L Ivanov and T Kress and M Baudin and D Guarin and D Abergel and G Bodenhausen and D Kurzbach}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85051239809&doi=10.1063%2f1.5031177&partnerID=40&md5=f335f115812c38354e4239f8c768a44b}, doi = {10.1063/1.5031177}, year = {2018}, date = {2018-01-01}, journal = {Journal of Chemical Physics}, volume = {149}, number = {5}, abstract = {Long-lived imbalances of spin state populations can circumvent fast quadrupolar relaxation by reducing effective longitudinal relaxation rates by about an order of magnitude. This opens new avenues for the study of dynamic processes in deuterated molecules. Here we present an analysis of the relaxation properties of deuterated methyl groups CD3. The number of coupled equations that describe cross-relaxation between the 27 symmetry-adapted spin states of a D3 system can be reduced to only 2 non-trivial "lumped modes" by (i) taking the sums of the populations of all states that equilibrate rapidly within each irreducible representation of the symmetry group, and (ii) by combining populations that have similar relaxation rates although they belong to different irreducible representations. The quadrupolar relaxation rates of the spin state imbalances in CD3 groups are determined not by the correlation time of overall tumbling of the molecule, but by the frequency of jumps of methyl groups about their three-fold symmetry axis. We access these states via dissolution dynamic nuclear polarization (D-DNP), a method that allows one to populate the desired long-lived states at cryogenic temperatures and their subsequent detection at ambient temperatures after rapid dissolution. Experimental examples of DMSO-d6 and ethanol-d6 demonstrate that long-lived deuterium spin states are indeed accessible and that their lifetimes can be determined. Our analysis of the system via "lumped" modes allows us to visualize different possible spin-state populations of symmetry A, B, or E. Thus, we identify a long-lived spin state involving all three deuterons in a CD3 group as an A/E imbalance that can be populated through DNP at low temperatures. © 2018 Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Long-lived imbalances of spin state populations can circumvent fast quadrupolar relaxation by reducing effective longitudinal relaxation rates by about an order of magnitude. This opens new avenues for the study of dynamic processes in deuterated molecules. Here we present an analysis of the relaxation properties of deuterated methyl groups CD3. The number of coupled equations that describe cross-relaxation between the 27 symmetry-adapted spin states of a D3 system can be reduced to only 2 non-trivial "lumped modes" by (i) taking the sums of the populations of all states that equilibrate rapidly within each irreducible representation of the symmetry group, and (ii) by combining populations that have similar relaxation rates although they belong to different irreducible representations. The quadrupolar relaxation rates of the spin state imbalances in CD3 groups are determined not by the correlation time of overall tumbling of the molecule, but by the frequency of jumps of methyl groups about their three-fold symmetry axis. We access these states via dissolution dynamic nuclear polarization (D-DNP), a method that allows one to populate the desired long-lived states at cryogenic temperatures and their subsequent detection at ambient temperatures after rapid dissolution. Experimental examples of DMSO-d6 and ethanol-d6 demonstrate that long-lived deuterium spin states are indeed accessible and that their lifetimes can be determined. Our analysis of the system via "lumped" modes allows us to visualize different possible spin-state populations of symmetry A, B, or E. Thus, we identify a long-lived spin state involving all three deuterons in a CD3 group as an A/E imbalance that can be populated through DNP at low temperatures. © 2018 Author(s). |
Rates of Chemical Reactions Embedded in a Metabolic Network by Dissolution Dynamic Nuclear Polarisation NMR Article de journal A Sadet; E M M Weber; A Jhajharia; D Kurzbach; G Bodenhausen; E Miclet; D Abergel Chemistry - A European Journal, 24 (21), p. 5456–5461, 2018. @article{Sadet:2018, title = {Rates of Chemical Reactions Embedded in a Metabolic Network by Dissolution Dynamic Nuclear Polarisation NMR}, author = {A Sadet and E M M Weber and A Jhajharia and D Kurzbach and G Bodenhausen and E Miclet and D Abergel}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85044503759&doi=10.1002%2fchem.201705520&partnerID=40&md5=1b9688fdca8e8a72897b2a42cbb1a150}, doi = {10.1002/chem.201705520}, year = {2018}, date = {2018-01-01}, journal = {Chemistry - A European Journal}, volume = {24}, number = {21}, pages = {5456--5461}, abstract = {The isomerisation of 6-phosphogluconolactones and their hydrolyses into 6-phosphogluconic acid form a non enzymatic side cycle of the pentose-phosphate pathway (PPP) in cells. Dissolution dynamic nuclear polarisation can be used for determining the kinetic rates of the involved transformations in real time. It is found that the hydrolysis of both lactones is significantly slower than the isomerisation process, thereby shedding new light onto this subtle chemical process. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } The isomerisation of 6-phosphogluconolactones and their hydrolyses into 6-phosphogluconic acid form a non enzymatic side cycle of the pentose-phosphate pathway (PPP) in cells. Dissolution dynamic nuclear polarisation can be used for determining the kinetic rates of the involved transformations in real time. It is found that the hydrolysis of both lactones is significantly slower than the isomerisation process, thereby shedding new light onto this subtle chemical process. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Overhauser effects in non-conducting solids at 1.2 K Article de journal X Ji; T V Can; F Mentink-Vigier; A Bornet; J Milani; B Vuichoud; M A Caporini; R G Griffin; S Jannin; M Goldman; G Bodenhausen Journal of Magnetic Resonance, 286 , p. 138–142, 2018. @article{Ji:2018, title = {Overhauser effects in non-conducting solids at 1.2 K}, author = {X Ji and T V Can and F Mentink-Vigier and A Bornet and J Milani and B Vuichoud and M A Caporini and R G Griffin and S Jannin and M Goldman and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85037687700&doi=10.1016%2fj.jmr.2017.11.017&partnerID=40&md5=064ae9d084fe65aa26ddbe158562ac5d}, doi = {10.1016/j.jmr.2017.11.017}, year = {2018}, date = {2018-01-01}, journal = {Journal of Magnetic Resonance}, volume = {286}, pages = {138--142}, abstract = {Recently, it was observed that protons in non-conducting solids doped with 1,3-bisdiphenylene-2-phenylallyl (BDPA) or its sulfonated derivative (SA-BDPA) can be polarized through Overhauser effects via resonant microwave irradiation. These effects were present under magic angle spinning conditions in magnetic fields between 5 and 18.8 T and at temperatures near 100 K. This communication reports similar effects in static samples at 6.7 T and, more importantly, at temperatures as low as 1.2 K, in a different dynamic regime than in the previous study. Our results provide new information towards understanding the mechanism of the Overhauser effect in non-conducting solids. We discuss possible origins of the fluctuations that can give rise to an Overhauser effect at such low temperatures. © 2017 Elsevier Inc.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Recently, it was observed that protons in non-conducting solids doped with 1,3-bisdiphenylene-2-phenylallyl (BDPA) or its sulfonated derivative (SA-BDPA) can be polarized through Overhauser effects via resonant microwave irradiation. These effects were present under magic angle spinning conditions in magnetic fields between 5 and 18.8 T and at temperatures near 100 K. This communication reports similar effects in static samples at 6.7 T and, more importantly, at temperatures as low as 1.2 K, in a different dynamic regime than in the previous study. Our results provide new information towards understanding the mechanism of the Overhauser effect in non-conducting solids. We discuss possible origins of the fluctuations that can give rise to an Overhauser effect at such low temperatures. © 2017 Elsevier Inc. |
2017 |
Ultra-wide range field-dependent measurements of the relaxivity of Gd1-x Eux VO4 nanoparticle contrast agents using a mechanical sample-shuttling relaxometer Article de journal C -Y Chou; M Abdesselem; C Bouzigues; M Chu; A Guiga; T -H Huang; F Ferrage; T Gacoin; A Alexandrou; D Sakellariou Scientific Reports, 7 , 2017. @article{Chou:2017, title = {Ultra-wide range field-dependent measurements of the relaxivity of Gd1-x Eux VO4 nanoparticle contrast agents using a mechanical sample-shuttling relaxometer}, author = {C -Y Chou and M Abdesselem and C Bouzigues and M Chu and A Guiga and T -H Huang and F Ferrage and T Gacoin and A Alexandrou and D Sakellariou}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015977501&doi=10.1038%2fsrep44770&partnerID=40&md5=b8e41b32dbcc097b80e689bd90ba5617}, doi = {10.1038/srep44770}, year = {2017}, date = {2017-01-01}, journal = {Scientific Reports}, volume = {7}, abstract = {The current trend for Magnetic Resonance Imaging points towards higher magnetic fields. Even though sensitivity and resolution are increased in stronger fields, T1 contrast is often reduced, and this represents a challenge for contrast agent design. Field-dependent measurements of relaxivity are thus important to characterize contrast agents. At present, the field-dependent curves of relaxivity are usually carried out in the field range of 0 T to 2 T, using fast field cycling relaxometers. Here, we employ a high-speed sample shuttling device to switch the magnetic fields experienced by the nuclei between virtually zero field, and the center of any commercial spectrometer. We apply this approach on rare-earth (mixed Gadolinium-Europium) vanadate nanoparticles, and obtain the dispersion curves from very low magnetic field up to 11.7 T. In contrast to the relaxivity profiles of Gd chelates, commonly used for clinical applications, which display a plateau and then a decrease for increasing magnetic fields, these nanoparticles provide maximum contrast enhancement for magnetic fields around 1-1.5 T. These field-dependent curves are fitted using the so-called Magnetic Particle (MP) model and the extracted parameters discussed as a function of particle size and composition. We finally comment on the new possibilities offered by this approach. © 2017 The Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } The current trend for Magnetic Resonance Imaging points towards higher magnetic fields. Even though sensitivity and resolution are increased in stronger fields, T1 contrast is often reduced, and this represents a challenge for contrast agent design. Field-dependent measurements of relaxivity are thus important to characterize contrast agents. At present, the field-dependent curves of relaxivity are usually carried out in the field range of 0 T to 2 T, using fast field cycling relaxometers. Here, we employ a high-speed sample shuttling device to switch the magnetic fields experienced by the nuclei between virtually zero field, and the center of any commercial spectrometer. We apply this approach on rare-earth (mixed Gadolinium-Europium) vanadate nanoparticles, and obtain the dispersion curves from very low magnetic field up to 11.7 T. In contrast to the relaxivity profiles of Gd chelates, commonly used for clinical applications, which display a plateau and then a decrease for increasing magnetic fields, these nanoparticles provide maximum contrast enhancement for magnetic fields around 1-1.5 T. These field-dependent curves are fitted using the so-called Magnetic Particle (MP) model and the extracted parameters discussed as a function of particle size and composition. We finally comment on the new possibilities offered by this approach. © 2017 The Author(s). |
Structure and Dynamics of an Intrinsically Disordered Protein Region That Partially Folds upon Binding by Chemical-Exchange NMR Article de journal C Charlier; G Bouvignies; P Pelupessy; A Walrant; R Marquant; M Kozlov; P De Ioannes; N Bolik-Coulon; S Sagan; P Cortes; A K Aggarwal; L Carlier; F Ferrage Journal of the American Chemical Society, 139 (35), p. 12219–12227, 2017. @article{Charlier:2017, title = {Structure and Dynamics of an Intrinsically Disordered Protein Region That Partially Folds upon Binding by Chemical-Exchange NMR}, author = {C Charlier and G Bouvignies and P Pelupessy and A Walrant and R Marquant and M Kozlov and P De Ioannes and N Bolik-Coulon and S Sagan and P Cortes and A K Aggarwal and L Carlier and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85028941202&doi=10.1021%2fjacs.7b05823&partnerID=40&md5=ce8846a9b03d31576ec301899a2c40f1}, doi = {10.1021/jacs.7b05823}, year = {2017}, date = {2017-01-01}, journal = {Journal of the American Chemical Society}, volume = {139}, number = {35}, pages = {12219--12227}, abstract = {Many intrinsically disordered proteins (IDPs) and protein regions (IDRs) engage in transient, yet specific, interactions with a variety of protein partners. Often, if not always, interactions with a protein partner lead to partial folding of the IDR. Characterizing the conformational space of such complexes is challenging: in solution-state NMR, signals of the IDR in the interacting region become broad, weak, and often invisible, while X-ray crystallography only provides information on fully ordered regions. There is thus a need for a simple method to characterize both fully and partially ordered regions in the bound state of IDPs. Here, we introduce an approach based on monitoring chemical exchange by NMR to investigate the state of an IDR that folds upon binding through the observation of the free state of the protein. Structural constraints for the bound state are obtained from chemical shifts, and site-specific dynamics of the bound state are characterized by relaxation rates. The conformation of the interacting part of the IDR was determined and subsequently docked onto the structure of the folded partner. We apply the method to investigate the interaction between the disordered C-terminal region of Artemis and the DNA binding domain of Ligase IV. We show that we can accurately reproduce the structure of the core of the complex determined by X-ray crystallography and identify a broader interface. The method is widely applicable to the biophysical investigation of complexes of disordered proteins and folded proteins. © 2017 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Many intrinsically disordered proteins (IDPs) and protein regions (IDRs) engage in transient, yet specific, interactions with a variety of protein partners. Often, if not always, interactions with a protein partner lead to partial folding of the IDR. Characterizing the conformational space of such complexes is challenging: in solution-state NMR, signals of the IDR in the interacting region become broad, weak, and often invisible, while X-ray crystallography only provides information on fully ordered regions. There is thus a need for a simple method to characterize both fully and partially ordered regions in the bound state of IDPs. Here, we introduce an approach based on monitoring chemical exchange by NMR to investigate the state of an IDR that folds upon binding through the observation of the free state of the protein. Structural constraints for the bound state are obtained from chemical shifts, and site-specific dynamics of the bound state are characterized by relaxation rates. The conformation of the interacting part of the IDR was determined and subsequently docked onto the structure of the folded partner. We apply the method to investigate the interaction between the disordered C-terminal region of Artemis and the DNA binding domain of Ligase IV. We show that we can accurately reproduce the structure of the core of the complex determined by X-ray crystallography and identify a broader interface. The method is widely applicable to the biophysical investigation of complexes of disordered proteins and folded proteins. © 2017 American Chemical Society. |
