Tuesday, July 16, 2013

1307.3998 (Kyogo Kawaguchi et al.)

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

Kyogo Kawaguchi, Shin-ichi Sasa, Takahiro Sagawa
Elucidating the mechanism of biomachines is the highway to break ground a new theory of nonequilibrium physics at nano-scale. Among many of the molecular motors, F1-ATPase (or F1), the reversible biochemical engine, has motivated physicists as well as biologists to imagine the possible design principles required 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 show in this letter that the totally asymmetric allosteric model, 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. Prediction on the dissipative feature of the ATP synthesis direction rotation is given. The principle adopted in the model is simple enough to be considered generic in molecular motors, and may help providing a blueprint for artificial nano-machines.
View original: http://arxiv.org/abs/1307.3998

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