You will find below the publication list of our pole.
For the publication list of each pole member, please see his/her personal webpage.
2007 |
Role of arginine 52 on the primary photoinduced events in the PYP photocycle Article de journal P Changenet-Barret; P Plaza; M M Martin; H Chosrowjan; S Taniguchi; N Mataga; Y Imamoto; M Kataoka Chemical Physics Letters, 434 (4-6), p. 320–325, 2007. @article{Changenet-Barret:2007, title = {Role of arginine 52 on the primary photoinduced events in the PYP photocycle}, author = {P Changenet-Barret and P Plaza and M M Martin and H Chosrowjan and S Taniguchi and N Mataga and Y Imamoto and M Kataoka}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33846203359&doi=10.1016%2fj.cplett.2006.12.027&partnerID=40&md5=63606ca56aff55ca2e30db6af88fa152}, doi = {10.1016/j.cplett.2006.12.027}, year = {2007}, date = {2007-01-01}, journal = {Chemical Physics Letters}, volume = {434}, number = {4-6}, pages = {320--325}, abstract = {We investigated the earliest steps of the photocycle of photoactive yellow protein (PYP) and its R52Q mutant in aqueous solution, by subpicosecond transient absorption spectroscopy. Our aim was to address the role of the positively charged Arg52 residue. We found that the relaxation mechanism of R52Q is similar to that of wt-PYP and discarded that Arg52 plays a key role in the chromophore photoreactivity. The excited-state decay of R52Q is however slower, confirming previous fluorescence up-conversion data. The experiments also reveal a slower stabilization of the cis isomer product. The loosening of the protein pocket and structural heterogeneities are discussed. © 2006 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigated the earliest steps of the photocycle of photoactive yellow protein (PYP) and its R52Q mutant in aqueous solution, by subpicosecond transient absorption spectroscopy. Our aim was to address the role of the positively charged Arg52 residue. We found that the relaxation mechanism of R52Q is similar to that of wt-PYP and discarded that Arg52 plays a key role in the chromophore photoreactivity. The excited-state decay of R52Q is however slower, confirming previous fluorescence up-conversion data. The experiments also reveal a slower stabilization of the cis isomer product. The loosening of the protein pocket and structural heterogeneities are discussed. © 2006 Elsevier B.V. All rights reserved. |
Target analysis of primary photoprocesses involved in the oxyblepharismin-binding protein Article de journal P Plaza; M Mahet; M M Martin; G Checcucci; F Lenci Journal of Physical Chemistry B, 111 (4), p. 690–696, 2007. @article{Plaza:2007, title = {Target analysis of primary photoprocesses involved in the oxyblepharismin-binding protein}, author = {P Plaza and M Mahet and M M Martin and G Checcucci and F Lenci}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33847050886&doi=10.1021%2fjp0642591&partnerID=40&md5=493aaa2ac98825d3cee9d4a879e14b4f}, doi = {10.1021/jp0642591}, year = {2007}, date = {2007-01-01}, journal = {Journal of Physical Chemistry B}, volume = {111}, number = {4}, pages = {690--696}, abstract = {Target analysis is performed on previously published transient absorption spectra of the 200-kDa oxyblepharismin-binding protein (OBIP) thought to trigger the photophobic response of the ciliate Blepharisma japonicum. The OBIP sample is considered as heterogeneous and made of two distinct classes of chromophore-protein complexes. A so-called nonreactive class is seen to be comparable to free oxyblepharismin in organic solution. Another, reactive, class is shown to undergo a fast picosecond photocycle involving the formation in 4 ps of an intermediate state noted Y1. The spectrum associated to Y1 bears striking similarities with that of the oxyblepharismin radical cation. This element favors the hypothesis that an excited-state intermolecular electron-transfer could be the primary step of the sensory transduction chain of B. japonicum. Proton release is also considered as a possible secondary step. These possibilities support the idea that reactive OBIP functions like an electron or proton pump. We alternatively propose a new hypothesis stating that the fast photocycle of reactive OBIP actually does not generate any photoproduct or protein change of conformation but is involved in another biological function. It would act as a kind of solar screen, providing additional protection to the light-adapted form of B. japonicum in case of excessive illumination. © 2007 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Target analysis is performed on previously published transient absorption spectra of the 200-kDa oxyblepharismin-binding protein (OBIP) thought to trigger the photophobic response of the ciliate Blepharisma japonicum. The OBIP sample is considered as heterogeneous and made of two distinct classes of chromophore-protein complexes. A so-called nonreactive class is seen to be comparable to free oxyblepharismin in organic solution. Another, reactive, class is shown to undergo a fast picosecond photocycle involving the formation in 4 ps of an intermediate state noted Y1. The spectrum associated to Y1 bears striking similarities with that of the oxyblepharismin radical cation. This element favors the hypothesis that an excited-state intermolecular electron-transfer could be the primary step of the sensory transduction chain of B. japonicum. Proton release is also considered as a possible secondary step. These possibilities support the idea that reactive OBIP functions like an electron or proton pump. We alternatively propose a new hypothesis stating that the fast photocycle of reactive OBIP actually does not generate any photoproduct or protein change of conformation but is involved in another biological function. It would act as a kind of solar screen, providing additional protection to the light-adapted form of B. japonicum in case of excessive illumination. © 2007 American Chemical Society. |
Temporal modulation of a spatially periodic potential for kinetically governed oriented motion Article de journal H Berthoumieux; L Jullien; A Lemarchand Journal of Physical Chemistry B, 111 (8), p. 2045–2051, 2007. @article{Berthoumieux:2007, title = {Temporal modulation of a spatially periodic potential for kinetically governed oriented motion}, author = {H Berthoumieux and L Jullien and A Lemarchand}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947412367&doi=10.1021%2fjp0669714&partnerID=40&md5=7fe1c3e7a7d426370505fe7f621596d3}, doi = {10.1021/jp0669714}, year = {2007}, date = {2007-01-01}, journal = {Journal of Physical Chemistry B}, volume = {111}, number = {8}, pages = {2045--2051}, abstract = {This theoretical paper introduces an experimental protocol derived from the concept of Brownian motors in order to selectively confer an oriented motion to given charged reactants. Instead of maintaining permanently the system in nonequilibrium conditions, we propose a simple experimental trick to restore periodically a transient out-of-equilibrium regime: the reactive medium is alternately submitted to a sawtooth potential and to a potential ramp. The model provides approximate analytical expressions for the operating conditions allowing us to design the extraction from a mixture of any desired reactant characterized by its rate constants. The orders of magnitude suggest a possible implementation in microsystems where the present approach could be used for separation and analysis. © 2007 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This theoretical paper introduces an experimental protocol derived from the concept of Brownian motors in order to selectively confer an oriented motion to given charged reactants. Instead of maintaining permanently the system in nonequilibrium conditions, we propose a simple experimental trick to restore periodically a transient out-of-equilibrium regime: the reactive medium is alternately submitted to a sawtooth potential and to a potential ramp. The model provides approximate analytical expressions for the operating conditions allowing us to design the extraction from a mixture of any desired reactant characterized by its rate constants. The orders of magnitude suggest a possible implementation in microsystems where the present approach could be used for separation and analysis. © 2007 American Chemical Society. |
