title: The quantum efficiency for the photochemical conversion of the purple membrane protein.
abstract: The quantum efficiency for the formation of M(412), an intermediate product in the photoconversion of the purple membrane protein of Halobacterium halobium, was determined to be 0.30 +/- 0.03 at -40 degrees C. This photochemical reaction was photoreversible to the original pigment and the ratio of the quantum efficiencies gamma PM(568 leads to M(412)/gamma M(412) leads to PM(568) was 0.39 +/- 0.02. No change was seen in either value when exciton interaction between chromophores was eliminated. The sum of gamma PM(568) leads to M(412) plus gamma M(412) leads to PM(568) was 1.07 +/- 0.10, approximately 1, suggesting that the pigment and its primary photoproduct share a common excited state.
mesh_terms: D001436:Bacteriorhodopsins / Q000378:metabolism; D002338:Carotenoids / Q000378:metabolism; D006217:Halobacterium / Q000378:metabolism; D008433:Mathematics; D010777:Photochemistry; D011789:Quantum Theory; D012243:Rhodopsin; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D002338:Carotenoids; D001436:Bacteriorhodopsins; D012243:Rhodopsin