Purification and properties of endoglucanase from a sugar cane bagasse hydrolyzing strain, Aspergillus glaucus XC9.
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.
Tao
Yi-Ming
YM
Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Sciences, Xiamen University, Xiamen 361005, China.
Zhu
Xiang-Zhi
XZ
Huang
Jian-Zhong
JZ
Ma
Su-Juan
SJ
Wu
Xiao-Bing
XB
Long
Min-Nan
MN
Chen
Qing-Xi
QX
D001230:Aspergillus / Q000201:enzymology* / Q000254:growth & development; D002266:Carboxymethylcellulose Sodium / Q000378:metabolism; D020134:Catalytic Domain; D002413:Cations, Divalent / Q000494:pharmacology; D002480:Cellulase / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D031786:Saccharum / Q000378:metabolism*; D013379:Substrate Specificity; D013696:Temperature
D002413:Cations, Divalent; D002480:Cellulase; D002266:Carboxymethylcellulose Sodium