The Research Of Fusing CBD₁/CBD₂ To The N-terminal Of The Xylanase XynⅢ

Xylanase can catalyze xylan into xylose or oligosaccharides, and it can be widely used in papermaking, feed,foodmaking,energy, industry and agriculture. As a protein, our enzyme can not work well in the high temperature or high alkali biological engineering environment, so transformation of the xylanase is making a great sence.In this study, we choose the wild type gene XynⅢ from Aspergillus niger A-25 which can encoding the mature protein of an endo-β-1,4-xylanase by way of the fusion-PCR.The other part of the fusion enzyme named CBD1 and CBD2 which are called the cellulose binding domain is come from Thermotoga maritime. We fuse the CBDs into the N-terminal of the XynⅢ, then overexpressed it in Escherichia coli to investigate the characterizations of the recombinant proteins.The optimal pH of recombinant protein CBDi-XynⅢ is 4.0, Linker-XynⅢ and XynⅢ both are 3.8.But CBD1-XynⅢ is much more stabilitier than any others, which means the recombinant protein CBD1-XynⅢ is much better used in acidic environment than the two others.The optimal temperature of the three enzymes are all found to be 48℃.Although the optimal temperature does not improve, the activity and half-life period of Linker-XynⅢ is close to the wild type which offset the negative effect of the foreign protein.So, we can obtain a result that CBD1 is important for pH activity while CBD2 is worked on thermal stability...