Pascal PLAZA

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.

Circular dichroism of the photoreceptor pigment oxyblepharismin Article de journal

O Pieroni; P Plaza; M Mahet; N Angelini; G Checcucci; M Malatesta; M M Martin; F Lenci

Photochemistry and Photobiology, 81 (6), p. 1343-1346, 2005, ISSN: 0031-8655.

Excitation energy effect on the early photophysics of hypericin in solution Article de journal

P Plaza; M Mahet; O N Tchaikovskaya; M M Martin

Chemical Physics Letters, 408 (1-3), p. 96–100, 2005.

Investigations of the primary events in a bacterial photoreceptor for photomotility: Photoactive yellow protein (PYP) Article de journal

P Changenet-Barret; A Espagne; P Plaza; K J Hellingwerf; M M Martin

New Journal of Chemistry, 29 (4), p. 527–534, 2005.

@article{Changenet-Barret:2005,
title = {Investigations of the primary events in a bacterial photoreceptor for photomotility: Photoactive yellow protein (PYP)},
author = {P Changenet-Barret and A Espagne and P Plaza and K J Hellingwerf and M M Martin},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17444406349&doi=10.1039%2fb418134d&partnerID=40&md5=9d0e9b7ebb687d0a3c802932712fef79},
doi = {10.1039/b418134d},
year = {2005},
date = {2005-01-01},
journal = {New Journal of Chemistry},
volume = {29},
number = {4},
pages = {527--534},
abstract = {PYP, the Photoactive Yellow Protein, is a small water-soluble protein extracted from the cytosol of the halophilic purple bacterium Halorhodospira halophila. PYP is thought to mediate the phototactic response of the bacterium against blue light. Its chromophore is the deprotonated trans-p-hydroxycinnamic acid covalently linked, via a thioester bond, to the unique cysteine residue of the protein. Upon blue-light irradiation, PYP undergoes a photocycle. As for rhodopsins, the trans to cis isomerization of the chromophore was shown to be the first overall step of this photocycle. From time-resolved spectroscopy measurements on native PYP in solution, it emerged that the reaction involves a series of fast events on the subpicosecond and picosecond timescales, but the reaction path that leads to the formation of the cis isomer is not clear yet. A few years ago, we initiated a comparative study of native PYP and several chromophore analogues in solution in order to try to further clarify the early steps of the photocycle. Our experimental approach consists in probing, in real-time, the ultrafast photoinduced events by transient absorption and gain spectroscopy using the pump-probe technique. In the present paper, we review our experimental results and discuss them within the context of the recent literature. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.},
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Photophysical properties of pyrrolobenzenes with different linking and substitution pattern: The transition between charge transfer states with large (MICT) and small (TICT) resonance interaction Article de journal

S Murali; P Changenet-Barret; C Ley; P Plaza; W Rettig; M M Martin; R Lapouyade

Chemical Physics Letters, 411 (1-3), p. 192–197, 2005.

Spectroscopic study of the chromophore–protein association and primary photoinduced events in the photoreceptor of Blepharisma japonicum Article de journal

P Plaza; M Mahet; M M Martin; N Angelini; M Malatesta; G Checcucci; F Lenci

Photochemical and Photobiological Sciences, 4 (9), p. 754–761, 2005.

