We use molecular dynamics simulations to investigate the displacement of a periodically folding molecular motor in a viscous environment. We observe two different time regimes. For slow foldings (regime I) the
diffusion evolves very slowly with τ, while for rapid foldings (regime II) the diffusion increases strongly with
τ, suggesting two different physical mechanisms.
We find that in regime I the motor’s displacement during the folding process is counteracted by a reverse displacement during the unfolding, while in regime II this counteraction is much weaker. Regime I behavior is reminiscent of the scallop theorem that holds for larger motors in a continuous medium.
For fast foldings the motor trajectories differ significantly from the opposite trajectories induced by the following unfolding process, resulting in a more efficient global motion than for slow foldings.
This result agrees with the fluctuation theorems expectation for time reversal mechanisms. In agreement with the fluctuation theorems we find that the motors are unexpectedly more efficient when they are generating more entropy, a result that can be used to increase dramatically the motor’s motion.