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Crystal structures of bR(D85S) favor a model of bacteriorhodopsin as a hydroxyl‐ion pump
Author(s) -
Facciotti Marc T,
Rouhani Shahab,
Glaeser Robert M
Publication year - 2004
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(04)00208-x
Subject(s) - bacteriorhodopsin , chemistry , protonation , ion , residue (chemistry) , schiff base , proton , crystal structure , mutant , ion pump , crystallography , stereochemistry , biochemistry , membrane , organic chemistry , physics , quantum mechanics , gene
Structural features on the extracellular side of the D85S mutant of bacteriorhodopsin (bR) suggest that wild‐type bR could be a hydroxyl‐ion pump. A position between the protonated Schiff base and residue 85 serves as an anion‐binding site in the mutant protein, and hydroxyl ions should have access to this site during the O‐intermediate of the wild‐type bR photocycle. The guanidinium group of R82 is proposed (1) to serve as a shuttle that eliminates the Born energy penalty for entry of an anion into this binding pocket, and conversely, (2) to block the exit of a proton or a related proton carrier.