Cloning, purification and characterization of an alkali-stable endoxylanase from thermophilic Geobacillus sp 71
Cloning, purification and characterization of an alkali-stable endoxylanase from thermophilic Geobacillus sp 71
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DOI：
10.1007/s11274-011-1000-3
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发表时间：
2012-05-01
影响因子：
4.1
通讯作者：
Belduz, Ali Osman
中科院分区：
文献类型：
--
作者：
Canakci, Sabriye;Cevher, Zeliha;Belduz, Ali Osman
从Geobacillussp.71中分离、克隆并测序了编码木聚糖酶的基因。土芽孢杆菌7.1木聚糖酶XyzGeo 71在E.大肠杆菌产酶的最适温度为75 A ℃，酶的分子量为47 kDa。该酶的最适pH为8.0，但它在很宽的pH范围内都有活性。该蛋白与来自嗜热土芽孢杆菌NG 80 -2的木聚糖酶具有最高的序列同源性（93%）。XyzGeo 71含有属于糖苷水解酶家族10（GH 10）的催化结构域。XyzGeo 71具有良好的pH稳定性，在pH 7.0至11.0的缓冲液中处理6 h后保持稳定。Al ~（3+）和Cu ~（2+）对该酶的活性有部分抑制作用，Hg ~（2+）对该酶的活性有强烈的抑制作用。该酶遵循Michaelis-Menten动力学，K-m和V-max值分别为0.425 mg木聚糖/ml和500 μ mol/min.mg。该酶无纤维素酶活性，以内切方式降解木聚糖。该酶对燕麦木聚糖的作用是产生木二糖和木四糖。
The gene encoding a xylanase from Geobacillus sp. 71 was isolated, cloned, and sequenced. Purification of the Geobacillus sp 7.1 xylanase, XyzGeo71, following overexpression in E. coli produced an enzyme of 47 kDa with an optimum temperature of 75A degrees C. The optimum pH of the enzyme is 8.0, but it is active over a broad pH range. This protein showed the highest sequence identity (93%) with the xylanase from Geobacillus thermodenitrificans NG80-2. XyzGeo71 contains a catalytic domain that belongs to the glycoside hydrolase family 10 (GH10). XyzGeo71 exhibited good pH stability, remaining stable after treatment with buffers ranging from pH 7.0 to 11.0 for 6 h. Its activity was partially inhibited by Al3+ and Cu2+ but strongly inhibited by Hg2+. The enzyme follows Michaelis-Menten kinetics, with K-m and V-max values of 0.425 mg xylan/ml and 500 mu mol/min.mg, respectively. The enzyme was free from cellulase activity and degraded xylan in an endo fashion. The action of the enzyme on oat spelt xylan produced xylobiose and xylotetrose.