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BUTYL CONFORMATIONAL REORGANIZATION AS A POSSIBLE EXPLANATION FOR THE LONGITUDINAL FLEXIBILITY OF THE BINDING SITE OF BACTERIORHODOPSIN. THE AZULENE and C‐22 RETINOID ANALOGS *
Author(s) -
Liut Robert S. H.,
Liu Corey W.,
Li XiaoYuan,
Asato Alfred E.
Publication year - 1991
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.1751-1097.1991.tb02066.x
Subject(s) - bacteriorhodopsin , chemistry , polyene , azulene , rhodopsin , stereochemistry , flexibility (engineering) , photochemistry , retinal , crystallography , biochemistry , statistics , mathematics , membrane
The UV‐VIS absorption data of four bacteriorhodopsin (BR) analogs formed from azulene‐retinals of varying polyene chain length show that the one‐bond‐shortened to one‐bond‐lengthened analogs possess comparable opsin shift values to that of BR. A two‐bond‐shortened analog exhibited a much smaller opsin shift. These data, combined with those reported for the C‐22 retinal analog (Tokunaga et al. , 1977, Biophys. J. 19,191–198) were analyzed by molecular modelling and computer graphics in terms of a model where conformational flexibility of the appended butyl is the controlling factor in determining ease of pigment formation and protein/substrate interaction.