The Catalytic Mechanism Based on a Four-State Model of F1-ATPase

F₁-ATPase, a rotary motor enzyme, can catalyse ATP hydrolysis in which the central γ-subunit ratates inside the α₃β₃ cylinder. Here, a four-state catalytic model of F₁-ATPase is studied in which we think that the ATP hydrolysis and synthesis are ATP-dependent and ADP/Pi-dependent, respectively. The results show that the catalytic ratation mechanism of F₁-ATPase is affected distinctly by the ATP/ADP/Pi concentrations. The model accords well with the expermental observations. Moreover, when the external load exists, the mean rotation rate of F₁-ATPase is also affected apparently, and the external torque which decreases the mean ratation rate of the F₁ motor to zero equals to the constant one which is produced during the ratation of the motor.