Phosphorylase is an important allosteric enzyme in carbohydrate metabolism. Enzymes from different sources differ in their regulatory mechanisms and in their natural substrates. However, all known phosphorylases share catalytic and structural properties (By similarity). May be not required for the degradation of starch, but the phosphorolysis of starch may play an important role in water stress tolerance.
Also known as Alpha-glucan phosphorylase 1 (AtPHS1) (Alpha-glucan phosphorylase, L isozyme) (Starch phosphorylase L). Encodes a plastidic alpha-glucan phosphorylase. In vitro, the enzyme has a preference for maltooligosaccharides, such as maltoheptaose.
Also known as Alpha-glucan phosphorylase 2, cytosolic (AtPHS2) (Alpha-glucan phosphorylase, H isozyme) (Starch phosphorylase H). Encodes a cytosolic alpha-glucan phosphorylase. In vitro, the enzyme has a preference for branched polysaccharides, such as glycogen.