摘要
海栖热袍菌内切葡聚糖酶Cel12B是极耐热胞外酶，氨基酸序列分析表明不含有纤维素结合结构域（CBD），对结晶纤维素无活性，但同样菌种来源的木聚糖酶XynA有催化结构域和纤维素结合结构城。用同样极耐热酶CBD区域和Cel12B融合构建重组质粒pET-20b—Cel12B—CBD，经诱导表达后，对结晶纤维素有活性，酶学特性研究表明：最适反应温度为100℃、最适pH为5．8、在pH4．5—7．0时酶活力稳定，90℃保温2h仍有87％的酶活。
Thermotoga maritima is strictly anaerobic and extremely thermophilic bacteria. The endoglucanase found in T. maritima showed extremely high thermostability and considerable potential in industrial application. Endoglucanase（Tm） Cel12B is extracellular enzyme. Tm Cel12B did not contain a cellulose-binding domain（CBD）and lacked activity on crystalline cellulose. Tm XynA is composed of catalytic domain（ CD） and cellulose-binding domain（CBD）. As such, the gene of CBD from Tm XynA was fused at the carboxyl-terminus of Tm Cel12B and recombinant plasmid pET-20b- Cel 12 B- CBD was obtained. The recombinant plasmid pET-20b- Cel 12 B- CBD was transformed to E. coli JM 109 （ DE3）, induced by IPTG. The properties of chimeric enzyme were determined. The chimeric enzyme displayed pH activity and stability profiles similar to those of parental enzyme with optimal pH 5.8. The optimal activity of the chimera was observed at 100 ℃ and the enzyme kept 87 % of original enzyme activity after incubated at 90 ℃ for 2h. A notable feature on substrate specificity is that the chimer/c enzyme has the capacity to hydrolases crystalline cellulose.
出处
《微生物学报》
CAS
CSCD
北大核心
2006年第5期726-729,共4页
Acta Microbiologica Sinica
基金
江苏省教育厅自然科学研究项目(05KJB180006)~~
