黑曲霉D2-26高温乳糖酶的酶学性质研究

Studies on the Characterization of a Thermostable Lactase from Aspergillus niger D2-26

摘要:

为研究黑曲霉来源的高温乳糖酶的酶学性质, 对黑曲霉D2-26发酵液进行分离纯化使酶蛋白达到电泳纯, 并对其进行酶学性质研究。结果表明：乳糖酶的最适温度70℃, 在30℃~60℃有较高的耐受性; 最适pH为2.5, pH稳定范围在2.0~9.0; Mn2+对乳糖酶活性有显著的激活作用, Hg2+、Pb2+对酶活有较强的抑制作用; SDS严重抑制了酶活性; 以ONPG为底物采用双倒数做图法测得Vmax为97 nmol/min, Km为8.77 mmol/L; 单亚基蛋白的分子量为116.978 kD ; 糖基化程度为11.3%。

Abstract:

The fermenting liquor from Aspergillus niger D2-26 was purified to obtain a single protein component, and then the characterization of thermostable lactase was studied. The enzyme had an optimum temperature of activity at 70℃ and an optimum pH of 2.5, and had good temperature tolerance from 30℃ to 60℃ and the pH stability at 2.0~9.0. Mn2+ had a significant activation on lactase activity, whereas the enzyme activity was inhibited strongly by Hg2+、Pb2+ and SDS; the Vmax, Km, molecular mass of single subunit protein and glycosylation of Lactase was 0.097 nmol/min, 8.77 mmol/L, 116.978 kD and 11.3%, respectively.