Endohydrolysis of (1->4)-alpha-D-glucosidic linkages in polysaccharides containing three or more (1->4)-alpha-linked D-glucose units. Binds 2 calcium ions per subunit (PubMed:6609921, PubMed:9283074, PubMed:16880540). Calcium is inhibitory at high concentrations. Monomer. Used in the brewing industry to increase the fermentability of beer worts (including those made from unmalted cereals), in the starch industry to make high maltose and high DE syrups (starch saccharification), in the alcohol industry to reduce fermentation time, in the cereal food industry for flour supplementation and improvement of chilled and frozen dough, and in the forestry industry for low-temperature modification of starch. Sold under the name Fungamyl by Novozymes. Belongs to the glycosyl hydrolase 13 family.