Abstract:

β-D-xylosidase of electrophoretic purity was obtained from leak after homogenization, buffer extraction,
ammonium sulfate fractionation precipitation, CM-Sepharose ion-exchange and Superdex-200 gel filtration chromatography.
Our results showed that the specific activity of β-D-xylosidase was 18.25 U/mg, purification fold was 12.59, and recovery
rate was 1.83% after purification. The relative molecular weight of β-D-xylosidase was approximately 123.02 kD, in which
the subunit molecular mass was 61.51 kD. Enzymatic properties of β-D-xylosidase showed that the optimal temperature and pH
were 65 ℃ and 4.0, respectively. It was relatively stable in the range of 25–55 ℃ and pH 3.0–5.0, respectively. Furthermore,
its Km was 0.28 mmol/L under the optimum conditions. The activity of β-D-xylosidase could be inhibited by methanol, ethanol,
isopropanol and sodium dodecyl sulfate and sodium salt (SDS) as well as Ag+, and activated by Mn2+ and Co2+.

Key words: leek, β-D-xylosidase, isolation and purification, enzymatic properties