Full Correlations across Broad NMR Spectra by Two-Field Total Correlation Spectroscopy Article de journal P Kadeřávek; L Strouk; S F Cousin; C Charlier; G Bodenhausen; T Marquardsen; J -M Tyburn; P -A Bovier; F Engelke; W Maas; F Ferrage ChemPhysChem, 18 (19), p. 2772–2776, 2017. @article{Kaderavek:2017, title = {Full Correlations across Broad NMR Spectra by Two-Field Total Correlation Spectroscopy}, author = {P Kade\v{r}\'{a}vek and L Strouk and S F Cousin and C Charlier and G Bodenhausen and T Marquardsen and J -M Tyburn and P -A Bovier and F Engelke and W Maas and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030717312&doi=10.1002%2fcphc.201700369&partnerID=40&md5=d073ea9e024a1ce650d0c4b2cf57df88}, doi = {10.1002/cphc.201700369}, year = {2017}, date = {2017-01-01}, journal = {ChemPhysChem}, volume = {18}, number = {19}, pages = {2772--2776}, abstract = {Total correlation spectroscopy (TOCSY) is a key experiment to assign nuclear magnetic resonance (NMR) spectra of complex molecules. Carbon-13 TOCSY experiments are essential to assign signals of protein side chains. However, the performance of carbon-13 TOCSY deteriorates at high magnetic fields since the necessarily limited radiofrequency irradiation fails to cover the broad range of carbon-13 frequencies. Here, we introduce a new concept to overcome the limitations of TOCSY by using two-field NMR spectroscopy. In two-field TOCSY experiments, chemical shifts are labelled at high field but isotropic mixing is performed at a much lower magnetic field, where the frequency range of the spectrum is drastically reduced. We obtain complete correlations between all carbon-13 nuclei belonging to amino acids across the entire spectrum: aromatic, aliphatic and carboxylic. Two-field TOCSY should be a robust and general approach for the assignment of uniformly carbon-13 labelled molecules in high-field and ultra-high field NMR spectrometers beyond 1000 MHz. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Total correlation spectroscopy (TOCSY) is a key experiment to assign nuclear magnetic resonance (NMR) spectra of complex molecules. Carbon-13 TOCSY experiments are essential to assign signals of protein side chains. However, the performance of carbon-13 TOCSY deteriorates at high magnetic fields since the necessarily limited radiofrequency irradiation fails to cover the broad range of carbon-13 frequencies. Here, we introduce a new concept to overcome the limitations of TOCSY by using two-field NMR spectroscopy. In two-field TOCSY experiments, chemical shifts are labelled at high field but isotropic mixing is performed at a much lower magnetic field, where the frequency range of the spectrum is drastically reduced. We obtain complete correlations between all carbon-13 nuclei belonging to amino acids across the entire spectrum: aromatic, aliphatic and carboxylic. Two-field TOCSY should be a robust and general approach for the assignment of uniformly carbon-13 labelled molecules in high-field and ultra-high field NMR spectrometers beyond 1000 MHz. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Tailored Polarizing Hybrid Solids with Nitroxide Radicals Localized in Mesostructured Silica Walls Article de journal D L Silverio; H A van Kalkeren; T -C Ong; M Baudin; M Yulikov; L Veyre; P Berruyer; S Chaudhari; D Gajan; D Baudouin; M Cavaillès; B Vuichoud; A Bornet; G Jeschke; G Bodenhausen; A Lesage; L Emsley; S Jannin; C Thieuleux; C Copéret Helvetica Chimica Acta, 100 (6), 2017. @article{Silverio:2017, title = {Tailored Polarizing Hybrid Solids with Nitroxide Radicals Localized in Mesostructured Silica Walls}, author = {D L Silverio and H A van Kalkeren and T -C Ong and M Baudin and M Yulikov and L Veyre and P Berruyer and S Chaudhari and D Gajan and D Baudouin and M Cavaill\`{e}s and B Vuichoud and A Bornet and G Jeschke and G Bodenhausen and A Lesage and L Emsley and S Jannin and C Thieuleux and C Cop\'{e}ret}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85019658726&doi=10.1002%2fhlca.201700101&partnerID=40&md5=921ea8dcdead16b9deee328ee5928200}, doi = {10.1002/hlca.201700101}, year = {2017}, date = {2017-01-01}, journal = {Helvetica Chimica Acta}, volume = {100}, number = {6}, abstract = {Hyperpolarization by dynamic nuclear polarization relies on the microwave irradiation of paramagnetic radicals dispersed in molecular glasses to enhance the nuclear magnetic resonance (NMR) signals of target molecules. However, magnetic or chemical interactions between the radicals and the target molecules can lead to attenuation of the NMR signal through paramagnetic quenching and/or radical decomposition. Here we describe polarizing materials incorporating nitroxide radicals within the walls of the solids to minimize interactions between the radicals and the solute. These materials can hyperpolarize pure pyruvic acid, a particularly important substrate of clinical interest, while nitroxide radicals cannot be used, even when incorporated in the pores of silica, because of reactions between pyruvic acid and the radicals. The properties of these materials can be engineered by tuning the composition of the wall by introducing organic functionalities. © 2017 Wiley-VHCA AG, Zurich, Switzerland}, keywords = {}, pubstate = {published}, tppubtype = {article} } Hyperpolarization by dynamic nuclear polarization relies on the microwave irradiation of paramagnetic radicals dispersed in molecular glasses to enhance the nuclear magnetic resonance (NMR) signals of target molecules. However, magnetic or chemical interactions between the radicals and the target molecules can lead to attenuation of the NMR signal through paramagnetic quenching and/or radical decomposition. Here we describe polarizing materials incorporating nitroxide radicals within the walls of the solids to minimize interactions between the radicals and the solute. These materials can hyperpolarize pure pyruvic acid, a particularly important substrate of clinical interest, while nitroxide radicals cannot be used, even when incorporated in the pores of silica, because of reactions between pyruvic acid and the radicals. The properties of these materials can be engineered by tuning the composition of the wall by introducing organic functionalities. © 2017 Wiley-VHCA AG, Zurich, Switzerland |
Susceptibility contrast by echo shifting in spatially encoded single-scan MRI Article de journal S Marhabaie; G Bodenhausen; P Pelupessy Physical Chemistry Chemical Physics, 19 (22), p. 14210–14213, 2017. @article{Marhabaie:2017, title = {Susceptibility contrast by echo shifting in spatially encoded single-scan MRI}, author = {S Marhabaie and G Bodenhausen and P Pelupessy}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85024128374&doi=10.1039%2fc7cp01898c&partnerID=40&md5=970ad3e337df7c1cbe673ca2013173d8}, doi = {10.1039/c7cp01898c}, year = {2017}, date = {2017-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {19}, number = {22}, pages = {14210--14213}, abstract = {To overcome the effects of static field inhomogeneities, single-scan hybrid imaging techniques that use k-space encoding in one direction and spatial encoding in the other have been shown to be superior to traditional imaging techniques based on full k-space encoding. Like traditional imaging methods, hybrid methods can be implemented in different ways that favor different sources of contrast. So far, little attention appears to have been paid to these aspects. By modifying an established hybrid imaging sequence called Rapid Acquisition by Sequential Excitation and Refocusing (RASER) so as to obtain Echo-Shifted RASER sequences, we show that by shifting spin echoes one can tune the contrast due to inhomogeneous Tinh2 decay. © the Owner Societies 2017.}, keywords = {}, pubstate = {published}, tppubtype = {article} } To overcome the effects of static field inhomogeneities, single-scan hybrid imaging techniques that use k-space encoding in one direction and spatial encoding in the other have been shown to be superior to traditional imaging techniques based on full k-space encoding. Like traditional imaging methods, hybrid methods can be implemented in different ways that favor different sources of contrast. So far, little attention appears to have been paid to these aspects. By modifying an established hybrid imaging sequence called Rapid Acquisition by Sequential Excitation and Refocusing (RASER) so as to obtain Echo-Shifted RASER sequences, we show that by shifting spin echoes one can tune the contrast due to inhomogeneous Tinh2 decay. © the Owner Societies 2017. |
Phenylazide Hybrid-Silica – Polarization Platform for Dynamic Nuclear Polarization at Cryogenic Temperatures Article de journal W R Grüning; H Bieringer; M Schwarzwälder; D Gajan; A Bornet; B Vuichoud; J Milani; D Baudouin; L Veyre; A Lesage; S Jannin; G Bodenhausen; C Thieuleux; C Copéret Helvetica Chimica Acta, 100 (1), 2017. @article{Gruning:2017, title = {Phenylazide Hybrid-Silica \textendash Polarization Platform for Dynamic Nuclear Polarization at Cryogenic Temperatures}, author = {W R Gr\"{u}ning and H Bieringer and M Schwarzw\"{a}lder and D Gajan and A Bornet and B Vuichoud and J Milani and D Baudouin and L Veyre and A Lesage and S Jannin and G Bodenhausen and C Thieuleux and C Cop\'{e}ret}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007036296&doi=10.1002%2fhlca.201600122&partnerID=40&md5=1414055479445c997af5fe23203e20e5}, doi = {10.1002/hlca.201600122}, year = {2017}, date = {2017-01-01}, journal = {Helvetica Chimica Acta}, volume = {100}, number = {1}, abstract = {Hyperpolarization of NMR-active nuclei is key to gather high quality spectra of rare species and insensitive isotopes. We have recently established that silica-based materials containing regularly distributed nitroxyl radicals connected to the silica matrix by flexible linkers can serve as promising polarization matrices for dynamic nuclear polarization (DNP). Here we investigate the influence of the linker on the efficiency of the polarization. The materials were fully characterized and exhibit high surface areas and narrow pore size distributions with a tunable amount of phenyl azide groups over a broad range of concentrations. The phenyl azide groups can be easily functionalized via a two-step procedure with 4-carboxy-2,2,6,6-tetramethyl-1-oxylpiperidine (TEMPO) to give polarizing matrices with controllable radical content. The DNP efficiency was found to be similar as in materials with flexible linkers, both for magic angle spinning at 105 K and dissolution DNP at 4 K. © 2017 Wiley-VHCA AG, Zurich, Switzerland}, keywords = {}, pubstate = {published}, tppubtype = {article} } Hyperpolarization of NMR-active nuclei is key to gather high quality spectra of rare species and insensitive isotopes. We have recently established that silica-based materials containing regularly distributed nitroxyl radicals connected to the silica matrix by flexible linkers can serve as promising polarization matrices for dynamic nuclear polarization (DNP). Here we investigate the influence of the linker on the efficiency of the polarization. The materials were fully characterized and exhibit high surface areas and narrow pore size distributions with a tunable amount of phenyl azide groups over a broad range of concentrations. The phenyl azide groups can be easily functionalized via a two-step procedure with 4-carboxy-2,2,6,6-tetramethyl-1-oxylpiperidine (TEMPO) to give polarizing matrices with controllable radical content. The DNP efficiency was found to be similar as in materials with flexible linkers, both for magic angle spinning at 105 K and dissolution DNP at 4 K. © 2017 Wiley-VHCA AG, Zurich, Switzerland |
Hyperpolarization of nitrogen-15 nuclei by cross polarization and dissolution dynamic nuclear polarization Article de journal J Milani; B Vuichoud; A Bornet; R Melzi; S Jannin; G Bodenhausen Review of Scientific Instruments, 88 (1), 2017. @article{Milani:2017, title = {Hyperpolarization of nitrogen-15 nuclei by cross polarization and dissolution dynamic nuclear polarization}, author = {J Milani and B Vuichoud and A Bornet and R Melzi and S Jannin and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010953781&doi=10.1063%2f1.4973777&partnerID=40&md5=71973092500768a264723534bade7492}, doi = {10.1063/1.4973777}, year = {2017}, date = {2017-01-01}, journal = {Review of Scientific Instruments}, volume = {88}, number = {1}, abstract = {Dynamic Nuclear Polarization (DNP) is often achieved by the direct transfer of polarization from electrons to nuclei such as 13C, induced by microwave saturation of the wings of narrow EPR lines of radicals like trityl. In the indirect approach on the other hand, DNP is used to transfer the polarization from the electrons of radicals such as nitroxides that have broad EPR lines to nuclear spins I = 1H, followed by cross-polarization (CP) from I = 1H to S = 13C or other nuclei with low gyromagnetic ratios. This approach is particularly attractive for S = 15N, since direct DNP yields modest polarizations P(15N) < 4% with build-up times that can be as long as τDNP(15N) > 2 h. In this paper, we show that CP from 1H to 15N at 1.2 K can yield P(15N) = 25% with τCP-DNP(15N) = 10-15 min. After rapid dissolution and transfer to a solution-state NMR spectrometer, a polarization P(15N) = 20% was observed at 300 K. The longitudinal relaxation times in solution can be as long as T1(15N) > 800 s in favorable cases. © 2017 Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dynamic Nuclear Polarization (DNP) is often achieved by the direct transfer of polarization from electrons to nuclei such as 13C, induced by microwave saturation of the wings of narrow EPR lines of radicals like trityl. In the indirect approach on the other hand, DNP is used to transfer the polarization from the electrons of radicals such as nitroxides that have broad EPR lines to nuclear spins I = 1H, followed by cross-polarization (CP) from I = 1H to S = 13C or other nuclei with low gyromagnetic ratios. This approach is particularly attractive for S = 15N, since direct DNP yields modest polarizations P(15N) < 4% with build-up times that can be as long as τDNP(15N) > 2 h. In this paper, we show that CP from 1H to 15N at 1.2 K can yield P(15N) = 25% with τCP-DNP(15N) = 10-15 min. After rapid dissolution and transfer to a solution-state NMR spectrometer, a polarization P(15N) = 20% was observed at 300 K. The longitudinal relaxation times in solution can be as long as T1(15N) > 800 s in favorable cases. © 2017 Author(s). |
Transportable hyperpolarized metabolites Article de journal X Ji; A Bornet; B Vuichoud; J Milani; D Gajan; A J Rossini; L Emsley; G Bodenhausen; S Jannin Nature Communications, 8 , 2017. @article{Ji:2017, title = {Transportable hyperpolarized metabolites}, author = {X Ji and A Bornet and B Vuichoud and J Milani and D Gajan and A J Rossini and L Emsley and G Bodenhausen and S Jannin}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85009165733&doi=10.1038%2fncomms13975&partnerID=40&md5=0b81d9bff7dc37c505405d6133b6a9e5}, doi = {10.1038/ncomms13975}, year = {2017}, date = {2017-01-01}, journal = {Nature Communications}, volume = {8}, abstract = {Nuclear spin hyperpolarization of 13 C-labelled metabolites by dissolution dynamic nuclear polarization can enhance the NMR signals of metabolites by several orders of magnitude, which has enabled in vivo metabolic imaging by MRI. However, because of the short lifetime of the hyperpolarized magnetization (typically textless1 min), the polarization process must be carried out close to the point of use. Here we introduce a concept that markedly extends hyperpolarization lifetimes and enables the transportation of hyperpolarized metabolites. The hyperpolarized sample can thus be removed from the polarizer and stored or transported for use at remote MRI or NMR sites. We show that hyperpolarization in alanine and glycine survives 16 h storage and transport, maintaining overall polarization enhancements of up to three orders of magnitude. © The Author(s) 2017.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nuclear spin hyperpolarization of 13 C-labelled metabolites by dissolution dynamic nuclear polarization can enhance the NMR signals of metabolites by several orders of magnitude, which has enabled in vivo metabolic imaging by MRI. However, because of the short lifetime of the hyperpolarized magnetization (typically textless1 min), the polarization process must be carried out close to the point of use. Here we introduce a concept that markedly extends hyperpolarization lifetimes and enables the transportation of hyperpolarized metabolites. The hyperpolarized sample can thus be removed from the polarizer and stored or transported for use at remote MRI or NMR sites. We show that hyperpolarization in alanine and glycine survives 16 h storage and transport, maintaining overall polarization enhancements of up to three orders of magnitude. © The Author(s) 2017. |
