Nonequilibrium energetics of a single F1-ATPase molecule

TL;DR

This study measures the energetics of a single F1-ATPase motor, revealing it operates with nearly 100% efficiency in converting chemical energy to mechanical work under thermal fluctuations.

Contribution

It applies a novel nonequilibrium equality and electrorotation to quantify single-molecule energetics, demonstrating high efficiency of F1-ATPase.

Findings

Heat flow plus work equals free energy change per ATP hydrolysis

F1-ATPase operates at nearly 100% efficiency

Method validates energy transduction in molecular motors

Abstract

Molecular motors drive mechanical motions utilizing the free energy liberated from chemical reactions such as ATP hydrolysis. Although it is essential to know the efficiency of this free energy transduction, it has been a challenge due to the system's microscopic scale. Here, we evaluate the single-molecule energetics of a rotary molecular motor, F1-ATPase, by applying a recently derived nonequilibrium equality together with an electrorotation method. We show that the sum of the heat flow through the probe's rotational degree of freedom and the work against external load is almost equal to the free energy change per a single ATP hydrolysis under various conditions. This implies that F1-ATPase works at an efficiency of nearly 100% in a thermally fluctuating environment.