2023
|
Multiscale Transient Absorption Study of the Fluorescent Protein Dreiklang and Two Point Variants Provides Insight into Photoswitching and Nonproductive Reaction Pathways Article de journal Emilie Renouard; Magdalena Nowinska; Fabien Lacombat; Pascal Plaza; Pavel Müller; Agathe Espagne The Journal of Physical Chemistry Letters, 14 (28), p. 6477-6485, 2023. @article{RN63c,
title = {Multiscale Transient Absorption Study of the Fluorescent Protein Dreiklang and Two Point Variants Provides Insight into Photoswitching and Nonproductive Reaction Pathways},
author = {Emilie Renouard and Magdalena Nowinska and Fabien Lacombat and Pascal Plaza and Pavel M\"{u}ller and Agathe Espagne},
url = {https://doi.org/10.1021/acs.jpclett.3c00431},
doi = {10.1021/acs.jpclett.3c00431},
year = {2023},
date = {2023-01-01},
journal = {The Journal of Physical Chemistry Letters},
volume = {14},
number = {28},
pages = {6477-6485},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Near-infrared co-illumination of fluorescent proteins reduces photobleaching and phototoxicity Article de journal L Ludvikova; E Simon; M Deygas; T Panier; M A Plamont; J Ollion; A Tebo; M Piel; L Jullien; L Robert; T Le Saux; A Espagne Nature Biotechnology, p. 12, 2023, ISSN: 1087-0156. @article{RN156,
title = {Near-infrared co-illumination of fluorescent proteins reduces photobleaching and phototoxicity},
author = {L Ludvikova and E Simon and M Deygas and T Panier and M A Plamont and J Ollion and A Tebo and M Piel and L Jullien and L Robert and T Le Saux and A Espagne},
url = {<Go to ISI>://WOS:001042699900001},
doi = {10.1038/s41587-023-01893-7},
issn = {1087-0156},
year = {2023},
date = {2023-01-01},
journal = {Nature Biotechnology},
pages = {12},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2021
|
Ultrafast photoreduction dynamics of a new class of CPD photolyases Article de journal Fabien Lacombat; Agathe Espagne; Nadia Dozova; Pascal Plaza; Pavel Müller; Hans-Joachim Emmerich; Martin Saft; Lars-Oliver Essen Photochemical & Photobiological Sciences, 20 (6), p. 733-746, 2021, ISSN: 1474-9092. @article{RN632,
title = {Ultrafast photoreduction dynamics of a new class of CPD photolyases},
author = {Fabien Lacombat and Agathe Espagne and Nadia Dozova and Pascal Plaza and Pavel M\"{u}ller and Hans-Joachim Emmerich and Martin Saft and Lars-Oliver Essen},
url = {https://doi.org/10.1007/s43630-021-00048-4},
doi = {10.1007/s43630-021-00048-4},
issn = {1474-9092},
year = {2021},
date = {2021-01-01},
journal = {Photochemical & Photobiological Sciences},
volume = {20},
number = {6},
pages = {733-746},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2020
|
Dynamic contrast for overcoming spectral interferences in fluorescence imaging Article de journal R Chouket; A Pellissier-Tanon; A Lemarchand; A Espagne; T Le Saux; L Jullien Journal of Physics-Photonics, 2 (3), p. 8, 2020, ISSN: 2515-7647. @article{RN1_30,
title = {Dynamic contrast for overcoming spectral interferences in fluorescence imaging},
author = {R Chouket and A Pellissier-Tanon and A Lemarchand and A Espagne and T Le Saux and L Jullien},
url = {<Go to ISI>://WOS:000572940200001},
doi = {10.1088/2515-7647/ab9099},
issn = {2515-7647},
year = {2020},
date = {2020-01-01},
journal = {Journal of Physics-Photonics},
volume = {2},
number = {3},
pages = {8},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Dynamic contrast with reversibly photoswitchable fluorescent labels for imaging living cells Article de journal R Chouket; A Pellissier-Tanon; A Lemarchand; A Espagne; T Le Saux; L Jullien Chemical Science, 11 (11), p. 2882-2887, 2020, ISSN: 2041-6520. @article{RN2x,
title = {Dynamic contrast with reversibly photoswitchable fluorescent labels for imaging living cells},
author = {R Chouket and A Pellissier-Tanon and A Lemarchand and A Espagne and T Le Saux and L Jullien},
url = {<Go to ISI>://WOS:000521247400002},
doi = {10.1039/d0sc00182a},
issn = {2041-6520},
year = {2020},
date = {2020-01-01},
journal = {Chemical Science},
volume = {11},
number = {11},
pages = {2882-2887},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
2019
|
