Dresden 2014 – scientific programme

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BP: Fachverband Biologische Physik

BP 16: Poster - Glasses / Stat. Phys. Bio. / Networks (joint DY/BP/CPP/SOE)

BP 16.17: Poster

Tuesday, April 1, 2014, 09:30–12:30, P1

Fluctuations of Probe Particles Coupled to Molecular Motors — •Patrick Pietzonka, Eva Zimmermann, and Udo Seifert — II. Institut für Theoretische Physik, Universität Stuttgart

In recent years, many experiments have been carried out in which the motion of molecular motors is probed by the observation of attached colloidal particles. For the experimental determination of the torque exerted by the rotational motor F₁-ATPase onto such a particle, the application of a fluctuation theorem (FT) for the motion of the colloid has been proposed [1].

However, we show that this approach is generally valid only in the limit of fluctuations on short timescales. The statistics of fluctuations during larger time-intervals depends significantly on the intrinsic behavior of the motor and the linker, which is not observable in experiments. In particular, we investigate a simple model characterized by discrete motor jumps and harmonic coupling between the motor and the colloid [2]. Using the framework of the theory of large deviations, we calculate the distribution of fluctuations of the colloid in the long-time limit. This result implies a refined formulation of the FT-like relation observed in experiments. Moreover, we gain general insight into the properties of stochastic processes with hidden degrees of freedom.

[1] K. Hayashi et al., Phys. Rev. Lett. 104, 218103 (2010)

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