A key amino acid residue for the pocessive activity of GH74 xyloglucanaze
A key amino acid residue for the pocessive activity of GH74 xyloglucanaze
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GH74 木葡聚糖酶必需活性的关键氨基酸残基
DOI：
10.1016/j.febslet.2014.03.023
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发表时间：
2014
期刊：
影响因子：
3.5
通讯作者：
Katsuro Yaoi
中科院分区：
文献类型：
--
作者：
Tomohiko Matsuzawa;Yuji Saito;Katsuro Yaoi
与内解离木葡聚糖酶不同，类芽孢杆菌 XEG74 是一种内加工木葡聚糖酶，如三维同源模型所示，在负亚位点（W61 和 W64）和正亚位点（W318 和 W319）中包含四个独特的色氨酸残基。用丙氨酸突变选择性替换阳性亚位点残基降低了持续活性的程度并导致更多的内解离活性。结果表明，在正亚位点中发现的 W318 和 W319 对于持续降解至关重要，并负责通过堆积效应维持与木葡聚糖多糖的结合相互作用。
Unlike endo-dissociative-xyloglucanases,PaenibacillusXEG74 is an endo-processive xyloglucanase that contains four unique tryptophan residues in the negative subsites (W61 and W64) and the positive subsites (W318 and W319), as indicated by three-dimensional homology modelling. Selective replacement of the positive subsite residues with alanine mutations reduced the degree of processive activity and resulted in the more endo-dissociative-activity. The results showed that W318 and W319, which are found in the positive subsites, are essential for processive degradation and are responsible for maintaining binding interactions with xyloglucan polysaccharide through a stacking effect.