Photosensitized oxidative addition to gold(i) enables alkynylative cyclization of o-alkylnylphenols with iodoalkynes Article de journal Zhonghua Xia; Vincent Corcé; Fen Zhao; Cédric Przybylski; Agathe Espagne; Ludovic Jullien; Thomas Le Saux; Yves Gimbert; Héloïse Dossmann; Virginie Mouriès-Mansuy; Cyril Ollivier; Louis Fensterbank Nature Chemistry, 11 (9), p. 797-805, 2019, ISSN: 1755-4349. @article{RN1_28,
title = {Photosensitized oxidative addition to gold(i) enables alkynylative cyclization of o-alkylnylphenols with iodoalkynes},
author = {Zhonghua Xia and Vincent Corc\'{e} and Fen Zhao and C\'{e}dric Przybylski and Agathe Espagne and Ludovic Jullien and Thomas Le Saux and Yves Gimbert and H\'{e}lo\"{i}se Dossmann and Virginie Mouri\`{e}s-Mansuy and Cyril Ollivier and Louis Fensterbank},
url = {https://doi.org/10.1038/s41557-019-0295-9},
doi = {10.1038/s41557-019-0295-9},
issn = {1755-4349},
year = {2019},
date = {2019-01-01},
journal = {Nature Chemistry},
volume = {11},
number = {9},
pages = {797-805},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Photosensitized oxidative addition to gold(I) enables alkynylative cyclization of o-alkylnylphenols with iodoalkynes Article de journal Z H Xia; V Corce; F Zhao; C Przybylski; A Espagne; L Jullien; T Le Saux; Y Gimbert; H Dossmann; V Mouries-Mansuy; C Ollivier; L Fensterbank Nature Chemistry, 11 (9), p. 797-805, 2019, ISSN: 1755-4330. @article{RN3s,
title = {Photosensitized oxidative addition to gold(I) enables alkynylative cyclization of o-alkylnylphenols with iodoalkynes},
author = {Z H Xia and V Corce and F Zhao and C Przybylski and A Espagne and L Jullien and T Le Saux and Y Gimbert and H Dossmann and V Mouries-Mansuy and C Ollivier and L Fensterbank},
url = {<Go to ISI>://WOS:000483307000010},
doi = {10.1038/s41557-019-0295-9},
issn = {1755-4330},
year = {2019},
date = {2019-01-01},
journal = {Nature Chemistry},
volume = {11},
number = {9},
pages = {797-805},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Ultrafast Oxidation of a Tyrosine by Proton-Coupled Electron Transfer Promotes Light Activation of an Animal-like Cryptochrome Article de journal Fabien Lacombat; Agathe Espagne; Nadia Dozova; Pascal Plaza; Pavel Müller; Klaus Brettel; Sophie Franz-Badur; Lars-Oliver Essen Journal of the American Chemical Society, 141 (34), p. 13394-13409, 2019, ISSN: 0002-7863. @article{RN479,
title = {Ultrafast Oxidation of a Tyrosine by Proton-Coupled Electron Transfer Promotes Light Activation of an Animal-like Cryptochrome},
author = {Fabien Lacombat and Agathe Espagne and Nadia Dozova and Pascal Plaza and Pavel M\"{u}ller and Klaus Brettel and Sophie Franz-Badur and Lars-Oliver Essen},
url = {https://doi.org/10.1021/jacs.9b03680},
doi = {10.1021/jacs.9b03680},
issn = {0002-7863},
year = {2019},
date = {2019-01-01},
journal = {Journal of the American Chemical Society},
volume = {141},
number = {34},
pages = {13394-13409},
abstract = {The animal-like cryptochrome of Chlamydomonas reinhardtii (CraCRY) is a recently discovered photoreceptor that controls the transcriptional profile and sexual life cycle of this alga by both blue and red light. CraCRY has the uncommon feature of efficient formation and longevity of the semireduced neutral form of its FAD cofactor upon blue light illumination. Tyrosine Y373 plays a crucial role by elongating , as fourth member, the electron transfer (ET) chain found in most other cryptochromes and DNA photolyases, which comprises a conserved tryptophan triad. Here, we report the full mechanism of light-induced FADH• formation in CraCRY using transient absorption spectroscopy from hundreds of femtoseconds to seconds. Electron transfer starts from ultrafast reduction of excited FAD to FAD•\textendash by the proximal tryptophan (0.4 ps) and is followed by delocalized migration of the produced WH•+ radical along the tryptophan triad (∼4 and ∼50 ps). Oxidation of Y373 by coupled ET to WH•+ and deprotonation then proceeds in ∼800 ps, without any significant kinetic isotope effect, nor a pH effect between pH 6.5 and 9.0. The FAD•\textendash/Y373• pair is formed with high quantum yield (∼60%); its intrinsic decay by recombination is slow (∼50 ms), favoring reduction of Y373• by extrinsic agents and protonation of FAD•\textendash to form the long-lived, red-light absorbing FADH• species. Possible mechanisms of tyrosine oxidation by ultrafast proton-coupled ET in CraCRY, a process about 40 times faster than the archetypal tyrosine-Z oxidation in photosystem II, are discussed in detail.