Purification and Enzyme Properties of a β-glucosidase

The factors affecting Aspergillus niger No.5.1 for β-glucosidase purification and enzyme properties have been investigated.β-glucosidase was purified to electrophoretic homogeneity by using ammonium sulfate precipitation,DEAE-chitopearl and Sephadex G-100 chromatography.Its molecular weight was estimated to be about 67.5 kD by SDS-PAGE.The enzyme showed optimal activity at pH 6.0 and 60 ℃.It was stable in pH 3.0～9.0 and under 80 ℃.The β-glucosidase activity was significantly inhibited by Ag+ and Fe2+ and stimulated by K+,Na+,Mg2+,Zn2+,respectively.The enzyme hydrolyzed cellobiose and salicin more efficiently than other substrates.Its michaelis constant for hydrolysis of salicin was 3.09 mmol/L.