 Glycogen (with n glucose units) is converted into G-1-P(a PO4 group now attaches to C1 where O used to ) and glycogen (with n-1 glucose units) by enzyme glycogen phosphorylase.G-1-P is then converted into G-6-P by enzyme phosphoglucomutase.A water molecule hydrolyses G-6-P to glucose, the enzyme is glucose-6-phosphatase.