| In the past 20 past years, scientists have carried out extensive and thorough researches of the degradation of organophosphorous by microorganisms, especially parathion. But concerning for the degradation of methyl parathion by microorganisms is not much. In preceding research, our research group, under the leading of Professor Li Shunpeng have cloned a novel gene-mpd successfully for the degradation of methyl parathion; have realized high level expression of the mpd gene in Escherichia coli, and have expounded the structure and characterization of methyl parathion hydrolysis. In order to compare the differentiation between the fusion protein and original protein, to offer background data for structural function and application research of methyl parathion, this paper aims at the research for purification and characterization of methyl parathion hydrolysis from original bacterium Plesiomonas sp.M6. And for other two, the characterization of the crude MPH has been carried out to compare with the characterization of MPH Plesiomonas sp. M6.Methyl parathion hydrolase from Plesiomonas sp. M6 has been purified to homogeneity by heat denaturation, ammonium sulfate precipitation, DEAE-Sephadex-A50 ion exchange chromatography and CM Sepharose Fast Flow cation exchange chromatography. After purification, specific activity of MPH has raised 61.18 times and during the entire purification course, the recovery of activity is 50.4%. Purified MPH has been verified homogeneity by SDS-PAGE and activity by zymogram. SDS-PAGE shows that after DEAE-Sephadex-A50, MPH has gotten better purification effect-only two tapes in outcome, and after CM Sepharose Fast Flow, the sample is homogeneity. Compared with low member protein standard, the directed member of MPH is 33 KD.Have established new MPH reaction system. One unit is defined as: under 25°C, the needed enzyme for the hydrolysis 1 nmol methyl parathion or parathion in one minute or the needed enzyme for production 1 nmol PNP.
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