Phosphorylase is an important allosteric enzyme in carbohydrate metabolism. Catalyzes the phospholytic cleavage of maltodextrins with a minimal chain length of five glucose residues to yield glucose-1-phosphate. Low activity with tetraose and no activity with triose and maltose. Long maltodextrins (8 to 15 glucose units), amylose and starch are not as good substrates as maltoheptaose. [(1->4)-alpha-D-glucosyl](n) + phosphate = [(1->4)-alpha-D-glucosyl](n-1) + alpha-D-glucose 1-phosphate Optimum temperature is 98 degrees Celsius. Trimer (at 25 degrees Celsius). Expressed constitutively. Belongs to the glycogen phosphorylase family.