STUDIES ON THE GENUS MONASCUS II. SUBSTRATE SPECIFICITY OF TWO GLUCOAMYLASES OBTAINED FROM MONASCUS KAOLIANG F-1

Substrate specificity of the two forms of glucoamylase (GA-I and GA-II) obtained from the culture of Monascus kaoliang F-1 on wheat bran was examined. Both glucoamylases hydrolyzed amylopectin, amylose, glycogen, soluble starch, maltotriose, and maltose but not isomaltose. The Km values of GA-I for maltose, amylose, amylopectin, and glycogen were 1.0×10-1%, 3.6×10-1%, 6.1×10-1%, and 1.6%, respectively, and the values of GA-II for these substrates were 1.0×10-1%, 1.9×10-2%, 3.0×10-3%, and 8.5×10-3%, respectively. The ratio of Vmax values of GA-I for various substrates with maltose as a standard was not so different from that of GA-II. The limits of hydrolysis of soluble starch, amylopectin, amylose, and glycogen by each glucoamylase were 70%, 90%, 100%, and 100%, respectively. GA-II hydrolyzed raw starch from wheat, corn, sweet potato, and potato more rapidly than GA-I. Both enzymes hydrolyzed soluble starch with the inversion of configuration, producing the β-anomer of glucose.