Ferredoxin-Dependent and Antimycin A-Sensitive Reduction of Cyiochrome b-559 by Far-Red Light in Maize Thylakoids : Participation of a Menadiol-Reducible Cytochrome b-559 in Cyclic Electron Flow : ENVIRONMENTAL AND STRESS RESPONSES : MEMBRANES AND BIOENER

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Thylakoids from mesophyll cells of maize showed a high rate of the ferredoxin (Fd)-dependent and antimycin A (AntiA)-sensitive cyclic electron flow as determined by the quenching of 9-aminoacridine fluorescence which indicates the formation of A pH across the membranes. Spectrophotometric survey of the thylakoids showed the reduction of a Cyt having an a-peak at 559 nm [Cyt b-559(Fd)] by far-red light, which depended on Fd and was sensitive to AntiA. Dose dependencies of Fd and AntiA on the photoreduction of Cyt b-559(Fd) were the same as those of the formation of ΔpH. Cyt b-559(Fd) occurred in an oxidized form even in the presence of ascorbate and was reduced by far-red light. In darkness, it was reduced only by menadiol (E_<m,7>= -10 mV). Thus, Cyt b-559(Fd) was distinguished from Cyt b-559 in the PSII complex by its low redox potential. The present results indicate that Cyt b-559(Fd) mediates electron transfer from Fd to plastoquinone during Fd-dependent cyclic electron flow around PSI.
日本植物生理学会の論文