黑曲霉发酵粉中一种β-葡萄糖苷酶的分离纯化与表征

Isolation purification and characterization of a β-glucosidase from Aspergillus niger

黑曲霉发酵酶粉通过硫酸铵分级沉淀、SephadexG-25脱盐、再通过两步DEAE-TOYOPEARL650M弱阴离子交换色谱,分离得到一个新的电泳纯的β-葡萄糖苷酶.该酶对水杨素的比活力为597.12IU mg,并对其专一,不能水解棉花和羧甲基纤维素钠;DTT处理前后分子量均为117.5kDa;最适pH和温度分别为4 5和70℃;在pH5.0、50℃下对水杨素钠的米氏常数Km为3.73mg mL,最大反应速率Vm为0.088mg葡萄糖 (mL·min).

A novel β-glucosidase was identified and isolated from a commercial Aspergillus niger cellulase preparation. It was prepared by precipitation of the water extract of the culture of Aspergillus niger with ammonium sulfate and desalted by Sephadex G-25, and further fractionated by two steps of DEAE-TOYOPEARL 650M chromatography. The specific activity of the β-glucosidase with salicin was 597.12 IU/mg. Its molecular weight was determined by SDS-PAGE to be 117.5?kDa under non-reduced and reduced conditions, the optimum pH is 4.5, and the optimum temperature is 70?℃, its K_m for sacilin at 50?℃ and pH 5.0 is 3.73?mg/mL.