Characterization And Preparation Of Methy1 Parathion Hydrolase (MPH)

A methyl parathion degradation enzyme, or methyl parathion hydrolase (MPH, EC 3.1.8.1), locating in the soluble intracellular fraction of Pseudomonas sp WBC-3, was purified 49.1-fold to homogeneity by one-step ion exchange chromatography. The physical and chemical properties of the purified MPH were studied. In the crude extracts, the specific activities of MPH for methyl parathion and fenitrothion were higher than those of OPH from F.sp, while the catalytical activity for parathion was lower than that of OPH. The comparison of native and subunit molecular weights of MPH suggested that this enzyme was a monomer of approximate 34,250 Dalton. The purified MPH displayed relatively broad optimal temperature around 40 癈. The activity of MPH was affected by pH and the optimal pH was 11.0. Cd2+ andFe2+ could enhance the catalytical efficiency of MPH while Hg2+, Zn2+, A13+ and Bi3+ showed inhibition effect. With methyl parathion as the optimal substrate, the Km was 0.0807mM and the kC3l was 2.1 X lOViin'1. In addition, MPH was also found to catalyze the hydrolysis of chlorpyrifos, which was commonly used as organophosphorus insecticide.In addition, the preparation of the crude enzyme was also studied. With the optimized economy stuff, we cultured the WBC-3 and collected the crude MPH. Using the crude enzymes, some kinds of surfactants and oil, we studied the compositions of different emulsions. From comparing the activity of MPH and the conserve conditions of the different emulsions, we got the composition of emulsion at last.