Universal Free Energy Landscape Produces Efficient and Reversible Electron Bifurcation

TL;DR

This paper proposes a universal free energy landscape model that explains how natural electron bifurcating systems achieve high efficiency and reversibility, providing a blueprint for designing synthetic molecular machines.

Contribution

It introduces a simple, universal free energy landscape (EB-scheme) that enables efficient and reversible electron bifurcation without complex rate adjustments.

Findings

The landscape relies on steep free energy slopes in redox branches.

It prevents energy-wasting short-circuiting reactions.

The model offers a blueprint for synthetic electron bifurcating machines.

Abstract

For decades, it was unknown how electron bifurcating systems in Nature prevented energy-wasting short-circuiting reactions that have large driving forces, so synthetic electron bifurcating molecular machines could not be designed and built. The underpinning free energy landscapes for electron bifurcation were also enigmatic. We predict that a simple and universal free energy landscape enables electron bifurcation, and we show that it enables high-efficiency bifurcation with limited short-circuiting (the EB-scheme). The landscape relies on steep free energy slopes in the two redox branches to insulate against short-circuiting without relying on nuanced changes in the microscopic rate constants for the short-circuiting reactions. The EB-scheme thus provides a blueprint for future campaigns to establish synthetic electron bifurcating machines.