PHOTOCHEMISTRY OF METHYLATED RHODOPSINS

Abstract— Rhodopsin, in which the active‐site Schiff‐base lysine has been chemically modified by monomethylation, is unable to form the deprotonated Schiff base bleaching intermediate, rnetarhodop‐sin II. The photochemistry of the methylated Schiff base rhodopsin stops at the metarhodopsin I stage, which then slowly decays to all‐trans retinal and opsin. Methylation of the non active‐site lysines does not block the photochemical transformation but does speed up the formation and decay of the metarhodopsins.

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