The chemo-mechanical coupled model for F1F0-motor

F1F0-motor (ATP synthase) is the universal enzyme in biological energy conversion that is present in the membranes of mitochondria, chloroplasts and bacteria. It uses the energy of the proton gradient across the membrane to synthesize ATP. Previous theory and model about rotation of the ATP synthase is reviewed, then a novel chemo-mechanical coupled model for rotation of the F1F0-motor is proposed. In the model, more events are considered simultaneously that includes the movement of F1, the movement of F0, reactions at F1 and reactions at F0. Using the model, the possible substep modes of the rotation for F1F0 are predicted, the dependence of the motor efficiency and its rotation rate on the rigidity of the γ shaft is investigated. We conclude that the γ shaft has a large rotation rate for a limited driving potential because two ends of the γ shaft can rotate alternately for its flexibility. The flexibility also makes the efficiency of F1F0 drop because elastic twisting deformation power is needed during alternate rotation of the γ shaft at two ends.