Alpha-amylase active towards amylose, starch, amylopectin and maltodextrins. Has lower activity towards glycogen, and is not active towards alpha/beta-cyclodextrin. Endohydrolysis of (1->4)-alpha-D-glucosidic linkages in polysaccharides containing three or more (1->4)-alpha-linked D-glucose units. Strongly inhibited by Hg (2+). Inhibited by Zn (2+). Activated by Fe (2+), Mg (2+) and Ba (2+). Optimum pH is 4.5. Stable from pH 4.0-7.5, activity decreases drastically above pH 7.5 and below pH 3.5. Optimum temperature is 70 degrees Celsius. Active from 30 to 75 degrees Celsius, inactivated following 150 minutes incubation at 85 degrees Celsius.