摘要
对来源于宇佐美曲霉（Aspergillus usamii）E001的木聚糖酶XynⅡ进行同源建模和序列比较,发现第11族木聚糖酶的催化结构域在β折叠股A3和B3之间存在一个保守的氨基酸位点,该位点与木聚糖酶的pH特性有关,据此设计了XynⅡ的D37N定点突变。酵母表达的XynⅡD37N经纯化后与原酶XynⅡ（同样经毕赤酵母表达后纯化）进行酶学性质比较,结果表明,XynⅡD37N的最适pH由4.2升高到5.3,pH稳定范围由3.0-7.5缩减为3.0-5.5,但最适温度和热稳定性基本保持不变。结果证实,木聚糖酶XynⅡ的第37位Asp与最适pH相关,为进一步的结构与功能研究提供了理论基础。
A homology modeling of xylanase Xyn Ⅱ from Aspergillus usamii E001 was constructed by SWISSMODEL and BLAST. A conserved amino acid had been found in the catalytic domain between β-sheet A3 and B3 in the tertiary structure, which influenced the pH properties of enzyme. Then a D37N mutation was introduced in Xyn Ⅱ by site-directed mutagenesis. The Xyn Ⅱ and mutant xylanase （ Xyn ⅡD37N ） expressed in Pichia pastoris were purified and their enzymatic properties were determined. The optimal temperature and thermostability of Xyn ⅡD37N had almost no changes, but the optimum pH of Xyn ⅡD37N was increased from 4. 2 to 5. 3 and the pH stability of Xyn ⅡD37N was narrowed from pH 3. 0 -7. 5 to pH 3. 0 -5. 5.
出处
《生物加工过程》
CAS
CSCD
2008年第3期62-67,共6页
Chinese Journal of Bioprocess Engineering
基金
国家863资助项目(2006AA10Z305)
关键词
宇佐美曲霉
突变
定点
木聚糖酶
Aspergillus usamii
mutagenesis
site-directed
xylanase
