Photoreverse Reaction Dynamics of Octopus Rhodopsin

AbstractPhotoreverse reactions of octopus rhodopsin (Rh) from acid-metarhodopsin (Acid-Meta), which is the final product of the photoreaction of Rh, to Rh were studied by the time-resolved transient absorption and transient grating methods. The time course of the absorption signal showed a rapid change within 500ns followed by one phase with a time constant of ∼470μs, whereas the transient grating signal indicates three phases with time constants of <500ns, ∼490μs, and 2.6ms. The faster two phases indicate the conformational change in the vicinity of the chromophore, and the slowest one represents conformational change far from the chromophore. The absorption spectrum of the first intermediate created just after the laser excitation (