Endohydrolysis of (1->4)-alpha-D-glucosidic linkages in polysaccharides containing three or more (1->4)-alpha-linked D-glucose units. Because of the indeterminate molecular weight of starch, an approximate KM value of 0.975 mg/ml was determined. Optimum pH is 5.0. Optimum temperature is 60 degrees Celsius. On the 2D-gel the determined pI of this protein is: 5.0, its MW is: 155 kDa. Belongs to the glycosyl hydrolase 13 family.