QUANTUM EFFICIENCY OF THE BACTERIORHODOPSIN PHOTOCYCLE

The electric signal corresponding to the M-O transition of the bacteri orhodopsin photocycle (L. Keszthelyi and P. Ormos, J. Membr. Biol., 10 9 (1989) 193) was measured by trains of exciting laser pulses of highl y different intensities in order to test a photocycle model suggested earlier (Birge et al., J. Am. Chem. Soc., 111 (1989) 4063). A transiti on from high quantum efficiency to low, a prerequisite for the model a t issue, should have produced an observable transition in the amplitud e of electric pulses from high to low values but it was absent. To che ck the method the known transition from dark to light adaptation was r ecorded and the cross section for light adaptation determined.