Expression,Purification and Enzymatic Characterization of Klebsiella sp.Glycerol Dehydrogenase in E.coli / 中国生物工程杂志

ABSTRACT

The dhaD gene encoding glycerol dehydrogenase(GDH) from Klebsiella sp.was amplified,and was inserted into expression vector pET-28a(+),the plasmid pET-28a-dhaD was constructed and was transformed into Escherichia coli BL21(DE3).SDS-PAGE showed that the gene dhaD was expressed successfully in recombinant E.coli BL21.Then GDH was purified by Ni-NTA affinity chromatography,the results showed a single band about 39kDa on SDS-PAGE gel,and the specified activity was about 156U/mg.The special activity of GDH is 4.6-fold higher than that of unpurified and the activity recovery is 67.4%.The optimum reaction pH was 11.0,and the GDH activity have little changed when incubated in the buffer of pH7.0～11.0.The optimum reactive temperature was 30℃,and the GDH was more stable on the temperature of 25℃～45℃.The Km value was 0.54mmol/L and Vmax was 0.49 ?mol/ml?min in the glycerol.