Nonequilibrium dissipation-free transport in F1-ATPase and the thermodynamic role of asymmetric allosterism

TL;DR

This paper investigates how F1-ATPase achieves near-zero internal dissipation during rotation, emphasizing the role of asymmetric allosterism and nonequilibrium effects, and introduces the TASAM model to explain experimental observations.

Contribution

The paper introduces the TASAM model, highlighting the importance of asymmetric allosterism and multiple timescales in explaining dissipation-free transport in F1-ATPase.

Findings

TASAM aligns with experimental torque and velocity data.

Internal dissipation remains low across various velocities.

Dissipation increases during ATP synthesis at low nucleotide levels.

Abstract

F1-ATPase (or F1), the highly-efficient and reversible biochemical engine, has motivated physicists as well as biologists to imagine the design principles governing machines in the fluctuating world. Recent experiments have clarified yet another interesting property of F1; the dissipative heat inside the motor is very small, irrespective of the velocity of rotation and energy transport. Conceptual interest is devoted to the fact that the amount of internal dissipation is not simply determined by the sequence of equilibrium pictures, but also relies on the rotational-angular dependence of nucleotide affinity, which is a truly nonequilibrium aspect. We propose that the totally asymmetric allosteric model (TASAM), where adenosine triphosphate (ATP) binding to F1 is assumed to have low dependence on the angle of the rotating shaft, produces results that are most consistent with the experiment. Theoretical analysis proves the crucial role of two time scales in the model, which explains the universal mechanism to produce the internal dissipation-free feature. The model reproduces the characteristic torque dependence of the rotational velocity of F1, and predicts that the internal dissipation upon the ATP synthesis direction rotation becomes large at the low nucleotide condition.