The existence of a high photochemical turnover rate at the reaction centers of system II in Tris-washed chloroplasts.
In Tris-washed chloroplasts the kinetics of the primary electron acceptor X 320 of reaction center II has been investigated by fast repetitive flash spectroscopy with a time resolution of approximately 1 mus. It has been found that X 320 is reduced by a flash in less than or equal to 1 mus. The subsequent reoxidation in the dark occurs mainly by a reaction with a 100-200 mus kinetics. The light-induced difference spectrum confirms X 320 to be the reactive species. From these results it is concluded that in Tris-washed chloroplasts the reaction centers of System II are characterized by a high photochemical turnover rate mediated either via rapid direct charge recombination or via fast cyclic electron flow.
D002736:Chloroplasts / Q000187:drug effects / Q000528:radiation effects*; D004579:Electron Transport / Q000528:radiation effects; D010084:Oxidation-Reduction; D010777:Photochemistry; D010788:Photosynthesis / Q000187:drug effects / Q000528:radiation effects*; D011830:Radiation Effects; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors; D014325:Tromethamine / Q000494:pharmacology
D014325:Tromethamine