FoF1-ATP synthase is a factory for synthesizing ATP in virtually all cells. Its core machinery is the subcomplex F1-motor (F1-ATPase) and performs the reversible mechanochemical coupling. Isolated F1-motor hydrolyzes ATP, which is accompanied by unidirectional rotation of its central γ-shaft. When a strong opposing torque is imposed, the γ-shaft rotates in the opposite direction and drives the F1-motor to synthesize ATP. This mechanical-to-chemical free-energy transduction is the final and central step of the multistep cellular ATP-synthetic pathway. Here, we determined the amount of mechanical work exploited by the F1-motor to synthesize an ATP molecule during forced rotations using methodology combining a nonequilibrium theory and single molecule measurements of responses to external torque. We found that the internal dissipation of the motor is negligible even during rotations far from a quasistatic process.
@article{arxiv.1210.4017,
title = {Single molecule thermodynamics of ATP synthesis by F$_1$-ATPase},
author = {Shoichi Toyabe and Eiro Muneyuki},
journal= {arXiv preprint arXiv:1210.4017},
year = {2015}
}