کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
35212 | 45081 | 2010 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Site-directed mutagenesis of an Aspergillus niger xylanase B and its expression, purification and enzymatic characterization in Pichia pastoris Site-directed mutagenesis of an Aspergillus niger xylanase B and its expression, purification and enzymatic characterization in Pichia pastoris](/preview/png/35212.png)
Xylanase is an important industrial enzyme. In this research, to improve the thermostability and biochemical properties of a xylanase from Aspergillus niger F19, five arginine substitutions and a disulfide bond were introduced by site-directed mutagenesis. The wild-type gene xylB and the mutant gene xylCX8 were expressed in Pichia pastoris. Compare to those of the wild-type enzyme, the optimal reaction temperature for the mutant enzyme increased from 45 °C to 50 °C, the half-life of the mutant enzyme extended from 10 min to 180 min, and the specific activity increased from 2127 U/mg to 3330 U/mg. However, the Vmax and Km of the mutant xylanase decreased. The enzyme activity in broth obtained from shake flask cultures could be induced to 1850 U/mL in 7 days, which is higher than results reported previously. Furthermore, the highest achievable enzyme activity was 7340 U/mL from 140 g/L of biomass in a 3 L fermentor used in our study.
Journal: Process Biochemistry - Volume 45, Issue 1, January 2010, Pages 75–80