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Title: Primary photochemical events in halorhodopsin studied by subpicosecond time-resolved spectroscopy

Abstract

Primary photochemical events of the light-driven chloride-pump halorhodopsin (hR) are studied at room temperature by subpicosecond transient absorption measurements. On excitation of hR with 600-nm, 0.6-ps pulse, excited-state absorption and stimulated emission appear immediately in the 420-530-nm and 650-770-nm wavelength regions, respectively, and both decay with a time constant of 2.3 ps. The calculated absorption spectrum of the excited state of hR (hR{sup *}) has a peak at 516 nm and a shoulder at about 460 nm. Accompanied by the decay of hR{sup *}, the primary ground-state product appears at around 645 nm. The quantum yield of the product ({le} 1.0 ps) than the decay of the excited state (2.3 ps), as well as the possible presence of the J-intermediate (hR{sub J}). Instead of the simple sequential kinetic model considering three states of hR{sup *}, hR{sub J}, and hR, which has been applied to the primary process of bacteriorhodopsin, a parallel channel model is suggested for the primary process of hR. After Franck-Condon excitation, the cis-trans isomerization to hR{sub J} and the relaxation to hR{sup *} take place simultaneously. The latter decays only to hR via radiative and nonradiative processes. The present results suggest that the excited state having amore » reaction channel to cis-trans isomerization is not located at the potential minimum of hR{sup *} and that the relaxation process in the excited state is a process in competition with isomerization. 26 refs., 8 figs.« less

Authors:
;  [1]; ;  [2]
  1. Institute for Molecular Science, Myodaiji, Obazaki (Japan)
  2. Institute of Physical and Chemical Research, Hirosawa, Wako (Japan)
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
273615
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry
Additional Journal Information:
Journal Volume: 96; Journal Issue: 14; Other Information: PBD: 9 Jul 1992
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; PIGMENTS; PHOTOCHEMISTRY; ISOMERIZATION; TIME RESOLUTION; STIMULATED EMISSION; ABSORPTION SPECTROSCOPY

Citation Formats

Kandori, Hideki, Yoshihara, Keitaro, Tomioka, Hiroaki, and Sasabe, Hiroyuki. Primary photochemical events in halorhodopsin studied by subpicosecond time-resolved spectroscopy. United States: N. p., 1992. Web. doi:10.1021/j100193a076.
Kandori, Hideki, Yoshihara, Keitaro, Tomioka, Hiroaki, & Sasabe, Hiroyuki. Primary photochemical events in halorhodopsin studied by subpicosecond time-resolved spectroscopy. United States. doi:10.1021/j100193a076.
Kandori, Hideki, Yoshihara, Keitaro, Tomioka, Hiroaki, and Sasabe, Hiroyuki. Thu . "Primary photochemical events in halorhodopsin studied by subpicosecond time-resolved spectroscopy". United States. doi:10.1021/j100193a076.
@article{osti_273615,
title = {Primary photochemical events in halorhodopsin studied by subpicosecond time-resolved spectroscopy},
author = {Kandori, Hideki and Yoshihara, Keitaro and Tomioka, Hiroaki and Sasabe, Hiroyuki},
abstractNote = {Primary photochemical events of the light-driven chloride-pump halorhodopsin (hR) are studied at room temperature by subpicosecond transient absorption measurements. On excitation of hR with 600-nm, 0.6-ps pulse, excited-state absorption and stimulated emission appear immediately in the 420-530-nm and 650-770-nm wavelength regions, respectively, and both decay with a time constant of 2.3 ps. The calculated absorption spectrum of the excited state of hR (hR{sup *}) has a peak at 516 nm and a shoulder at about 460 nm. Accompanied by the decay of hR{sup *}, the primary ground-state product appears at around 645 nm. The quantum yield of the product ({le} 1.0 ps) than the decay of the excited state (2.3 ps), as well as the possible presence of the J-intermediate (hR{sub J}). Instead of the simple sequential kinetic model considering three states of hR{sup *}, hR{sub J}, and hR, which has been applied to the primary process of bacteriorhodopsin, a parallel channel model is suggested for the primary process of hR. After Franck-Condon excitation, the cis-trans isomerization to hR{sub J} and the relaxation to hR{sup *} take place simultaneously. The latter decays only to hR via radiative and nonradiative processes. The present results suggest that the excited state having a reaction channel to cis-trans isomerization is not located at the potential minimum of hR{sup *} and that the relaxation process in the excited state is a process in competition with isomerization. 26 refs., 8 figs.},
doi = {10.1021/j100193a076},
journal = {Journal of Physical Chemistry},
number = 14,
volume = 96,
place = {United States},
year = {1992},
month = {7}
}