Universal bound on the efficiency of molecular motors

TL;DR

This paper derives universal bounds on the efficiency of molecular motors using thermodynamic uncertainty relations, applicable without detailed mechanistic knowledge, based solely on measurable quantities.

Contribution

It introduces a universal efficiency bound for molecular motors derived from thermodynamic uncertainty relations, independent of specific mechanochemical details.

Findings

Efficiency bounds depend only on measurable quantities.

Universal bounds apply to motors against external forces or torque.

Results extend to chemically driven molecular synthesis.

Abstract

The thermodynamic uncertainty relation provides an inequality relating any mean current, the associated dispersion and the entropy production rate for arbitrary non-equilibrium steady states. Applying it here to a general model of a molecular motor running against an external force or torque, we show that the thermodynamic efficiency of such motors is universally bounded by an expression involving only experimentally accessible quantities. For motors pulling cargo through a viscous fluid, a universal bound for the corresponding Stokes efficiency follows as a variant. A similar result holds if mechanical force is used to synthesize molecules of high chemical potential. Crucially, no knowledge of the detailed underlying mechano-chemical mechanism is required for applying these bounds.