黑曲霉木聚糖酶的纯化与性质

由凝胶电泳酶谱检测到黑曲霉１４９发酵液中存在两型木聚糖酶，依次为Ｘ－Ⅰ和Ｘ－Ⅱ．通过硫酸铵分级沉淀及ＤＥＡＥ－ＳｅｐｈａｄｅｘＡ５０柱层析分别将Ｘ－Ⅰ、Ｘ－Ⅱ纯化到凝胶电泳均一。由ＳＤＳ一凝胶电泳和浓度梯度凝胶电泳测得Ｘ－Ⅰ和Ｘ－Ⅱ的分子量分别为３７ｋＤａ，７６ｋＤａ，２４ｋＤａ和２３ｋＤａ，Ｘ－Ⅰ具有亚基。二者的含糖量分别为２７６％和７．３％。Ｘ－Ⅰ和Ｘ－Ⅱ最适反应温度分别为５０℃和５５℃，ｐＨ为４６和５．２。在ｐＨ４．６～９．２和ｐＨ４．０～１０．０之间Ｘ－Ⅰ、Ｘ－Ⅱ活力稳定。５０℃保温２４ｈ，Ｘ－Ⅰ活力仍为１００％，而Ｘ－Ⅱ的活力已降为２．８％。ＨｇＣｌ２和ＡｇＮＯ３显著抑制Ｘ－Ⅰ、Ｘ－Ⅱ的活力。Ｘ－Ⅰ与Ｘ－Ⅱ水解不同来源的木聚糖，其产物有所不同。

PURIFICATION AND SOME PROPERTIES OF XYLANASEFROM ASPERGILLUS NIGER

Zymograms of the cultrual supernatant of Aspergillus niger 149 showed xylanase's two bandstentatively named X-I and X-II. X-I and X-II were purified to PAGE homogenity by (NH4)2So4 fractionationand DEAE-Sephadex A50 column chlomatography. The molecular mass of X-I and X-II eshmated by SDS-PAGEand concentrahon gradient PAGE were 37kDa,76kDa,24kDa, and 23kDa. respechvely. X-I and X-II contained27.6% and 7.3% carbohydrate residues, respechvely. The optimal reachon conditions for X-I and X-II were at50℃ pH4.6 and 55℃ PHS.2. X-I and X-II retained 100% and 2.8% respechvely, of the original activity afterheating at 50℃ for 24h. The achvihes of X-I and X-II were considerably inhibited by HgCl2 and AgNO3. Thehydrolysis products from different xylan with X-I and X-II were different.