Regensburg 2013 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 12: Molecular Motors

BP 12.6: Vortrag

Dienstag, 12. März 2013, 11:00–11:15, H43

Efficiencies of a molecular motor with application to the F₁-ATPase — •Eva Zimmermann and Udo Seifert — II. Institut für Theoretische Physik, Universität Stuttgart

In experiments, the properties of a molecular motor are often inferred by measuring the stochastic trajectory of an attached probe particle. Recently, Toyabe et al. measured the heat dissipated by the probe particle to investigate the efficiency of the F₁-ATPase and found values for this efficiency close to 1 [1].

We discuss a simple model consisting of two degrees of freedom representing the motor and the probe which are elastically coupled. In this model, the motor protein hydrolyzes (or synthesizes) one ATP molecule per mechanical step which represents tight mechanochemical coupling. We apply the model to the F₁-ATPase and investigate three types of efficiencies both in simulations and in a Gaussian approximation [2]. In particular, we clarify the conditions under which the definition of efficiency used in [1] can become even larger than 1 and should therefore not be interpreted as efficiency in the thermodynamic sense. Overall, we obtain good quantitative agreement with the experimental data.

[1] S. Toyabe et al., Phys. Rev. Lett. 104, 198103 (2010)

[2] E. Zimmermann and U. Seifert, New J. Phys. 14, 103023 (2012)