Reaction: [(1→4)-α-D-glucosyl]n + phosphate = [(1→4)-α-D-glucosyl]n-1 + α-D-glucose 1-phosphate
For diagram of reaction click here.
Other name(s): muscle phosphorylase a and b; amylophosphorylase; polyphosphorylase; amylopectin phosphorylase; glucan phosphorylase; α-glucan phosphorylase; 1,4-α-glucan phosphorylase; glucosan phosphorylase; granulose phosphorylase; maltodextrin phosphorylase; muscle phosphorylase; myophosphorylase; potato phosphorylase; starch phosphorylase; 1,4-α-D-glucan:phosphate α-D-glucosyltransferase; phosphorylase (ambiguous)
Systematic name: (1→4)-α-D-glucan:phosphate α-D-glucosyltransferase
Comments: This entry covers several enzymes from different sources that act in vivo on different forms of (1→4)-α-D-glucans. Some of these enzymes catalyse the first step in the degradation of large branched glycan polymers - the phosphorolytic cleavage of α-1,4-glucosidic bonds from the non-reducing ends of linear poly(1→4)-α-D-glucosyl chains within the polymers. The enzyme stops when it reaches the fourth residue away from an α-1,6 branching point, leaving a highly branched core known as a limit dextrin. The 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.
Links to other databases: BRENDA, EXPASY, KEGG, PDB, Metacyc, CAS registry number: 9035-74-9
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