The Nature and Efficiency of Neurotransmitter Exocytosis Also Depend on Physicochemical Parameters Article de journal Christian Amatore; Stephane Arbault; Manon Guille; Frederic Lemaitre Chemphyschem, 8 (11), p. 1597-1605, 2007, ISSN: 1439-4235. @article{RN21b, title = {The Nature and Efficiency of Neurotransmitter Exocytosis Also Depend on Physicochemical Parameters}, author = {Christian Amatore and Stephane Arbault and Manon Guille and Frederic Lemaitre}, doi = {10.1002/cphc.200700225}, issn = {1439-4235}, year = {2007}, date = {2007-01-01}, journal = {Chemphyschem}, volume = {8}, number = {11}, pages = {1597-1605}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Thermal characterization of a microfluidic cell using the 3ωmethod Inproceedings T Barilero; P -O Chapuis; D Pujade; S Guilet; V Croquette; L Jullien; S Volz; C Gosse TRANSDUCERS and EUROSENSORS '07 - 4th International Conference on Solid-State Sensors, Actuators and Microsystems, p. 1849–1852, 2007. @inproceedings{Barilero:2007, title = {Thermal characterization of a microfluidic cell using the 3ωmethod}, author = {T Barilero and P -O Chapuis and D Pujade and S Guilet and V Croquette and L Jullien and S Volz and C Gosse}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-50049116299&doi=10.1109%2fSENSOR.2007.4300516&partnerID=40&md5=79f1cc20e9e80b3a75700b59074ba356}, doi = {10.1109/SENSOR.2007.4300516}, year = {2007}, date = {2007-01-01}, booktitle = {TRANSDUCERS and EUROSENSORS '07 - 4th International Conference on Solid-State Sensors, Actuators and Microsystems}, pages = {1849--1852}, abstract = {Resistive heaters, 36 μm to 2 mm side, were microfabricated in indium-tin-oxide (ITO) using ion beam etching (IBE). A microfluidic cell was subsequently assembled and its thermal behavior was studied by the 3ω method. Experiments and finite element model (FEM) simulations both satisfactorily agreed with a simple one-dimensional model for heat diffusion. ©2007 IEEE.}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } Resistive heaters, 36 μm to 2 mm side, were microfabricated in indium-tin-oxide (ITO) using ion beam etching (IBE). A microfluidic cell was subsequently assembled and its thermal behavior was studied by the 3ω method. Experiments and finite element model (FEM) simulations both satisfactorily agreed with a simple one-dimensional model for heat diffusion. ©2007 IEEE. |
Two-photon uncaging with fluorescence reporting: Evaluation of the o-hydroxycinnamic platform Article de journal N Gagey; P Neveu; C Benbrahim; B Goetz; I Aujard; J -B Baudin; L Jullien Journal of the American Chemical Society, 129 (32), p. 9986–9998, 2007. @article{Gagey:2007, title = {Two-photon uncaging with fluorescence reporting: Evaluation of the o-hydroxycinnamic platform}, author = {N Gagey and P Neveu and C Benbrahim and B Goetz and I Aujard and J -B Baudin and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34547870514&doi=10.1021%2fja0722022&partnerID=40&md5=680a2519805e064c0d94072f36b1e534}, doi = {10.1021/ja0722022}, year = {2007}, date = {2007-01-01}, journal = {Journal of the American Chemical Society}, volume = {129}, number = {32}, pages = {9986--9998}, abstract = {This paper evaluates the ohydroxycinnamic platform for designing efficient caging groups with fluorescence reporting upon one- and two-photon excitation. The model cinnamates are easily prepared in one step by coupling commercial or readily available synthons. They exhibit a large one-photon absorption that can be tuned in the near-UV range. Uncaging after one-photon excitation was investigated by 1H NMR, UV-vis absorption, and steady-state fluorescence emission. In the whole investigated series, the caged substrate is quantitatively released upon photolysis. At the same time, uncaging releases a strongly fluorescent coproduct that can be used as a reporter for quantitative substrate delivery. The quantum yield of double bond photoisomerization leading to uncaging after one-photon absorption mostly lies in the 10% range. Taking advantage of the favorable photophysical properties of the uncaging coproduct, we use a series of techniques based on fluorescence emission to measure the action uncaging cross sections with two-photon excitation of the present cinnamates. Exhibiting values in the 1-10 GM range at 750 nm, they satisfactorily compare with the most efficient caging groups reported to date. Noticeably, the uncaging behavior with two-photon excitation is retained in vivo as suggested by the results observed in living zebrafish embryos. Reliable structure property relationships were extracted from analysis of the present collected data. In particular, the careful kinetic analysis allows us to discuss the relevance of the ohydroxycinnamic platform for diverse caging applications with one- and two-photon excitation. © 2007 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper evaluates the ohydroxycinnamic platform for designing efficient caging groups with fluorescence reporting upon one- and two-photon excitation. The model cinnamates are easily prepared in one step by coupling commercial or readily available synthons. They exhibit a large one-photon absorption that can be tuned in the near-UV range. Uncaging after one-photon excitation was investigated by 1H NMR, UV-vis absorption, and steady-state fluorescence emission. In the whole investigated series, the caged substrate is quantitatively released upon photolysis. At the same time, uncaging releases a strongly fluorescent coproduct that can be used as a reporter for quantitative substrate delivery. The quantum yield of double bond photoisomerization leading to uncaging after one-photon absorption mostly lies in the 10% range. Taking advantage of the favorable photophysical properties of the uncaging coproduct, we use a series of techniques based on fluorescence emission to measure the action uncaging cross sections with two-photon excitation of the present cinnamates. Exhibiting values in the 1-10 GM range at 750 nm, they satisfactorily compare with the most efficient caging groups reported to date. Noticeably, the uncaging behavior with two-photon excitation is retained in vivo as suggested by the results observed in living zebrafish embryos. Reliable structure property relationships were extracted from analysis of the present collected data. In particular, the careful kinetic analysis allows us to discuss the relevance of the ohydroxycinnamic platform for diverse caging applications with one- and two-photon excitation. © 2007 American Chemical Society. |
