Abstract
The photoelectrochemical response of bacteriorhodopsin (bR) was studied in buffered electrolyte solutions. The photocurrent intensity was inversely proportional to the buffer concentration in a wide range, and the response time became shorter with increasing buffer concentration. When plotted as a function of the electrolyte pH, the ratio of the peak photocurrent in the presence of a buffer to that in the absence of the buffer exhibited a minimum at a pH nearly equal to the pK′a of the buffer. These results are explained by invoking the buffering capacity, and are in line with the view that the transient bR photoresponse originates in the pH change near the electrode due to proton release/uptake by bR molecules.
