Abstract
Several models have been proposed to interpret the mechanism of proton-pumping associated with the electron transfer reactions in the cytochrome b/f complex. Energetics considerations suggest that the proton pump is coupled to the oxidation of cytochrome b by plastoquinone. Experiments performed in living cells under anaerobic conditions suggest that proton-pumping can occur through two independent mechanisms. When the two b cytochromes are reduced prior to a flash illumination i.e. after a long dark anaerobic incubation (>10 minutes), proton-pumping is very likely associated with the reduction of a semiquinone by cyt b which occurs at a site close to the inner face of the membrane. The electrogenic phase is associated with the tranfer of protons via a transmembrane channel. This process is not inhibited by 2-n-nonyl-4-hydroxyquinoline N-oxide (NQNO). Under repetitive-flash or under aerobic conditions, proton-pumping occurs according to a modified Q-cycle mechanism, which is inhibited by NQNO.
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Dedicated to Prof. L.N.M. Duysens on the occasion of his retirement
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Joliot, P., Joliot, A. Mechanism of proton-pumping in the cytochrome b/f complex. Photosynth Res 9, 113–124 (1986). https://doi.org/10.1007/BF00029737
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DOI: https://doi.org/10.1007/BF00029737