山羊瘤胃微生物宏基因组来源的低温木聚糖酶XynGR40冷适应机制的研究

项目名称： 山羊瘤胃微生物宏基因组来源的低温木聚糖酶XynGR40冷适应机制的研究

项目编号： No.31301406

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 农业科学

项目作者： 王国增

作者单位： 福州大学

项目金额： 23万元

中文摘要： 低温木聚糖酶在低温下比中高温木聚糖酶催化效率更高以及对热很不稳定，这种特性使其在酶的结构与功能以及在面包烘焙和果汁澄清等食品工业应用中具有重要的研究价值。然而，相对于高温和碱性木聚糖酶，现在对于低温木聚糖酶以及其冷适应机制方面的研究还很滞后。我们从山羊瘤胃微生物宏基因组中获得了一个低温木聚糖酶XynGR40，其在低温下要比已报道的低温酶具有更高的催化效率，而且该酶在结构上与已报道的低温酶有很大的差异。本项目以XynGR40为核心材料，基于已有的低温木聚糖酶的序列比对、同源建模以及结构比对，通过非催化结构域的删除和重构、蛋白表面多余的Loop结构的删除与替换以及参与形成盐桥的关键氨基酸的突变来研究XynGR40可能的冷适应机制。本研究旨在通过对可能影响低温木聚糖酶XynGR40低温性能的关键因素的研究，初步探究低温木聚糖酶的冷适应的分子机理，并为进一步的木聚糖酶冷适性改造提供理论依据。

中文关键词： 木聚糖酶；低温酶；冷适应；盐桥；定点突变

英文摘要： Cold active xylanase has great application in baking,fruit juice and other food industry because of its high catalytic effience at low temperature and its thermoliablity than mesophilic and thermophilic xylanase. However, the study of the cold active xylanase and their srtucture and function are far less than those of thermophilic,alkaliphilic and acidophilic xylanase. We obtained a cold active xylanase XynGR40 from the metagenome of rumen microorganisms, which has higher catalytic effeciece at low temperature than other cold active xylanase have been reported. Moreover,XynGR40 has great differences in the structure compared with other cold active xylanase. Based on the sequence alignment ,homology modeling and structre comparison of known cold active xylanase,through the deletion of non-catalytic domain, the surface Loop deletion and reorganisation,and the site-dereted mutation of the amino acid which involed in the formation of salt brige to study the potential cold-adaption mechanisms of the XynGR40. The aime of this study is to get an insight into the molecular mechanisms of the cold active xylanase for cold adaption based on the study of possible key factors that influence the cold active characterization of XynGR40, which will pave the way for the engginering modification of other xylanase to get a cold ac

英文关键词： Xylanase；Cold-active enzyme；Cold-adaption；Salt-bridge；Site-directed mutagenesis