Dynamic Nuclear Polarization of Long-Lived Nuclear Spin States in Methyl Groups Article de journal J -N Dumez; B Vuichoud; D Mammoli; A Bornet; A C Pinon; G Stevanato; B Meier; G Bodenhausen; S Jannin; M H Levitt Journal of Physical Chemistry Letters, 8 (15), p. 3549–3555, 2017. @article{Dumez:2017, title = {Dynamic Nuclear Polarization of Long-Lived Nuclear Spin States in Methyl Groups}, author = {J -N Dumez and B Vuichoud and D Mammoli and A Bornet and A C Pinon and G Stevanato and B Meier and G Bodenhausen and S Jannin and M H Levitt}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85026809825&doi=10.1021%2facs.jpclett.7b01512&partnerID=40&md5=b99fe8c7360f052321110d45375d87ba}, doi = {10.1021/acs.jpclett.7b01512}, year = {2017}, date = {2017-01-01}, journal = {Journal of Physical Chemistry Letters}, volume = {8}, number = {15}, pages = {3549--3555}, abstract = {We have induced hyperpolarized long-lived states in compounds containing 13C-bearing methyl groups by dynamic nuclear polarization (DNP) at cryogenic temperatures, followed by dissolution with a warm solvent. The hyperpolarized methyl long-lived states give rise to enhanced antiphase 13C NMR signals in solution, which often persist for times much longer than the 13C and 1H spin-lattice relaxation times under the same conditions. The DNP-induced effects are similar to quantum-rotor-induced polarization (QRIP) but are observed in a wider range of compounds because they do not depend critically on the height of the rotational barrier. We interpret our observations with a model in which nuclear Zeeman and methyl tunnelling reservoirs adopt an approximately uniform temperature, under DNP conditions. The generation of hyperpolarized NMR signals that persist for relatively long times in a range of methyl-bearing substances may be important for applications such as investigations of metabolism, enzymatic reactions, protein-ligand binding, drug screening, and molecular imaging. © 2017 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We have induced hyperpolarized long-lived states in compounds containing 13C-bearing methyl groups by dynamic nuclear polarization (DNP) at cryogenic temperatures, followed by dissolution with a warm solvent. The hyperpolarized methyl long-lived states give rise to enhanced antiphase 13C NMR signals in solution, which often persist for times much longer than the 13C and 1H spin-lattice relaxation times under the same conditions. The DNP-induced effects are similar to quantum-rotor-induced polarization (QRIP) but are observed in a wider range of compounds because they do not depend critically on the height of the rotational barrier. We interpret our observations with a model in which nuclear Zeeman and methyl tunnelling reservoirs adopt an approximately uniform temperature, under DNP conditions. The generation of hyperpolarized NMR signals that persist for relatively long times in a range of methyl-bearing substances may be important for applications such as investigations of metabolism, enzymatic reactions, protein-ligand binding, drug screening, and molecular imaging. © 2017 American Chemical Society. |
Communication: Dissolution DNP reveals a long-lived deuterium spin state imbalance in methyl groups Article de journal A Jhajharia; E M M Weber; J G Kempf; D Abergel; G Bodenhausen; D Kurzbach Journal of Chemical Physics, 146 (4), 2017. @article{Jhajharia:2017, title = {Communication: Dissolution DNP reveals a long-lived deuterium spin state imbalance in methyl groups}, author = {A Jhajharia and E M M Weber and J G Kempf and D Abergel and G Bodenhausen and D Kurzbach}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85010822015&doi=10.1063%2f1.4974358&partnerID=40&md5=da0569dbc85b8455d2d0e731c7bcec69}, doi = {10.1063/1.4974358}, year = {2017}, date = {2017-01-01}, journal = {Journal of Chemical Physics}, volume = {146}, number = {4}, abstract = {We report the generation and observation of long-lived spin states in deuterated methyl groups by dissolution DNP. These states are based on population imbalances between manifolds of spin states corresponding to irreducible representations of the C3v point group and feature strongly dampened quadrupolar relaxation. Their lifetime depends on the activation energies of methyl group rotation. With dissolution DNP, we can reduce the deuterium relaxation rate by a factor up to 20, thereby extending the experimentally available time window. The intrinsic limitation of NMR spectroscopy of quadrupolar spins by short relaxation times can thus be alleviated. © 2017 Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report the generation and observation of long-lived spin states in deuterated methyl groups by dissolution DNP. These states are based on population imbalances between manifolds of spin states corresponding to irreducible representations of the C3v point group and feature strongly dampened quadrupolar relaxation. Their lifetime depends on the activation energies of methyl group rotation. With dissolution DNP, we can reduce the deuterium relaxation rate by a factor up to 20, thereby extending the experimentally available time window. The intrinsic limitation of NMR spectroscopy of quadrupolar spins by short relaxation times can thus be alleviated. © 2017 Author(s). |
Characterizing Thermal Mixing Dynamic Nuclear Polarization via Cross-Talk between Spin Reservoirs Article de journal D Guarin; S Marhabaie; A Rosso; D Abergel; G Bodenhausen; K L Ivanov; D Kurzbach Journal of Physical Chemistry Letters, 8 (22), p. 5531–5536, 2017. @article{Guarin:2017, title = {Characterizing Thermal Mixing Dynamic Nuclear Polarization via Cross-Talk between Spin Reservoirs}, author = {D Guarin and S Marhabaie and A Rosso and D Abergel and G Bodenhausen and K L Ivanov and D Kurzbach}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034211190&doi=10.1021%2facs.jpclett.7b02233&partnerID=40&md5=f1e49f904e8912b8d96da78d3eb1f74a}, doi = {10.1021/acs.jpclett.7b02233}, year = {2017}, date = {2017-01-01}, journal = {Journal of Physical Chemistry Letters}, volume = {8}, number = {22}, pages = {5531--5536}, abstract = {Dynamic nuclear polarization (DNP) embraces a family of methods to increase signal intensities in nuclear magnetic resonance (NMR) spectroscopy. Despite extensive theoretical work that allows one to distinguish at least five distinct mechanisms, it remains challenging to determine the relative weights of the processes that are responsible for DNP in state-of-the-art experiments operating with stable organic radicals like nitroxides at high magnetic fields and low temperatures. Specifically, determining experimental conditions where DNP involves thermal mixing, which denotes a spontaneous heat exchange between different spin reservoirs, remains challenging. We propose an experimental approach to ascertain the prevalence of the thermal mixing regime by monitoring characteristic signature properties of the time evolution of the hyperpolarization. We find that thermal mixing is the dominant DNP mechanism at high nitroxide radical concentrations, while a mixture of different mechanisms prevails at lower concentrations. © 2017 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Dynamic nuclear polarization (DNP) embraces a family of methods to increase signal intensities in nuclear magnetic resonance (NMR) spectroscopy. Despite extensive theoretical work that allows one to distinguish at least five distinct mechanisms, it remains challenging to determine the relative weights of the processes that are responsible for DNP in state-of-the-art experiments operating with stable organic radicals like nitroxides at high magnetic fields and low temperatures. Specifically, determining experimental conditions where DNP involves thermal mixing, which denotes a spontaneous heat exchange between different spin reservoirs, remains challenging. We propose an experimental approach to ascertain the prevalence of the thermal mixing regime by monitoring characteristic signature properties of the time evolution of the hyperpolarization. We find that thermal mixing is the dominant DNP mechanism at high nitroxide radical concentrations, while a mixture of different mechanisms prevails at lower concentrations. © 2017 American Chemical Society. |
Anisotropic longitudinal electronic relaxation affects DNP at cryogenic temperatures Article de journal E M M Weber; H Vezin; J G Kempf; G Bodenhausen; D Abergél; D Kurzbach Physical Chemistry Chemical Physics, 19 (24), p. 16087–16094, 2017. @article{Weber:2017, title = {Anisotropic longitudinal electronic relaxation affects DNP at cryogenic temperatures}, author = {E M M Weber and H Vezin and J G Kempf and G Bodenhausen and D Aberg\'{e}l and D Kurzbach}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85024380057&doi=10.1039%2fc7cp03242k&partnerID=40&md5=9d33aebbe861cd60df34b3c575d7f425}, doi = {10.1039/c7cp03242k}, year = {2017}, date = {2017-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {19}, number = {24}, pages = {16087--16094}, abstract = {We report the observation of anisotropic longitudinal electronic relaxation in nitroxide radicals under typical dynamic nuclear polarization conditions. This anisotropy affects the efficiency of dynamic nuclear polarization at cryogenic temperatures of 4 K and high magnetic fields of 6.7 T. Under our experimental conditions, the electron paramagnetic resonance spectrum of nitroxides such as TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl) is only partly averaged by electronic spectral diffusion, so that the relaxation times T1e(ω) vary across the spectrum. We demonstrate how the anisotropy of T1e(ω) can be taken into account in simple DNP models. © the Owner Societies 2017.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report the observation of anisotropic longitudinal electronic relaxation in nitroxide radicals under typical dynamic nuclear polarization conditions. This anisotropy affects the efficiency of dynamic nuclear polarization at cryogenic temperatures of 4 K and high magnetic fields of 6.7 T. Under our experimental conditions, the electron paramagnetic resonance spectrum of nitroxides such as TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidin-1-oxyl) is only partly averaged by electronic spectral diffusion, so that the relaxation times T1e(ω) vary across the spectrum. We demonstrate how the anisotropy of T1e(ω) can be taken into account in simple DNP models. © the Owner Societies 2017. |
Investigation of Intrinsically Disordered Proteins through Exchange with Hyperpolarized Water Article de journal D Kurzbach; E Canet; A G Flamm; A Jhajharia; E M M Weber; R Konrat; G Bodenhausen Angewandte Chemie - International Edition, 56 (1), p. 389–392, 2017. @article{Kurzbach:2017a, title = {Investigation of Intrinsically Disordered Proteins through Exchange with Hyperpolarized Water}, author = {D Kurzbach and E Canet and A G Flamm and A Jhajharia and E M M Weber and R Konrat and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85006414901&doi=10.1002%2fanie.201608903&partnerID=40&md5=2354f596f17737b81159a7a466e656ff}, doi = {10.1002/anie.201608903}, year = {2017}, date = {2017-01-01}, journal = {Angewandte Chemie - International Edition}, volume = {56}, number = {1}, pages = {389--392}, abstract = {Hyperpolarized water can selectively enhance NMR signals of rapidly exchanging protons in osteopontin (OPN), a metastasis-associated intrinsically disordered protein (IDP), at near-physiological pH and temperature. The transfer of magnetization from hyperpolarized water is limited to solvent-exposed residues and therefore selectively enhances signals in1H-15N correlation spectra. Binding to the polysaccharide heparin was found to induce the unfolding of preformed structural elements in OPN. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Hyperpolarized water can selectively enhance NMR signals of rapidly exchanging protons in osteopontin (OPN), a metastasis-associated intrinsically disordered protein (IDP), at near-physiological pH and temperature. The transfer of magnetization from hyperpolarized water is limited to solvent-exposed residues and therefore selectively enhances signals in1H-15N correlation spectra. Binding to the polysaccharide heparin was found to induce the unfolding of preformed structural elements in OPN. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Exciting Wide NMR Spectra of Static Solid Samples with Weak Radiofrequency Fields Article de journal D Carnevale; S Chinthalapalli; G Bodenhausen Zeitschrift fur Physikalische Chemie, 231 (3), p. 527–543, 2017. @article{Carnevale:2017, title = {Exciting Wide NMR Spectra of Static Solid Samples with Weak Radiofrequency Fields}, author = {D Carnevale and S Chinthalapalli and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85012216626&doi=10.1515%2fzpch-2016-0808&partnerID=40&md5=32259c37aa915ab1830416eb76105f61}, doi = {10.1515/zpch-2016-0808}, year = {2017}, date = {2017-01-01}, journal = {Zeitschrift fur Physikalische Chemie}, volume = {231}, number = {3}, pages = {527--543}, abstract = {Trains of short pulses in the manner of 'delays alternating with nutations for tailored excitation' (DANTE) have been applied to the Pake patterns of protons of water molecules trapped in a static powdered sample of barium chlorate monohydrate. The spin dynamics in the course of such experiments have been investigated by means of numerical simulations and compared with the ideal refocusing that can be achieved under magic-angle spinning (MAS). Solid echoes yield essentially undistorted lineshapes, in contrast to direct excitation without refocusing that leads to severe dispersions of the phases because of inhomogeneous interactions such as homonuclear dipolar couplings and anisotropic chemical shifts. The selectivity of DANTE sequences allows one to access 'slices' of the Pake pattern that can be related to particular crystallite orientations. Single-crystal spectra can therefore be extracted from powder spectra. A similar behavior is expected for both dipolar and quadrupolar echoes. © 2017 Walter de Gruyter GmbH, Berlin/Boston.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Trains of short pulses in the manner of 'delays alternating with nutations for tailored excitation' (DANTE) have been applied to the Pake patterns of protons of water molecules trapped in a static powdered sample of barium chlorate monohydrate. The spin dynamics in the course of such experiments have been investigated by means of numerical simulations and compared with the ideal refocusing that can be achieved under magic-angle spinning (MAS). Solid echoes yield essentially undistorted lineshapes, in contrast to direct excitation without refocusing that leads to severe dispersions of the phases because of inhomogeneous interactions such as homonuclear dipolar couplings and anisotropic chemical shifts. The selectivity of DANTE sequences allows one to access 'slices' of the Pake pattern that can be related to particular crystallite orientations. Single-crystal spectra can therefore be extracted from powder spectra. A similar behavior is expected for both dipolar and quadrupolar echoes. © 2017 Walter de Gruyter GmbH, Berlin/Boston. |
Double cross polarization for the indirect detection of nitrogen-14 nuclei in magic angle spinning NMR spectroscopy Article de journal D Carnevale; X Ji; G Bodenhausen Journal of Chemical Physics, 147 (18), 2017. @article{Carnevale:2017a, title = {Double cross polarization for the indirect detection of nitrogen-14 nuclei in magic angle spinning NMR spectroscopy}, author = {D Carnevale and X Ji and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85034078953&doi=10.1063%2f1.5000689&partnerID=40&md5=7b31b83894df20496dfd7e71f6c9c6ba}, doi = {10.1063/1.5000689}, year = {2017}, date = {2017-01-01}, journal = {Journal of Chemical Physics}, volume = {147}, number = {18}, abstract = {Nitrogen-14 NMR spectra at fast magic-angle spinning rates can be acquired indirectly by means of two-dimensional techniques based on double cross polarization transfer 1H → 14N →1H. Experimental evidence is given for polycrystalline samples of glycine, l-histidine, and the dipeptide Ala-Gly. Either one-bond or long-range correlations can be favored by choosing the length of the cross polarization contact pulses. Longer contact pulses allow the detection of unprotonated nitrogen sites. In contrast to earlier methods that exploited second-order quadrupolar/dipolar cross-terms, cross polarization operates in the manner of the method of Hartmann and Hahn, even for 14N quadrupolar couplings up to 4 MHz. Simulations explain why amorphous samples tend to give rise to featureless spectra because the 14N quadrupolar interactions may vary dramatically with the lattice environment. The experiments are straightforward to set up and are shown to be effective for different nitrogen environments and robust with respect to the rf-field strengths and to the 14N carrier frequency during cross polarization. The efficiency of indirect detection of 14N nuclei by double cross polarization is shown to be similar to that of isotopically enriched 13C nuclei. © 2017 Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nitrogen-14 NMR spectra at fast magic-angle spinning rates can be acquired indirectly by means of two-dimensional techniques based on double cross polarization transfer 1H → 14N →1H. Experimental evidence is given for polycrystalline samples of glycine, l-histidine, and the dipeptide Ala-Gly. Either one-bond or long-range correlations can be favored by choosing the length of the cross polarization contact pulses. Longer contact pulses allow the detection of unprotonated nitrogen sites. In contrast to earlier methods that exploited second-order quadrupolar/dipolar cross-terms, cross polarization operates in the manner of the method of Hartmann and Hahn, even for 14N quadrupolar couplings up to 4 MHz. Simulations explain why amorphous samples tend to give rise to featureless spectra because the 14N quadrupolar interactions may vary dramatically with the lattice environment. The experiments are straightforward to set up and are shown to be effective for different nitrogen environments and robust with respect to the rf-field strengths and to the 14N carrier frequency during cross polarization. The efficiency of indirect detection of 14N nuclei by double cross polarization is shown to be similar to that of isotopically enriched 13C nuclei. © 2017 Author(s). |
