The mean velocity of two-state models of molecular motor

TL;DR

This paper analyzes the mean velocity of two-state models of molecular motors, revealing conditions under which the velocity can be nonzero without energy input and how transition rates influence motor movement.

Contribution

It provides explicit expressions for the mean velocity in two-state models, highlighting novel insights into motor behavior without energy input.

Findings

Mean velocity can be nonzero even with periodic potentials and no energy input.

Velocity can be zero despite energy input, depending on transition rates.

Transition rates between states significantly affect the motor's velocity.

Abstract

The motion of molecular motor is essential to the biophysical functioning of living cells. In principle, this motion can be regraded as a multiple chemical states process. In which, the molecular motor can jump between different chemical states, and in each chemical state, the motor moves forward or backward in a corresponding potential. So, mathematically, the motion of molecular motor can be described by several coupled one-dimensional hopping models or by several coupled Fokker-Planck equations. To know the basic properties of molecular motor, in this paper, we will give detailed analysis about the simplest cases: in which there are only two chemical states. Actually, many of the existing models, such as the flashing ratchet model, can be regarded as a two-state model. From the explicit expression of the mean velocity, we find that the mean velocity of molecular motor might be nonzero even if the potential in each state is periodic, which means that there is no energy input to the molecular motor in each of the two states. At the same time, the mean velocity might be zero even if there is energy input to the molecular motor. Generally, the velocity of molecular motor depends not only on the potentials (or corresponding forward and backward transition rates) in the two states, but also on the transition rates between the two chemical states.