Pyridoxal phosphate is required for

Glycogen phosphorylase removes glucose as glucose-1-phosphate from glycogen (phosphorolysis). It contains pyridoxal. Formation of branches in glycogen phosphate (PLP) as a prosthetic group. The alpha-1,4 linkages in the glycogen are cleaved. removes glucose units one at a time. Enzyme sequentially hydrolyses alpha-1,4 glycosidic linkages, till it reaches a glucose residue, 3-4 glucose units away from a branch point. It cannot attack the 1,6 linkage at branch point.Ref: DM Vasudevan, 7th edition, page no: 124