Two-photon uncaging with the efficient 3,5-dibromo-2,4-dihydroxycinnamic caging group Article de journal N Gagey; P Neveu; L Jullien Angewandte Chemie - International Edition, 46 (14), p. 2467–2469, 2007. @article{Gagey:2007a, title = {Two-photon uncaging with the efficient 3,5-dibromo-2,4-dihydroxycinnamic caging group}, author = {N Gagey and P Neveu and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34250818700&doi=10.1002%2fanie.200604598&partnerID=40&md5=8e8a20b5554d394654aed024d24583b4}, doi = {10.1002/anie.200604598}, year = {2007}, date = {2007-01-01}, journal = {Angewandte Chemie - International Edition}, volume = {46}, number = {14}, pages = {2467--2469}, abstract = {(Chemical Equation Presented) An optical syringe for targeted delivery of a substrate in vivo has been developed on the basis of the 3,5-dibromo-2,4- dihydroxycinnamic caging group. Two-photon excitation of the caged compound uncages the substrate (ethanol in the scheme) and forms a coumarin whose fluorescence allows the concentration of released substrate to be quantified. Single-cell release can be achieved with a focused laser (shown schematically for a zebrafish embryo). © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } (Chemical Equation Presented) An optical syringe for targeted delivery of a substrate in vivo has been developed on the basis of the 3,5-dibromo-2,4- dihydroxycinnamic caging group. Two-photon excitation of the caged compound uncages the substrate (ethanol in the scheme) and forms a coumarin whose fluorescence allows the concentration of released substrate to be quantified. Single-cell release can be achieved with a focused laser (shown schematically for a zebrafish embryo). © 2007 Wiley-VCH Verlag GmbH & Co. KGaA. |
Ultrafast light-induced response of photoactive yellow protein chromophore analogues Article de journal A Espagne; D H Paik; P Changenet-Barret; P Plaza; M M Martin; A H Zewail Photochemical and Photobiological Sciences, 6 (7), p. 780–787, 2007. @article{Espagne:2007, title = {Ultrafast light-induced response of photoactive yellow protein chromophore analogues}, author = {A Espagne and D H Paik and P Changenet-Barret and P Plaza and M M Martin and A H Zewail}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-34447134184&doi=10.1039%2fb700927e&partnerID=40&md5=f30b6c18d177d6acc83123a44276d1be}, doi = {10.1039/b700927e}, year = {2007}, date = {2007-01-01}, journal = {Photochemical and Photobiological Sciences}, volume = {6}, number = {7}, pages = {780--787}, abstract = {The fluorescence decays of several analogues of the photoactive yellow protein (PYP) chromophore in aqueous solution have been measured by femtosecond fluorescence up-conversion and the corresponding time-resolved fluorescence spectra have been reconstructed. The native chromophore of PYP is a thioester derivative of p-coumaric acid in its trans deprotonated form. Fluorescence kinetics are reported for a thioester phenyl analogue and for two analogues where the thioester group has been changed to amide and carboxylate groups. The kinetics are compared to those we previously reported for the analogues bearing ketone and ester groups. The fluorescence decays of the full series are found to lie in the 1-10 ps range depending on the electron-acceptor character of the substituent, in good agreement with the excited-state relaxation kinetics extracted from transient absorption measurements. Steady-state photolysis is also examined and found to depend strongly on the nature of the substituent. While it has been shown that the ultrafast light-induced response of the chromophore in PYP is controlled by the properties of the protein nanospace, the present results demonstrate that, in solution, the relaxation dynamics and pathway of the chromophore is controlled by its electron donor-acceptor structure: structures of stronger electron donor-acceptor character lead to faster decays and less photoisomerisation. © The Royal Society of Chemistry and Owner Societies.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The fluorescence decays of several analogues of the photoactive yellow protein (PYP) chromophore in aqueous solution have been measured by femtosecond fluorescence up-conversion and the corresponding time-resolved fluorescence spectra have been reconstructed. The native chromophore of PYP is a thioester derivative of p-coumaric acid in its trans deprotonated form. Fluorescence kinetics are reported for a thioester phenyl analogue and for two analogues where the thioester group has been changed to amide and carboxylate groups. The kinetics are compared to those we previously reported for the analogues bearing ketone and ester groups. The fluorescence decays of the full series are found to lie in the 1-10 ps range depending on the electron-acceptor character of the substituent, in good agreement with the excited-state relaxation kinetics extracted from transient absorption measurements. Steady-state photolysis is also examined and found to depend strongly on the nature of the substituent. While it has been shown that the ultrafast light-induced response of the chromophore in PYP is controlled by the properties of the protein nanospace, the present results demonstrate that, in solution, the relaxation dynamics and pathway of the chromophore is controlled by its electron donor-acceptor structure: structures of stronger electron donor-acceptor character lead to faster decays and less photoisomerisation. © The Royal Society of Chemistry and Owner Societies. |
Ultrafast Structural Dynamics of Water Induced by Dissipation of Vibrational Energy Article de journal S Ashihara; N Huse; A Espagne; E T J Nibbering; T Elsaesser Journal of Physical Chemistry A, 111 (5), p. 743-746, 2007, ISSN: 1089-5639. @article{RN53, title = {Ultrafast Structural Dynamics of Water Induced by Dissipation of Vibrational Energy}, author = {S Ashihara and N Huse and A Espagne and E T J Nibbering and T Elsaesser}, doi = {10.1021/jp0676538}, issn = {1089-5639}, year = {2007}, date = {2007-01-01}, journal = {Journal of Physical Chemistry A}, volume = {111}, number = {5}, pages = {743-746}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Vesicular exocytosis under hypotonic conditions shows two distinct populations of dense core vesicles in bovine chromaffin cells Article de journal C Amatore; S Arbault; I Bonifas; F Lemaître; Y Verchier ChemPhysChem, 8 (4), p. 578–585, 2007. @article{Amatore:2007p, title = {Vesicular exocytosis under hypotonic conditions shows two distinct populations of dense core vesicles in bovine chromaffin cells}, author = {C Amatore and S Arbault and I Bonifas and F Lema\^{i}tre and Y Verchier}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33947203763&doi=10.1002%2fcphc.200600607&partnerID=40&md5=b2b8413df28dc06b218792682443845e}, doi = {10.1002/cphc.200600607}, year = {2007}, date = {2007-01-01}, journal = {ChemPhysChem}, volume = {8}, number = {4}, pages = {578--585}, abstract = {Several previous reports have discussed the effects of external osmolarity on vesicular exocytotic processes. However, few of these studies considered hypotonic conditions on chromaffin cells. Herein, the exocytosis of catecholamines by chromaffin cells was investigated in a medium of low osmolarity (200 mOsm) by amperometry at carbon fiber microelectrodes. It is observed that the frequency of the exocytotic events is significantly higher under hypotonic conditions than under physiological conditions (315 mOsm). This further confirms that the swelling of the polyelectrolytic matrix (which follows ionic exchanges) contained in dense core vesicles is the energetic driving force of the exocytotic phenomenon, being favored by a lower osmolarity. The mean amount of catecholamines released during secretory events also increases importantly under the hypotonic condition. This may be rationalized by the coexistence of two distinct populations of dense core vesicles with a relative content ratio of 4.7. The larger content population is favored under hypotonic conditions but plays only a side role under isotonic conditions. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Several previous reports have discussed the effects of external osmolarity on vesicular exocytotic processes. However, few of these studies considered hypotonic conditions on chromaffin cells. Herein, the exocytosis of catecholamines by chromaffin cells was investigated in a medium of low osmolarity (200 mOsm) by amperometry at carbon fiber microelectrodes. It is observed that the frequency of the exocytotic events is significantly higher under hypotonic conditions than under physiological conditions (315 mOsm). This further confirms that the swelling of the polyelectrolytic matrix (which follows ionic exchanges) contained in dense core vesicles is the energetic driving force of the exocytotic phenomenon, being favored by a lower osmolarity. The mean amount of catecholamines released during secretory events also increases importantly under the hypotonic condition. This may be rationalized by the coexistence of two distinct populations of dense core vesicles with a relative content ratio of 4.7. The larger content population is favored under hypotonic conditions but plays only a side role under isotonic conditions. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA. |
