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Expression and characterization of dextransucrase gene dsrX from Leuconostoc mesenteroides in Escherichia coli

文献类型： 外文期刊

作者： Yang Yalin;Luo Jin;Wang Jianhua;Teng Da;Tian Zigang

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期刊名称： JOURNAL OF BIOTECHNOLOGY

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收录情况： SCI

摘要： The dextransucrase gene dsrX from Leuconostoc mesenteroides CGMCC 1.544 was cloned into the vector pET-28a(+) and expressed as a N-terminal His(6)-tag fusion protein of 167.57kDa in Escherichia coli BL21(DE3). DsrX with the high volumetric activity of 8.8Uml(-1) culture and the specific activity of 97.37Umg(-1) crude enzyme extracts was measured in the optimized recombinant expression system. The resultant expression level of the fusion protein amounted to 24.5% of the total cell proteins. The results of affinity chromatography and western blotting indicated that the three sensitive sites of proteolysis existed in the N-terminal catalytic domain of DsrX. Both the recombinant and native enzyme activity were slightly activated by 1mmoll(-1) Mn(2+) and strongly inhibited by 1mmoll(-1) Cu(2+) or Al(3+), and their optimum pH values were 5.4. The optimum temperature of the recombinant enzyme for dextran synthesis was 30 degrees C, which was 10 degrees C less than that of the native one. The transglucosylation products of two enzymes were studied by using thin layer chromatography and high-performance anion exchange chromatography. It could be concluded that the better sample-pretreatment temperature in SDS-PAGE was 37 degrees C, which significantly improved the detection of thermal instable enzyme than that of 100 degrees C.

分类号： Q81

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