title: The quantum efficiency of the bacteriorhodopsin photocycle.
abstract: The quantum yield of the primary photoprocess in light-adapted bacteriorhodopsin (phi 1) was determined at room temperature with low-intensity 530 nm neodymium laser excitation, with bovine rhodopsin as a relative actinometer. The observed value of phi 1 - 0.25 +/- 0.05, and the previously determined parameter phi 1/phi 2 - 0.4 [where phi 2 denotes the quantum efficiency of the back photoprecess from the primary species K (590)] imply that phi 1 + phi 2 approximately equal 1. This feature, also characterizing the photochemistry of rhodopsin, bears on the nature and mechanism of the primary event in both systems.
mesh_terms: D001436:Bacteriorhodopsins / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D003624:Darkness; D006217:Halobacterium / Q000378:metabolism; D008027:Light; D008433:Mathematics; D011789:Quantum Theory; D012243:Rhodopsin
chemical_list: D002338:Carotenoids; D001436:Bacteriorhodopsins; D012243:Rhodopsin