A proposed hydrogen transfer function for cytochrome c.

Outlines of proposed mechanisms for cytochrome c oxidoreduction are presented which differ in detail from those previously published. The mechanisms, while accommodating the fact that cytochrome c is a net electron acceptor and donor in its catalytic cycle, dictate that the enzyme catalyses hydrogen transfer. It is shown that the mechanism of cytochrome c reduction fulfills a recent proposal that the transition state is an analogue of the structure of ferricytochrome c(2). The implications of a hydrogen transfer role of cytochrome c are discussed.