(5-demethyl)-Bacteriorhodopsin analogue: its formation and light-driven proton pump action

AbstractThe binding of the isomers (all-trans, 13-cis, 11-cis and 9-cis) of 5-demethylretinal to bacterioopsin and the light—dark adaptation as well as the light-driven proton pump action of the resulting bacteriorhodopsin analogue were studied. The (5-demethyl)-bacteriorhodopsinis formed ≈ 3-times faster than unmodified bacteriorhodopsin and shows an efficient light-driven proton pump action. These findings show that upon binding of retinal to bacterioopsin the protein forces the chromophore to adopt a more planar ring-chain conformation than in free retinal