Tools for resolving complexity in the electron transfer networks of multiheme cytochromes c

Examining electron transfer between two proteins with identical spectroscopic signatures is a challenging task. It is supposed that several multiheme cytochromes in Shewanella oneidensis form a molecular “wire” through which electrons are transported across the cellular space and a direct study of this transient protein–protein interaction has not yet been reported. In this study, we present variations on catalytic protein film voltammetry and an anaerobic affinity chromatography assay to demonstrate unidirectional electron transfer between proposed protein pairs. Through use of these techniques, we are able to confirm the transient interactions between these cytochromes, supporting the model of electron transfer that is present in the literature. Electrochemical and affinity chromatography techniques are developed to decipher the directionality and stoichiometry of the branched electron transfer networks of Shewanella oneidensis that make use of multiheme cytochromes c.