Electrochemistry of flavin-based electron bifurcation: ‘Current’ past and ‘potential’ futures

Flavin-based electron bifurcation (FBEB) was discovered as a significant process of microbial energy conservation less than two decades ago. Since then, several classes of enzymes engaging in FBEB have been identified, all of which utilize a flavin cofactor that accepts two electrons and then transfers one along an exergonic (high-potential) pathway and the other along an endergonic (low-potential) pathway. We describe the critical role of electrochemical techniques, especially protein-film voltammetry and spectroelectrochemistry, in determining the mechanism and energetic landscape of FBEB in a characteristic enzyme. A prospectus of future directions involving currently unutilized electrochemical techniques is discussed with regards to the salient open questions in the field of FBEB.