ORDERED MECHANISM OF BINDING OF PHOSPHORYLASE KINASE AND GLYCOGEN PHOSPHORYLASE b TO GLYCOGEN

The kinetics of the interaction of rabbit skeletal muscle phosphorylase kinase with glycogen has been studied using turbidimetric method (40 mM Hepes, pH 6.8, and 8.2; 20◦C). The binding of phosphorylase kinase with glycogen occurs only in the presence of Ca and Mg . According to the kinetic data, phosphorylase b favors the binding of phosphorylase kinase with glycogen. This conclusion is supported by the direct study of the influence of phosphorylase b on the binding of phosphorylase kinase with glycogen by sedimentation velocity in an analytical ultracentrifuge. A model for adsorbtion of phosphorylase b and phosphorylase kinase on the surface of the glycogen particle has been proposed. The model explains how phosphorylase b favors the tighter binding of phosphorylase kinase with glycogen.