KINETICS OF LIGHT-INDUCED INTRAMOLECULAR CHARGE-TRANSFER AND PROTON RELEASE IN BACTERIORHODOPSIN

Recent advances in understanding the intramolecular charge transfer an d proton release by the light-driven proton pump bacteriorhodopsin (bR ) are critically reviewed. The focus is on the time-resolved electrica l methods, i.e., photocurrent and photovoltage measurements, and on tr ansient absorption experiments with pH-sensitive dyes. Particular atte ntion is paid to the following topics: charge translocation in the low -pH forms of bR (acid-blue and acid-purple); electrogenicity of the 13 -cis cycle; results with bR mutants; surface-bound dyes to detect the proton release at specific sites on either side of the protein; the qu estion of kinetic coupling between the deprotonation of the Schiff bas e and proton release: and rapid long-range migration of protons along the surface of the purple membrane.