Determination of fast exchange of protons by NMR spectroscopy Article de journal E Canet; F Kateb; T F Segawa; A A Sehgal; G Bodenhausen; P Pelupessy Actualite Chimique, (416), p. 19–25, 2017. @article{Canet:2017, title = {Determination of fast exchange of protons by NMR spectroscopy}, author = {E Canet and F Kateb and T F Segawa and A A Sehgal and G Bodenhausen and P Pelupessy}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85032975115&partnerID=40&md5=3f76f5bc71e9721294e608126488a7b6}, year = {2017}, date = {2017-01-01}, journal = {Actualite Chimique}, number = {416}, pages = {19--25}, abstract = {Owing to the development of new methods that exploit nuclear magnetic resonance (NMR), it has become possible to determine exchange rates of protons that hop between amino acids and water. This paper describes how these novel methods result from a long history, and how the authors have been able to push the limits in terms of exchange rates by nearly two orders of magnitude, up to 105 events per second.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Owing to the development of new methods that exploit nuclear magnetic resonance (NMR), it has become possible to determine exchange rates of protons that hop between amino acids and water. This paper describes how these novel methods result from a long history, and how the authors have been able to push the limits in terms of exchange rates by nearly two orders of magnitude, up to 105 events per second. |
Single-Scan 13C Diffusion-Ordered NMR Spectroscopy of DNP-Hyperpolarised Substrates Article de journal L Guduff; D Kurzbach; C van Heijenoort; D Abergel; J -N Dumez Chemistry - A European Journal, 23 (66), p. 16722–16727, 2017. @article{Guduff:2017, title = {Single-Scan 13C Diffusion-Ordered NMR Spectroscopy of DNP-Hyperpolarised Substrates}, author = {L Guduff and D Kurzbach and C van Heijenoort and D Abergel and J -N Dumez}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85030115327&doi=10.1002%2fchem.201703300&partnerID=40&md5=79d87b5569bb4558d83ce5b0ef10f083}, doi = {10.1002/chem.201703300}, year = {2017}, date = {2017-01-01}, journal = {Chemistry - A European Journal}, volume = {23}, number = {66}, pages = {16722--16727}, abstract = {Diffusion-ordered NMR spectroscopy (DOSY) is a powerful approach for the analysis of molecular mixtures, yet its application range is limited by the relatively low sensitivity of NMR. We show here that spectrally resolved 13C DOSY data can be collected, in a single scan, for substrates hyperpolarised by dissolution dynamic nuclear polarisation (D-DNP), which provides signal enhancements of several orders of magnitude. For this we use a convection-compensation pulse scheme, which we also analyse by numerical simulation. The proposed method further allows the acquisition of several consecutive DOSY spectra in a single D-DNP experiment. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Diffusion-ordered NMR spectroscopy (DOSY) is a powerful approach for the analysis of molecular mixtures, yet its application range is limited by the relatively low sensitivity of NMR. We show here that spectrally resolved 13C DOSY data can be collected, in a single scan, for substrates hyperpolarised by dissolution dynamic nuclear polarisation (D-DNP), which provides signal enhancements of several orders of magnitude. For this we use a convection-compensation pulse scheme, which we also analyse by numerical simulation. The proposed method further allows the acquisition of several consecutive DOSY spectra in a single D-DNP experiment. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim |
Decomposition of proteins into dynamic units from atomic cross-correlation functions Article de journal P Calligari; M Gerolin; D Abergel; A Polimeno Journal of Chemical Theory and Computation, 13 (1), p. 309–319, 2017. @article{Calligari:2017, title = {Decomposition of proteins into dynamic units from atomic cross-correlation functions}, author = {P Calligari and M Gerolin and D Abergel and A Polimeno}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85016270051&doi=10.1021%2facs.jctc.6b00702&partnerID=40&md5=ab88646baeb0653b03b259bb4fb41d26}, doi = {10.1021/acs.jctc.6b00702}, year = {2017}, date = {2017-01-01}, journal = {Journal of Chemical Theory and Computation}, volume = {13}, number = {1}, pages = {309--319}, abstract = {In this article, we present a clustering method of atoms in proteins based on the analysis of the correlation times of interatomic distance correlation functions computed from MD simulations. The goal is to provide a coarse-grained description of the protein in terms of fewer elements that can be treated as dynamically independent subunits. Importantly, this domain decomposition method does not take into account structural properties of the protein. Instead, the clustering of protein residues in terms of networks of dynamically correlated domains is defined on the basis of the effective correlation times of the pair distance correlation functions. For these properties, our method stands as a complementary analysis to the customary protein decomposition in terms of quasi-rigid, structure-based domains. Results obtained for a prototypal protein structure illustrate the approach proposed. © 2016 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In this article, we present a clustering method of atoms in proteins based on the analysis of the correlation times of interatomic distance correlation functions computed from MD simulations. The goal is to provide a coarse-grained description of the protein in terms of fewer elements that can be treated as dynamically independent subunits. Importantly, this domain decomposition method does not take into account structural properties of the protein. Instead, the clustering of protein residues in terms of networks of dynamically correlated domains is defined on the basis of the effective correlation times of the pair distance correlation functions. For these properties, our method stands as a complementary analysis to the customary protein decomposition in terms of quasi-rigid, structure-based domains. Results obtained for a prototypal protein structure illustrate the approach proposed. © 2016 American Chemical Society. |
Optimizing symmetry-based recoupling sequences in solid-state NMR by pulse-transient compensation and asynchronous implementation Article de journal Johannes Hellwagner; Kshama Sharma; Kong Ooi Tan; Johannes J Wittmann; Beat H Meier; Perunthiruthy K Madhu; Matthias Ernst The Journal of chemical physics, 146 (24), p. 244202, 2017. @article{hellwagner2017optimizing, title = {Optimizing symmetry-based recoupling sequences in solid-state NMR by pulse-transient compensation and asynchronous implementation}, author = {Johannes Hellwagner and Kshama Sharma and Kong Ooi Tan and Johannes J Wittmann and Beat H Meier and Perunthiruthy K Madhu and Matthias Ernst}, year = {2017}, date = {2017-01-01}, journal = {The Journal of chemical physics}, volume = {146}, number = {24}, pages = {244202}, publisher = {AIP Publishing}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Peptide and protein dynamics and low-temperature/DNP magic angle spinning NMR Article de journal Qing Zhe Ni; Evgeny Markhasin; Thach V Can; Björn Corzilius; Kong Ooi Tan; Alexander B Barnes; Eugenio Daviso; Yongchao Su; Judith Herzfeld; Robert G Griffin The Journal of Physical Chemistry B, 121 (19), p. 4997–5006, 2017. @article{ni2017peptide, title = {Peptide and protein dynamics and low-temperature/DNP magic angle spinning NMR}, author = {Qing Zhe Ni and Evgeny Markhasin and Thach V Can and Björn Corzilius and Kong Ooi Tan and Alexander B Barnes and Eugenio Daviso and Yongchao Su and Judith Herzfeld and Robert G Griffin}, year = {2017}, date = {2017-01-01}, journal = {The Journal of Physical Chemistry B}, volume = {121}, number = {19}, pages = {4997\textendash5006}, publisher = {American Chemical Society}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2016 |
Collisional cross-section of water molecules in vapour studied by means of 1H relaxation in NMR Article de journal D Mammoli; E Canet; R Buratto; P Miéville; L Helm; G Bodenhausen Scientific Reports, 6 , 2016. @article{Mammoli:2016, title = {Collisional cross-section of water molecules in vapour studied by means of 1H relaxation in NMR}, author = {D Mammoli and E Canet and R Buratto and P Mi\'{e}ville and L Helm and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85007239998&doi=10.1038%2fsrep38492&partnerID=40&md5=39b1fe17ac1f8524c81635fd14cf0ba3}, doi = {10.1038/srep38492}, year = {2016}, date = {2016-01-01}, journal = {Scientific Reports}, volume = {6}, abstract = {In gas phase, collisions that affect the rotational angular momentum lead to the return of the magnetization to its equilibrium (relaxation) in Nuclear Magnetic Resonance (NMR). To the best of our knowledge, the longitudinal relaxation rates R1 = 1/T1 of protons in H2O and HDO have never been measured in gas phase. We report R1 in gas phase in a field of 18.8 T, i.e., at a proton Larmor frequency ν0 = 800 MHz, at temperatures between 353 and 373 K and pressures between 9 and 101 kPa. By assuming that spin rotation is the dominant relaxation mechanism, we estimated the effective cross-section σJ for the transfer of angular momentum due to H2O-H2O and HDO-D2O collisions. Our results allow one to test theoretical predictions of the intermolecular potential of water in gas phase. © The Author(s) 2016.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In gas phase, collisions that affect the rotational angular momentum lead to the return of the magnetization to its equilibrium (relaxation) in Nuclear Magnetic Resonance (NMR). To the best of our knowledge, the longitudinal relaxation rates R1 = 1/T1 of protons in H2O and HDO have never been measured in gas phase. We report R1 in gas phase in a field of 18.8 T, i.e., at a proton Larmor frequency ν0 = 800 MHz, at temperatures between 353 and 373 K and pressures between 9 and 101 kPa. By assuming that spin rotation is the dominant relaxation mechanism, we estimated the effective cross-section σJ for the transfer of angular momentum due to H2O-H2O and HDO-D2O collisions. Our results allow one to test theoretical predictions of the intermolecular potential of water in gas phase. © The Author(s) 2016. |
Ligand-Protein Affinity Studies Using Long-Lived States of Fluorine-19 Nuclei Article de journal R Buratto; D Mammoli; E Canet; G Bodenhausen Journal of Medicinal Chemistry, 59 (5), p. 1960–1966, 2016. @article{Buratto:2016, title = {Ligand-Protein Affinity Studies Using Long-Lived States of Fluorine-19 Nuclei}, author = {R Buratto and D Mammoli and E Canet and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84960925798&doi=10.1021%2facs.jmedchem.5b01583&partnerID=40&md5=56abcf88f773a71d7e4f8fbfbe82df21}, doi = {10.1021/acs.jmedchem.5b01583}, year = {2016}, date = {2016-01-01}, journal = {Journal of Medicinal Chemistry}, volume = {59}, number = {5}, pages = {1960--1966}, abstract = {The lifetimes TLLS of long-lived states or TLLC of long-lived coherences can be used for the accurate determination of dissociation constants of weak protein-ligand complexes. The remarkable contrast between signals derived from LLS or LLC in free and bound ligands can be exploited to search for weak binders with large dissociation constants KD > 1 mM that are important for fragment-based drug discovery but may escape detection by other screening techniques. Alternatively, the high sensitivity of the proposed method can be exploited to work with large ligand-to-protein ratios, with an evident advantage of reduced consumption of precious proteins. The detection of 19F-19F long-lived states in suitably designed fluorinated spy molecules allows one to perform competition binding experiments with high sensitivity while avoiding signal overlap that tends to hamper the interpretation of proton spectra of mixtures. © 2016 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The lifetimes TLLS of long-lived states or TLLC of long-lived coherences can be used for the accurate determination of dissociation constants of weak protein-ligand complexes. The remarkable contrast between signals derived from LLS or LLC in free and bound ligands can be exploited to search for weak binders with large dissociation constants KD > 1 mM that are important for fragment-based drug discovery but may escape detection by other screening techniques. Alternatively, the high sensitivity of the proposed method can be exploited to work with large ligand-to-protein ratios, with an evident advantage of reduced consumption of precious proteins. The detection of 19F-19F long-lived states in suitably designed fluorinated spy molecules allows one to perform competition binding experiments with high sensitivity while avoiding signal overlap that tends to hamper the interpretation of proton spectra of mixtures. © 2016 American Chemical Society. |
Kinetic isotope effects for fast deuterium and proton exchange rates Article de journal E Canet; D Mammoli; P Kadeřávek; P Pelupessy; G Bodenhausen Physical Chemistry Chemical Physics, 18 (15), p. 10144–10151, 2016. @article{Canet:2016, title = {Kinetic isotope effects for fast deuterium and proton exchange rates}, author = {E Canet and D Mammoli and P Kade\v{r}\'{a}vek and P Pelupessy and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84965043079&doi=10.1039%2fc5cp07459b&partnerID=40&md5=4400fb526a30354ed99294920d784850}, doi = {10.1039/c5cp07459b}, year = {2016}, date = {2016-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {18}, number = {15}, pages = {10144--10151}, abstract = {By monitoring the effect of deuterium decoupling on the decay of transverse 15N magnetization in D-15N spin pairs during multiple-refocusing echo sequences, we have determined fast D-D exchange rates kD and compared them with fast H-H exchange rates kH in tryptophan to determine the kinetic isotope effect as a function of pH and temperature. © the Owner Societies 2016.}, keywords = {}, pubstate = {published}, tppubtype = {article} } By monitoring the effect of deuterium decoupling on the decay of transverse 15N magnetization in D-15N spin pairs during multiple-refocusing echo sequences, we have determined fast D-D exchange rates kD and compared them with fast H-H exchange rates kH in tryptophan to determine the kinetic isotope effect as a function of pH and temperature. © the Owner Societies 2016. |
Hyperpolarization of Frozen Hydrocarbon Gases by Dynamic Nuclear Polarization at 1.2 K Article de journal B Vuichoud; E Canet; J Milani; A Bornet; D Baudouin; L Veyre; D Gajan; L Emsley; A Lesage; C Copéret; C Thieuleux; G Bodenhausen; I Koptyug; S Jannin Journal of Physical Chemistry Letters, 7 (16), p. 3235–3239, 2016. @article{Vuichoud:2016, title = {Hyperpolarization of Frozen Hydrocarbon Gases by Dynamic Nuclear Polarization at 1.2 K}, author = {B Vuichoud and E Canet and J Milani and A Bornet and D Baudouin and L Veyre and D Gajan and L Emsley and A Lesage and C Cop\'{e}ret and C Thieuleux and G Bodenhausen and I Koptyug and S Jannin}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983762693&doi=10.1021%2facs.jpclett.6b01345&partnerID=40&md5=7a2f09dbdb0223ca9b52725174917c4c}, doi = {10.1021/acs.jpclett.6b01345}, year = {2016}, date = {2016-01-01}, journal = {Journal of Physical Chemistry Letters}, volume = {7}, number = {16}, pages = {3235--3239}, abstract = {We report a simple and general method for the hyperpolarization of condensed gases by dynamic nuclear polarization (DNP). The gases are adsorbed in the pores of structured mesoporous silica matrices known as HYPSOs (HYper Polarizing SOlids) that have paramagnetic polarizing agents covalently bound to the surface of the mesopores. DNP is performed at low temperatures and moderate magnetic fields (T = 1.2 K and B0 = 6.7 T). Frequency-modulated microwave irradiation is applied close to the electron spin resonance frequency (f = 188.3 GHz), and the electron spin polarization of the polarizing agents of HYPSO is transferred to the nuclear spins of the frozen gas. A proton polarization as high as P(1H) = 70% can be obtained, which can be subsequently transferred to 13C in natural abundance by cross-polarization, yielding up to P(13C) = 27% for ethylene. © 2016 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report a simple and general method for the hyperpolarization of condensed gases by dynamic nuclear polarization (DNP). The gases are adsorbed in the pores of structured mesoporous silica matrices known as HYPSOs (HYper Polarizing SOlids) that have paramagnetic polarizing agents covalently bound to the surface of the mesopores. DNP is performed at low temperatures and moderate magnetic fields (T = 1.2 K and B0 = 6.7 T). Frequency-modulated microwave irradiation is applied close to the electron spin resonance frequency (f = 188.3 GHz), and the electron spin polarization of the polarizing agents of HYPSO is transferred to the nuclear spins of the frozen gas. A proton polarization as high as P(1H) = 70% can be obtained, which can be subsequently transferred to 13C in natural abundance by cross-polarization, yielding up to P(13C) = 27% for ethylene. © 2016 American Chemical Society. |
