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. Binds 1 Cl(-) ion per subunit. Monomer. Expressed in liver and saliva. Hepatic and salivary alpha-amylases are encoded by the same gene; however, their mRNAs have different 5'-UTR sequences. Belongs to the glycosyl hydrolase 13 family.