2004 年 72 巻 1 号 p. 2-4
Photo-induced transient responses corresponding to proton release and uptake of bacteriorhodopsin at the electrode/electrolyte interface were investigated for the purpose to clarify the role of charged amino acid residues in the retinal binding pocket. Mutants of bacteriorhodopsin, lacking one or both of the charged amino acid residues Arg-82 and Asp-212 in the pocket, were investigated. pH-dependent photoresponse profiles revealed that proton pumping activity nearly disappears in single mutants R82Q, R82A and D212N while it is well recovered in a double mutant R82Q/D212 N, indicating that a net charge balance created by ion pairs between charged residues is crucial for driving the photocycle and proton transport reaction.
