Hoppe-Seyler's Zeitschrift für physiologische Chemie. vol:358 issue:5 pages:575-81
The effect of Mg2, ATP and some of its analogs was studied on the spontaneously active and the ATP-Mg-dependent forms of phosphorylase phosphatase extracted from adrenal cortex. Inhibition of the spontaneously active form was observed with Mg2 (Ki - 9mM), ATP (Ki = 9micronM), 2'-doxy-ATP (Ki = 8 micronM), AtetraP (Ki = 9 micronM), AMP(CH2)PP (Ki = 11 micronM), ADP(CH2)P (Ki = 19 micronM), ADP(NH)P (Ki = 16micronM) and ADP (Ki = 25micronM). Activation of the ATP-Mg-dependent form was obtained with Mg2 (Ka = 0.55mM) (to a lower extent) and with ATP (Ka = 2micronM), 2'-deoxy-ATP (Ka = 6micronM) or AtetraP (Ka = 15micronM) in the presence of 0.5mM Mg2. Activation with AMP(CH2)PP was only observed in the presence of high concentrations (5mM) of Mg2 (Ka = 13micronM). No activation at all was observed with ADP(CH2)P or ADP(NH)P. Even though the activation of the ATP-Mg-dependent form does not seem to involve a kinase reaction, the stimulation by ATP or its analogs is rather specific, since it does not occur with analogs in which a methylene group or a nitrogen is substituted for the oxygen between the beta- and gamma-phosphates.