The Activation and Inactivation of Phosphorylase Phosphatase from Bovine Adrenal Cortex

Preincubation of a partially purified enzyme preparation, obtained from bovine adrenal cortex, in the presence of adenosine triphosphate and magnesium ions resulted in a time-, temperature-, and concentration-dependent increase in the phosphorylase phosphatase activity. Preincubation of the activated enzyme fraction in the presence of ATP or one of several other phosphonucleosides, resulted in a time-, temperature-, and concentration-dependent inactivation of the phosphorylase phosphatase activity. The inactive enzyme fraction could then be reactivated in the presence of ATP plus magnesium ions or, at a slower rate, with magnesium ions alone, provided the inactivation was brought about in the presence of ATP. Adenosine 3',5'-phosphate, in the presence of ATP and magnesium ions converted the active form of the enzyme to a less active form The effect of adenosine 3',5'-phosphate could not be reversed under the conditions used in this study unless the enzyme fraction was first inactivated in the presence of ATP.