Abstract
We have developed a new technique that allows to monitor mechanical and ligand-binding events in a single myosin molecule simultaneously. We describe how ATPase reaction are temporally related to mechanical events at the single molecule level. The results show that the force generation does not always coincide with the release of bound nucleotide, presumably ADP, but the myosin head produces force several hundreds of milliseconds after bound nucleotide is released. This finding does not support the widely accepted hypothesis that force generation is directly coupled to the release of bound ligands. It suggests that myosin has a hysteresis state which stores chemical energy due to ATP hydrolysis.