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The animal-like cryptochrome of Chlamydomonas reinhardtii (CraCRY) is a recently discovered photoreceptor that controls the transcriptional profile and sexual life cycle of this alga by both blue and red light. CraCRY has the uncommon feature of efficient formation and longevity of the semireduced neutral form of its FAD cofactor upon blue light illumination. Tyrosine Y373 plays a crucial role by elongating , as fourth member, the electron transfer (ET) chain found in most other cryptochromes and DNA photolyases, which comprises a conserved tryptophan triad. Here, we report the full mechanism of light-induced FADH• formation in CraCRY using transient absorption spectroscopy from hundreds of femtoseconds to seconds. Electron transfer starts from ultrafast reduction of excited FAD to FAD•– by the proximal tryptophan (0.4 ps) and is followed by delocalized migration of the produced WH•+ radical along the tryptophan triad (∼4 and ∼50 ps). Oxidation of Y373 by coupled ET to WH•+ and deprotonation then proceeds in ∼800 ps, without any significant kinetic isotope effect, nor a pH effect between pH 6.5 and 9.0. The FAD•–/Y373• pair is formed with high quantum yield (∼60%); its intrinsic decay by recombination is slow (∼50 ms), favoring reduction of Y373• by extrinsic agents and protonation of FAD•– to form the long-lived, red-light absorbing FADH• species. Possible mechanisms of tyrosine oxidation by ultrafast proton-coupled ET in CraCRY, a process about 40 times faster than the archetypal tyrosine-Z oxidation in photosystem II, are discussed in detail. |
2018
|
Delocalized hole transport coupled to sub-ns tryptophanyl deprotonation promotes photoreduction of class II photolyases Article de journal F Lacombat; A Espagne; N Dozova; P Plaza; E Ignatz; S Kiontke; L O Essen Physical Chemistry Chemical Physics, 20 (39), p. 25446-25457, 2018, ISSN: 1463-9076. @article{RN114,
title = {Delocalized hole transport coupled to sub-ns tryptophanyl deprotonation promotes photoreduction of class II photolyases},
author = {F Lacombat and A Espagne and N Dozova and P Plaza and E Ignatz and S Kiontke and L O Essen},
url = {<Go to ISI>://WOS:000448345400028},
doi = {10.1039/c8cp04548h},
issn = {1463-9076},
year = {2018},
date = {2018-01-01},
journal = {Physical Chemistry Chemical Physics},
volume = {20},
number = {39},
pages = {25446-25457},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Macroscale fluorescence imaging against autofluorescence under ambient light Article de journal R Zhang; R Chouket; M -A Plamont; Z Kelemen; A Espagne; A G Tebo; A Gautier; L Gissot; J -D Faure; L Jullien; V Croquette; T Le Saux Light: Science and Applications, 7 (1), 2018. @article{Zhang:2018c,
title = {Macroscale fluorescence imaging against autofluorescence under ambient light},
author = {R Zhang and R Chouket and M -A Plamont and Z Kelemen and A Espagne and A G Tebo and A Gautier and L Gissot and J -D Faure and L Jullien and V Croquette and T Le Saux},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058077105&doi=10.1038%2fs41377-018-0098-6&partnerID=40&md5=958a21f219ba413e687d1860d21c2767},
doi = {10.1038/s41377-018-0098-6},
year = {2018},
date = {2018-01-01},
journal = {Light: Science and Applications},
volume = {7},
number = {1},
abstract = {Macroscale fluorescence imaging is increasingly used to observe biological samples. However, it may suffer from spectral interferences that originate from ambient light or autofluorescence of the sample or its support. In this manuscript, we built a simple and inexpensive fluorescence macroscope, which has been used to evaluate the performance of Speed OPIOM (Out of Phase Imaging after Optical Modulation), which is a reference-free dynamic contrast protocol, to selectively image reversibly photoswitchable fluorophores as labels against detrimental autofluorescence and ambient light. By tuning the intensity and radial frequency of the modulated illumination to the Speed OPIOM resonance and adopting a phase-sensitive detection scheme that ensures noise rejection, we enhanced the sensitivity and the signal-to-noise ratio for fluorescence detection in blot assays by factors of 50 and 10, respectively, over direct fluorescence observation under constant illumination. Then, we overcame the strong autofluorescence of growth media that are currently used in microbiology and realized multiplexed fluorescence observation of colonies of spectrally similar fluorescent bacteria with a unique configuration of excitation and emission wavelengths. Finally, we easily discriminated fluorescent labels from the autofluorescent and reflective background in labeled leaves, even under the interference of incident light at intensities that are comparable to sunlight. The proposed approach is expected to find multiple applications, from biological assays to outdoor observations, in fluorescence macroimaging. © 2018, The Author(s).