2006 |
An Unusual Functional Group Interaction and Its Potential to Reproduce Steric and Electrostatic Features of the Transition States of Peptidolysis Article de journal Arnaud Gautier; Delphine Pitrat; Jens Hasserodt Bioorganic & Medicinal Chemistry, 14 (11), p. 3835-3847, 2006, ISSN: 0968-0896. @article{RN47b, title = {An Unusual Functional Group Interaction and Its Potential to Reproduce Steric and Electrostatic Features of the Transition States of Peptidolysis}, author = {Arnaud Gautier and Delphine Pitrat and Jens Hasserodt}, doi = {https://doi.org/10.1016/j.bmc.2006.01.031}, issn = {0968-0896}, year = {2006}, date = {2006-01-01}, journal = {Bioorganic & Medicinal Chemistry}, volume = {14}, number = {11}, pages = {3835-3847}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Assessment of the electrochemical behavior of two-dimensional networks of single-walled carbon nanotubes Article de journal Neil R Wilson; Manon Guille; Ioana Dumitrescu; Virginia R Fernandez; Nicola C Rudd; Cara G Williams; Patrick R Unwin; Julie V Macpherson Analytical Chemistry, 78 (19), p. 7006-7015, 2006, (Times Cited: 28). @article{, title = {Assessment of the electrochemical behavior of two-dimensional networks of single-walled carbon nanotubes}, author = {Neil R Wilson and Manon Guille and Ioana Dumitrescu and Virginia R Fernandez and Nicola C Rudd and Cara G Williams and Patrick R Unwin and Julie V Macpherson}, year = {2006}, date = {2006-01-01}, journal = {Analytical Chemistry}, volume = {78}, number = {19}, pages = {7006-7015}, note = {Times Cited: 28}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Coupling of electrochemistry and fluorescence microscopy at indium tin oxide microelectrodes for the analysis of single exocytotic events Article de journal C Amatore; S Arbault; Y Chen; C Crozatier; F Lemaître; Y Verchier Angewandte Chemie - International Edition, 45 (24), p. 4000–4003, 2006. @article{Amatore:2006, title = {Coupling of electrochemistry and fluorescence microscopy at indium tin oxide microelectrodes for the analysis of single exocytotic events}, author = {C Amatore and S Arbault and Y Chen and C Crozatier and F Lema\^{i}tre and Y Verchier}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33746309503&doi=10.1002%2fanie.200600510&partnerID=40&md5=6db1449bc0c22c777137713c0df11dc1}, doi = {10.1002/anie.200600510}, year = {2006}, date = {2006-01-01}, journal = {Angewandte Chemie - International Edition}, volume = {45}, number = {24}, pages = {4000--4003}, abstract = {(Figure Presented) One-off analysis: Quantitative, kinetic, and spatial monitoring of single biological events involving vesicular secretion such as exocytosis may be achieved by combining electrochemistry with fluorescence microscopy at indium tin oxide (ITO) transparent microelectrodes. This method paves the way for real-time tracking of the intracellular fate of vesicles while monitoring precisely their dynamics of fusion. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } (Figure Presented) One-off analysis: Quantitative, kinetic, and spatial monitoring of single biological events involving vesicular secretion such as exocytosis may be achieved by combining electrochemistry with fluorescence microscopy at indium tin oxide (ITO) transparent microelectrodes. This method paves the way for real-time tracking of the intracellular fate of vesicles while monitoring precisely their dynamics of fusion. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA. |
Excited-state dynamics of the PYP chromophore in solution. Environment and structure effects Inproceedings A Espagne; P Changenet-Barret; J -B Baudin; P Plaza; M M Martin Jr, Castleman A W; Kimble, M L (Ed.): VIIth International Conference on Femtochemistry, p. 204-214, Elsevier, 2006. @inproceedings{RN101, title = {Excited-state dynamics of the PYP chromophore in solution. Environment and structure effects}, author = {A Espagne and P Changenet-Barret and J -B Baudin and P Plaza and M M Martin}, editor = {A W Castleman Jr and M L Kimble}, year = {2006}, date = {2006-01-01}, booktitle = {VIIth International Conference on Femtochemistry}, pages = {204-214}, publisher = {Elsevier}, series = {Femtochemistry VII: Fundamental Ultrafast Processes in Chemistry, Physics and Biology}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Glutamatergic control of microvascular tone by distinct GABA neurons in the cerebellum Article de journal Armelle Rancillac; Jean Rossier; Manon Guille; Xin-Kang Tong; Helene Geoffroy; Christian Amatore; Stephane Arbault; Edith Hamel; Bruno Cauli Journal of Neuroscience, 26 (26), p. 6997-7006, 2006, (Times Cited: 79). @article{, title = {Glutamatergic control of microvascular tone by distinct GABA neurons in the cerebellum}, author = {Armelle Rancillac and Jean Rossier and Manon Guille and Xin-Kang Tong and Helene Geoffroy and Christian Amatore and Stephane Arbault and Edith Hamel and Bruno Cauli}, year = {2006}, date = {2006-01-01}, journal = {Journal of Neuroscience}, volume = {26}, number = {26}, pages = {6997-7006}, note = {Times Cited: 79}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
T Le Saux; H Hisamoto; S Terabe Journal of Chromatography A, 1104 (1-2), p. 352–358, 2006. @article{LeSaux:2006, title = {Measurement of monomolecular binding constants of neutral phenols into the β-cyclodextrin by continuous frontal analysis in capillary and microchip electrophoresis via a competitive assay}, author = {T Le Saux and H Hisamoto and S Terabe}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-30744434624&doi=10.1016%2fj.chroma.2005.11.125&partnerID=40&md5=14f091ebb68d0f9dcda8c11cd172fce0}, doi = {10.1016/j.chroma.2005.11.125}, year = {2006}, date = {2006-01-01}, journal = {Journal of Chromatography A}, volume = {1104}, number = {1-2}, pages = {352--358}, abstract = {Measurement of binding constant by chip electrophoresis is a very promising technique for the high throughput screening of non-covalent interactions. Among the different electrophoretic methods available that yield the binding parameters, continuous frontal analysis is the most appropriate for a transposition from capillary electrophoresis (CE) to microchip electrophoresis. Implementation of this methodology in microchip was exemplified by the measurement of inclusion constants of 2-naphtalenesulfonate and neutral phenols (phenol, 4-chlorophenol and 4-nitrophenol) into β-cyclodextrin by competitive assays. The issue of competitor choice is discussed in relation to its appropriateness for proper monitoring of the interaction. © 2005 Elsevier B.V. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Measurement of binding constant by chip electrophoresis is a very promising technique for the high throughput screening of non-covalent interactions. Among the different electrophoretic methods available that yield the binding parameters, continuous frontal analysis is the most appropriate for a transposition from capillary electrophoresis (CE) to microchip electrophoresis. Implementation of this methodology in microchip was exemplified by the measurement of inclusion constants of 2-naphtalenesulfonate and neutral phenols (phenol, 4-chlorophenol and 4-nitrophenol) into β-cyclodextrin by competitive assays. The issue of competitor choice is discussed in relation to its appropriateness for proper monitoring of the interaction. © 2005 Elsevier B.V. All rights reserved. |
