Photocycle in the M-form in bacteriorhodopsin mutants devoid of primary proton acceptor Asp-85.
Photoinduced changes in absorption of the deprotonated M-form in the mutant bacteriorhodopsin without primary proton acceptor Asp-85 were studied and additional evidence in support of the complete transmembrane proton transfer in photocycle was obtained. Measurements of the absorption spectrum were carried out at various pH, temperature, and humidity. The direction of proton transfer was the same as in the normal photocycle of the wild-type bacteriorhodopsin: from the internal to the external side of the membrane. The effect on this process of a terminal acceptor Glu-204 was shown.
Lukashev
E P
EP
Biophysical Department, Biological Faculty, Lomonosov Moscow State University, Russia. lukashev@biophys.msu.ru
Kolodner
P
P
D001224:Aspartic Acid / Q000737:chemistry*; D001436:Bacteriorhodopsins / Q000737:chemistry* / Q000235:genetics; D019617:Halobacterium salinarum; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009154:Mutation; D010777:Photochemistry; D011522:Protons; D013057:Spectrum Analysis; D013696:Temperature
D011522:Protons; D001224:Aspartic Acid; D001436:Bacteriorhodopsins