@article{Plaza:2005a,
title = {Spectroscopic study of the chromophore\textendashprotein association and primary photoinduced events in the photoreceptor of Blepharisma japonicum},
author = {P Plaza and M Mahet and M M Martin and N Angelini and M Malatesta and G Checcucci and F Lenci},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-25444441088&doi=10.1039%2fb417086e&partnerID=40&md5=dd3ced0e70c892fd5e0234b3abb6ea0f},
doi = {10.1039/b417086e},
year = {2005},
date = {2005-01-01},
journal = {Photochemical and Photobiological Sciences},
volume = {4},
number = {9},
pages = {754--761},
abstract = {Blepharisma japonicum is a ciliated protozoan exhibiting a strong step-up photophobic response upon illumination. The photoreceptor chromophores responsible for this response have been identified to be hypericin-like chromophores (blepharismin and oxyblepharismin), complexed to a 200 kDa non-water-soluble protein. The present work opens up new perspectives on the primary phototransduction steps of B. japonicum’s light perception through a joined approach by steady-state fluorescence spectroscopy, time-resolved fluorescence anisotropy and sub-picosecond transient absorption spectroscopy. The free chromophore of the light-adapted form of the cell (oxyblepharismin) was studied in various solvents and its spectroscopic properties, as well as its primary excited-state reactivity, compared with those of the corresponding pigment\textendashprotein complex, extracted by phosphate-concentration-step chromatography on a hydroxyapatite column. Fluorescence anisotropy together with SDS PAGE electrophoresis results confirm that oxyblepharismin is non-covalently bound to the apoprotein and show that, in the excited state, it is free to rotate in all directions within the binding site where it experiences a large local viscosity. Time-resolved anisotropy measurements on aromatic amino acids confirm that the molecular weight of the protein is of the order of 200 kDa. Although showing very similar steady-state spectra, free oxyblepharismin and its protein complex have noticeably different excited-state behaviours. In particular, the protein complex exhibits a pronounced short-lived absorption feature in the 640\textendash750 nm range, decaying biexponentially in 4 ps and 56 ps. Those decays, also observed in other spectral regions, are not found in the corresponding kinetics of the isolated pigment in solution. This early behaviour of the protein complex might be the signature of the primary phototransduction process, possibly involving an electron transfer from the pigment to a neighbouring protein acceptor residue as it had been suggested in previous studies. © 2005 The Royal Society of Chemistry and Owner Societies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fermer

Blepharisma japonicum is a ciliated protozoan exhibiting a strong step-up photophobic response upon illumination. The photoreceptor chromophores responsible for this response have been identified to be hypericin-like chromophores (blepharismin and oxyblepharismin), complexed to a 200 kDa non-water-soluble protein. The present work opens up new perspectives on the primary phototransduction steps of B. japonicum’s light perception through a joined approach by steady-state fluorescence spectroscopy, time-resolved fluorescence anisotropy and sub-picosecond transient absorption spectroscopy. The free chromophore of the light-adapted form of the cell (oxyblepharismin) was studied in various solvents and its spectroscopic properties, as well as its primary excited-state reactivity, compared with those of the corresponding pigment–protein complex, extracted by phosphate-concentration-step chromatography on a hydroxyapatite column. Fluorescence anisotropy together with SDS PAGE electrophoresis results confirm that oxyblepharismin is non-covalently bound to the apoprotein and show that, in the excited state, it is free to rotate in all directions within the binding site where it experiences a large local viscosity. Time-resolved anisotropy measurements on aromatic amino acids confirm that the molecular weight of the protein is of the order of 200 kDa. Although showing very similar steady-state spectra, free oxyblepharismin and its protein complex have noticeably different excited-state behaviours. In particular, the protein complex exhibits a pronounced short-lived absorption feature in the 640–750 nm range, decaying biexponentially in 4 ps and 56 ps. Those decays, also observed in other spectral regions, are not found in the corresponding kinetics of the isolated pigment in solution. This early behaviour of the protein complex might be the signature of the primary phototransduction process, possibly involving an electron transfer from the pigment to a neighbouring protein acceptor residue as it had been suggested in previous studies. © 2005 The Royal Society of Chemistry and Owner Societies.

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Chemical structure effect on the excited-state relaxation dynamics of the PYP chromophore Inproceedings

A Espagne; P Changenet-Barret; S Charier; J -B Baudin; L Jullien; P Plaza; M M Martin

Martin, M M; Hynes, J T (Ed.): VIth International Conference on Femtochemistry, p. 421-424, Elsevier, 2004.

Early molecular events in the photoactive yellow protein: Role of the chromophore photophysics Article de journal

P Changenet-Barret; A Espagne; S Charier; J -B Baudin; L Jullien; P Plaza; K J Hellingwerf; M M Martin

Photochemical and Photobiological Sciences, 3 (8), p. 823–829, 2004.

