Fluctuation theorem for a single enzym or molecular motorU. Seifert
II. Institut für Theoretische Physik, Universität Stuttgart - 70550 Stuttgart, Germany
received 25 January 2005; accepted 11 February 2005
published online 4 March 2005
Cyclically operating enzyms and molecular motors are shown to be restricted non-linearly by a fluctuation theorem that basically relates the number of backward steps to that of forward steps. Only if the rates obey a quasi-equilibrium form in terms of chemical potentials and mechanical load, this fluctuation theorem becomes the usual one for entropy fluctuations. Boundary terms can be subsumed under an entropy change if one defines a trajectory-dependent entropy of the enzym or motor. Explicit expressions are derived for a three-state motor with and without an intermediate state and an enzym with Michaelis-Menten kinetics.
05.40.-a - Fluctuation phenomena, random processes, noise and Brownian motion.
82.39.-k - Chemical kinetics in biological systems.
87.16.Nn - Motor proteins (myosin, kinesin, dynein).
© EDP Sciences 2005