Description
Glycogen phosphorylase is one of the phosphorylaseenzymes (EC 2.4.1.1). It breaks up glycogeninto glucosesubunits. Glycogenis left with one less glucosemolecule, and the free glucosemolecule is in the form of glucose-1-phosphate. In order to be used for metabolism, it must be converted to glucose-6-phosphateby the enzyme phosphoglucomutase. Glycogen phosphorylase can only act on linearchainsof glycogen (a 1-4 glycosidic linkage). Its work will immediately come to a halt four residues away from a 1-6 branch (which are exceedingly common in glycogen). In these situations, a debranching enzymeis necessary, which will straighten out the chain in that area. Additionally, an alpha 1-6 glucosidaseenzymeis required to break the remaining 1-6 residue that remains in the new linear chain. After all this is done, glycogen phosphorylase can continue