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Research was conducted to examine the single-turnover kinetics of the bacteriorhodopsin photocycle and proton-pumping capabilities of whole cells. The objective was to achieve more detailed information about the modifications of the photocycle observed in nonvesicular PM preparations imposed by the conditions of Delta-mu(sub H+) which are present in whole cell preparations. Results indicate that Delta-mu(sub H+) has a profound effect on the kinetics of the photocycle and the ability to pump protons from the cell interior to the external medium.

Studies have focused on the specific, intimate interactions between lipids of the purple membrane (PM) and bacteriorhodopsin (BR), which alter the photocycle decay pathways and kinetics. Disruptions of the photocycle were investigated and found to occur with minimum delipidation of the membrane, and with the trimer structure remaining intact. Laser light is able to regulate Mf and Ms levels in the photocycle.