Study on purification and some properties of intracellular β-glucosidase from Aspergillus niger

A kind of intracellular β-glucosidases is purified to homogeneous β-glucosidase from an Aspergillus niger mycelia by the acetone precipitation,DEAE-Sepharose ion exchange chromatography,Sephacryl S-200 HR gel layer chromatography and Phenyl Sepharose CL-4B hydrophobic interaction chromatography.The final purification factor of 7.2 and yield of 19.3% are obtained.The enzyme single subunit molecular weight is about 122.7 kmol/g which is identified by SDS-PAGE.The Ki,Km and Vmax values of the enzyme are 0.19 mmol/L,2.99 mM/L and 1.49 μmol/min,respectively,using cellobiose as a substrate.The optimum reaction temperature and pH for β-glucosidase are 60℃ and 5.0,respectively.The enzyme is stable in the pH value range of 3.0-6.0 and at the temperature up to 60℃.Organic solvent such as methanol,ethanol,1-butanol,acetone and acetoacetate have great effects on the activity of β-glucosidase.