Purification and Properties of Endoglucanase from a Sugar Cane Bagasse Hydrolyzing Strain, Aspergillus glaucus XC9
Zhu, Xiang-Zhi（Fujian Inst Sci & Technol Informat）
Huang, Jian-Zhong（Fujian Normal Univ, Minist Educ, Engn Res Ctr Ind Microbiol）
- 生命科学－已发表论文 
An endoglucanase (EG) from Aspergillus glaucus XC9 grown on 0.3% sugar cane bagasse as a carbon source was purified from the culture filtrate using ammonium sulfate, an anion exchange DEAE Sepharose fast flow column, and a Sephadex G-100 column, with a purification fold of 21.5 and a recovery of 22.3%. The ideal time for EG production is on the fourth day at 30 degrees C using bagasse as a substrate. Results obtained indicate that the enzyme was a monomer protein, and the molecular weight was determined to be 31 kDa. The optimum pH and temperature of EG for the hydrolysis of carboxymethylcellulose sodium (CMC-Na) were pH 4.0 and 50 degrees C, respectively. EG was stable over the pH range from 3.5 to 7.5 and at temperatures below 55 degrees C. Kinetic behavior of EG in the hydrolysis of CMC-Na followed Michaelis-Menten kinetics with constant K-m of 5.0 mg/mL at pH 4.0 and 50 degrees C. The enzyme activity was stimulated by Fe2+ and Mn2+ but inhibited by Cd2+, Pb2+, and Cu2+. The EDC chemical modification suggested that at least one carboxyl group probably acted as a proton donor in the enzyme active site.