A theory for high efficiency electron bifurcation

David N. Beratan

Duke University

Electron bifurcation is used in living systems for energy conservation and to drive biocatalysis. The reaction involves a sequence of coordinated vibronically coupled electron tunneling reactions among multiple cofactors that oxidize a two-electron donor at medium potential, reducing spatially separated high-and  low-potential acceptors. Electron bifurcation is often energy efficient, allowing the creation of strong reductants at minimal free energy cost. For many years, the internal workings of electron bifurcating enzymes were poorly understood, and their success at avoiding short-circuiting reactions was not understood. I will describe a redox energy landscape for electron bifurcation that naturally insulates against short-circuiting and enables access to both high efficiency electron bifurcation and confurcation. I will review the physical principles that underpin this electron bifurcation scheme, will describe how this scheme is distinct from previous perspectives, and will describe open questions and opportunities. References: K. Terai, J. Yuly, P. Zhang, and D.N. Beratan, “Correlated particle transport enables biological free energy transduction,” Biophysical J., in press (2023); J. Yuly, P. Zhang, and D.N. Beratan, “Energy transduction by reversible electron bifurcation,” Curr. Op. Electrochem., 29, 100767 (2021); J.L. Yuly, P. Zhang, X. Ru, K. Terai, N. Singh, and D.N. Beratan, “Efficient and reversible electron bifurcation with either normal or inverted potentials at the bifurcating cofactor,” Chem, 8, 1870-1886 (2021); J. Yuly, P. Zhang, C.E. Lubner, J.W. Peters, and D.N. Beratan, “Universal free energy landscape produces efficient and reversible electron bifurcation,” Proc. Natl. Acad. Sci (USA), 117, 21045-21051 (2020).

This abstract is for the Florida Award Symposium in honor of M.J. Therien.