Electron Bifurcation Reaction Mechanisms


Electron bifurcation is a biological energy conversion process that oxidizes a two-electron donor at medium potential, coupled to the reduction of high-and a low-potential acceptor species. This process is often fully reversible (can occur close to zero driving force), allowing the creation of strong reductants with minimal free energy cost. For many years, the internal workings of electron bifurcating enzymes were poorly understood, especially regarding how short-circuit reactions are prevented. I will describe a free energy landscape that naturally insulates near-reversible electron bifurcation reactions from short-circuiting, thus enabling efficient and reversible electron bifurcation.  I will review the physical principles that underpin the electron bifurcation scheme, describe how the reversible electron bifurcation scheme is distinct from previous views, and will describe open challenges and opportunities in this area of research.