The structure-function analysis of the fast photoelectric signal from bacteriorhodopsin and related point mutations of Halobacterium halobium

Bacteriorhodopsin (BR), the light driven proton pump found in Halobacteria halobium, is one of the most extensively researched proteins. Since 1977, fast photoelectric signals have been shown in bacteriorhodopsin. These signals result from rapid charge separation which can be described analytically by an equivalent circuit model (Hong and Okajima, 1978). The fast photosignal can be separated into three components (B1, B2, and B2;One main focus of this research is the effect of anions and anion inhibitors on the fast photoelectric signal from BR. This is investigated, in the low pH range, on both wild-type and mutant forms of BR. It is shown that the fast photoelectric signal demonstrates an increase in positive amplitude in the presence of Cl;Another focus of this research is the cation effect on the fast photosignal from BR and related mutants. This effect is observable only in the mid to high pH range. It is shown that in the presence of the divalent cations Ca;Additional observations are reported with mutants that affect the immediate area of the retinal binding pocket. These mutants had crucial charged residues neutralized by point mutations. They include D212N, D96N, R82A, R227Q, T46...