F1-ATPase Is a Highly Efficient Molecular Motor that Rotates with Discrete 120° Steps

AbstractA single molecule of F1-ATPase, a portion of ATP synthase, is by itself a rotary motor in which a central γ subunit rotates against a surrounding cylinder made of α3β3 subunits. Driven by three catalytic βs, each fueled with ATP, γ makes discrete 120° steps, occasionally stepping backward. The work done in each step is constant over a broad range of imposed load and is close to the free energy of hydrolysis of one ATP molecule