Hydrodynamic Interactions Introduce Differences in the Behaviour of a Ratchet Dimer Brownian Motor

José A Fornés

doi:10.4236/jbnb.2015.62008

Abstract

We use the Brownian dynamics with hydrodynamic interactions simulation in order to describe the movement of an elastically coupled dimer Brownian motor in a ratchet potential. The only external forces considered in our system were the load, the random thermal noise and an unbiased thermal fluctuation. We observe differences in the dynamic behaviour if hydrodynamic interactions are considered as compared with the case without them. In conclusion, hydrodynamic interactions influence substantially the dynamics of a ratchet dimer Brownian motor; consequently they have to be considered in any theory where the molecular motors are in a liquid medium.

Highlights

Brownian motors are small physical micro- or even nano-machines that operate far from thermal equilibrium by extracting the energy from both thermal and non-equilibrium fluctuations in order to generate work against external loads
They present the physical analogue of bio-molecular motors that work out of equilibrium to direct intracellular transport and to control motion in cells. In such bio-molecular motors, proteins such as kinesins, myosins and dyneins, move unidirectionally on one-dimensional “tracks” while hydrolysing adenosine triphosphate (ATP). These molecular motors are powered by a ratchet mechanism [1]; they convert the nonequilibrium fluctuation into directed flow of Brownian particles in an asymmetrical periodic potential with
We show that hydrodynamic interactions introduce differences in the behaviour of a ratchet dimer Brownian motor as compared without them

Summary

Introduction

Brownian motors are small physical micro- or even nano-machines that operate far from thermal equilibrium by extracting the energy from both thermal and non-equilibrium fluctuations in order to generate work against external loads. They present the physical analogue of bio-molecular motors that work out of equilibrium to direct intracellular transport and to control motion in cells. Fornés, [21], showed that hydrodynamic interactions induced movement against an external load in a ratchet dimer Brownian motor. We show that hydrodynamic interactions introduce differences in the behaviour of a ratchet dimer Brownian motor as compared without them. We report differences in the Peclet number, effective diffusion coefficient, mean x component of the mass center position and velocity and particles positions cross correlations in x direction

The Model

Brownian Dynamics with Hydrodynamic Interactions

Results