Homonuclear decoupling for spectral simplification of carbon-13 enriched molecules in solution-state NMR enhanced by dissolution DNP Article de journal S Chinthalapalli; A Bornet; D Carnevale; S Jannin; G Bodenhausen Physical Chemistry Chemical Physics, 18 (16), p. 11480–11487, 2016. @article{Chinthalapalli:2016, title = {Homonuclear decoupling for spectral simplification of carbon-13 enriched molecules in solution-state NMR enhanced by dissolution DNP}, author = {S Chinthalapalli and A Bornet and D Carnevale and S Jannin and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84967239612&doi=10.1039%2fc5cp07884a&partnerID=40&md5=ee5e74b0d9a19de9049ec12d01917b0f}, doi = {10.1039/c5cp07884a}, year = {2016}, date = {2016-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {18}, number = {16}, pages = {11480--11487}, abstract = {Complex overlapping multiplets due to scalar couplings nJ(13C, 13C) in fully 13C-enriched molecules can be simplified by polychromatic irradiation of selected spins. The signal intensities of the remaining non-irradiated signals are proportional to the concentrations, as shown in this work for the anomeric 13C signals of the α- and β-conformers of glucose. Homonuclear decoupling can therefore be useful for quantitative NMR studies. The resulting decoupled lineshapes show residual fine structures that have been investigated by means of numerical simulations. Simulations also show that homonuclear decoupling schemes remain effective despite inhomogeneous static fields that tend to hamper in cellulo and in vivo studies. Homonuclear decoupling schemes can be combined with dissolution DNP to obtain signal enhancements of more than four orders of magnitude. Polychromatic irradiation of selected spins does not cause significant losses of hyperpolarization of the remaining non-irradiated spins. © the Owner Societies 2016.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Complex overlapping multiplets due to scalar couplings nJ(13C, 13C) in fully 13C-enriched molecules can be simplified by polychromatic irradiation of selected spins. The signal intensities of the remaining non-irradiated signals are proportional to the concentrations, as shown in this work for the anomeric 13C signals of the α- and β-conformers of glucose. Homonuclear decoupling can therefore be useful for quantitative NMR studies. The resulting decoupled lineshapes show residual fine structures that have been investigated by means of numerical simulations. Simulations also show that homonuclear decoupling schemes remain effective despite inhomogeneous static fields that tend to hamper in cellulo and in vivo studies. Homonuclear decoupling schemes can be combined with dissolution DNP to obtain signal enhancements of more than four orders of magnitude. Polychromatic irradiation of selected spins does not cause significant losses of hyperpolarization of the remaining non-irradiated spins. © the Owner Societies 2016. |
Highly Repeatable Dissolution Dynamic Nuclear Polarization for Heteronuclear NMR Metabolomics Article de journal A Bornet; M Maucourt; C Deborde; D Jacob; J Milani; B Vuichoud; X Ji; J -N Dumez; A Moing; G Bodenhausen; S Jannin; P Giraudeau Analytical Chemistry, 88 (12), p. 6179–6183, 2016. @article{Bornet:2016, title = {Highly Repeatable Dissolution Dynamic Nuclear Polarization for Heteronuclear NMR Metabolomics}, author = {A Bornet and M Maucourt and C Deborde and D Jacob and J Milani and B Vuichoud and X Ji and J -N Dumez and A Moing and G Bodenhausen and S Jannin and P Giraudeau}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84975801435&doi=10.1021%2facs.analchem.6b01094&partnerID=40&md5=7271510044ca0ce1b48babc9f27a264e}, doi = {10.1021/acs.analchem.6b01094}, year = {2016}, date = {2016-01-01}, journal = {Analytical Chemistry}, volume = {88}, number = {12}, pages = {6179--6183}, abstract = {At natural 13C abundance, metabolomics based on heteronuclear NMR is limited by sensitivity. We have recently demonstrated how hyperpolarization by dissolution dynamic nuclear polarization (D-DNP) assisted by cross-polarization (CP) provides a reliable way of enhancing the sensitivity of heteronuclear NMR in dilute mixtures of metabolites. In this Technical Note, we evaluate the precision of this experimental approach, a critical point for applications to metabolomics. The higher the repeatability, the greater the likelihood that one can detect small biologically relevant differences between samples. The average repeatability of our state-of-the-art D-DNP NMR equipment for samples of metabolomic relevance (20 mg dry weight tomato extracts) is 3.6% for signals above the limit of quantification (LOQ) and 6.4% when all the signals above the limit of detection (LOD) are taken into account. This first report on the repeatability of D-DNP highlights the compatibility of the technique with the requirements of metabolomics and confirms its potential as an analytical tool for such applications. © 2016 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } At natural 13C abundance, metabolomics based on heteronuclear NMR is limited by sensitivity. We have recently demonstrated how hyperpolarization by dissolution dynamic nuclear polarization (D-DNP) assisted by cross-polarization (CP) provides a reliable way of enhancing the sensitivity of heteronuclear NMR in dilute mixtures of metabolites. In this Technical Note, we evaluate the precision of this experimental approach, a critical point for applications to metabolomics. The higher the repeatability, the greater the likelihood that one can detect small biologically relevant differences between samples. The average repeatability of our state-of-the-art D-DNP NMR equipment for samples of metabolomic relevance (20 mg dry weight tomato extracts) is 3.6% for signals above the limit of quantification (LOQ) and 6.4% when all the signals above the limit of detection (LOD) are taken into account. This first report on the repeatability of D-DNP highlights the compatibility of the technique with the requirements of metabolomics and confirms its potential as an analytical tool for such applications. © 2016 American Chemical Society. |
Filterable Agents for Hyperpolarization of Water, Metabolites, and Proteins Article de journal B Vuichoud; A Bornet; F de Nanteuil; J Milani; E Canet; X Ji; P Miéville; E Weber; D Kurzbach; A Flamm; R Konrat; A D Gossert; S Jannin; G Bodenhausen Chemistry - A European Journal, 22 (41), p. 14696–14700, 2016. @article{Vuichoud:2016a, title = {Filterable Agents for Hyperpolarization of Water, Metabolites, and Proteins}, author = {B Vuichoud and A Bornet and F de Nanteuil and J Milani and E Canet and X Ji and P Mi\'{e}ville and E Weber and D Kurzbach and A Flamm and R Konrat and A D Gossert and S Jannin and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988672502&doi=10.1002%2fchem.201602506&partnerID=40&md5=ea462f461e4105109278fd1b33dded67}, doi = {10.1002/chem.201602506}, year = {2016}, date = {2016-01-01}, journal = {Chemistry - A European Journal}, volume = {22}, number = {41}, pages = {14696--14700}, abstract = {Hyperpolarization is generated by dissolution dynamic nuclear polarization (d-DNP) using a polymer-based polarizing agent dubbed FLAP (filterable labeled agents for polarization). It consists of a thermo-responsive poly(N-isopropylacrylamide), also known as pNiPAM-COOH, labeled with nitroxide radicals. The polymer powder is impregnated with an arbitrary solution of interest and frozen as is. Dissolution is followed by a simple filtration, leading to hyperpolarized solutions free from any contaminants. We demonstrated the use of FLAP to hyperpolarize partially deuterated water up to P(1H)=6 % with a long relaxation T1>36 s characteristic of high purity. Water hyperpolarization can be transferred to drugs, metabolites, or proteins that are waiting in an NMR spectrometer, either by exchange of labile protons or through intermolecular Overhauser effects. We also show that FLAPs are suitable polarizing agents for13C-labeled metabolites such as pyruvate, acetate, and alanine. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Hyperpolarization is generated by dissolution dynamic nuclear polarization (d-DNP) using a polymer-based polarizing agent dubbed FLAP (filterable labeled agents for polarization). It consists of a thermo-responsive poly(N-isopropylacrylamide), also known as pNiPAM-COOH, labeled with nitroxide radicals. The polymer powder is impregnated with an arbitrary solution of interest and frozen as is. Dissolution is followed by a simple filtration, leading to hyperpolarized solutions free from any contaminants. We demonstrated the use of FLAP to hyperpolarize partially deuterated water up to P(1H)=6 % with a long relaxation T1>36 s characteristic of high purity. Water hyperpolarization can be transferred to drugs, metabolites, or proteins that are waiting in an NMR spectrometer, either by exchange of labile protons or through intermolecular Overhauser effects. We also show that FLAPs are suitable polarizing agents for13C-labeled metabolites such as pyruvate, acetate, and alanine. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim |
Dissolution dynamic nuclear polarization of deuterated molecules enhanced by cross- polarization Article de journal D Kurzbach; E M M Weber; A Jhajharia; S F Cousin; A Sadet; S Marhabaie; E Canet; N Birlirakis; J Milani; S Jannin; D Eshchenko; A Hassan; R Melzi; S Luetolf; M Sacher; M Rossire; J Kempf; J A B Lohman; M Weller; G Bodenhausen; D Abergel Journal of Chemical Physics, 145 (19), 2016. @article{Kurzbach:2016b, title = {Dissolution dynamic nuclear polarization of deuterated molecules enhanced by cross- polarization}, author = {D Kurzbach and E M M Weber and A Jhajharia and S F Cousin and A Sadet and S Marhabaie and E Canet and N Birlirakis and J Milani and S Jannin and D Eshchenko and A Hassan and R Melzi and S Luetolf and M Sacher and M Rossire and J Kempf and J A B Lohman and M Weller and G Bodenhausen and D Abergel}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84998723887&doi=10.1063%2f1.4967402&partnerID=40&md5=5682345f396b249d7aa641f3c27a8850}, doi = {10.1063/1.4967402}, year = {2016}, date = {2016-01-01}, journal = {Journal of Chemical Physics}, volume = {145}, number = {19}, abstract = {We present novel means to hyperpolarize deuterium nuclei in 13CD2 groups at cryogenic temperatures. The method is based on cross-polarization from 1H to 13C and does not require any radio-frequency fields applied to the deuterium nuclei. After rapid dissolution, a new class of long-lived spin states can be detected indirectly by 13C NMR in solution. These long-lived states result from a sextet-triplet imbalance (STI) that involves the two equivalent deuterons with spin I = 1. An STI has similar properties as a triplet-singlet imbalance that can occur in systems with two equivalent I = 1/2 spins. Although the lifetimes TSTI are shorter than T1(Cz), they can exceed the life-time T1(Dz) of deuterium Zeeman magnetization by a factor of more than 20. © 2016 Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } We present novel means to hyperpolarize deuterium nuclei in 13CD2 groups at cryogenic temperatures. The method is based on cross-polarization from 1H to 13C and does not require any radio-frequency fields applied to the deuterium nuclei. After rapid dissolution, a new class of long-lived spin states can be detected indirectly by 13C NMR in solution. These long-lived states result from a sextet-triplet imbalance (STI) that involves the two equivalent deuterons with spin I = 1. An STI has similar properties as a triplet-singlet imbalance that can occur in systems with two equivalent I = 1/2 spins. Although the lifetimes TSTI are shorter than T1(Cz), they can exceed the life-time T1(Dz) of deuterium Zeeman magnetization by a factor of more than 20. © 2016 Author(s). |
A generalized theoretical framework for the description of spin decoupling in solid-state MAS NMR: Offset effect on decoupling performance Article de journal Kong Ooi Tan; Vipin Agarwal; Beat H Meier; Matthias Ernst The Journal of chemical physics, 145 (9), p. 094201, 2016. @article{tan2016generalized, title = {A generalized theoretical framework for the description of spin decoupling in solid-state MAS NMR: Offset effect on decoupling performance}, author = {Kong Ooi Tan and Vipin Agarwal and Beat H Meier and Matthias Ernst}, year = {2016}, date = {2016-01-01}, journal = {The Journal of chemical physics}, volume = {145}, number = {9}, pages = {094201}, publisher = {AIP Publishing}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Improved transfer efficiencies in radio-frequency-driven recoupling solid-state NMR by adiabatic sweep through the dipolar recoupling condition Article de journal Lasse A Straasø; Ravi Shankar; Kong Ooi Tan; Johannes Hellwagner; Beat H Meier; Michael Ryan Hansen; Niels Chr Nielsen; Thomas Vosegaard; Matthias Ernst; Anders B Nielsen The Journal of chemical physics, 145 (3), p. 034201, 2016. @article{straaso2016improved, title = {Improved transfer efficiencies in radio-frequency-driven recoupling solid-state NMR by adiabatic sweep through the dipolar recoupling condition}, author = {Lasse A Straas\o and Ravi Shankar and Kong Ooi Tan and Johannes Hellwagner and Beat H Meier and Michael Ryan Hansen and Niels Chr Nielsen and Thomas Vosegaard and Matthias Ernst and Anders B Nielsen}, year = {2016}, date = {2016-01-01}, journal = {The Journal of chemical physics}, volume = {145}, number = {3}, pages = {034201}, publisher = {AIP Publishing}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Theoretical description of RESPIRATION-CP Article de journal Anders B Nielsen; Kong Ooi Tan; Ravi Shankar; Susanne Penzel; Riccardo Cadalbert; Ago Samoson; Beat H Meier; Matthias Ernst Chemical Physics Letters, 645 , p. 150–156, 2016. @article{nielsen2016theoretical, title = {Theoretical description of RESPIRATION-CP}, author = {Anders B Nielsen and Kong Ooi Tan and Ravi Shankar and Susanne Penzel and Riccardo Cadalbert and Ago Samoson and Beat H Meier and Matthias Ernst}, year = {2016}, date = {2016-01-01}, journal = {Chemical Physics Letters}, volume = {645}, pages = {150\textendash156}, publisher = {North-Holland}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Sample Shuttling Relaxometry of Contrast Agents: NMRD Profiles above 1 Ŧ with a Single Device Article de journal Y Gossuin; Z Serhan; L Sandiford; D Henrard; T Marquardsen; R T M de Rosales; D Sakellariou; F Ferrage Applied Magnetic Resonance, 47 (3), p. 237–246, 2016. @article{Gossuin:2016, title = {Sample Shuttling Relaxometry of Contrast Agents: NMRD Profiles above 1 {T} with a Single Device}, author = {Y Gossuin and Z Serhan and L Sandiford and D Henrard and T Marquardsen and R T M de Rosales and D Sakellariou and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84956993966&doi=10.1007%2fs00723-015-0751-7&partnerID=40&md5=b321e483eb6d41b44065a0926ca8de06}, doi = {10.1007/s00723-015-0751-7}, year = {2016}, date = {2016-01-01}, journal = {Applied Magnetic Resonance}, volume = {47}, number = {3}, pages = {237--246}, abstract = {Nuclear magnetic relaxation dispersion (NMRD) profiles are essential tools to evaluate the efficiency and investigate the properties of magnetic compounds used as contrast agents for magnetic resonance imaging (MRI), namely gadolinium chelates and superparamagnetic iron oxide particles. These curves represent the evolution of proton relaxation rates with the magnetic field. NMRD profiles are unparalleled to probe extensively the spectral density function involved in the relaxation of water in the presence of the paramagnetic ion or the magnetic nanoparticles. This makes such profiles an excellent test of the adequacy of a theoretical relaxation model and allow for a predictive approach to the development and optimization of contrast agents. From a practical point of view they also allow to evaluate the efficiency of a contrast agent in a certain range of magnetic fields. Nowadays, these curves are recorded with commercial fast field cycling devices, often limited to a maximum Larmor frequency of 40 MHz (0.94 T). In this article, relaxation data were acquired on a wide range of magnetic fields, from 3.5 × 10−4 to 14 T, for a gadolinium-based contrast agent and for PEGylated iron oxide nanoparticles. We show that the low-field NMRD curves can be completed with high-field data obtained on a shuttle apparatus device using the superconductive magnet of a high-field spectrometer. This allows a better characterization of the contrast agents at relevant magnetic fields for clinical and preclinical MRI, but also refines the experimental data that could be used for the validation of relaxation models. © 2016, The Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nuclear magnetic relaxation dispersion (NMRD) profiles are essential tools to evaluate the efficiency and investigate the properties of magnetic compounds used as contrast agents for magnetic resonance imaging (MRI), namely gadolinium chelates and superparamagnetic iron oxide particles. These curves represent the evolution of proton relaxation rates with the magnetic field. NMRD profiles are unparalleled to probe extensively the spectral density function involved in the relaxation of water in the presence of the paramagnetic ion or the magnetic nanoparticles. This makes such profiles an excellent test of the adequacy of a theoretical relaxation model and allow for a predictive approach to the development and optimization of contrast agents. From a practical point of view they also allow to evaluate the efficiency of a contrast agent in a certain range of magnetic fields. Nowadays, these curves are recorded with commercial fast field cycling devices, often limited to a maximum Larmor frequency of 40 MHz (0.94 T). In this article, relaxation data were acquired on a wide range of magnetic fields, from 3.5 × 10−4 to 14 T, for a gadolinium-based contrast agent and for PEGylated iron oxide nanoparticles. We show that the low-field NMRD curves can be completed with high-field data obtained on a shuttle apparatus device using the superconductive magnet of a high-field spectrometer. This allows a better characterization of the contrast agents at relevant magnetic fields for clinical and preclinical MRI, but also refines the experimental data that could be used for the validation of relaxation models. © 2016, The Author(s). |