Modelling release of nitric oxide in a slice of rat's brain: describing stimulated functional hyperemia with diffusion-reaction equations Article de journal A I Oleinick; C Amatore; M Guille; S Arbault; O V Klymenko; I Svir Mathematical Medicine and Biology-a Journal of the Ima, 23 (1), p. 27-44, 2006, (Times Cited: 12). @article{, title = {Modelling release of nitric oxide in a slice of rat's brain: describing stimulated functional hyperemia with diffusion-reaction equations}, author = {A I Oleinick and C Amatore and M Guille and S Arbault and O V Klymenko and I Svir}, year = {2006}, date = {2006-01-01}, journal = {Mathematical Medicine and Biology-a Journal of the Ima}, volume = {23}, number = {1}, pages = {27-44}, note = {Times Cited: 12}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Nitric oxide release during evoked neuronal activity in cerebellum slices: Detection with platinized carbon-fiber microelectrodes Article de journal C Amatore; S Arbault; Y Bouret; B Cauli; M Guille; A Rancillac; J Rossier ChemPhysChem, 7 (1), p. 181–187, 2006. @article{Amatore:2006e, title = {Nitric oxide release during evoked neuronal activity in cerebellum slices: Detection with platinized carbon-fiber microelectrodes}, author = {C Amatore and S Arbault and Y Bouret and B Cauli and M Guille and A Rancillac and J Rossier}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-31144464236&doi=10.1002%2fcphc.200500202&partnerID=40&md5=98d8f71d47f6a9199678a764ed645e15}, doi = {10.1002/cphc.200500202}, year = {2006}, date = {2006-01-01}, journal = {ChemPhysChem}, volume = {7}, number = {1}, pages = {181--187}, abstract = {Nitric oxide is an important biological messenger that particularly induces the relaxation of smooth muscle cells surrounding vessels, and, hence, controls the flow of blood. This mechanism is essential for brain function, and its fine control, termed functional hyperemia, is supposed to be realized by certain neurons that may release bursts of NO•. The aim of the present study is to examine the advantages of platinized carbon-fiber microelectrodes (5-7 μm tip diameter) for the direct and in situ electrochemical detection of NO• released by neurons into ex vivo cerebellum slices. After establishing the different analytical properties of the platinized carbon-fiber microelectrodes in vitro on NO• solutions at 50 nM to 1 mM concentration, they were characterized using DEA-NONOate solutions that chemically decompose into NO•, and therefore mimic the measurement of transient variations of NO• concentration in biological samples. This validated the present approach, so that direct, in situ ex vivo measurements of nitric oxide released by neurons in a rat cerebellar slice are presented and discussed. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Nitric oxide is an important biological messenger that particularly induces the relaxation of smooth muscle cells surrounding vessels, and, hence, controls the flow of blood. This mechanism is essential for brain function, and its fine control, termed functional hyperemia, is supposed to be realized by certain neurons that may release bursts of NO•. The aim of the present study is to examine the advantages of platinized carbon-fiber microelectrodes (5-7 μm tip diameter) for the direct and in situ electrochemical detection of NO• released by neurons into ex vivo cerebellum slices. After establishing the different analytical properties of the platinized carbon-fiber microelectrodes in vitro on NO• solutions at 50 nM to 1 mM concentration, they were characterized using DEA-NONOate solutions that chemically decompose into NO•, and therefore mimic the measurement of transient variations of NO• concentration in biological samples. This validated the present approach, so that direct, in situ ex vivo measurements of nitric oxide released by neurons in a rat cerebellar slice are presented and discussed. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA. |
O-nitrobenzyl photolabile protecting groups with red-shifted absorption: Syntheses and uncaging cross-sections for one- And two-photon excitation Article de journal I Aujard; C Benbrahim; M Gouget; O Ruel; J -B Baudin; P Neveu; L Jullien Chemistry - A European Journal, 12 (26), p. 6865–6879, 2006. @article{Aujard:2006, title = {O-nitrobenzyl photolabile protecting groups with red-shifted absorption: Syntheses and uncaging cross-sections for one- And two-photon excitation}, author = {I Aujard and C Benbrahim and M Gouget and O Ruel and J -B Baudin and P Neveu and L Jullien}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33748546615&doi=10.1002%2fchem.200501393&partnerID=40&md5=d3011a8b9ba16aa9a425b2fd309a5fac}, doi = {10.1002/chem.200501393}, year = {2006}, date = {2006-01-01}, journal = {Chemistry - A European Journal}, volume = {12}, number = {26}, pages = {6865--6879}, abstract = {We evaluated the o-nitrobenzyl platform for designing photolabile protecting groups with red-shifted absorption that could be photolyzed upon one- and two-photon excitation. Several synthetic pathways to build different conjugated o-nitrobenzyl backbones, as well as to vary the benzylic position, are reported. Relative to the reference 4,5-dimethoxy-2-nitrobenzyl group, several o-nitrobenzyl derivatives exhibit a large and red-shifted one-photon absorption within the near-UV range. Uncaging after one-photon excitation was studied by measuring UV-visible absorption and steady-state fluorescence emission on model caged ethers and esters. In the whole series investi gated, the caged substrates were released cleanly upon photolysis. Quantum yields of uncaging after one-photon absorption lie within the 0.11% range. We observed that these drop as the maximum wavelength absorption of the o-nitrobenzyl protecting group is increased. A new method based on fluorescence correlation spectroscopy (PCS) after two-photon excitation was used to measure the action uncaging cross section for two-photon excitation. The series of o-nitrobenzyl caged fluorescent coumarins investigated exhibit values within the 0.10.01 Goeppert-Mayer (GM) range. Such results are in line with the low quantum yields of uncaging associated with cross-sections of 1-50 GM for two-photon absorption. Although the cross-sections for one- and two-photon absorption of o-nitrobenzyl photolabile protecting groups can be readily improved, we emphasize the difficulty in enlarging the corresponding action uncaging cross-sections in view of the observed trend of their quantum yield of uncaging. © 2006 Wiley-VCH Verlag GmbH & Co, KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We evaluated the o-nitrobenzyl platform for designing photolabile protecting groups with red-shifted absorption that could be photolyzed upon one- and two-photon excitation. Several synthetic pathways to build different conjugated o-nitrobenzyl backbones, as well as to vary the benzylic position, are reported. Relative to the reference 4,5-dimethoxy-2-nitrobenzyl group, several o-nitrobenzyl derivatives exhibit a large and red-shifted one-photon absorption within the near-UV range. Uncaging after one-photon excitation was studied by measuring UV-visible absorption and steady-state fluorescence emission on model caged ethers and esters. In the whole series investi gated, the caged substrates were released cleanly upon photolysis. Quantum yields of uncaging after one-photon absorption lie within the 0.11% range. We observed that these drop as the maximum wavelength absorption of the o-nitrobenzyl protecting group is increased. A new method based on fluorescence correlation spectroscopy (PCS) after two-photon excitation was used to measure the action uncaging cross section for two-photon excitation. The series of o-nitrobenzyl caged fluorescent coumarins investigated exhibit values within the 0.10.01 Goeppert-Mayer (GM) range. Such results are in line with the low quantum yields of uncaging associated with cross-sections of 1-50 GM for two-photon absorption. Although the cross-sections for one- and two-photon absorption of o-nitrobenzyl photolabile protecting groups can be readily improved, we emphasize the difficulty in enlarging the corresponding action uncaging cross-sections in view of the observed trend of their quantum yield of uncaging. © 2006 Wiley-VCH Verlag GmbH & Co, KGaA. |
