QUANTUM EFFICIENCY OF THE BACTERIORHODOPSIN PHOTOCYCLE

The electric signal corresponding to the M-O transition of the bacteriorhodopsin photocycle (L. Keszthelyi and P. Ormos, J. Membr. Biol., 109 (1989) 193) was measured by trains of exciting laser pulses of highly different intensities in order to test a photocycle model suggested earlier (Birge et al., J. Am. Chem. Soc., 111 (1989) 4063). A transition from high quantum efficiency to low, a prerequisite for the model at issue, should have produced an observable transition in the amplitude of electric pulses from high to low values but it was absent. To check the method the known transition from dark to light adaptation was recorded and the cross section for light adaptation determined.