College of Animal Sciences, Zhejiang University, Hangzhou, China.
Anim Biotechnol. 2012;23(3):156-73. doi: 10.1080/10495398.2012.662925.
The glycosyl hydrolase family 11, which is responsible for carbohydrate metabolism, was identified in the open reading frame (ORF) 6 of a xylanase positive clone from a fosmid library of rumen microbiota of Hu sheep. A BLASTP search of GenBank revealed that ORF6 encoded a 355-amino acid putative endoxylanase, having 61% similarity (e(-73)) to endo-1,4-β-xylanase of Fibrobacter succinogenes S85 (YP_003250510.1). Predicted with the SWISS-MODEL, there were two separate β-sandwich clusters linked with a high serine containing linker in ORF6. The N-terminal β-sandwich is a novel endoxylanase of the glycosyl hydrolase family 11 with a specific activity of 1150.00 U/mg. The optimal pH and temperature for this enzyme were shown to be pH 5.0 and 50°C, respectively. The C-terminal helped increase the stability of the xylanase but decreased the activity to some degree. The C-terminal β-sandwich could bind avicel, but no conserved domain could be found. It may be a novel carbohydrate-binding module.
糖苷水解酶家族 11 负责碳水化合物代谢，在从绵羊瘤胃微生物宏基因组的纤维二糖酶阳性克隆的开放阅读框（ORF）6 中被鉴定出来。GenBank 的 BLASTP 搜索显示，ORF6 编码一个 355 个氨基酸的假定内切木聚糖酶，与纤维二糖水解酶 Fibrobacter succinogenes S85 的内切-1,4-β-木聚糖酶（YP_003250510.1）有 61%的相似性（e(-73)）。SWISS-MODEL 预测，ORF6 中有两个独立的β-三明治结构域，通过一个富含丝氨酸的连接子连接。N 端的β-三明治是一种新型的内切木聚糖酶，属于糖苷水解酶家族 11，比活为 1150.00 U/mg。该酶的最适 pH 和温度分别为 pH 5.0 和 50°C。C 端有助于提高木聚糖酶的稳定性，但在一定程度上降低了活性。C 端的β-三明治可以结合微晶纤维素，但没有发现保守结构域。它可能是一种新型的碳水化合物结合模块。
