INCREASING THE PH OPTIMUM OF THE TRICHODERMA REESEI XYLANASE XYN II BY ASN44 SITE-DIRECTED MUTAGENESIS
Xylanases are drawing increased attention because of their usefulness in facilitating the bleaching of kraft pulp. Of them, the alkali-tolerant xylanases are preferred for these applications, because these industrial processes are carried out under neutral or alkaline condition. The purpose of this study was to increase the pH optimum of the Trichoderma reesei xylanase XYN II by Asn44 Site-saturation Mutagenesis and to facilitate its potential application for pulp bleaching. Here we performed one round mutagenesis and about 6 mutants were identified. Wide Type and all mutated xylanases were successfully expressed in Pichia pastoris. All combinant xylanases from P. pastoris were purified to further study their enzymatic properties. Of these xylanases, N44S led to the 34.05％ increase of the specific enzyme activity, but the pH optimum had no change. Other mutant xylanases caused a notable shift in the pH optimum of the enzyme from 5.2 to 5.8, 5.6 and 5.0 if substituted by methionine (Met), glutamic acid (Glu) and threonine (Thr) were found. However, the specific enzyme activity of N44M, N44T and N44E were all depressed.
Xylanase Trichoderma reesei Mutagenesis pH
Han Chengye OuYang Jia Li Xin Zhou Juan Xu Yan Yu Shiyuan
Key Laboratory of Forest Genetics and Biotechnology,Nanjing Forestry University, Nanjing, 210037, China
国际会议
广州
英文
438-441
2010-11-08（万方平台首次上网日期，不代表论文的发表时间）