The influence of membrane potentials on reaction rates. Control in free-energy-transducing systems.

The influence of membrane potentials on the rates of reactions involving the translocation of charged species across the membrane has been studied. Depending on the location of the rate-limiting step relative to the potential gradient either the forward or the backward rate is most strongly influenced by the potential. The rate of a proton translocation process in general is thus not a unique function of the protonmotive force. It is essential to include an explicit potential dependence in the kinetic coefficients to obtain a realistic description of the dynamics.