@article{Changenet-Barret:2004,
title = {Early molecular events in the photoactive yellow protein: Role of the chromophore photophysics},
author = {P Changenet-Barret and A Espagne and S Charier and J -B Baudin and L Jullien and P Plaza and K J Hellingwerf and M M Martin},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-4644243446&doi=10.1039%2fb400398e&partnerID=40&md5=45520bcadbdf2612c16ef874b207d73b},
doi = {10.1039/b400398e},
year = {2004},
date = {2004-01-01},
journal = {Photochemical and Photobiological Sciences},
volume = {3},
number = {8},
pages = {823--829},
abstract = {We report a comparative study of the isomerization reaction in native and denatured photoactive yellow protein (PYP) and in various chromophore analogues in their trans deprotonated form. The excited-state relaxation dynamics was followed by subpicosecond transient absorption and gain spectroscopy. The free p-hydroxycinnamate (pCA2−) and its amide analogue (pCM-) are found to display a quite different transient spectroscopy from that of PYP. The excited-state deactivation leads to the formation of the ground-state cis isomer without any detectable intermediate with a mechanism comparable to trans-stilbene photoisomerization. On the contrary, the early stage of the excited-state deactivation of the free thiophenyl-p-hydroxycinnamate (pCT-) and of the denatured PYP is similar to that of the native protein. It involves the formation of an intermediate absorbing in the spectral region located between the bleaching and gain bands in less than 2 ps. However, in these two cases, the formation of the cis isomer has not been proved yet. This difference with pCA- and pCM- might result from the fact that, in the thioester substituted chromophore, simultaneous population of two quasi-degenerate excited states occurs upon excitation. This comparative study highlights the determining role of the chromophore structure and of its intrinsic properties in the primary molecular events in native PYP. © 2004 The Royal Society of Chemistry and Owner Societies.},
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pubstate = {published},
tppubtype = {article}
}

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Fast excited-state reaction in the photoreceptor pigment-protein complex of the ciliate Blepharisma japonicum Inproceedings

M Mahet; P Plaza; M M Martin; G Checcucci; F Lenci

Martin, M M; Hynes, J T (Ed.): VIth International Conference on Femtochemistry, p. 441-444, Elsevier, 2004.

Isomerization process in the native and denatured Photoactive Yellow Protein probed by subpicosecond absorption spectroscopy Inproceedings

P Changenet-Barret; A Espagne; P Plaza; M M Martin; Y J Hellingwerf

Martin, M M; Hynes, J T (Ed.): VIth International Conference on Femtochemistry, p. 417-420, Elsevier, 2004.

Ultrafast photoinduced charge transfer in fluorinated derivatives of DMABN Inproceedings

S Murali; P Changenet-Barret; C Ley; P Plaza; W Rettig; M M Martin; A I Tolmachev

Martin, M M; Hynes, J T (Ed.): VIth International Conference on Femtochemistry, p. 323-326, Elsevier, 2004.

Calcium photorelease from a symmetrical donor-acceptor-donor bis-crown-fluoroionophore evidenced by ultrafast absorption spectroscopy Article de journal

N Marcotte; P Plaza; D Lavabre; S Fery-Forgues; M M Martin

The Journal of Physical Chemistry A, 107 (14), p. 2394-2402, 2003, ISSN: 1089-5639.

A new analysis of the solvent-induced charge transfer in ADMA by subpicosecond spectroscopy Inproceedings

M M Martin; P Plaza; P Changenet; A Siemiarczuk

Douhal, A; Santamaría, J (Ed.): Vth International Conference on Femtochemistry, p. 280-288, World Scientific Publishing, 2002, ISBN: 0-444-51656-5.

Excited-state relation dynamics of a PYP chromophore model in solution: Influence of the thioester group Article de journal

P Changenet-Barret; A Espagne; N Katsonis; S Charier; J -B Baudin; L Jullien; P Plaza; M M Martin

Chemical Physics Letters, 365 (3-4), p. 285–291, 2002.

Multiple relaxation pathways in push-pull polyenes Article de journal

D Laage; P Plaza; M Blanchard-Desce; M M Martin

Photochemical and Photobiological Sciences, 1 (7), p. 526–535, 2002.

