[Kinetics of dissociating inactive tetramers of muscle glycogen phosphorylase b in active dimers].

Recovery of enzymatic activity of rabbit skeletal muscle glycogen phosphorylase b preincubated with 1 mM AMP and 0.125 M K2SO4 (0.05 M glycyl-glycine buffer pH 6.8; 17 degrees C) has been studied. According to sedimentation data, preincubation conditions favor the formation of the tetrameric form of the enzyme. When registering the kinetics of the enzymatic reaction catalyzed by phosphorylase b preincubated with AMP and K2SO4, acceleration of the reaction in the course of the enzymatic process was observed. On the basis of kinetic data, the rate of constant for the dissociation of phosphorylase b tetramers into dimers has been calculated: k = (8.3 +/- 0.3) 10(-3) sec-1 (0.05 M glycyl-glycine buffer pH 6.8; 17 degrees C).