期刊
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
卷 86, 期 -, 页码 269-276出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.ijbiomac.2016.01.068
关键词
EngZ; Thermostability; Cellulolytic efficiency; Family 9 endoglucanase; Site-directed mutagenesis
资金
- Industrial Strategic Technology Development Program - Ministry of Trade, Industry & Energy (MI, Korea) [10051513]
- R&D Convergence Program of NST (National Research Council of Science & Technology) of the Republic of Korea/KIST (Korea Institute of Science and Technology) [2E25402]
This is the first study for therrmostable mutants of mesophilic endoglucanase EngZ from Clostridium cellulovorans using by site-directed mutagenesis. K94R, S365P and their double mutant K94R/S365P had a wide range of active temperatures (30-60 degrees C). In addition, the optimal temperature of K94R/S365P was increased by 7.5 degrees C. K94R/S365P retained 78.3% relative activity at 70 degrees C, while the wild type retained only 5.8%. Especially, K94R/S365P remained 45.1-fold higher activity than the wild type at 70 degrees C. In addition, K94R/S365P was 3.1-fold higher activity than the wild type at 42.5 degrees C, which is the optimal temperature of the wild type. K94R/S365P showed also stimulated in 2.5-fold lower concentration of CaCl2 and delayed aggregation temperature in the presence of CaCl2 compared to the wild type. In pH stability, K94R/S365P was not influenced, but the optimum pH was transferred from pH 7 to pH 6. In long-term hydrolysis, K94R/S365P reduced the newly released reducing sugar yields after 12 h reaction; however, the yields consistently increased until 72 h. Finally, the total reducing sugar of K94R/S365P was 5.0-fold higher than the wild type at 50 degrees C, pH6. EngZ (K94R/S365P) can support information to develop thermostability of GH9 endoglucanase with a high catalytic efficiency as the potential industrial bioprocess candidate. (C) 2016 Elsevier B.V. All rights reserved.
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