香葱中蒜氨酸酶的分离纯化及其酶学性质

对香葱中蒜氨酸酶进行分离纯化并研究其酶学性质。通过均浆、离心、硫酸铵分级沉淀、透析、DEAE-52离子交换层析和Sephadex G200凝胶过滤层析技术分离纯化得到纯度较高的蒜氨酸酶，并利用SDS-PAGE电泳对其纯度进行鉴定。结果表明，经分离纯化可得纯化倍数为19.6倍的蒜氨酸酶，酶比活力为11.44U/mg，酶活回收率为32.1%，达到电泳纯，其亚基的分子质量约为54.5ku。纯酶的最适反应温度为45℃，最适pH7.0，以S-甲基-L-半胱氨酸亚砜为底物，蒜氨酸酶的Km为45.31mmol/L，Vmax为40.32μmol/(mg·min)。

Purification and Enzymatic Properties of Alliinase from Chive (Allium schoenoprasum L.)

Alliinase(EC 4.4.1.4) was isolated from stalks of chive(Allium schoenoprasum L.),and its enzymatic properties were investigated.The enzyme was purified to apparent homogeneity using various steps,including homogenizing,centrifuging,ammonium sulfate precipitating,dialyzing,DEAE-52 ion exchange chromatography and Sephadex G200 gel filtration chromatography.SDS-PAGE electrophoresis was used to analyze the purity of alliinase.The results showed that the purity of alliinase was high and reached up to electrophoresis purity.The molecular weight of the subunit was 54.5 ku.The specific activity of the pure alliinase was 11.44 U/mg,and the activity recovery rate was 32.1%,which exhibited 19.6-fold enhancement in purity.The optimal reaction temperature and pH of purified alliinase were 45 ℃ and 7.0,respectively.Kinetic studies showed that Kmand Vmaxof alliinase using S-methyl-L-cysteine sulfoxide as the substrate were 45.31 mmol/L and 40.32 μmol/(mg.min),respectively.