Abstract
The mechanism of secondary active transport processes has been proposed as an ordered binding model, based on substrate binding studies dependent on coupling cation concentrations (Yamato, I. (1992) FEBS Lett., 298, 1-5). The reason why the systems adopt the ordered binding mechanism is discussed from the point of view of the coupling efficiency of the energy transduction. It is proposed that the mechanism guarantees the tight coupling of the system. The ordered binding mechanism is then proposed as the general mechanistic model for various bioenergy transducing systems with tight coupling.
