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A HIGHLY REACTIVE HETEROATOM ANALOG OF RETINAL AND ITS INTERACTION WITH BACTERIORHODOPSIN
Author(s) -
Birnbaum Dov,
Seltzer Stanley
Publication year - 1984
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.1751-1097.1984.tb08381.x
Subject(s) - chemistry , bacteriorhodopsin , formate , moiety , retinal , photochemistry , membrane , absorption (acoustics) , stereochemistry , organic chemistry , biochemistry , physics , acoustics , catalysis
C 18 formate ester (5) [2‐(6‐methyl‐8‐(2,6,6‐trimethyl‐1‐cyclohexen‐1‐yl)‐3E,5E,7E‐octatrienyl formate], a highly reactive analog of retinal, was synthesized and its interaction with bacterioopsin studied. The formate ester, in the absence of purple or bleached membrane, undergoes very rapid reaction (t l/2 = 0.9 min) in neutral buffer but with membrane present it diffuses more rapidly into the membrane where it reacts slowly. Incorporation of 5 in the membrane results in a 38 nm (3900 cm ‐1 ) red shift which remains after reconstitution with retinal. Similar experiments with the corresponding C 18 alcohol (4) results in a red shift, but this absorption blue shifts upon reconstitution with retinal. Washing the formate ester‐treated membrane with bovine serum albumin or the corresponding lyophilized preparation with hexane, treatments that remove retinal oxime, fails to remove the UV‐visible absorption, suggesting that a covalent bond between the C 18 moiety and a nucleophilic group of the protein has probably formed.