Phenomenological energetics for molecular motors

A phenomenologically closed framework is presented to evaluate the energy balance on a molecular motor at a nonequilibrium steady state. We employed a generalized Langevin equation as a coarse-grained model of a motor, based on which the efficiency of the motor can be calculated from macroscopic observables alone. It is shown that the energy fluxes at a nonequilibrium steady state are related to the extent of the violation of fluctuation-dissipation relation for the velocity fluctuation. We show that the present framework adequately explains the recent experimental result for kinesin