Hydrogen bridges and electron transfer in biomolecules. Study of a possible mechanism on a model charge–recombination system

Abstract

It is suggested that internal electron transfer in biomolecules such as multiheme proteins can take place along H-bridge/peptide-link chains by a proton-relay process followed by radicalic return to the initial condition. The plausibility of such a process is assessed by (a) reference to published suggestions and evidence; (b) estimates of vibrational characteristics and of the free energies of the various states of a model system consisting of three H-bridges and one peptide group. It appears that the proposed mechanism is highly efficient and very fast, at least if the H-bonds formed by a peptide group evolve in a concerted manner.