Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China.
J Agric Food Chem. 2010 May 26;58(10):6126-30. doi: 10.1021/jf1003896.
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 Fe(2+) and Mn(2+) but inhibited by Cd(2+), Pb(2+), and Cu(2+). The EDC chemical modification suggested that at least one carboxyl group probably acted as a proton donor in the enzyme active site.
从以 0.3%甘蔗渣为碳源生长的aspergillus glaucus XC9 中培养的内切葡聚糖酶（EG），使用硫酸铵、阴离子交换 DEAE Sepharose 快速流动柱和 Sephadex G-100 柱从培养液中进行纯化，得到 21.5 倍的纯化倍数和 22.3%的回收率。EG 生产的理想时间是在 30°C 下以甘蔗渣为底物的第四天。结果表明，该酶为单体蛋白，分子量为 31 kDa。EG 水解羧甲基纤维素钠（CMC-Na）的最适 pH 和温度分别为 pH 4.0 和 50°C。EG 在 pH 3.5 到 7.5 的范围内和 55°C 以下的温度下稳定。EG 在 CMC-Na 水解中的动力学行为遵循米氏动力学，在 pH 4.0 和 50°C 时，常数 K(m)为 5.0mg/mL。该酶的活性受到 Fe(2+)和 Mn(2+)的刺激，但受到 Cd(2+)、Pb(2+)和 Cu(2+)的抑制。EDC 化学修饰表明，至少有一个羧基可能在酶的活性位点中充当质子供体。
