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Primary structural response in tryptophan residues ofAnabaenasensory rhodopsin to photochromic reactions of the retinal chromophore

Authors
Journal
Chemical Physics
0301-0104
Publisher
Elsevier
Publication Date
Volume
419
Identifiers
DOI: 10.1016/j.chemphys.2013.01.031
Keywords
  • Protein Dynamics
  • Time-Resolved Resonance Raman Spectroscopy
  • Photoreceptor Protein
Disciplines
  • Biology
  • Physics

Abstract

Abstract Anabaena sensory rhodopsin (ASR) is a microbial rhodopsin found in eubacteria and functions as a photosensor. The photoreaction of ASR is photochromic between all-trans, 15-anti (ASRAT), and 13-cis, 15-syn (ASR13C) isomers. To understand primary protein dynamics in the photoreaction starting in ASRAT and ASR13C, picosecond time-resolved ultraviolet resonance Raman spectra were obtained. In the intermediate state appearing in the picosecond temporal region, spectral changes of Trp bands were observed. For both ASRAT and ASR13C, the intensities of the Trp bands were bleached within the instrumental response time and recovered with a time constant of 30ps. This suggests that the rates of structural changes in the Trp residue in the vicinity of the chromophore do not depend on the direction of the isomerization of retinal. A comparison between spectra of the wild-type and Trp mutants indicates that the structures of Trp76 and Trp46 change upon the primary photoreaction of retinal.

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