摘要
A gene encoding for xylanase activity in the rumen hemicellulolytic bacterium Eubacterium ruminantium was cloned into pBR322 in Escherichia coli (E. coli ). The primary clone had a 5.7 kb insert produced by Eco RI partial digestion. Subcloning followed by sequencing allowed for the discovery that this enzyme has a glycosyl-hydrolase family 10 catalytic domain with a family 9 carbohydrate binding module at C-terminus and a region partially homologous to a family 22 carbohydrate binding module at N-terminus. Cloned xylanase is specifically active against xylan and oligoxyloside to produce xylobiose and xylotriose, showing optimal pH and temperature at 7.0 and 50°C, respectively. Molecular size of the xylanase (91 kDa) was confirmed by zymogram analysis of the E. coli clone, which agreed with the predicted size from the DNA sequence. Functions of the two modules at C- and N-termini were evaluated by using xylanase variants with and without the respective module and the C-terminal module was found to be functional in binding to acid-swollen cellulose and insoluble oat-spelt xylan, whereas the N-terminal module was inactive for binding them.
摘要译文
在瘤胃半纤维素分解菌真杆菌反刍木聚糖酶活性的基因编码被克隆到pBR322中大肠杆菌（大肠杆菌7 kb的插入了生态RI部分消化产生。具有一个家族9碳水化合物结合在C末端和一个区域的模块部分同源的家族22糖结合组件在N-末端糖基水解酶家族10的催化域。克隆的木聚糖酶是特别有效对抗木聚糖和oligoxyloside分别以产生木二糖和木三糖，表示最适pH和温度在7.0和50℃，。木聚糖酶（91 kDa）的分子大小是由大肠杆菌克隆，其与从DNA序列预测的大小一致的酶谱分析证实。通过使用木聚糖酶变体的使用和不使用的各个模块和C末端模块进行评价被认为是功能性的结合对酸溶胀纤维素和不溶性燕麦木聚糖，而N-末端模块是不活泼的结合它们。
Hidenori TAGUCHI[1]; Satoshi KOIKE[2,† Yasuo KOBAYASHI[2,*]; Isaac K. O. CANN[1,†] and Shuichi KARITA[1];. Partial characterization of structure and function of a xylanase gene from the rumen hemicellulolytic bacterium Eubacterium ruminantium[J]. Animal Science Journal, 2004,75(4): 325-332