Protein dynamics from nuclear magnetic relaxation Article de journal C Charlier; S F Cousin; F Ferrage Chemical Society Reviews, 45 (9), p. 2410–2422, 2016. @article{Charlier:2016, title = {Protein dynamics from nuclear magnetic relaxation}, author = {C Charlier and S F Cousin and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84968834767&doi=10.1039%2fc5cs00832h&partnerID=40&md5=d1695ff88ad83ccfad98b81c2681b00d}, doi = {10.1039/c5cs00832h}, year = {2016}, date = {2016-01-01}, journal = {Chemical Society Reviews}, volume = {45}, number = {9}, pages = {2410--2422}, abstract = {Nuclear magnetic resonance is a ubiquitous spectroscopic tool to explore molecules with atomic resolution. Nuclear magnetic relaxation is intimately connected to molecular motions. Many methods and models have been developed to measure and interpret the characteristic rates of nuclear magnetic relaxation in proteins. These approaches shed light on a rich and diverse range of motions covering timescales from picoseconds to seconds. Here, we introduce some of the basic concepts upon which these approaches are built and provide a series of illustrations. © 2016 The Royal Society of Chemistry.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nuclear magnetic resonance is a ubiquitous spectroscopic tool to explore molecules with atomic resolution. Nuclear magnetic relaxation is intimately connected to molecular motions. Many methods and models have been developed to measure and interpret the characteristic rates of nuclear magnetic relaxation in proteins. These approaches shed light on a rich and diverse range of motions covering timescales from picoseconds to seconds. Here, we introduce some of the basic concepts upon which these approaches are built and provide a series of illustrations. © 2016 The Royal Society of Chemistry. |
Nuclear overhauser spectroscopy of chiral CHD methylene groups Article de journal R Augustyniak; J Stanek; H Colaux; G Bodenhausen; W Koźmiński; T Herrmann; F Ferrage Journal of Biomolecular NMR, 64 (1), p. 27–37, 2016. @article{Augustyniak:2016, title = {Nuclear overhauser spectroscopy of chiral CHD methylene groups}, author = {R Augustyniak and J Stanek and H Colaux and G Bodenhausen and W Ko\'{z}mi\'{n}ski and T Herrmann and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957938000&doi=10.1007%2fs10858-015-0002-0&partnerID=40&md5=e030127e44f952f166811ff046087bff}, doi = {10.1007/s10858-015-0002-0}, year = {2016}, date = {2016-01-01}, journal = {Journal of Biomolecular NMR}, volume = {64}, number = {1}, pages = {27--37}, abstract = {Nuclear magnetic resonance spectroscopy (NMR) can provide a great deal of information about structure and dynamics of biomolecules. The quality of an NMR structure strongly depends on the number of experimental observables and on their accurate conversion into geometric restraints. When distance restraints are derived from nuclear Overhauser effect spectroscopy (NOESY), stereo-specific assignments of prochiral atoms can contribute significantly to the accuracy of NMR structures of proteins and nucleic acids. Here we introduce a series of NOESY-based pulse sequences that can assist in the assignment of chiral CHD methylene protons in random fractionally deuterated proteins. Partial deuteration suppresses spin-diffusion between the two protons of CH2 groups that normally impedes the distinction of cross-relaxation networks for these two protons in NOESY spectra. Three and four-dimensional spectra allow one to distinguish cross-relaxation pathways involving either of the two methylene protons so that one can obtain stereospecific assignments. In addition, the analysis provides a large number of stereospecific distance restraints. Non-uniform sampling was used to ensure optimal signal resolution in 4D spectra and reduce ambiguities of the assignments. Automatic assignment procedures were modified for efficient and accurate stereospecific assignments during automated structure calculations based on 3D spectra. The protocol was applied to calcium-loaded calbindin D9k. A large number of stereospecific assignments lead to a significant improvement of the accuracy of the structure. © 2015 Springer Science+Business Media Dordrecht.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nuclear magnetic resonance spectroscopy (NMR) can provide a great deal of information about structure and dynamics of biomolecules. The quality of an NMR structure strongly depends on the number of experimental observables and on their accurate conversion into geometric restraints. When distance restraints are derived from nuclear Overhauser effect spectroscopy (NOESY), stereo-specific assignments of prochiral atoms can contribute significantly to the accuracy of NMR structures of proteins and nucleic acids. Here we introduce a series of NOESY-based pulse sequences that can assist in the assignment of chiral CHD methylene protons in random fractionally deuterated proteins. Partial deuteration suppresses spin-diffusion between the two protons of CH2 groups that normally impedes the distinction of cross-relaxation networks for these two protons in NOESY spectra. Three and four-dimensional spectra allow one to distinguish cross-relaxation pathways involving either of the two methylene protons so that one can obtain stereospecific assignments. In addition, the analysis provides a large number of stereospecific distance restraints. Non-uniform sampling was used to ensure optimal signal resolution in 4D spectra and reduce ambiguities of the assignments. Automatic assignment procedures were modified for efficient and accurate stereospecific assignments during automated structure calculations based on 3D spectra. The protocol was applied to calcium-loaded calbindin D9k. A large number of stereospecific assignments lead to a significant improvement of the accuracy of the structure. © 2015 Springer Science+Business Media Dordrecht. |
Recovering Invisible Signals by Two-Field NMR Spectroscopy Article de journal S F Cousin; P Kadeřávek; B Haddou; C Charlier; T Marquardsen; J -M Tyburn; P -A Bovier; F Engelke; W Maas; G Bodenhausen; P Pelupessy; F Ferrage Angewandte Chemie - International Edition, 55 (34), p. 9886–9889, 2016. @article{Cousin:2016, title = {Recovering Invisible Signals by Two-Field NMR Spectroscopy}, author = {S F Cousin and P Kade\v{r}\'{a}vek and B Haddou and C Charlier and T Marquardsen and J -M Tyburn and P -A Bovier and F Engelke and W Maas and G Bodenhausen and P Pelupessy and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84978505346&doi=10.1002%2fanie.201602978&partnerID=40&md5=4461b77dffa32e9cd4094582a4e8241a}, doi = {10.1002/anie.201602978}, year = {2016}, date = {2016-01-01}, journal = {Angewandte Chemie - International Edition}, volume = {55}, number = {34}, pages = {9886--9889}, abstract = {Nuclear magnetic resonance (NMR) studies have benefited tremendously from the steady increase in the strength of magnetic fields. Spectacular improvements in both sensitivity and resolution have enabled the investigation of molecular systems of rising complexity. At very high fields, this progress may be jeopardized by line broadening, which is due to chemical exchange or relaxation by chemical shift anisotropy. In this work, we introduce a two-field NMR spectrometer designed for both excitation and observation of nuclear spins in two distinct magnetic fields in a single experiment. NMR spectra of several small molecules as well as a protein were obtained, with two dimensions acquired at vastly different magnetic fields. Resonances of exchanging groups that are broadened beyond recognition at high field can be sharpened to narrow peaks in the low-field dimension. Two-field NMR spectroscopy enables the measurement of chemical shifts at optimal fields and the study of molecular systems that suffer from internal dynamics, and opens new avenues for NMR spectroscopy at very high magnetic fields. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nuclear magnetic resonance (NMR) studies have benefited tremendously from the steady increase in the strength of magnetic fields. Spectacular improvements in both sensitivity and resolution have enabled the investigation of molecular systems of rising complexity. At very high fields, this progress may be jeopardized by line broadening, which is due to chemical exchange or relaxation by chemical shift anisotropy. In this work, we introduce a two-field NMR spectrometer designed for both excitation and observation of nuclear spins in two distinct magnetic fields in a single experiment. NMR spectra of several small molecules as well as a protein were obtained, with two dimensions acquired at vastly different magnetic fields. Resonances of exchanging groups that are broadened beyond recognition at high field can be sharpened to narrow peaks in the low-field dimension. Two-field NMR spectroscopy enables the measurement of chemical shifts at optimal fields and the study of molecular systems that suffer from internal dynamics, and opens new avenues for NMR spectroscopy at very high magnetic fields. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim |
High-resolution two-field nuclear magnetic resonance spectroscopy Article de journal S F Cousin; C Charlier; P Kadeřávek; T Marquardsen; J -M Tyburn; P -A Bovier; S Ulzega; T Speck; D Wilhelm; F Engelke; W Maas; D Sakellariou; G Bodenhausen; P Pelupessy; F Ferrage Physical Chemistry Chemical Physics, 18 (48), p. 33187–33194, 2016. @article{Cousin:2016a, title = {High-resolution two-field nuclear magnetic resonance spectroscopy}, author = {S F Cousin and C Charlier and P Kade\v{r}\'{a}vek and T Marquardsen and J -M Tyburn and P -A Bovier and S Ulzega and T Speck and D Wilhelm and F Engelke and W Maas and D Sakellariou and G Bodenhausen and P Pelupessy and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85011895555&doi=10.1039%2fc6cp05422f&partnerID=40&md5=a4f118c70abcc3192ed0f1d61e213b0d}, doi = {10.1039/c6cp05422f}, year = {2016}, date = {2016-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {18}, number = {48}, pages = {33187--33194}, abstract = {Nuclear magnetic resonance (NMR) is a ubiquitous branch of spectroscopy that can explore matter at the scale of an atom. Significant improvements in sensitivity and resolution have been driven by a steady increase of static magnetic field strengths. However, some properties of nuclei may be more favourable at low magnetic fields. For example, transverse relaxation due to chemical shift anisotropy increases sharply at higher magnetic fields leading to line-broadening and inefficient coherence transfers. Here, we present a two-field NMR spectrometer that permits the application of rf-pulses and acquisition of NMR signals in two magnetic centres. Our prototype operates at 14.1 T and 0.33 T. The main features of this system are demonstrated by novel NMR experiments, in particular a proof-of-concept correlation between zero-quantum coherences at low magnetic field and single quantum coherences at high magnetic field, so that high resolution can be achieved in both dimensions, despite a ca. 10 ppm inhomogeneity of the low-field centre. Two-field NMR spectroscopy offers the possibility to circumvent the limits of high magnetic fields, while benefiting from their exceptional sensitivity and resolution. This approach opens new avenues for NMR above 1 GHz. © the Owner Societies 2016.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nuclear magnetic resonance (NMR) is a ubiquitous branch of spectroscopy that can explore matter at the scale of an atom. Significant improvements in sensitivity and resolution have been driven by a steady increase of static magnetic field strengths. However, some properties of nuclei may be more favourable at low magnetic fields. For example, transverse relaxation due to chemical shift anisotropy increases sharply at higher magnetic fields leading to line-broadening and inefficient coherence transfers. Here, we present a two-field NMR spectrometer that permits the application of rf-pulses and acquisition of NMR signals in two magnetic centres. Our prototype operates at 14.1 T and 0.33 T. The main features of this system are demonstrated by novel NMR experiments, in particular a proof-of-concept correlation between zero-quantum coherences at low magnetic field and single quantum coherences at high magnetic field, so that high resolution can be achieved in both dimensions, despite a ca. 10 ppm inhomogeneity of the low-field centre. Two-field NMR spectroscopy offers the possibility to circumvent the limits of high magnetic fields, while benefiting from their exceptional sensitivity and resolution. This approach opens new avenues for NMR above 1 GHz. © the Owner Societies 2016. |
Theory for spiralling ions for 2D FT-ICR and comparison with precessing magnetization vectors in 2D NMR Article de journal A A Sehgal; P Pelupessy; C Rolando; G Bodenhausen Physical Chemistry Chemical Physics, 18 (13), p. 9167–9175, 2016. @article{Sehgal:2016, title = {Theory for spiralling ions for 2D FT-ICR and comparison with precessing magnetization vectors in 2D NMR}, author = {A A Sehgal and P Pelupessy and C Rolando and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84962023042&doi=10.1039%2fc6cp00641h&partnerID=40&md5=316bee117405d529541106cc30d12423}, doi = {10.1039/c6cp00641h}, year = {2016}, date = {2016-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {18}, number = {13}, pages = {9167--9175}, abstract = {Two-dimensional (2D) Fourier transform ion cyclotron resonance (FT-ICR) offers an approach to mass spectrometry (MS) that pursuits similar objectives as MS/MS experiments. While the latter must focus on one ion species at a time, 2D FT ICR can examine all possible correlations due to ion fragmentation in a single experiment: correlations between precursors, charged and neutral fragments. We revisited the original 2D FT-ICR experiment that has hitherto fallen short of stimulating significant analytical applications, probably because it is technically demanding. These shortcomings can now be overcome by improved FT-ICR instrumentation and computer hard- and software. We seek to achieve a better understanding of the intricacies of the behavior of ions during a basic two-dimensional ICR sequence comprising three simple monochromatic pulses. Through simulations based on Lorentzian equations, we have mapped the ion trajectories for different pulse durations and phases. © the Owner Societies 2016.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two-dimensional (2D) Fourier transform ion cyclotron resonance (FT-ICR) offers an approach to mass spectrometry (MS) that pursuits similar objectives as MS/MS experiments. While the latter must focus on one ion species at a time, 2D FT ICR can examine all possible correlations due to ion fragmentation in a single experiment: correlations between precursors, charged and neutral fragments. We revisited the original 2D FT-ICR experiment that has hitherto fallen short of stimulating significant analytical applications, probably because it is technically demanding. These shortcomings can now be overcome by improved FT-ICR instrumentation and computer hard- and software. We seek to achieve a better understanding of the intricacies of the behavior of ions during a basic two-dimensional ICR sequence comprising three simple monochromatic pulses. Through simulations based on Lorentzian equations, we have mapped the ion trajectories for different pulse durations and phases. © the Owner Societies 2016. |
