Endohydrolysis of (1->4)-alpha-D-glucosidic linkages in polysaccharides containing three or more (1->4)-alpha-linked D-glucose units. Binds 3 Ca(2+) ions per subunit. Binds 1 sodium ion per subunit. Active up to pH 11. Active up to 100 degrees Celsius. Monomer. Used in the food industry for high temperature liquefaction of starch-containing mashes and in the detergent industry to remove starch. Sold under the name Termamyl by Novozymes. Belongs to the glycosyl hydrolase 13 family.