【摘要】 用分子筛和离子交换等色谱分离技术,由黑曲霉An-76的木聚糖酶系中分离纯化到一种β-木糖苷酶(βX)和三种内切-β-木聚糖酶组分(EX1,EX2,EX3)。这几种酶均达到凝胶电泳纯和聚焦电泳纯。用凝胶过滤方法测得βX的分子量为147000,用凝胶电泳法测得EX1、EX2和EX3的分子量分别为23000、22000和41000;βX、EX1、EX2和EX3的等电点分别为4.6、5.9、4.1和3.9。本文还研究了各种酶的最适反应温度和pH、酶的热稳定性和pH稳定性;研究了金属离子和巯基试剂对酶活力的影响、动力学参数、氨基酸组成、底物特异性和反应产物等。各酶组份不具有分解纤维素的交叉活力。巯基试剂能完全抑制βX活力,其活力丧失可被半胱氨酸恢复。更多还原

【Abstract】 The conponents of Aspergillus niger An76 xylanase system, a β-xylosidase (βX) and three endo-β-xylanases (X1, X2, X3), were purified by gel filtration and ion exchange. All of them showed homogeneity in the gel electrophoresis and polyacrylamide gel isoelectric focusing. The molecular weight of βX was 147000 as estimated by gel filtration, and X1, X2, X3 were 23000, 22000, 41000 respectively as estimated by SDS gel isoelectrophoresis. The isoelectric points of βX, X1, X2, and X3 were 4.6, 5.9, 4.1 and 3.9 as estimated by disc gel isoelectric focusing. Properties of the purified enzymes and the hydrolysis products of xylan were intensively inverstigated. All of the components of xylanase can not degrate CMC. pCMB can inhibit βX activity, but addition of an excess of cysteine resulted in complete recovery of the lost activity.更多还原