This activates glycogen phosphorylase and inhibits glycogen synthase. Quinine may target the malaria purine nucleoside phosphorylase enzyme. Glycogen phosphorylase is the primary enzyme of glycogen breakdown. Phosphorylated phosphorylase clips glucose units from glycogen as glucose 1-phosphate. Glycogen debranching enzymes assist phosphorylase, the primary enzyme involved in glycogen breakdown, mobilize glycogen stores. Ser-14 is modified by phosphorylase kinase during activation of the enzyme. Glycogen phosphorylase is regulated through allosteric control and through phosphorylation. This dissociation activates glycogen synthase and converts phosphorylase "a" to phosphorylase "b". Glycogen phosphorylase was the first allosteric enzyme to be discovered. PLP is a required coenzyme of glycogen phosphorylase, the enzyme necessary for glycogenolysis to occur. This amplifies the effect of activating glycogen phosphorylase. Glycogen can be converted into glucose 6-phosphate as well with the help of glycogen phosphorylase. The problem occurring in IXa is a defect in phosphorylase b kinase (PHK). It is also required for muscle phosphorylase activity associated with glycogen metabolism. Glycogen phosphorylase is one of the phosphorylase enzymes ().