title: Cellulase hydrolysis of rice straw and inactivation of endoglucanase in urea solution.
abstract: In order to optimize the cellulase (from Aspergillus glaucus) hydrolysis of pretreated rice straw, the effects of varying enzyme concentration, temperature, and pH were studied. The best experimental conditions found to degrade the pretreated rice straws were 24 h of incubation at 55 °C and pH 5.0, with an enzyme concentration of 48 mg/L. Urea is one of the important nitrogen sources used in fungi culture, but it is also a denaturant. The model of denaturation of endoglucanase (EG) in urea solutions was established. The denaturation was a slow, reversible reaction. Determination of microscopic rate constants showed k(+0) > k'(+0), indicating that EG was protected by the substrate to a certain extent during denaturation. Comparison with the results from fluorescence emission spectroscopy revealed that the inactivation of EG occurred before the marked conformational changes could be detected.
authors.affiliation: Key Laboratory of the Ministry of Education for Coastal and Wetland Ecosystems, School of Life Science, Xiamen University, Xiamen 361005, China.
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Tao
authors.forename: Xin-Qi
authors.initials: XQ
authors.lastname: Xu
authors.forename: Su-Juan
authors.initials: SJ
authors.lastname: Ma
authors.forename: Ge
authors.initials: G
authors.lastname: Liang
authors.forename: Xiao-Bing
authors.initials: XB
authors.lastname: Wu
authors.forename: Min-Nan
authors.initials: MN
authors.lastname: Long
authors.forename: Qing-Xi
authors.initials: QX
authors.lastname: Chen
mesh_terms: D001230:Aspergillus / Q000201:enzymology; D002480:Cellulase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D006868:Hydrolysis; D012275:Oryza / Q000187:drug effects / Q000378:metabolism*; D011489:Protein Denaturation; D012996:Solutions; D013050:Spectrometry, Fluorescence; D014508:Urea / Q000494:pharmacology*
chemical_list: D012996:Solutions; D014508:Urea; D002480:Cellulase