Efficiently Driving F_{1} Molecular Motor in Experiment by Suppressing Nonequilibrium Variation

F_{1}-ATPase (F_{1}) is central to cellular energy transduction. Forcibly rotated by another motor F_{o}, F_{1} catalyzes adenosine triphosphate (ATP) synthesis by converting mechanical work into chemical free energy stored in the molecule ATP. The details of how F_{o} drives F_{1} are not fully understood; however, evaluating efficient ways to rotate F_{1} could provide fruitful insights into this driving since there is a selective pressure to improve efficiency. Here, we show that rotating F_{1} with an angle clamp is significantly more efficient than a constant torque. Our experiments, combined with theory and simulation, indicate that the angle clamp significantly suppresses the nonequilibrium variation that contributes to the futile dissipation of input work.