Kinetic modeling of ATP synthesis by ATP synthase and its mechanistic implications

Based on the torsional mechanism of ATP synthesis by ATP synthase, a kinetic scheme has been developed in this work. The scheme considers adenine nucleotide transport, binding of substrates ADP and P(i), unbinding of product ATP, and ATP synthesis. This kinetic scheme has been analyzed mathematically, and a kinetic model has been obtained to explain the experimentally observed hyperbolic Michaellian dependence of the rate of ATP synthesis on the ADP concentration by ATP synthase under physiological steady-state operating conditions. The principal results of the kinetic model have been compared with the experimental data and an estimate of the enzymological kinetic parameters V(max), K(M), and K(I) has been determined. Mechanistic implications arising from further analysis of the kinetic model have been discussed. These biological implications provide deep insight into the sequence of events leading to ATP synthesis.