@article{Laage:2002,
title = {Multiple relaxation pathways in push-pull polyenes},
author = {D Laage and P Plaza and M Blanchard-Desce and M M Martin},
url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-17444378861&doi=10.1039%2fb203201p&partnerID=40&md5=98848a0a1dd2e3c4a3b3b4729e644636},
doi = {10.1039/b203201p},
year = {2002},
date = {2002-01-01},
journal = {Photochemical and Photobiological Sciences},
volume = {1},
number = {7},
pages = {526--535},
abstract = {Subpicosecond absorption and gain spectroscopy are used to investigate the excited-state behavior of push-pull polyenes made of a diethylthiobarbituric acid electron-acceptor group and a dibutylaniline electron-donor group linked by a π-conjugated chain. Four polyenes of increasing length, ranging from n = 2 to 5 double bonds, are compared. The relaxation path and relaxation kinetics are studied in dioxane and in cyclohexane, a polar and a nonpolar solvent, respectively. In dioxane, the results provide evidence for the formation of an emissive transient state on an ultrashort time scale (2\textendash3 ps) attributed to a charge transfer (CT) state. The regular shift of the gain peak of this transient state with increase in the chain length (ca. 100 nm per added double bond) indicates that its structure is similar to that of a cyanine, i.e. with a fully conjugated polyenic chain. Its lifetime ranges from a few tens to a few hundreds of picoseconds depending on the chain length. When the number of double bonds increases from n = 2 to 3, the lifetime increases, then decreases continuously for longer chains. In cyclohexane, where the transient CT state is not formed, the decay of the initial excited state follows the same trend when the chain length increases but the lifetimes are shorter than that of the CT state in dioxane. In both solvents, the characterization of long-lived photoproducts by synchronizing two low repetition-rate subpicosecond laser systems demonstrates a change in the relaxation route as the chain length increases. Isomerization occurs for n = 2, whereas intersystem crossing to the triplet state occurs for n = 4. The change in the relaxation channel is observed for n = 3 in both solvents with however a solvent-dependent behavior. In dioxane, relaxation to the triplet state is already observed for n = 3, while an intermediate regime with a relaxation directly to the ground state is observed in cyclohexane. The photophysics of the studied push-pull polyenes is tentatively compared to that of polymethine cyanines and substituted carotenoids. © 2002 The Royal Society of Chemistry and Owner Societies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

Fermer

Subpicosecond absorption and gain spectroscopy are used to investigate the excited-state behavior of push-pull polyenes made of a diethylthiobarbituric acid electron-acceptor group and a dibutylaniline electron-donor group linked by a π-conjugated chain. Four polyenes of increasing length, ranging from n = 2 to 5 double bonds, are compared. The relaxation path and relaxation kinetics are studied in dioxane and in cyclohexane, a polar and a nonpolar solvent, respectively. In dioxane, the results provide evidence for the formation of an emissive transient state on an ultrashort time scale (2–3 ps) attributed to a charge transfer (CT) state. The regular shift of the gain peak of this transient state with increase in the chain length (ca. 100 nm per added double bond) indicates that its structure is similar to that of a cyanine, i.e. with a fully conjugated polyenic chain. Its lifetime ranges from a few tens to a few hundreds of picoseconds depending on the chain length. When the number of double bonds increases from n = 2 to 3, the lifetime increases, then decreases continuously for longer chains. In cyclohexane, where the transient CT state is not formed, the decay of the initial excited state follows the same trend when the chain length increases but the lifetimes are shorter than that of the CT state in dioxane. In both solvents, the characterization of long-lived photoproducts by synchronizing two low repetition-rate subpicosecond laser systems demonstrates a change in the relaxation route as the chain length increases. Isomerization occurs for n = 2, whereas intersystem crossing to the triplet state occurs for n = 4. The change in the relaxation channel is observed for n = 3 in both solvents with however a solvent-dependent behavior. In dioxane, relaxation to the triplet state is already observed for n = 3, while an intermediate regime with a relaxation directly to the ground state is observed in cyclohexane. The photophysics of the studied push-pull polyenes is tentatively compared to that of polymethine cyanines and substituted carotenoids. © 2002 The Royal Society of Chemistry and Owner Societies.

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2005

2004

2003

2002