State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology,130 Meilong Road, Shanghai 200237, China.
Bioresour Technol. 2013 Aug;142:338-44. doi: 10.1016/j.biortech.2013.05.037. Epub 2013 May 18.
A novel β-1,4-endoglucanase gene was cloned from Dictyoglomus thermophilum, designated as Cel5H for being a member of glycoside hydrolase family 5. The purified recombinant endoglucanase showed high hydrolytic activities on carboxylmethyl cellulose with a broad optimal temperature of 50-85°C and an optimal pH of 5.0. Furthermore, this enzyme was highly thermostable with a half-life of 336 h at 70°C and retained more than 80% of the initial activity after 135 days incubation at 50°C. To enhance the performance of the thermophilic endoglucanase, chimeric enzymes containing Cel5H and syncretic cellulose binding module (CBM) were constructed. The results showed that all the CBMs were effective. In addition, Cel5H was highly tolerant against high salt concentration and distinguished from salt-tolerant bacteria since it was independent of high salt concentration. Three-dimensional structure of Cel5H was developed by homology modeling methods and surface electrostatic analysis was performed.
从嗜热纤维单胞菌中克隆了一种新型的β-1,4-内切葡聚糖酶基因，命名为 Cel5H，因其属于糖苷水解酶家族 5 的成员。纯化的重组内切葡聚糖酶对羧甲基纤维素具有很高的水解活性，最适温度范围很宽，为 50-85°C，最适 pH 值为 5.0。此外，该酶具有很高的热稳定性，在 70°C 下半衰期为 336 h，在 50°C 孵育 135 天后仍保留初始活性的 80%以上。为了提高嗜热内切葡聚糖酶的性能，构建了含有 Cel5H 和协同纤维素结合模块（CBM）的嵌合酶。结果表明，所有的 CBM 都是有效的。此外，Cel5H 对高盐浓度有很强的耐受性，与耐盐细菌不同，它不依赖于高盐浓度。通过同源建模方法构建了 Cel5H 的三维结构，并进行了表面静电分析。
