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POWER‐ AND TIME‐RESOLVED RESONANCE RAMAN STUDIES AND CONFORMATIONAL CHANGES IN BACTERIORHODOPSIN
Author(s) -
ElSayed M. A.,
Terner James
Publication year - 1979
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1979.tb07124.x
Subject(s) - bacteriorhodopsin , retinal , chemistry , retinaldehyde , chromophore , deprotonation , resonance (particle physics) , rhodopsin , photochemistry , resonance raman spectroscopy , protonation , conformational change , raman spectroscopy , halobacteriaceae , biophysics , halobacterium salinarum , stereochemistry , biology , optics , biochemistry , membrane , physics , atomic physics , ion , organic chemistry
— By comparing the resonance Raman spectra of the retinal of the intermediates of bacteriorho‐dopsin (obtained by using fixed flow with residence of time of 10 ps. variable laser power and frequency as well as computer subtraction techniques) with those of model compounds and with each other, the following possible conclusions can be obtained: (1) There exists stronger interaction between the retinal and the opsin in bacteriorhodopsin than that present in rhodopsin. (2) Conformational changes seem to take place during the dark light adaptation process as well as during the photosynthetic cycle. (3) The appearance of the spectrum of the retinal in the fingerprint region for the bL 550 and bM 412 intermediates is similar despite large shifts in their optical absorption maxima. This might argue against the theory that proposes ground state retinal conformational changes to explain the observed red shift in the optical spectra of retinal upon combining with the opsin. (4) Contrary to bM 412 , the bL 550 species seems to be protonated. The fact that loss of proton does not seem to change the retinal conformation greatly might suggest that the protein and its ionic environment might carry the larger share of the load in the deprotonation process.