Photophysics of a series of efficient fluorescent pH probes for dual-emission-wavelength measurements in aqueous solutions Article de journal S Charier; O Ruel; J -B Baudin; D Alcor; J -F Allemand; A Meglio; L Jullien; B Valeur Chemistry - A European Journal, 12 (4), p. 1097–1113, 2006. @article{Charier:2006, title = {Photophysics of a series of efficient fluorescent pH probes for dual-emission-wavelength measurements in aqueous solutions}, author = {S Charier and O Ruel and J -B Baudin and D Alcor and J -F Allemand and A Meglio and L Jullien and B Valeur}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-31344460620&doi=10.1002%2fchem.200500619&partnerID=40&md5=ba45e0a9ace96d749f8d4a985ed8a55c}, doi = {10.1002/chem.200500619}, year = {2006}, date = {2006-01-01}, journal = {Chemistry - A European Journal}, volume = {12}, number = {4}, pages = {1097--1113}, abstract = {This paper evaluates the 5-aryl-2-pyridyloxazole backbone to engineer donor-acceptor fluorescent pH probes after one- or two-photon absorption. Parent fluorophores, as well as derivatives that can be used to label biomolecules, can be easily obtained in good yields. These molecules exhibit a large one-photon absorption in the near-UV range, and a strong fluorescence emission that covers the whole visible domain. The 5-aryl-2-pyridyloxazole derivatives also possess significant cross sections for two-photon absorption. Upon pyridine protonation, large shifts were observed in the absorption spectra after one- and two-photon excitation, as well as in the emission spectra. This feature was used to measure the pKa of the investigated compounds that range between 2 and 8. In most of the investigated derivatives, the pKa increased upon light excitation and protonation exchanges took place during the lifetime of the excited state, as shown by phase-modulation fluorometry analysis. Several 5-aryl-2-pyridyloxazole derivatives are suggested as efficient probes to reliably measure the pH of aqueous solutions by means of ratiometric methods that are dependent on fluorescence emission. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } This paper evaluates the 5-aryl-2-pyridyloxazole backbone to engineer donor-acceptor fluorescent pH probes after one- or two-photon absorption. Parent fluorophores, as well as derivatives that can be used to label biomolecules, can be easily obtained in good yields. These molecules exhibit a large one-photon absorption in the near-UV range, and a strong fluorescence emission that covers the whole visible domain. The 5-aryl-2-pyridyloxazole derivatives also possess significant cross sections for two-photon absorption. Upon pyridine protonation, large shifts were observed in the absorption spectra after one- and two-photon excitation, as well as in the emission spectra. This feature was used to measure the pKa of the investigated compounds that range between 2 and 8. In most of the investigated derivatives, the pKa increased upon light excitation and protonation exchanges took place during the lifetime of the excited state, as shown by phase-modulation fluorometry analysis. Several 5-aryl-2-pyridyloxazole derivatives are suggested as efficient probes to reliably measure the pH of aqueous solutions by means of ratiometric methods that are dependent on fluorescence emission. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA. |
Quadruplex-based molecular beacons as tunable DNA probes Article de journal A Bourdoncle; A E Torres; C Gosse; L Lacroix; P Vekhoff; T Le Saux; L Jullien; J -L Mergny Journal of the American Chemical Society, 128 (34), p. 11094–11105, 2006. @article{Bourdoncle:2006, title = {Quadruplex-based molecular beacons as tunable DNA probes}, author = {A Bourdoncle and A E Torres and C Gosse and L Lacroix and P Vekhoff and T Le Saux and L Jullien and J -L Mergny}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33748052721&doi=10.1021%2fja0608040&partnerID=40&md5=68c9f7b0a980f51035c5a06b54023673}, doi = {10.1021/ja0608040}, year = {2006}, date = {2006-01-01}, journal = {Journal of the American Chemical Society}, volume = {128}, number = {34}, pages = {11094--11105}, abstract = {Molecular beacons (MBs) are fluorescent nucleic acid probes with a hairpin-shaped structure in which the 5′ and 3′ ends are self-complementary. Due to a change in their emissive properties upon recognition with complementary sequences, MBs allow the diagnosis of single-stranded DNA or RNA with high mismatch discrimination, in vitro and in vivo. Whereas the stems of MB hairpins usually rely on the formation of a Watson-Crick duplex, we demonstrate in this report that the preceding structure can be replaced by a G-quadruplex motif (G4). Intramolecular quadruplexes may still be formed with a central loop composed of 12 to 21 bases, therefore extending the sequence repertoire of quadruplex formation. G4-MB can efficiently be used for oligonucleotide discrimination: in the presence of a complementary sequence, the central loop hybridizes and forms a duplex that causes opening of the quadruplex stem. The corresponding G4-MB unfolding can be detected by a change in its fluorescence emission. We discuss the thermodynamic and kinetic opportunities that are provided by using G4-MB instead of traditional MB. In particular, the intrinsic feature of the quadruplex motif facilitates the design of functional molecular beacons by independently varying the concentration of monovalent or divalent cations in the medium. © 2006 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Molecular beacons (MBs) are fluorescent nucleic acid probes with a hairpin-shaped structure in which the 5′ and 3′ ends are self-complementary. Due to a change in their emissive properties upon recognition with complementary sequences, MBs allow the diagnosis of single-stranded DNA or RNA with high mismatch discrimination, in vitro and in vivo. Whereas the stems of MB hairpins usually rely on the formation of a Watson-Crick duplex, we demonstrate in this report that the preceding structure can be replaced by a G-quadruplex motif (G4). Intramolecular quadruplexes may still be formed with a central loop composed of 12 to 21 bases, therefore extending the sequence repertoire of quadruplex formation. G4-MB can efficiently be used for oligonucleotide discrimination: in the presence of a complementary sequence, the central loop hybridizes and forms a duplex that causes opening of the quadruplex stem. The corresponding G4-MB unfolding can be detected by a change in its fluorescence emission. We discuss the thermodynamic and kinetic opportunities that are provided by using G4-MB instead of traditional MB. In particular, the intrinsic feature of the quadruplex motif facilitates the design of functional molecular beacons by independently varying the concentration of monovalent or divalent cations in the medium. © 2006 American Chemical Society. |
