Expression of recombinant Aspergillus niger xylanase A in Pichia pastoris and its action on xylan.
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.
Liu
Ming-Qi
MQ
Microbiology Division, Feed Science Institute, College of Animal Science, Zhejiang University, Hangzhou, China.
Weng
Xiao-Yan
XY
Sun
Jian-Yi
JY
D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics; D043364:Endo-1,4-beta Xylanases / Q000235:genetics* / Q000378:metabolism*; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D010843:Pichia / Q000235:genetics*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D014990:Xylans / Q000378:metabolism*
D011994:Recombinant Proteins; D014990:Xylans; D043364:Endo-1,4-beta Xylanases