AN AZULENIC BACTERIORHODOPSIN ANALOG HAS PHOTOINDUCED ACTIVITY

The photoinduced changes of absorbance as well as proton release and u ptake have been observed for an azulenic analog of wild-type bacterior hodopsin. The release and uptake of protons have been measured using a highly sensitive electrochemical technique. Bacteriorhodopsin membran e patches on a tin-oxide electrode produce a transient photocurrent th at is negative for proton release and positive for proton uptake. For azulenic bacteriorhodopsin the photocurrent is approximately 20% of th e transient observed with native bacteriorhodopsin. The existence of t he photoinduced absorbance changes and the transient photocurrent are important results for gaining further insight into the photoinduced fu nction of bacteriorhodopsin.