PURIFICATION AND PROPERTIES OFβ-GLUCOSIDASE FROM ASPERGILLUS ACULEATUS SM-L22

A β-glucosidase component from Aspergillus aculeatus SM-L22 was seperated and purified by exclution chromatography and ion-exchange chromatography. By SDS-PAGE and IEF, the molecular weight of the enzyme was determined as 57.9 kD and the isoelectric point was pH 4.5. The enzyme showed optimal activity at pH 5.0 and 60℃. It was stable in pH 3.0~10.0 and under 40℃. The result showed that the enzyme can only act low molecular β-glucosidic compounds such as cellobiose, Salicin and lactose. The Km, Vm and Kcat was 17.13 10-3 mol/L, 3.456 10-4 mol/L/min and 3.75 S-1 when cellobiose was as substrate, and the parameters were 11.93 10-3 mol/L, 7.139 10-4 mol/L/min and 7.73 S-1 respectively, when D-(-)-Salicin as substrate. Fe2+, Mn2+ can activate the enzymatic activity and EDTA inhibite it.