Comparative studies of three exo-beta-glycosidases of Aspergillus oryzae

Abstract

beta-Glucosidase [beta-D-glucoside glucohydrolase EC 3.2.1.21] and beta-galactosidase [beta-D-galactoside galactohydrolase, EC 3.2.1.23] of Takadiastase were purified by acetone fractionation, DEAE-cellulose, and hydroxylapatite chromatography. Purity was confirmed by disc electrophoresis, ultracentrifugation and measurement of other glycosidase activities which coexisted in Takadiastase. Molecular weight of the beta-glucosidase was 218,000 by sedimentation equilibrium and 110,000-116,000 by SDS-disc electrophoresis. Molecular weight of the beta-galactosidase was 112,000 by sedimentation and 56,000-59,000 by SDS-disc electrophoresis. These values showed that both enzymes consisted of two subunits. Taka-beta-N-acetylglucosaminidase also consisted of two subunits. Both enzymes were glycoproteins containing glucosamine and neutral sugar. Stability, pH optima, isoelectric points, and some specificities were observed.