Studies on interaction of phosphorylase kinase from rabbit skeletal musclewith glycogen in the presence of ATP and ADP

The influence of ATP on complex formation of phosphorylase kinase (PhK) wit h glycogen in the presence of Ca2+ and Mg2+ has been studied. The initial r ate of complex formation decreases with increasing ATP concentration, the d ependence of the initial rate on the concentration of ATP having a cooperat ive character. Formation of the complex of PhK with glycogen in the presenc e of ATP occurs after a lag period, which increases with increasing ATP con centration. The dependence of the initial rate of complex formation (nu) on the concentration of non-hydrolyzed ATP analogue, beta,gamma -methylene-AT P, follows the hyperbolic law. A correlation between PhK-glycogen complex f ormation and P-32 incorporation catalyzed by PhK itself and by the catalyti c subunit of cAMP-dependent protein kinase has been shown. For ADP (the pro duct and allosteric effector of the PhK reaction) the dependence of nu on A DP concentration has a complicated form, probably due to the sequential bin ding of ADP at two allosteric sites on the beta subunit and the active site on the gamma subunit. (C) 2001 Elsevier Science B.V. All rights reserved.