-!- This entry covers several enzymes from different sources that act in vivo on different forms of (1->4)-alpha-D-glucans. -!- Some of these enzymes catalyze the first step in the degradation of large branched glycan polymers - the phosphorolytic cleavage of alpha-1,4-glucosidic bonds from the non-reducing ends of linear poly(1->4)-alpha-D-glucosyl chains within the polymers. -!- The enzyme stops when it reaches the fourth residue away from an alpha-1,6 branching point, leaving a highly branched core known as a limit dextrin. -!- The description (accepted name) of the enzyme should be modified for each specific instance by substituting 'glycogen' with the name of the natural substrate, e.g. maltodextrin phosphorylase, starch phosphorylase, etc.