Exo-inulinase of Aspergillus niger N402:: A hydrolytic enzyme with significant transfructosylating activity
Exo-inulinase of Aspergillus niger N402:: A hydrolytic enzyme with significant transfructosylating activity
复制标题
DOI：
10.1080/10242420701806686
复制
发表时间：
2008-01-01
影响因子：
1.8
通讯作者：
Dijkhuizen, L.
中科院分区：
文献类型：
--
作者：
Goosen, C.;Van der Maarel, M. J. E. C.;Dijkhuizen, L.
纯化的黑曲霉N402 （AngInuE；在大肠杆菌中异种表达）的菊粉酶的蔗糖：菊粉（S/I）水解比为2.3，为典型的菊粉酶的特征。随着蔗糖浓度的增加，该酶也具有显著的转果糖基化活性，产生各种低聚糖。AngInuE蛋白分子量为57 kDa，接近成熟蛋白的计算值。因此，AngInuE作为一种单体、非糖基化蛋白具有活性。其他曲霉的（几乎）相同的（但单体或二聚体和糖基化的）外链菊粉酶的水解/转果糖基化活性比率的矛盾数据已经发表。我们的数据清楚地表明，从大肠杆菌中产生和纯化的AngInuE酶是一种广泛特异性的外链菊粉酶，也具有显著的蔗糖转果糖基化活性。对位点导向突变体AngInuE的分析表明，糖苷水解酶家族32保守结构域G对催化效率很重要，在蔗糖和果聚糖的水解中都有明确的作用。
The purified exo-inulinase enzyme of Aspergillus niger N402 (AngInuE; heterologously expressed in Escherichia coli) displayed a sucrose:inulin (S/I) hydrolysis ratio of 2.3, characteristic for a typical exo-inulinase. The enzyme also had significant transfructosylating activity with increasing sucrose concentrations, producing various oligosaccharides. The AngInuE protein molecular mass was 57 kDa, close to the calculated value for the mature protein. AngInuE thus was active as a monomeric, non-glycosylated protein. Contradictory data on hydrolysis/transfructosylation activity ratios have been published for the (almost) identical (but monomeric or dimeric and glycosylated) exo-inulinases of other aspergilli. Our data clearly show that the AngInuE enzyme, produced in and purified from E. coli, is a broad specificity exo-inulinase that also has significant transfructosylating activity with sucrose. Analysis of site-directed mutants of AngInuE showed that the glycoside hydrolase family 32 conserved domain G is important for catalytic efficiency, with a clear role in hydrolysis of both sucrose and fructans.