Transfer of ubiquinol from the reaction center to the bc1 complex in Rhodobacter sphaeroides chromatophores under oxidizing conditions

Publisher Website
Google Scholar
Abstract
The mechanism of interaction between the photosynthetic reaction center (RC) and bc 1 complex has been investigated in chromatophores of Rhodobacter sphaeroides. The kinetics of cytochrome b h reduction and formation of the transmembrane electric potential were measured at high E h, a condition where ubiquinol is formed in the RC only on the second light flash. In the presence of antimycin A, the kinetics of cytochrome b h reduction have been shown to be sensitive neither to the amount of ubiquinol produced nor to the number of active bc 1 complexes. It is concluded that the reaction between the ubiquinol produced on the second flash and the bc 1 complex is monomolecular. To explain the monomolecular pattern of this reaction under oxidizing conditions (the present work) and the previously described bimolecular pattern under reducing conditions [(1983) Biochim. Biophys. Acta 723, 202–218], it is proposed that (i) quinone exchange between the RC and bc 1 complex occurs via a local quinone pool and (ii) the rate of exchange between the quinone pools is very much slower than cytochrome b h reduction.

This publication has 14 references indexed in Scilit: