Synthesis of ATP from ADP and Inorganic Phosphate at the Myosin‐Subfragment 1 Active Site

Abstract

Experiments on the synthesis of ATP from ADP and Pi bound at the active site of the myosin S1 fragment show that the rate limiting step in the ATPase mechanism at 23 °C is associated with a surprisingly low equilibrium constant (about 16 at pH 8.). This, together with the dissociation constant of Pi from the S1 · ADP complex (about 10 mM) obtained from these measurements, and the previously measured rate constants for this system indicate that the dissociation constant of ATP is extremely small, probably in the region of 0.10 pM. Copyright © 1974, Wiley Blackwell. All rights reserved