The effects of molecular diffusion in spatially encoded magnetic resonance imaging Article de journal S Marhabaie; G Bodenhausen; P Pelupessy Journal of Magnetic Resonance, 273 , p. 98–104, 2016. @article{Marhabaie:2016, title = {The effects of molecular diffusion in spatially encoded magnetic resonance imaging}, author = {S Marhabaie and G Bodenhausen and P Pelupessy}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84992734394&doi=10.1016%2fj.jmr.2016.10.010&partnerID=40&md5=70ceb672fc9d062053adabbb366c076a}, doi = {10.1016/j.jmr.2016.10.010}, year = {2016}, date = {2016-01-01}, journal = {Journal of Magnetic Resonance}, volume = {273}, pages = {98--104}, abstract = {In spatially encoded MRI, the signal is acquired sequentially for different coordinates. In particular for single-scan acquisitions in inhomogeneous fields, spatially encoded methods improve the image quality compared to traditional k-space encoding. Previously, much attention has been paid in order to homogenize T2 losses across the sample. In this work, we investigate the effects of diffusion on the image quality in spatially encoded MRI. We show that losses due to diffusion are often not uniform along the spatially encoded dimension, and how to adapt spatially encoded sequences in order to obtain uniformly diffusion-weighted images. © 2016 Elsevier Inc.}, keywords = {}, pubstate = {published}, tppubtype = {article} } In spatially encoded MRI, the signal is acquired sequentially for different coordinates. In particular for single-scan acquisitions in inhomogeneous fields, spatially encoded methods improve the image quality compared to traditional k-space encoding. Previously, much attention has been paid in order to homogenize T2 losses across the sample. In this work, we investigate the effects of diffusion on the image quality in spatially encoded MRI. We show that losses due to diffusion are often not uniform along the spatially encoded dimension, and how to adapt spatially encoded sequences in order to obtain uniformly diffusion-weighted images. © 2016 Elsevier Inc. |
Cubic three-dimensional hybrid silica solids for nuclear hyperpolarization Article de journal D Baudouin; H A Van Kalkeren; A Bornet; B Vuichoud; L Veyre; M Cavaillès; M Schwarzwälder; W -C Liao; D Gajan; G Bodenhausen; L Emsley; A Lesage; S Jannin; C Copéret; C Thieuleux Chemical Science, 7 (11), p. 6846–6850, 2016. @article{Baudouin:2016, title = {Cubic three-dimensional hybrid silica solids for nuclear hyperpolarization}, author = {D Baudouin and H A Van Kalkeren and A Bornet and B Vuichoud and L Veyre and M Cavaill\`{e}s and M Schwarzw\"{a}lder and W -C Liao and D Gajan and G Bodenhausen and L Emsley and A Lesage and S Jannin and C Cop\'{e}ret and C Thieuleux}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84983737605&doi=10.1039%2fc6sc02055k&partnerID=40&md5=ae24c373f19f995d6679a3007620c89e}, doi = {10.1039/c6sc02055k}, year = {2016}, date = {2016-01-01}, journal = {Chemical Science}, volume = {7}, number = {11}, pages = {6846--6850}, abstract = {Hyperpolarization of metabolites by dissolution dynamic nuclear polarization (D-DNP) for MRI applications often requires fast and efficient removal of the radicals (polarizing agents). Ordered mesoporous SBA-15 silica materials containing homogeneously dispersed radicals, referred to as HYperPolarizing SOlids (HYPSOs), enable high polarization-P(1H) = 50% at 1.2 K-and straightforward separation of the polarizing HYPSO material from the hyperpolarized solution by filtration. However, the one-dimensional tubular pores of SBA-15 type materials are not ideal for nuclear spin diffusion, which may limit efficient polarization. Here, we develop a generation of hyperpolarizing solids based on a SBA-16 structure with a network of pores interconnected in three dimensions, which allows a significant increase of polarization, i.e. P(1H) = 63% at 1.2 K. This result illustrates how one can improve materials by combining a control of the incorporation of radicals with a better design of the porous network structures. © The Royal Society of Chemistry 2016.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Hyperpolarization of metabolites by dissolution dynamic nuclear polarization (D-DNP) for MRI applications often requires fast and efficient removal of the radicals (polarizing agents). Ordered mesoporous SBA-15 silica materials containing homogeneously dispersed radicals, referred to as HYperPolarizing SOlids (HYPSOs), enable high polarization-P(1H) = 50% at 1.2 K-and straightforward separation of the polarizing HYPSO material from the hyperpolarized solution by filtration. However, the one-dimensional tubular pores of SBA-15 type materials are not ideal for nuclear spin diffusion, which may limit efficient polarization. Here, we develop a generation of hyperpolarizing solids based on a SBA-16 structure with a network of pores interconnected in three dimensions, which allows a significant increase of polarization, i.e. P(1H) = 63% at 1.2 K. This result illustrates how one can improve materials by combining a control of the incorporation of radicals with a better design of the porous network structures. © The Royal Society of Chemistry 2016. |
2015 |
Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets Article de journal C -Y Chou; F Ferrage; G Aubert; D Sakellariou Scientific Reports, 5 , 2015. @article{Chou:2015, title = {Simple method for the generation of multiple homogeneous field volumes inside the bore of superconducting magnets}, author = {C -Y Chou and F Ferrage and G Aubert and D Sakellariou}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84937458390&doi=10.1038%2fsrep12200&partnerID=40&md5=2a5c32c6d505a3820042f573884c23f9}, doi = {10.1038/srep12200}, year = {2015}, date = {2015-01-01}, journal = {Scientific Reports}, volume = {5}, abstract = {Standard Magnetic Resonance magnets produce a single homogeneous field volume, where the analysis is performed. Nonetheless, several modern applications could benefit from the generation of multiple homogeneous field volumes along the axis and inside the bore of the magnet. In this communication, we propose a straightforward method using a combination of ring structures of permanent magnets in order to cancel the gradient of the stray field in a series of distinct volumes. These concepts were demonstrated numerically on an experimentally measured magnetic field profile. We discuss advantages and limitations of our method and present the key steps required for an experimental validation.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Standard Magnetic Resonance magnets produce a single homogeneous field volume, where the analysis is performed. Nonetheless, several modern applications could benefit from the generation of multiple homogeneous field volumes along the axis and inside the bore of the magnet. In this communication, we propose a straightforward method using a combination of ring structures of permanent magnets in order to cancel the gradient of the stray field in a series of distinct volumes. These concepts were demonstrated numerically on an experimentally measured magnetic field profile. We discuss advantages and limitations of our method and present the key steps required for an experimental validation. |
Identification of hydrophobic interfaces in protein-ligand complexes by selective saturation transfer NMR spectroscopy Article de journal F Ferrage; K Dutta; D Cowburn Molecules, 20 (12), p. 21992–21999, 2015. @article{Ferrage:2015, title = {Identification of hydrophobic interfaces in protein-ligand complexes by selective saturation transfer NMR spectroscopy}, author = {F Ferrage and K Dutta and D Cowburn}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954357489&doi=10.3390%2fmolecules201219824&partnerID=40&md5=a6e6ae48b26f8cf4911c7e6b66825451}, doi = {10.3390/molecules201219824}, year = {2015}, date = {2015-01-01}, journal = {Molecules}, volume = {20}, number = {12}, pages = {21992--21999}, abstract = {The proper characterization of protein-ligand interfaces is essential for structural biology, with implications ranging from the fundamental understanding of biological processes to pharmacology. Nuclear magnetic resonance is a powerful technique for such studies. We propose a novel approach to the direct determination of the likely pose of a peptide ligand onto a protein partner, by using frequency-selective cross-saturation with a low stringency isotopic labeling methods. Our method illustrates a complex of the Src homology 3 domain of C-terminal Src kinase with a peptide from the proline-enriched tyrosine phosphatase. © 2015 by The Authors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The proper characterization of protein-ligand interfaces is essential for structural biology, with implications ranging from the fundamental understanding of biological processes to pharmacology. Nuclear magnetic resonance is a powerful technique for such studies. We propose a novel approach to the direct determination of the likely pose of a peptide ligand onto a protein partner, by using frequency-selective cross-saturation with a low stringency isotopic labeling methods. Our method illustrates a complex of the Src homology 3 domain of C-terminal Src kinase with a peptide from the proline-enriched tyrosine phosphatase. © 2015 by The Authors. |
Distribution of Pico- and Nanosecond Motions in Disordered Proteins from Nuclear Spin Relaxation Article de journal S N Khan; C Charlier; R Augustyniak; N Salvi; V Déjean; G Bodenhausen; O Lequin; P Pelupessy; F Ferrage Biophysical Journal, 109 (5), p. 988–999, 2015. @article{Khan:2015, title = {Distribution of Pico- and Nanosecond Motions in Disordered Proteins from Nuclear Spin Relaxation}, author = {S N Khan and C Charlier and R Augustyniak and N Salvi and V D\'{e}jean and G Bodenhausen and O Lequin and P Pelupessy and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84940502229&doi=10.1016%2fj.bpj.2015.06.069&partnerID=40&md5=a733f31f586712b6335e41bab2799af1}, doi = {10.1016/j.bpj.2015.06.069}, year = {2015}, date = {2015-01-01}, journal = {Biophysical Journal}, volume = {109}, number = {5}, pages = {988--999}, abstract = {Intrinsically disordered proteins and intrinsically disordered regions (IDRs) are ubiquitous in the eukaryotic proteome. The description and understanding of their conformational properties require the development of new experimental, computational, and theoretical approaches. Here, we use nuclear spin relaxation to investigate the distribution of timescales of motions in an IDR from picoseconds to nanoseconds. Nitrogen-15 relaxation rates have been measured at five magnetic fields, ranging from 9.4 to 23.5 T (400-1000 MHz for protons). This exceptional wealth of data allowed us to map the spectral density function for the motions of backbone NH pairs in the partially disordered transcription factor Engrailed at 11 different frequencies. We introduce an approach called interpretation of motions by a projection onto an array of correlation times (IMPACT), which focuses on an array of six correlation times with intervals that are equidistant on a logarithmic scale between 21 ps and 21 ns. The distribution of motions in Engrailed varies smoothly along the protein sequence and is multimodal for most residues, with a prevalence of motions around 1 ns in the IDR. We show that IMPACT often provides better quantitative agreement with experimental data than conventional model-free or extended model-free analyses with two or three correlation times. We introduce a graphical representation that offers a convenient platform for a qualitative discussion of dynamics. Even when relaxation data are only acquired at three magnetic fields that are readily accessible, the IMPACT analysis gives a satisfactory characterization of spectral density functions, thus opening the way to a broad use of this approach. © 2015 The Authors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Intrinsically disordered proteins and intrinsically disordered regions (IDRs) are ubiquitous in the eukaryotic proteome. The description and understanding of their conformational properties require the development of new experimental, computational, and theoretical approaches. Here, we use nuclear spin relaxation to investigate the distribution of timescales of motions in an IDR from picoseconds to nanoseconds. Nitrogen-15 relaxation rates have been measured at five magnetic fields, ranging from 9.4 to 23.5 T (400-1000 MHz for protons). This exceptional wealth of data allowed us to map the spectral density function for the motions of backbone NH pairs in the partially disordered transcription factor Engrailed at 11 different frequencies. We introduce an approach called interpretation of motions by a projection onto an array of correlation times (IMPACT), which focuses on an array of six correlation times with intervals that are equidistant on a logarithmic scale between 21 ps and 21 ns. The distribution of motions in Engrailed varies smoothly along the protein sequence and is multimodal for most residues, with a prevalence of motions around 1 ns in the IDR. We show that IMPACT often provides better quantitative agreement with experimental data than conventional model-free or extended model-free analyses with two or three correlation times. We introduce a graphical representation that offers a convenient platform for a qualitative discussion of dynamics. Even when relaxation data are only acquired at three magnetic fields that are readily accessible, the IMPACT analysis gives a satisfactory characterization of spectral density functions, thus opening the way to a broad use of this approach. © 2015 The Authors. |
Cross-correlated relaxation measurements under adiabatic sweeps: Determination of local order in proteins Article de journal P Kadeřávek; S Grutsch; N Salvi; M Tollinger; L Žídek; G Bodenhausen; F Ferrage Journal of Biomolecular NMR, 63 (4), p. 353–365, 2015. @article{Kaderavek:2015, title = {Cross-correlated relaxation measurements under adiabatic sweeps: Determination of local order in proteins}, author = {P Kade\v{r}\'{a}vek and S Grutsch and N Salvi and M Tollinger and L \v{Z}\'{i}dek and G Bodenhausen and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84957936663&doi=10.1007%2fs10858-015-9994-8&partnerID=40&md5=f9d604e7442d0e345608c3837e35b0d5}, doi = {10.1007/s10858-015-9994-8}, year = {2015}, date = {2015-01-01}, journal = {Journal of Biomolecular NMR}, volume = {63}, number = {4}, pages = {353--365}, abstract = {Adiabatically swept pulses were originally designed for the purpose of broadband spin inversion. Later, unexpected advantages of their utilization were also found in other applications, such as refocusing to excite spin echoes, studies of chemical exchange or fragment-based drug design. Here, we present new experiments to characterize fast (ps-ns) protein dynamics, which benefit from little-known properties of adiabatic pulses. We developed a strategy for measuring cross-correlated cross-relaxation (CCCR) rates during adiabatic pulses. This experiment provides a linear combination of longitudinal and transverse CCCR rates, which is offset-independent across a typical amide 15N spectrum. The pulse sequence can be recast to provide accurate transverse CCCR rates weighted by the populations of exchanging states. Sensitivity can be improved in systems in slow exchange. Finally, the experiments can be easily modified to yield residue-specific correlation times. The average correlation time of motions can be determined with a single experiment while at least two different experiments had to be recorded until now. © 2015 The Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Adiabatically swept pulses were originally designed for the purpose of broadband spin inversion. Later, unexpected advantages of their utilization were also found in other applications, such as refocusing to excite spin echoes, studies of chemical exchange or fragment-based drug design. Here, we present new experiments to characterize fast (ps-ns) protein dynamics, which benefit from little-known properties of adiabatic pulses. We developed a strategy for measuring cross-correlated cross-relaxation (CCCR) rates during adiabatic pulses. This experiment provides a linear combination of longitudinal and transverse CCCR rates, which is offset-independent across a typical amide 15N spectrum. The pulse sequence can be recast to provide accurate transverse CCCR rates weighted by the populations of exchanging states. Sensitivity can be improved in systems in slow exchange. Finally, the experiments can be easily modified to yield residue-specific correlation times. The average correlation time of motions can be determined with a single experiment while at least two different experiments had to be recorded until now. © 2015 The Author(s). |
