摘要
对来源于黑曲霉（Aspergillus niger）XZ-3S的中温木聚糖酶Xyn ZF-2进行热稳定性改造,定点突变v1c,构建重组突变酶Xyn ZF-2V1C。重组原酶Xyn ZF-2与突变酶Xyn ZF-2V1C基因分别在大肠杆菌BL21（DE3）中表达并进行酶学性质分析。结果发现,突变酶Xyn ZF-2V1C最适温度为50℃,相比原酶Xyn ZF-2最适温度提高了10℃;在45℃条件下的半衰期t45℃1/2,突变酶Xyn ZF-2V1C相对于原酶Xyn ZF-2提高了10 min;原酶Xyn ZF-2与突变酶Xyn ZF-2V1C最适p H均为5.0,p H稳定范围均为5.0～9.0,基本没有变化;原酶Xyn ZF-2和突变酶Xyn ZF-2V1C的Km分别9.96 mg/m L和12.4 mg/m L,Vmax分别为74.63 U/mg和90.91 U/mg。
A mesophilic xylanase（ Xyn ZF-2） from Aspergillus niger was modified. Mutant enzyme Xyn ZF-2V1 C was constructed by site-directed mutagenesis of v1 c. xyn ZF-2. xyn ZF-2v1c-encoding genes were expressed in E. coli BL21（ DE3） and the recombinant enzyme characterizations were analyzed. The optimum temperature of recombinant Xyn ZF-2V1 C was 50 ℃,which was increased by 10 ℃ compared to the recombinant Xyn ZF-2. At 45 ℃,the halftime of inactivation for Xyn ZF-2V1 C was improved by 10 min. The optimum p H of Xyn ZF-2V1 C was p H 5. 0,which was similar to that of recombinant Xyn ZF-2. Both recombinant Xyn ZF-2V1 C and Xyn ZF-2 could retain over 50% activity from p H 5. 0 to 9. 0. The Kmof recombinant Xyn ZF-2 and Xyn ZF-2V1 C were 9. 96 mg / m L and 12. 4 mg / m L,and the Vmaxof recombinant Xyn ZF-2 and Xyn ZF-2V1 C were 74. 63 U / mg and 90. 91 U / mg,respectively.
出处
《食品与发酵工业》
CAS
CSCD
北大核心
2015年第4期39-43,共5页
Food and Fermentation Industries
基金
河南省教育厅科学技术研究重点项目(13A180861)
河南省高等学校青年骨干教师资助计划项目(2011GGJS-125)
新乡医学院科研项目培育基金(2013ZD113)
新乡医学院研究生科研创新支持计划资助项目(YJSCX20434Y)
关键词
木聚糖酶
定点突变
热稳定性
xylanase
site-directed mutagenesis
thermostability
