F-1-ATPASE IS A HIGHLY EFFICIENT MOLECULAR MOTOR THAT ROTATES WITH DISCRETE 120-DEGREES STEPS

A single molecule of F-1-ATPase, a portion of ATP synthase, is by itse lf a rotary motor in which a central gamma subunit rotates against a s urrounding cylinder made of alpha(3)beta(3) subunits. Driven by three catalytic beta s, each fueled with ATP, gamma makes discrete 120 degre es steps, occasionally stepping backward. The work done in each step i s constant over a broad range of imposed load and is close to the free energy of hydrolysis of one ATP molecule.