Purification and Biochemical Characteristics of β-Glucosidase from Aspergillus Awamori K-1

ABSTRACT

An extracellular β-glucosidase (β-D-glucoside glucohydrolase, EC 3.2.1.21) produced by Aspergillus awamori K-1 was purified to electrophoretic homogeneity. The purified enzyme, which had a glycoprotein nature, was a monomer with a relative molecular mass of 116 kDa and pI= 5.8. The β-glucosidase was the most active against aryl-β-glucosides and cellobiose. In addition, the enzyme was able to catalyze the hydrolysis of β-1→2 and β-1 →6-linked diglucosides. The apparent K_m and V values for p-nitrophenyl-β-D-gluco-pyranoside were calculated to be 0.8 mM and 5.29 μmol.min⁻¹ respectively. Maximal β- glucosidase activity occurred at 60 °C and pH 5.0. This enzyme was competitively inhibited by β-D-glucose with K₁ value of 13.15 mM.