},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Macroscale fluorescence imaging is increasingly used to observe biological samples. However, it may suffer from spectral interferences that originate from ambient light or autofluorescence of the sample or its support. In this manuscript, we built a simple and inexpensive fluorescence macroscope, which has been used to evaluate the performance of Speed OPIOM (Out of Phase Imaging after Optical Modulation), which is a reference-free dynamic contrast protocol, to selectively image reversibly photoswitchable fluorophores as labels against detrimental autofluorescence and ambient light. By tuning the intensity and radial frequency of the modulated illumination to the Speed OPIOM resonance and adopting a phase-sensitive detection scheme that ensures noise rejection, we enhanced the sensitivity and the signal-to-noise ratio for fluorescence detection in blot assays by factors of 50 and 10, respectively, over direct fluorescence observation under constant illumination. Then, we overcame the strong autofluorescence of growth media that are currently used in microbiology and realized multiplexed fluorescence observation of colonies of spectrally similar fluorescent bacteria with a unique configuration of excitation and emission wavelengths. Finally, we easily discriminated fluorescent labels from the autofluorescent and reflective background in labeled leaves, even under the interference of incident light at intensities that are comparable to sunlight. The proposed approach is expected to find multiple applications, from biological assays to outdoor observations, in fluorescence macroimaging. © 2018, The Author(s). |
2017
|
Photoinduced Chromophore Hydration in the Fluorescent Protein Dreiklang Is Triggered by Ultrafast Excited-State Proton Transfer Coupled to a Low-Frequency Vibration Article de journal F Lacombat; P Plaza; M -A Plamont; A Espagne Journal of Physical Chemistry Letters, 8 (7), p. 1489–1495, 2017. @article{Lacombat:2017,
title = {Photoinduced Chromophore Hydration in the Fluorescent Protein Dreiklang Is Triggered by Ultrafast Excited-State Proton Transfer Coupled to a Low-Frequency Vibration},
author = {F Lacombat and P Plaza and M -A Plamont and A Espagne},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85017130354&doi=10.1021%2facs.jpclett.7b00348&partnerID=40&md5=dba41290a37553caaabb354a87ad0ec6},
doi = {10.1021/acs.jpclett.7b00348},
year = {2017},
date = {2017-01-01},
journal = {Journal of Physical Chemistry Letters},
volume = {8},
number = {7},
pages = {1489--1495},
abstract = {Because of growing applications in advanced fluorescence imaging, the mechanisms and dynamics of photoinduced reactions in reversibly photoswitchable fluorescent proteins are currently attracting much interest. We report the first time-resolved study of the photoswitching of Dreiklang, so far the only fluorescent protein to undergo reversible photoinduced chromophore hydration. Using broadband femtosecond transient absorption spectroscopy, we show that the reaction is triggered by an ultrafast deprotonation of the chromophore phenol group in the excited state in 100 fs. This primary step is accompanied by coherent oscillations that we assign to its coupling with a low-frequency mode, possibly a deformation of the chromophore hydrogen bond network. A ground-state intermediate is formed in the picosecond-nanosecond regime that we tentatively assign to the deprotonated water adduct. We suggest that proton ejection from the phenol group leads to a charge transfer from the phenol to the imidazolinone ring, which triggers imidazolinone protonation by nearby Glu222 and catalyzes the