Kinetic characterization of glycogen phosphorylase [formula omitted] from skeletal muscle of the mullet Liza ramada

Abstract

1. 1. Glycogen phosphorylase purified from muscle of mullet ( Liza ramada) has been kinetically characterized. 2. 2. Kinetic analysis for the substrates glucose-1-P and glycogen showed no homotropic co-operativity. AMP exhibited only a slight homotropic co-operative behaviour, although it caused a decrease in the K m for glucose-1-P. 3. 3. Glucose, ATP and glucose-6-P behaved as phosphorylase b inhibitors. Kinetic analysis of the inhibition showed the characteristic heterotropic effect both for the substrate glucose-1-P and the activator AMP. 4. 4. However, glucose-6-P, which enhances the co-operativity between AMP molecules, lost its heterotropic effect on the glucose-1-P saturation curve.