The mechanism of bacteriorhodopsin functioning. II. Ejection and injection of proton

Abstract

AbstractTransmission of vibrational excitation energy conserved in cis‐conformation of retinal to the outlet proton channel is considered from the perspective of quantum theory. A distribution of vibrational excitations in the channel is found; it allowed to calculate the magnitude of the directed drift proton current. The differences between velocities of proton movement in active and passive channels are considered. A transition of retinal from cis‐ to all ‐trans‐ conformation with the subsequent capture of proton by Schiff base out of the inlet channel is described. The lack of proton in this channel, i.e., in the H‐bonded chain, is eliminated at the expense of the capture of a proton out of the cytoplasmic water enviroment. The correspondence between theoretically established states and spectroscopically identified forms of bacteriorhodopsin (inter‐mediates L, M, N, and O) is proposed.