Electrochemical Study of Phototransduction in Protein Pigment-Containing Model Membranes.

摘要

The objective of this project is to use primarily an electrochemical approach to study the fundamental molecular processes that underlie the light-mediated sensory (visual) and energy (photosynthetic) transduction in model retinal protein membranes. We study the fast photoelectric signal which appears both in the visual photoreceptor membrane as well as in model membranes reconstituted from bacteriorhodopsin or halorhodopsin. We experimentally distinguished three reporter signals from the hydrophobic chromophore binding pocket region (B1 component) and from the hydrophilic domains of the two membrane surfaces (B2 and B2' components). We developed a concept of local reaction conditions which is applicable to all pigment-containing thin films or membranes. We analyzed the photosignals in the framework of intelligent materials. A similar photosignal was discovered in a reconstituted halorhodopsin membrane. Preliminary data from mutant bacteriorhodopsins synthesized by site-directed mutagenesis are also reported. An electrostatic mechanism of visual transduction mechanism is proposed. Our analysis suggests that there is a common mechanistic design among these membranes.