Has a high rate of hydrolysis for glycogen. Does not cleave pullulan. Hydrolysis of (1->6)-alpha-D-glucosidic branch linkages in glycogen, amylopectin and their beta-limit dextrins. Binds 1 Ca(2+) ion per subunit. Optimum pH is 6-7. Monomer. Belongs to the glycosyl hydrolase 13 family.