Efficiency of Free Energy Transduction in Autonomous Systems

TL;DR

This paper analyzes the thermodynamic efficiency of chemical coupling in autonomous systems, revealing it is limited by a ratio of Kullback-Leibler distances and demonstrating this in a minimal two-state biomolecular model.

Contribution

It introduces a new bound on free energy transduction efficiency in autonomous systems based on Kullback-Leibler divergence ratios.

Findings

Efficiency is bounded by the ratio of non-symmetric to symmetrized Kullback-Leibler distances.

Efficiency is significantly lower than unity in autonomous chemical coupling.

The two-state model illustrates the fundamental limits of biomolecular energetics.

Abstract

We consider the thermodynamics of chemical coupling from the viewpoint of free energy transduction efficiency. In contrast to an external parameter-driven stochastic energetics setup, the dynamic change of the equilibrium distribution induced by chemical coupling, adopted, for example, in biological systems, is inevitably an autonomous process. We found that the efficiency is bounded by the ratio between the non-symmetric and the symmetrized Kullback-Leibler distance, which is significantly lower than unity. Consequences of this low efficiency are demonstrated in the simple two-state case, which serves as an important minimal model for studying the energetics of biomolecules.