黑曲霉β-葡萄糖苷酶的酶学特性研究

Enzymologic Properties of β-Glucosidase from Aspergillus niger

研究黑曲霉β-葡萄糖苷酶的酶学特性,采用酶学研究方法,通过硫酸铵沉淀、Sephadex G-25脱盐和Sephadex G-100纯化了β-葡萄糖苷酶,并进行了黑曲霉β-葡萄糖苷酶的最适反应温度、最适pH、热稳定性、pH稳定性及米氏常数等特性研究,采用SDS-PAGE凝胶电泳测定了分子量。研究表明,β-葡萄糖苷酶的最适反应温度为70℃、最适反应pH为4.5;在40、50和60℃下较稳定,80℃以上稳定性差;β-葡萄糖苷酶在pH为3、7、8、9的缓冲液中的稳定性很差,在pH为4、5、6的缓冲液中稳定性较好,其中在pH为5时,稳定性最好;酶的Km=41.67 mmol/L,Vmax=23.81 U/L;其分子量为65.2 ku。β-葡萄糖苷酶在饲料工业具有良好的应用前景。

This study was to find the enzymologic properties of β-glucosidase from Aspergillus niger. The enzyme was precipitated with ammonium sulfate, desalinated with Sephadex G-25, and purified with Sephadex G-100. The properties of β-glucosidase including its molecular weight adopted by SDS-PAGE gel electrophoresis, the optimal reaction temperature, the optimal pH, thermal stability, pH stability and Michaelis constant were studied. The results indicated that the optimal reaction temperature and pH were 70 ℃and 4.5 respectively. The enzyme was stable under 40 ℃, 50 ℃ and 60 ℃,but had poor stability above 80 ℃. It was poorly stable in the buffer when pH were at 3, 7, 8, 9, it had fairly good stability in the buffer of pH at were 4, 5, 6, and the best when pH at 5. The enzyme molecular weight was 65.2 ku and its Km=41.67 mmol/L, Vmax=23.81 U/L. β-Glucosidase enzymes has a good application prospect in the forage industry.