Regulation of exocytosis in chromaffin cells by Trans-insertion of lysophosphatidylcholine and arachidonic acid into the outer leaflet of the cell membrane Article de journal C Amatore; S Arbault; Y Bouret; M Guille; F Lemaître; Y Verchier ChemBioChem, 7 (12), p. 1998–2003, 2006. @article{Amatore:2006i, title = {Regulation of exocytosis in chromaffin cells by Trans-insertion of lysophosphatidylcholine and arachidonic acid into the outer leaflet of the cell membrane}, author = {C Amatore and S Arbault and Y Bouret and M Guille and F Lema\^{i}tre and Y Verchier}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33845431788&doi=10.1002%2fcbic.200600194&partnerID=40&md5=ee09aa44f07bb791da49cab4b5ce936a}, doi = {10.1002/cbic.200600194}, year = {2006}, date = {2006-01-01}, journal = {ChemBioChem}, volume = {7}, number = {12}, pages = {1998--2003}, abstract = {Vesicular exocytosis is an important complex process in the communication between cells in organisms. It controls the release of chemical and biochemical messengers stored in an emitting cell. In this report, exocytosis is studied amperometrically (at carbon fiber ultramicroelectrodes) at adrenal chromaffin cells, which release catecholamines after appropriate stimulation, while testing the effects due to trans-insertion of two exogenous compounds (lysophosphatidylcholine (LPC) and arachidonic acid (AA)) on the kinetics of exocytotic events. Amperometric analyses showed that, under the present conditions (short incubation times and micromolar LPC or AA solutions), LPC favors catecholamine release (rate, event frequency, charge released) while AA disfavors the exocytotic processes. The observed kinetic features are rationalized quantitatively by considering a stalk model, for the fusion pore formation, and the physical constraints applied to the cell membrane by the presence of small fractions of LPC and AA diluted in its external leaflet (trans-insertion). We also observed that the detected amount of neurotransmitters in the presence of LPC was larger than under control conditions, while the opposite trend is observed with AA. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Vesicular exocytosis is an important complex process in the communication between cells in organisms. It controls the release of chemical and biochemical messengers stored in an emitting cell. In this report, exocytosis is studied amperometrically (at carbon fiber ultramicroelectrodes) at adrenal chromaffin cells, which release catecholamines after appropriate stimulation, while testing the effects due to trans-insertion of two exogenous compounds (lysophosphatidylcholine (LPC) and arachidonic acid (AA)) on the kinetics of exocytotic events. Amperometric analyses showed that, under the present conditions (short incubation times and micromolar LPC or AA solutions), LPC favors catecholamine release (rate, event frequency, charge released) while AA disfavors the exocytotic processes. The observed kinetic features are rationalized quantitatively by considering a stalk model, for the fusion pore formation, and the physical constraints applied to the cell membrane by the presence of small fractions of LPC and AA diluted in its external leaflet (trans-insertion). We also observed that the detected amount of neurotransmitters in the presence of LPC was larger than under control conditions, while the opposite trend is observed with AA. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. |
Solvent effect on the excited-state dynamics of analogues of the photoactive Yellow Protein chromophore Article de journal A Espagne; P Changenet-Barret; P Plaza; M M Martin Journal of Physical Chemistry A, 110 (10), p. 3393–3404, 2006. @article{Espagne:2006a, title = {Solvent effect on the excited-state dynamics of analogues of the photoactive Yellow Protein chromophore}, author = {A Espagne and P Changenet-Barret and P Plaza and M M Martin}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33645500398&doi=10.1021%2fjp0563843&partnerID=40&md5=d174de26213df87496872cae2ddf21dd}, doi = {10.1021/jp0563843}, year = {2006}, date = {2006-01-01}, journal = {Journal of Physical Chemistry A}, volume = {110}, number = {10}, pages = {3393--3404}, abstract = {We previously reported that two analogues of the Photoactive Yellow Protein chromophore, trans-p-hydroxycinnamic acid (pCA2-) and its amide derivative (pCM-) in their deprotonated forms, undergo a transcis photoisomerization whereas the thioester derivative, trans-p-hydroxythiophenyl cinnamate (pCT-), does not. pCT- is also the only one to exhibit a short-lived intermediate on its excited-state deactivation pathway. We here further stress the existence of two different relaxation mechanisms for these molecules and examine the reaction coordinates involved. We looked at the effect of the solvent properties (viscosity, polarity, solvation dynamics) on their excited-state relaxation dynamics, probed by ultrafast transient absorption spectroscopy. Sensitivity to the solvent properties is found to be larger for pCT- than for pCA2- and pCM-. This difference is considered to reveal that either the relaxation pathway or the reaction coordinate is different for these two classes of analogues. It is also found to be correlated to the electron donor - acceptor character of the molecule. We attribute the excited-state deactivation of analogues bearing a weaker acceptor group, pCA2- and pCM-, to a stilbene-like photoisomerization mechanism with the concerted rotation of the ethylenic bond and one adjacent single bond. For pCT-, which contains a stronger acceptor group, we consider a photoisomerization mechanism mainly involving the single torsion of the ethylenic bond. The excited-state deactivation of pCT - would lead to the formation of a ground-state intermediate at the "perp" geometry, which would return to the initial trans conformation without net isomerization. © 2006 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We previously reported that two analogues of the Photoactive Yellow Protein chromophore, trans-p-hydroxycinnamic acid (pCA2-) and its amide derivative (pCM-) in their deprotonated forms, undergo a transcis photoisomerization whereas the thioester derivative, trans-p-hydroxythiophenyl cinnamate (pCT-), does not. pCT- is also the only one to exhibit a short-lived intermediate on its excited-state deactivation pathway. We here further stress the existence of two different relaxation mechanisms for these molecules and examine the reaction coordinates involved. We looked at the effect of the solvent properties (viscosity, polarity, solvation dynamics) on their excited-state relaxation dynamics, probed by ultrafast transient absorption spectroscopy. Sensitivity to the solvent properties is found to be larger for pCT- than for pCA2- and pCM-. This difference is considered to reveal that either the relaxation pathway or the reaction coordinate is different for these two classes of analogues. It is also found to be correlated to the electron donor - acceptor character of the molecule. We attribute the excited-state deactivation of analogues bearing a weaker acceptor group, pCA2- and pCM-, to a stilbene-like photoisomerization mechanism with the concerted rotation of the ethylenic bond and one adjacent single bond. For pCT-, which contains a stronger acceptor group, we consider a photoisomerization mechanism mainly involving the single torsion of the ethylenic bond. The excited-state deactivation of pCT - would lead to the formation of a ground-state intermediate at the "perp" geometry, which would return to the initial trans conformation without net isomerization. © 2006 American Chemical Society. |
Tuning of Co (I) X Reactivity Towards Aromatic Halides by the Presence of Allylic and Vinylic Derivatives Inproceedings Olivier Buriez; Eric Labbe ECS Meeting Abstracts, p. 1430, IOP Publishing 2006. @inproceedings{buriez2006tuning, title = {Tuning of Co (I) X Reactivity Towards Aromatic Halides by the Presence of Allylic and Vinylic Derivatives}, author = {Olivier Buriez and Eric Labbe}, year = {2006}, date = {2006-01-01}, booktitle = {ECS Meeting Abstracts}, number = {38}, pages = {1430}, organization = {IOP Publishing}, keywords = {}, pubstate = {published}, tppubtype = {inproceedings} } |