addition of the water molecule. © 2017 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Because of growing applications in advanced fluorescence imaging, the mechanisms and dynamics of photoinduced reactions in reversibly photoswitchable fluorescent proteins are currently attracting much interest. We report the first time-resolved study of the photoswitching of Dreiklang, so far the only fluorescent protein to undergo reversible photoinduced chromophore hydration. Using broadband femtosecond transient absorption spectroscopy, we show that the reaction is triggered by an ultrafast deprotonation of the chromophore phenol group in the excited state in 100 fs. This primary step is accompanied by coherent oscillations that we assign to its coupling with a low-frequency mode, possibly a deformation of the chromophore hydrogen bond network. A ground-state intermediate is formed in the picosecond-nanosecond regime that we tentatively assign to the deprotonated water adduct. We suggest that proton ejection from the phenol group leads to a charge transfer from the phenol to the imidazolinone ring, which triggers imidazolinone protonation by nearby Glu222 and catalyzes the addition of the water molecule. © 2017 American Chemical Society. |
Ultrafast flavin photoreduction in an oxidized animal (6-4) photolyase through an unconventional tryptophan tetrad Article de journal P R Martin; F Lacombat; A Espagne; N Dozova; P Plaza; J Yamamoto; P Müller; K Brettel; A De La Lande Physical Chemistry Chemical Physics, 19 (36), p. 24493–24504, 2017. @article{Martin:2017a,
title = {Ultrafast flavin photoreduction in an oxidized animal (6-4) photolyase through an unconventional tryptophan tetrad},
author = {P R Martin and F Lacombat and A Espagne and N Dozova and P Plaza and J Yamamoto and P M\"{u}ller and K Brettel and A De La Lande},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85029817108&doi=10.1039%2fc7cp04555g&partnerID=40&md5=b5966e02f7c4f4fa9b385f15647311c3},
doi = {10.1039/c7cp04555g},
year = {2017},
date = {2017-01-01},
journal = {Physical Chemistry Chemical Physics},
volume = {19},
number = {36},
pages = {24493--24504},
abstract = {Photolyases are flavoenzymes repairing UV-induced lesions in DNA, which may be activated by a photoreduction of their FAD cofactor. In most photolyases, this photoreduction proceeds by electron transfer along a chain of three tryptophan (Trp) residues, connecting the flavin to the protein surface. Much less studied, animal (6-4) photolyases (repairing pyrimidine-pyrimidone (6-4) photoproducts) are particularly interesting as they were recently shown to have a longer electron transfer chain, counting four Trp residues. Using femtosecond polarized transient absorption spectroscopy, we performed a detailed analysis of the photoactivation reaction in the (6-4) photolyase of Xenopus laevis with oxidized FAD. We showed that the excited flavin is very quickly reduced (∼0.5 ps) by a nearby tryptophan residue, yielding FAD•- and WH•+ radicals. Subsequent kinetic steps in the picosecond regime were assigned to the migration of the positive charge along the Trp tetrad, in competition with charge recombination. We propose that the positive charge is actually delocalized over various Trp residues during most of the dynamics and that charge recombination essentially occurs through the proximal tryptophanyl radical. Oxidation of the fourth tryptophan is thought to be reached about as fast as that of the third one (∼40 ps), based on a comparison with a mutant protein lacking the distal Trp, implying ultrafast electron transfer between these two residues. This unusual mechanism sheds light on the rich diversity of electron transfer pathways found in various photolyases, and evolution-related cryptochromes alike. © the Owner Societies 2017.