Abstract
A light-induced intermolecular oxidation-reduction reaction between bacterial chlorophyll and a cytochrome of type c that is temperature independent to 80[degree]K is described. The reaction, in which the cytochrome is oxidized from the ferrous to the ferric state with an overall quantum requirement of about 2/electron, is not slowed from 300[degree]K to 80[degree]K, suggesting that a special reaction mechanism between chlorophyll and cytochrome should be considered. Possible mechanisms are considered in detail in the light of the experimental evidence and the existing literature.