A kinetic completion of the cyclic photosynthetic electron pathway of Rhodopseudomonas sphaeroides: cytochrome b-cytochrome c2 oxidation-reduction.

In Rhodopseudomonas sphaeroides, following a single-turnover flash of light, cytochrome c2 is oxidized by reaction center bacteriochlorophyll, and a cytochrome b is reduced by the primary electron acceptor, probably via ubiquinone. In this report we show that, in the uncoupled state, the rate of re-oxidation of the cytochrome b is identical to the rate of reduction of the cytochrome c2, a kinetic completion of the cyclic photosynthetic electron transport system.