Identification and glucan-binding properties of a new carbohydrate-binding module family
Identification and glucan-binding properties of a new carbohydrate-binding module family
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DOI：
10.1042/0264-6021:3610035
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发表时间：
2002-01-01
影响因子：
4.1
通讯作者：
Kilburn, DG
中科院分区：
文献类型：
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作者：
Boraston, AB;Ghaffari, M;Kilburn, DG
嗜碱芽孢杆菌（Bacillus sp. 1139） Cel5A的c端191残基模块包含一个碳水化合物结合模块（CBM），该模块属于一个先前未确定的家族，我们将其归类为CBM家族28。这个例子被称为CBM28，它与纤维素寡糖特异性结合，并混合（1,3）(1,4)-葡聚糖（大麦β -葡聚糖），其结合常数约为（1-4）× 10(4) M-1。它与大麦β -葡聚糖的结合对pH值在7.0 ~ 10.9之间不敏感，这与它的亲碱来源保持一致。CBM28与纤维素的结合具有显著的非晶含量，其结合常数与与可溶性葡聚糖的结合常数相似。CBM17 （CBM家族17）和CBM28模块自然串联出现。来自Cel5A的CBM17/CBM28序列与大麦β -葡聚糖结合，具有明显的协同作用。CBM28与纤维素寡糖的结合是由焓驱动的，并以容纳纤维素己糖分子的三个假定结合亚位的不同热力学贡献为标志。
The C-terminal 191-residue module of Cel5A from the alkalophilic Bacillus sp. 1139 comprises a carbohydrate-binding module (CBM) belonging to a previously unidentified family that we have classified as CBM family 28. This example, called CBM28, bound specifically to cello-oligosaccharides and mixed (1,3)(1,4)-glucans (barley beta-glucan) with association constants of approximately (1-4) x 10(4) M-1. Its binding to barley beta-glucan was remarkably insensitive to pH between 7.0 and 10.9, in keeping with its alkalophilic source. CBM28 bound to cellulose having a significant non-crystalline content with an association constant similar to that for its binding to soluble glucans. CBM17 (CBM family 17) and CBM28 modules naturally occur as tandems. The CBM17/CBM28 tandem from Cel5A bound with apparent co-operativity to barley beta-glucan. The association of CBM28 with cello-oligosaccharides was driven enthalpically and marked by the different thermodynamic contribution of three putative binding subsites that accommodate a cellohexaose molecule.