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Transmembrane Signaling Mediated by Water in Bovine Rhodopsin
Author(s) -
Nishimura Shoko,
Kandori Hideki,
Maeda Akio
Publication year - 1997
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.1751-1097.1997.tb03227.x
Subject(s) - materials science , molecule , rhodopsin , fourier transform infrared spectroscopy , photochromism , membrane , photochemistry , crystallography , chemical engineering , chemistry , nanotechnology , organic chemistry , retinal , biochemistry , engineering
— Unhydrated air‐dried films of rhodopsin from bovine rod outer segment membranes do not produce its active state, metarhodopsin II. In order to reveal requirements for its formation, we studied changes in H‐bonding of water, peptide carbonyl and carboxylic acid in the photochemical reactions by means of difference Fourier transform infrared spectroscopy, under both hydrated and unhydrated conditions. A water molecule near Glull3, which undergoes H‐bonding change in bathorhodopsin, remained in the unhydrated film, but with a weaker H‐bonding state than in the hydrated film. The other water molecules, which shift in lumirhodopsin and metarhodopsin I as well as in bathorhodopsin of the hydrated film, were not observed in the unhydrated film. Effects of the dehydration were detected in all the C=O stretching vibrations of the peptide backbone and of Asp83 in the formation of bathorhodopsin. The C=O stretching band of Asp83 of lumirhodopsin and metarhodopsin I is intensified in the unhydrated film. We propose that structural changes at the intradiscal site in the interaction between the Schiff base and Glull3 affect water molecules, the peptide backbone, Asp83 and Glul22 in helices B and C through consecutive photochemical processes to metarhodopsin II.