Characterization of β-Galactosidase from a Special Strain of Aspergillus oryzae1

Abstract

β-Galactosidase (EC 3.2.1.23) was isolated from a partially purified preparation obtained from cultured cells of a special strain of Aspergillus oryzae, RT 102 (FERM-P1680). The enzyme preparation gave a single protein band on polyacrylamide gel electrophoresis and was free from α-galactosidase, α- and β-mannosidase, α- and β-N-acetylhexosaminidase, and protease activities. The β-galactosidase was capable of acting on aryl β-galactosides, lactose, and lactosides. It also hydrolyzed β-galactosl linkages in urinary glycoasparagines and asialo α₁-acid glycoprotein. The enzyme was rather stable in aqueous solution, retaining full activity at 4° for at least several months. At pH 4.5, the optimum pH for the enzyme activity, and 37°, full activity was maintained for several days.