Endohydrolysis of (1->4)-alpha-D-glucosidic linkages in polysaccharides containing three or more (1->4)-alpha-linked D-glucose units. Binds 1 Ca(2+) ion per subunit. Monomer. The profile of production of reducing sugar from soluble starch by the action of AmyC was intermediate between those of AmyA and AmyB. Belongs to the glycosyl hydrolase 13 family.