Patterns of action of glucoamylase isozymes from Aspergillus species on glycogen

Glucoamylase isozymes from black Aspergillus species have been freed of all traces of alpha-amylase by chromatography on Bio-Gel P-100, as evidenced by limited hydrolysis of oxidized amylose. Glucoamylase I retains its ability to hydrolyze rabbit-liver glycogen rapidly. By contrast, glucoamylase II hydrolyzes glycogen slowly, and addition of alpha-amylase to glucoamylase II does not enhance its activity toward glycogen. These results indicate that alpha-amylase is not involved in hydrolysis of glycogen by glucoamylase.