Expression of recombinant Aspergillus niger xylanase A in Pichia pastoris and its action on xylan |
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Authors: | Liu Ming-Qi Weng Xiao-Yan Sun Jian-Yi |
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Affiliation: | Microbiology Division, Feed Science Institute, College of Animal Science, Zhejiang University, Hangzhou, China. |
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Abstract: | The mature peptide of Aspergillus niger xylanase A (AnxA) was successfully expressed in Pichia pastoris at high levels under the control of AOX1 promoter. The recombinant AnxA (reAnxA) was secreted into culture medium. After 96-h 0.25% methanol induction, the activity of reAnxA in the culture supernatant reached the peak, 175 U/mg, which was 1.9 times as high as that of the native AnxA (92 U/mg). Studies on enzymatic properties showed that the optimum temperature and optimum pH of reAnxA were 50 degrees C and 5.0, respectively. The reAnxA was very stable in a wide pH range of 3.0-8.0. After incubation at the pH 3.0-8.0, 25 degrees C for 1h, all the residual activities of reAnxA were over 80%. The K(m) and k(cat) values for reAnxA were 4.8 mg/ml and 123.2s(-1), respectively. HPLC analysis showed that xylotriose was the main hydrolysis product of birchwood xylan and bran insoluble xylan by reAnxA. |
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Keywords: | Aspergillus niger xylanase A (AnxA) Expression Pichia pastoris Xylotriose Xylooligosaccharide |
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