Acid-stable α-Amylase of Black Aspergilli

Part III. Separation of Acid-stable α-Amylase and Acid-unstable α-Amylase from the Same Mold Amylase Preparation

Abstract

From the amylase preparation of black Aspergillus acid-stable α-amylase and acid-unstable α-amylase were separated by gel filtration on sephadex G-100 column. From the acid-unstable α-amylase fraction this enzyme was purified by fractionations with rivanol and acetone, and finally obtained as a homogeneous protein after gel filtration with sephadex G-50. Comparison of some general properties between the two α-amylases was carried out. Catalytic action was quite similar with both enzymes, but dextrinizing unit per mg enzyme protein of the acid-unstable α-amylase was about 5.6 times as large as that of the acid-stable a-amylase. The acid-unstable α-amylase was less heat-stable than the acid-stable a-amylase. Acid stability and pH-activity curve were compared with both a-amylases. High stability of the acid-stable α-amylase in acidic condition was observed, but, in alkaline range, it was more sensitive than the acid-unstable α-amylase.