The glycogen phosphorase is limited to what it can actually do. The glycogen phosphorolase can only cleave alpha one four glycocitic bonds. It cannot cleave alpha one six glycocitic bonds. In fact, it stops cleaving the alpha one four glycocitic bonds for residues for glucose molecules away from the branching point, the nearest alpha one six glycocitic bond. So glycogen phosphoralase, the enzyme that catalyzes step one of glycogen breakdown, can only cleave alpha one four glycocitic bonds. It does not cleave alpha one six glycocitic bonds that are found in glycogen.