An Azulenic Bacteriorhodopsin Analog Has Photoinduced Activity

— The photoinduced changes of absorbance as well as proton release and uptake have been observed for an azulenic analog of wild‐type bacteriorhodopsin. The release and uptake of protons have been measured using a highly sensitive electrochemical technique. Bacteriorhodopsin membrane patches on a tin‐oxide electrode produce a transient photocurrent that is negative for proton release and positive for proton uptake. For azulenic bacteriorhodopsin the photocurrent is approximately 20% of the transient observed with native bacteriorhodopsin. The existence of the photoinduced absorbance changes and the transient photocurrent are important results for gaining further insight into the photoinduced function of bacteriorhodopsin.