Ultrafast photoisomerization of photoactive yellow protein chromophore analogues in solution: Influence of the protonation state Article de journal A Espagne; D H Paik; P Changenet-Barret; M M Martin; A H Zewail ChemPhysChem, 7 (8), p. 1717–1726, 2006. @article{Espagne:2006b, title = {Ultrafast photoisomerization of photoactive yellow protein chromophore analogues in solution: Influence of the protonation state}, author = {A Espagne and D H Paik and P Changenet-Barret and M M Martin and A H Zewail}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-33748194569&doi=10.1002%2fcphc.200600137&partnerID=40&md5=1e4642cd9b9e7e944526096c65c4fc00}, doi = {10.1002/cphc.200600137}, year = {2006}, date = {2006-01-01}, journal = {ChemPhysChem}, volume = {7}, number = {8}, pages = {1717--1726}, abstract = {We investigate solvent viscosity and polarity effects on the photoisomerization of the protonated and deprotonated forms of two analogues of the photoactive yellow protein (PYP) chromophore. These are trans-p- hydroxybenzylidene acetone and trans-p-hydroxyphenyl cinnamate, studied in solutions of different polarity and viscosity at room temperature, by means of femtosecond fluorescence up-conversion. The fluorescence lifetimes of the protonated forms are found to be barely sensitive to solvent viscosity, and to increase with increasing solvent polarity. In contrast, the fluorescence decays of the deprotonated forms are significantly slowed down in viscous media and accelerated in polar solvents. These results elucidate the dramatic influence of the protonation state of the PYP chromophore analogues on their photoinduced dynamics. The viscosity and polarity effects are, respectively, interpreted in terms of different isomerization coordinates and charge redistribution in S 1. A trans-to-cis isomerization mechanism involving mainly the ethylenic double-bond torsion and/or salvation is proposed for the anionic forms, whereas "concerted" intramolecular motions are proposed for the neutral forms. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.}, keywords = {}, pubstate = {published}, tppubtype = {article} } We investigate solvent viscosity and polarity effects on the photoisomerization of the protonated and deprotonated forms of two analogues of the photoactive yellow protein (PYP) chromophore. These are trans-p- hydroxybenzylidene acetone and trans-p-hydroxyphenyl cinnamate, studied in solutions of different polarity and viscosity at room temperature, by means of femtosecond fluorescence up-conversion. The fluorescence lifetimes of the protonated forms are found to be barely sensitive to solvent viscosity, and to increase with increasing solvent polarity. In contrast, the fluorescence decays of the deprotonated forms are significantly slowed down in viscous media and accelerated in polar solvents. These results elucidate the dramatic influence of the protonation state of the PYP chromophore analogues on their photoinduced dynamics. The viscosity and polarity effects are, respectively, interpreted in terms of different isomerization coordinates and charge redistribution in S 1. A trans-to-cis isomerization mechanism involving mainly the ethylenic double-bond torsion and/or salvation is proposed for the anionic forms, whereas "concerted" intramolecular motions are proposed for the neutral forms. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA. |
Unexpected stabilization of a simple cobalt (I) salt in acetonitrile at a glassy carbon electrode Article de journal Olivier Buriez; Eric Labbé; Jacques Périchon Journal of Electroanalytical Chemistry, 593 (1-2), p. 99–104, 2006. @article{buriez2006unexpected, title = {Unexpected stabilization of a simple cobalt (I) salt in acetonitrile at a glassy carbon electrode}, author = {Olivier Buriez and Eric Labb\'{e} and Jacques P\'{e}richon}, year = {2006}, date = {2006-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {593}, number = {1-2}, pages = {99--104}, publisher = {Elsevier}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Unexpected stabilization of a simple cobalt(I) salt in acetonitrile at a glassy carbon electrode Article de journal Olivier Buriez; Eric Labbe; Jacques Perichon Journal of Electroanalytical Chemistry, 593 (1-2), p. 99-104, 2006. @article{RID:0721150706479-26, title = {Unexpected stabilization of a simple cobalt(I) salt in acetonitrile at a glassy carbon electrode}, author = {Olivier Buriez and Eric Labbe and Jacques Perichon}, year = {2006}, date = {2006-01-01}, journal = {Journal of Electroanalytical Chemistry}, volume = {593}, number = {1-2}, pages = {99-104}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Vibrational Couplings and Ultrafast Relaxation of the O-Ħ Bending Mode in Liquid H2O Article de journal S Ashihara; N Huse; A Espagne; E T J Nibbering; T Elsaesser Chemical Physics Letters, 424 (1-3), p. 66-70, 2006, ISSN: 0009-2614. @article{RN54b, title = {Vibrational Couplings and Ultrafast Relaxation of the O-{H} Bending Mode in Liquid H2O}, author = {S Ashihara and N Huse and A Espagne and E T J Nibbering and T Elsaesser}, doi = {10.1016/j.cplett.2006.04.051}, issn = {0009-2614}, year = {2006}, date = {2006-01-01}, journal = {Chemical Physics Letters}, volume = {424}, number = {1-3}, pages = {66-70}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
2005 |
An approach to extract rate constants from reaction-diffusion dynamics in a microchannel Article de journal J -B Salmon; C Dubrocq; P Tabeling; S Charier; D Alcor; L Jullien; F Ferrage Analytical Chemistry, 77 (11), p. 3417–3424, 2005. @article{Salmon:2005, title = {An approach to extract rate constants from reaction-diffusion dynamics in a microchannel}, author = {J -B Salmon and C Dubrocq and P Tabeling and S Charier and D Alcor and L Jullien and F Ferrage}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-20444391378&doi=10.1021%2fac0500838&partnerID=40&md5=069b35f666f1edab8f021528a9616794}, doi = {10.1021/ac0500838}, year = {2005}, date = {2005-01-01}, journal = {Analytical Chemistry}, volume = {77}, number = {11}, pages = {3417--3424}, abstract = {A theoretical model is proposed to extract rate constants of second-order chemical reactions down to the millisecond time scale from the observation of reaction-diffusion processes in a microchannel. We validate this theoretical approach by examining an appropriate model reaction. The measured rate constant is in excellent agreement with this obtained from nuclear magnetic resonance experiments. © 2005 American Chemical Society.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A theoretical model is proposed to extract rate constants of second-order chemical reactions down to the millisecond time scale from the observation of reaction-diffusion processes in a microchannel. We validate this theoretical approach by examining an appropriate model reaction. The measured rate constant is in excellent agreement with this obtained from nuclear magnetic resonance experiments. © 2005 American Chemical Society. |
Biophysics: fluorescent biomolecules Book Chapter F Lenci; M M Martin; P Plaza; G Checcucci; N Angelini; A Sgarbossa Liedl, G L; Wyder, P (Ed.): Encyclopedia of Condensed Matter Physics, p. 222-235, Elsevier, 2005. @inbook{RN84, title = {Biophysics: fluorescent biomolecules}, author = {F Lenci and M M Martin and P Plaza and G Checcucci and N Angelini and A Sgarbossa}, editor = {G L Liedl and P Wyder}, year = {2005}, date = {2005-01-01}, booktitle = {Encyclopedia of Condensed Matter Physics}, pages = {222-235}, publisher = {Elsevier}, keywords = {}, pubstate = {published}, tppubtype = {inbook} } |