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Photolyases are flavoenzymes repairing UV-induced lesions in DNA, which may be activated by a photoreduction of their FAD cofactor. In most photolyases, this photoreduction proceeds by electron transfer along a chain of three tryptophan (Trp) residues, connecting the flavin to the protein surface. Much less studied, animal (6-4) photolyases (repairing pyrimidine-pyrimidone (6-4) photoproducts) are particularly interesting as they were recently shown to have a longer electron transfer chain, counting four Trp residues. Using femtosecond polarized transient absorption spectroscopy, we performed a detailed analysis of the photoactivation reaction in the (6-4) photolyase of Xenopus laevis with oxidized FAD. We showed that the excited flavin is very quickly reduced (∼0.5 ps) by a nearby tryptophan residue, yielding FAD•- and WH•+ radicals. Subsequent kinetic steps in the picosecond regime were assigned to the migration of the positive charge along the Trp tetrad, in competition with charge recombination. We propose that the positive charge is actually delocalized over various Trp residues during most of the dynamics and that charge recombination essentially occurs through the proximal tryptophanyl radical. Oxidation of the fourth tryptophan is thought to be reached about as fast as that of the third one (∼40 ps), based on a comparison with a mutant protein lacking the distal Trp, implying ultrafast electron transfer between these two residues. This unusual mechanism sheds light on the rich diversity of electron transfer pathways found in various photolyases, and evolution-related cryptochromes alike. © the Owner Societies 2017. |
2016
|
Ultrafast Dynamics of a Green Fluorescent Protein Chromophore Analogue: Competition between Excited-State Proton Transfer and Torsional Relaxation Article de journal T Chatterjee; F Lacombat; D Yadav; M Mandal; P Plaza; A Espagne; P K Mandal Journal of Physical Chemistry B, 120 (36), p. 9716–9722, 2016. @article{Chatterjee:2016,
title = {Ultrafast Dynamics of a Green Fluorescent Protein Chromophore Analogue: Competition between Excited-State Proton Transfer and Torsional Relaxation},
author = {T Chatterjee and F Lacombat and D Yadav and M Mandal and P Plaza and A Espagne and P K Mandal},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84987847663&doi=10.1021%2facs.jpcb.6b05795&partnerID=40&md5=dbc7a71ee9d3e1a62872f19c1f0c7204},
doi = {10.1021/acs.jpcb.6b05795},
year = {2016},
date = {2016-01-01},
journal = {Journal of Physical Chemistry B},
volume = {120},
number = {36},
pages = {9716--9722},
abstract = {The competition between excited-state proton transfer (ESPT) and torsion plays a central role in the photophysics of fluorescent proteins of the green fluorescent protein (GFP) family and their chromophores. Here, it was investigated in a single GFP chromophore analogue bearing o-hydroxy and p-diethylamino substituents, OHIM. The light-induced dynamics of OHIM was studied by femtosecond transient absorption spectroscopy, at different pH. We found that the photophysics of OHIM is determined by the electron-donating character of the diethylamino group: torsional relaxation dominates when the diethylamino group is neutral, whereas ultrafast ESPT followed by cis/trans isomerization and ground-state reprotonation are observed when the diethylamino group is protonated and therefore inactive as an electron donor. © 2016 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The competition between excited-state proton transfer (ESPT) and torsion plays a central role in the photophysics of fluorescent proteins of the green fluorescent protein (GFP) family and their chromophores. Here, it was investigated in a single GFP chromophore analogue bearing o-hydroxy and p-diethylamino substituents, OHIM. The light-induced dynamics of OHIM was studied by femtosecond transient absorption spectroscopy, at different pH. We found that the photophysics of OHIM is determined by the electron-donating character of the diethylamino group: torsional relaxation dominates when the diethylamino group is neutral, whereas ultrafast ESPT followed by cis/trans isomerization and ground-state reprotonation are observed when the diethylamino group is protonated and therefore inactive as an electron donor. © 2016 American Chemical Society. |
2015
|
Photoswitching Kinetics and Phase-Sensitive Detection Add Discriminative Dimensions for Selective Fluorescence Imaging Article de journal Jérôme Querard; Tal-Zvi Markus; Marie-Aude Plamont; Carole Gauron; Pengcheng Wang; Agathe Espagne; Michel Volovitch; Sophie Vriz; Vincent Croquette; Arnaud Gautier; Thomas Le Saux; Ludovic Jullien Angewandte Chemie International Edition, 54 (9), p. 2633-2637, 2015, ISSN: 1433-7851. @article{RN43b,
