Study of properties of phosphorylase kinase using hydrophobic chromatography

The structure of nonactivated and activated forms of phosphorylase kinase has been investigated. The enzyme activation was achieved by phosphorylation with cAMP-dependent protein kinase as well as by incubation of the enzyme in an alkaline medium (pH 8.8). For structural comparison of the enzymic forms, hydrophobic chromatography on phenyl-Sepharose and polyacrylamide gel electrophoresis were used. It has been shown that the enzyme activation results in a release of a low molecular weight component (Mr 16 000). The properties of this component resemble those of calmodulin. Evidence for the formation of an unstable nonactivated phosphorylase kinase - calmodulin complex may be important for the correct understanding of the mechanism of enzyme activation.