Abstract
F1-ATPase is a rotary molecular motor in which unidirectional rotation of the central γ-subunit is powered by ATP hydrolysis in three catalytic sites arranged 120° apart around γ. To see how hydrolysis reactions produce mechanical rotation, we observed rotation of γ under the optical microscope, while watching which of the three sites bound and released a fluorescent ATP analog. The reaction scheme, including both the number of site occupancy and reactions that trigger substeps, is now established.