title = {Photoswitching Kinetics and Phase-Sensitive Detection Add Discriminative Dimensions for Selective Fluorescence Imaging},
author = {J\'{e}r\^{o}me Querard and Tal-Zvi Markus and Marie-Aude Plamont and Carole Gauron and Pengcheng Wang and Agathe Espagne and Michel Volovitch and Sophie Vriz and Vincent Croquette and Arnaud Gautier and Thomas Le Saux and Ludovic Jullien},
doi = {10.1002/anie.201408985},
issn = {1433-7851},
year = {2015},
date = {2015-01-01},
journal = {Angewandte Chemie International Edition},
volume = {54},
number = {9},
pages = {2633-2637},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
|
Real-time monitoring of chromophore isomerization and deprotonation during the photoactivation of the fluorescent protein Dronpa Article de journal D Yadav; F Lacombat; N Dozova; F Rappaport; P Plaza; A Espagne Journal of Physical Chemistry B, 119 (6), p. 2404–2414, 2015. @article{Yadav:2015,
title = {Real-time monitoring of chromophore isomerization and deprotonation during the photoactivation of the fluorescent protein Dronpa},
author = {D Yadav and F Lacombat and N Dozova and F Rappaport and P Plaza and A Espagne},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-84922794115&doi=10.1021%2fjp507094f&partnerID=40&md5=6618718bf1ba6e1f5e5f2194c9480d5b},
doi = {10.1021/jp507094f},
year = {2015},
date = {2015-01-01},
journal = {Journal of Physical Chemistry B},
volume = {119},
number = {6},
pages = {2404--2414},
abstract = {Dronpa is a photochromic green fluorescent protein (GFP) homologue used as a probe in super-resolution microscopy. It is known that the photochromic reaction involves cis/trans isomerization of the chromophore and protonation/deprotonation of its phenol group, but the sequence in time of the two steps and their characteristic time scales are still the subject of much debate. We report here a comprehensive UV-visible transient absorption spectroscopy study of the photoactivation mechanism of Dronpa, covering all relevant time scales from ∼100 fs to milliseconds. The Dronpa-2 variant was also studied and showed the same behavior. By carefully controlling the excitation energy to avoid multiphoton processes, we could measure both the spectrum and the anisotropy of the first photoactivation intermediate. We show that the observed few nanometer blue-shift of this intermediate is characteristic for a neutral cis chromophore, and that its anisotropy of ∼0.2 is in good agreement with the reorientation of the transition dipole moment expected upon isomerization. These data constitute the first clear evidence that trans → cis isomerization of the chromophore precedes its deprotonation and occurs on the picosecond time scale, concomitantly to the excited-state decay. We found the deprotonation step to follow in ∼10 μs and lead directly from the neutral cis intermediate to the final state. © 2014 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Dronpa is a photochromic green fluorescent protein (GFP) homologue used as a probe in super-resolution microscopy. It is known that the photochromic reaction involves cis/trans isomerization of the chromophore and protonation/deprotonation of its phenol group, but the sequence in time of the two steps and their characteristic time scales are still the subject of much debate. We report here a comprehensive UV-visible transient absorption spectroscopy study of the photoactivation mechanism of Dronpa, covering all relevant time scales from ∼100 fs to milliseconds. The Dronpa-2 variant was also studied and showed the same behavior. By carefully controlling the excitation energy to avoid multiphoton processes, we could measure both the spectrum and the anisotropy of the first photoactivation intermediate. We show that the observed few nanometer blue-shift of this intermediate is characteristic for a neutral cis chromophore, and that its anisotropy of ∼0.2 is in good agreement with the reorientation of the transition dipole moment expected upon isomerization. These data constitute the first clear evidence that trans → cis isomerization of the chromophore precedes its deprotonation and occurs on the picosecond time scale, concomitantly to the excited-state decay. We found the deprotonation step to follow in ∼10 μs and lead directly from the neutral cis intermediate to the final state. © 2014 American Chemical Society. |
