The formation and properties of subtilisn-modified glucoamylase.

The glucoamylase I which was purified from a culture of Aspergillus awamori var. kawachi as an enzyme having an ability to digest raw starch, was converted to a modified enzyme with decrease in molecular weight and carbohydrate content by incubation with subtilisin in 0.01M phosphate buffer, pH 6.8, at 30°C. The modified glucoamylase, isolated by the DEAE-Sephadex A-50 column chromatography, showed a 77% specific activity, and the same manner of the hydrolysis curve for gelatinized potato starch and maltose as the native enzyme, but showed no digestibility for raw starches nor adsorbability onto raw corn-starch, and a lower hydrolysis limit of 80 per cent for glycogen. Stabilities also decreased at pH 9 and at 65°C, respectively. Protease was proved to change the properties of glucoamylase.