Rotation-induced recovery and bleaching in magnetic resonance Article de journal A J Perez Linde; S Chinthalapalli; D Carnevale; G Bodenhausen Physical Chemistry Chemical Physics, 17 (9), p. 6415–6422, 2015. @article{PerezLinde:2015, title = {Rotation-induced recovery and bleaching in magnetic resonance}, author = {A J Perez Linde and S Chinthalapalli and D Carnevale and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84923347606&doi=10.1039%2fc4cp05735j&partnerID=40&md5=79ad442f3e6bb5c72dfe27402b05c186}, doi = {10.1039/c4cp05735j}, year = {2015}, date = {2015-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {17}, number = {9}, pages = {6415--6422}, abstract = {Thurber and Tycko recently described a 'bleaching effect' that occurs in magnetic resonance when solid samples that are doped with paramagnetic agents are subjected to rotation by magic angle spinning (MAS) in a static magnetic field with a rotation period comparable to the longitudinal relaxation time T1e of the electron spins. The bleaching effect has been investigated by Thurber and Tycko in samples spinning at temperatures near 20 K in a field of 9.4 T and by Corzilius et al. near 80 K in a field of 4.9 T. In our experience, the bleaching effect is not very severe at temperatures near 100 K in a field of 9.4 T at spinning frequencies up to 12 kHz. Bleaching can partly cancel DNP enhancements that are normally evaluated by comparing signal intensities with and without microwave irradiation. The signal attenuation due to doping and sample rotation is usually not taken into consideration when defining enhancement factors. In this paper, we describe a novel observation that the rotation of glassy samples doped with lanthanides spinning at frequencies as low as 0.1 kHz can lead to a significant reduction of the spin-lattice relaxation times T1(1H) of protons. This effect, which bears similarities with the so-called spin refrigerators, may contribute to the success of 'brute force polarization' at sample temperatures in the mK range. The acceleration of longitudinal proton relaxation also allows one to improve the signal-to-noise ratio per unit time. This journal is © the Owner Societies 2015.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Thurber and Tycko recently described a 'bleaching effect' that occurs in magnetic resonance when solid samples that are doped with paramagnetic agents are subjected to rotation by magic angle spinning (MAS) in a static magnetic field with a rotation period comparable to the longitudinal relaxation time T1e of the electron spins. The bleaching effect has been investigated by Thurber and Tycko in samples spinning at temperatures near 20 K in a field of 9.4 T and by Corzilius et al. near 80 K in a field of 4.9 T. In our experience, the bleaching effect is not very severe at temperatures near 100 K in a field of 9.4 T at spinning frequencies up to 12 kHz. Bleaching can partly cancel DNP enhancements that are normally evaluated by comparing signal intensities with and without microwave irradiation. The signal attenuation due to doping and sample rotation is usually not taken into consideration when defining enhancement factors. In this paper, we describe a novel observation that the rotation of glassy samples doped with lanthanides spinning at frequencies as low as 0.1 kHz can lead to a significant reduction of the spin-lattice relaxation times T1(1H) of protons. This effect, which bears similarities with the so-called spin refrigerators, may contribute to the success of 'brute force polarization' at sample temperatures in the mK range. The acceleration of longitudinal proton relaxation also allows one to improve the signal-to-noise ratio per unit time. This journal is © the Owner Societies 2015. |
Spin Noise Detection of Nuclear Hyperpolarization at 1.2 K Article de journal M T Pöschko; B Vuichoud; J Milani; A Bornet; M Bechmann; G Bodenhausen; S Jannin; N Müller ChemPhysChem, 16 (18), p. 3859–3864, 2015. @article{Poschko:2015, title = {Spin Noise Detection of Nuclear Hyperpolarization at 1.2 K}, author = {M T P\"{o}schko and B Vuichoud and J Milani and A Bornet and M Bechmann and G Bodenhausen and S Jannin and N M\"{u}ller}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949871165&doi=10.1002%2fcphc.201500805&partnerID=40&md5=aa463269691b5a486ff7b4f95f2c6654}, doi = {10.1002/cphc.201500805}, year = {2015}, date = {2015-01-01}, journal = {ChemPhysChem}, volume = {16}, number = {18}, pages = {3859--3864}, abstract = {We report proton spin noise spectra of a hyperpolarized solid sample of commonly used "DNP (dynamic nuclear polarization) juice" containing TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxide) and irradiated by a microwave field at a temperature of 1.2 K in a magnetic field of 6.7 T. The line shapes of the spin noise power spectra are sensitive to the variation of the microwave irradiation frequency and change from dip to bump, when the electron Larmor frequency is crossed, which is shown to be in good accordance with theory by simulations. Small but significant deviations from these predictions are observed, which can be related to spin noise and radiation damping phenomena that have been reported in thermally polarized systems. The non-linear dependence of the spin noise integral on nuclear polarization provides a means to monitor hyperpolarization semi-quantitatively without any perturbation of the spin system by radio frequency irradiation. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report proton spin noise spectra of a hyperpolarized solid sample of commonly used "DNP (dynamic nuclear polarization) juice" containing TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxide) and irradiated by a microwave field at a temperature of 1.2 K in a magnetic field of 6.7 T. The line shapes of the spin noise power spectra are sensitive to the variation of the microwave irradiation frequency and change from dip to bump, when the electron Larmor frequency is crossed, which is shown to be in good accordance with theory by simulations. Small but significant deviations from these predictions are observed, which can be related to spin noise and radiation damping phenomena that have been reported in thermally polarized systems. The non-linear dependence of the spin noise integral on nuclear polarization provides a means to monitor hyperpolarization semi-quantitatively without any perturbation of the spin system by radio frequency irradiation. © 2015 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. |
Effects of inherent rf field inhomogeneity on heteronuclear decoupling in solid-state NMR Article de journal R N Purusottam; G Bodenhausen; P Tekely Chemical Physics Letters, 635 , p. 157–162, 2015. @article{Purusottam:2015, title = {Effects of inherent rf field inhomogeneity on heteronuclear decoupling in solid-state NMR}, author = {R N Purusottam and G Bodenhausen and P Tekely}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84936930232&doi=10.1016%2fj.cplett.2015.06.051&partnerID=40&md5=ea6630e9898c0d569d9fea19df3a5797}, doi = {10.1016/j.cplett.2015.06.051}, year = {2015}, date = {2015-01-01}, journal = {Chemical Physics Letters}, volume = {635}, pages = {157--162}, abstract = {Efficient heteronuclear decoupling is essential to obtain high-resolution NMR spectra of organic and biological solids containing protons and low-gamma nuclei such as carbon-13. All modern decoupling sequences employ pulse lengths that are optimized for a given radio-frequency (rf) power. However, there is an unavoidable distribution of rf field amplitudes across the volume of the sample. Inevitably, the effect of the rf field distribution manifests itself for fully packed rotors during any decoupling irradiation. In this study we present a detailed analysis of the effect of the inherent rf field inhomogeneity on decoupling by the low-power phase-inverted supercycled sequence for attenuation of rotary resonance (PISSARRO). This reveals a potential for further improvements of its efficiency. © 2015 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Efficient heteronuclear decoupling is essential to obtain high-resolution NMR spectra of organic and biological solids containing protons and low-gamma nuclei such as carbon-13. All modern decoupling sequences employ pulse lengths that are optimized for a given radio-frequency (rf) power. However, there is an unavoidable distribution of rf field amplitudes across the volume of the sample. Inevitably, the effect of the rf field distribution manifests itself for fully packed rotors during any decoupling irradiation. In this study we present a detailed analysis of the effect of the inherent rf field inhomogeneity on decoupling by the low-power phase-inverted supercycled sequence for attenuation of rotary resonance (PISSARRO). This reveals a potential for further improvements of its efficiency. © 2015 Elsevier B.V. All rights reserved. |
Challenges in preparing, preserving and detecting para-water in bulk: overcoming proton exchange and other hurdles Article de journal D Mammoli; N Salvi; J Milani; R Buratto; A Bornet; A A Sehgal; E Canet; P Pelupessy; D Carnevale; S Jannin; G Bodenhausen Physical Chemistry Chemical Physics, 17 (40), p. 26819–26827, 2015. @article{Mammoli:2015, title = {Challenges in preparing, preserving and detecting para-water in bulk: overcoming proton exchange and other hurdles}, author = {D Mammoli and N Salvi and J Milani and R Buratto and A Bornet and A A Sehgal and E Canet and P Pelupessy and D Carnevale and S Jannin and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84943643930&doi=10.1039%2fc5cp03350k&partnerID=40&md5=8498dc5035e5d1c3d9af08e2fb25ca08}, doi = {10.1039/c5cp03350k}, year = {2015}, date = {2015-01-01}, journal = {Physical Chemistry Chemical Physics}, volume = {17}, number = {40}, pages = {26819--26827}, abstract = {Para-water is an analogue of para-hydrogen, where the two proton spins are in a quantum state that is antisymmetric under permutation, also known as singlet state. The populations of the nuclear spin states in para-water are believed to have long lifetimes just like other Long-Lived States (LLSs). This hypothesis can be verified by measuring the relaxation of an excess or a deficiency of para-water, also known as a "Triplet-Singlet Imbalance" (TSI), i.e., a difference between the average population of the three triplet states T (that are symmetric under permutation) and the population of the singlet state S. In analogy with our recent findings on ethanol and fumarate, we propose to adapt the procedure for Dissolution Dynamic Nuclear Polarization (D-DNP) to prepare such a TSI in frozen water at very low temperatures in the vicinity of 1.2 K. After rapid heating and dissolution using an aprotic solvent, the TSI should be largely preserved. To assess this hypothesis, we studied the lifetime of water as a molecular entity when diluted in various solvents. In neat liquid H2O, proton exchange rates have been characterized by spin-echo experiments on oxygen-17 in natural abundance, with and without proton decoupling. One-dimensional exchange spectroscopy (EXSY) has been used to study proton exchange rates in H2O, HDO and D2O mixtures diluted in various aprotic solvents. In the case of 50 mM H2O in dioxane-d8, the proton exchange lifetime is about 20 s. After dissolving, one can observe this TSI by monitoring intensities in oxygen-17 spectra of H2O (if necessary using isotopically enriched samples) where the AX2 system comprising a "spy" oxygen A and two protons X2 gives rise to binomial multiplets only if the TSI vanishes. Alternatively, fast chemical addition to a suitable substrate (such as an activated aldehyde or ketone) can provide AX2 systems where a carbon-13 acts as a spy nucleus. Proton signals that relax to equilibrium with two distinct time constants can be considered as a hallmark of a TSI. We optimized several experimental procedures designed to preserve and reveal dilute para-water in bulk. This journal is © the Owner Societies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Para-water is an analogue of para-hydrogen, where the two proton spins are in a quantum state that is antisymmetric under permutation, also known as singlet state. The populations of the nuclear spin states in para-water are believed to have long lifetimes just like other Long-Lived States (LLSs). This hypothesis can be verified by measuring the relaxation of an excess or a deficiency of para-water, also known as a "Triplet-Singlet Imbalance" (TSI), i.e., a difference between the average population of the three triplet states T (that are symmetric under permutation) and the population of the singlet state S. In analogy with our recent findings on ethanol and fumarate, we propose to adapt the procedure for Dissolution Dynamic Nuclear Polarization (D-DNP) to prepare such a TSI in frozen water at very low temperatures in the vicinity of 1.2 K. After rapid heating and dissolution using an aprotic solvent, the TSI should be largely preserved. To assess this hypothesis, we studied the lifetime of water as a molecular entity when diluted in various solvents. In neat liquid H2O, proton exchange rates have been characterized by spin-echo experiments on oxygen-17 in natural abundance, with and without proton decoupling. One-dimensional exchange spectroscopy (EXSY) has been used to study proton exchange rates in H2O, HDO and D2O mixtures diluted in various aprotic solvents. In the case of 50 mM H2O in dioxane-d8, the proton exchange lifetime is about 20 s. After dissolving, one can observe this TSI by monitoring intensities in oxygen-17 spectra of H2O (if necessary using isotopically enriched samples) where the AX2 system comprising a "spy" oxygen A and two protons X2 gives rise to binomial multiplets only if the TSI vanishes. Alternatively, fast chemical addition to a suitable substrate (such as an activated aldehyde or ketone) can provide AX2 systems where a carbon-13 acts as a spy nucleus. Proton signals that relax to equilibrium with two distinct time constants can be considered as a hallmark of a TSI. We optimized several experimental procedures designed to preserve and reveal dilute para-water in bulk. This journal is © the Owner Societies. |
A magnetic tunnel to shelter hyperpolarized fluids Article de journal J Milani; B Vuichoud; A Bornet; P Miéville; R Mottier; S Jannin; G Bodenhausen Review of Scientific Instruments, 86 (2), 2015. @article{Milani:2015, title = {A magnetic tunnel to shelter hyperpolarized fluids}, author = {J Milani and B Vuichoud and A Bornet and P Mi\'{e}ville and R Mottier and S Jannin and G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84923913955&doi=10.1063%2f1.4908196&partnerID=40&md5=c812f3b55cf0e14828c79fbd6b066ed9}, doi = {10.1063/1.4908196}, year = {2015}, date = {2015-01-01}, journal = {Review of Scientific Instruments}, volume = {86}, number = {2}, abstract = {To shield solutions carrying hyperpolarized nuclear magnetization from rapid relaxation during transfer through low fields, the transfer duct can be threaded through an array of permanent magnets. The advantages are illustrated for solutions containing hyperpolarized 1H and 13C nuclei in a variety of molecules. © 2015 Author(s).}, keywords = {}, pubstate = {published}, tppubtype = {article} } To shield solutions carrying hyperpolarized nuclear magnetization from rapid relaxation during transfer through low fields, the transfer duct can be threaded through an array of permanent magnets. The advantages are illustrated for solutions containing hyperpolarized 1H and 13C nuclei in a variety of molecules. © 2015 Author(s). |
A bright future for magnetic resonance Article de journal G Bodenhausen Resonance, 20 (11), p. 1066–1074, 2015. @article{Bodenhausen:2015, title = {A bright future for magnetic resonance}, author = {G Bodenhausen}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84949947467&doi=10.1007%2fs12045-015-0274-4&partnerID=40&md5=e457a71187f47465016bdc68e5294534}, doi = {10.1007/s12045-015-0274-4}, year = {2015}, date = {2015-01-01}, journal = {Resonance}, volume = {20}, number = {11}, pages = {1066--1074}, abstract = {This contribution seeks to identify a few factors that have contributed to the success of a thriving discipline, and to identify threats that could put future prospects at risk. Many of these factors are not specific to magnetic resonance, and may also apply to other areas of scientific research. © 2015, Indian Academy of Sciences.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This contribution seeks to identify a few factors that have contributed to the success of a thriving discipline, and to identify threats that could put future prospects at risk. Many of these factors are not specific to magnetic resonance, and may also apply to other areas of scientific research. © 2015, Indian Academy of Sciences. |