Improving Catalytic Activity and Thermal Stability of Methyl-Parathion Hydrolase for Degrading the Pesticide of Methyl-Parathion

Pesticides are indispensable in today's agriculture. Methyl-parathion hydrolase (MPH, E.C.3.1.8.1) could hydrolyze organophosphorus pesticides, including methyl-parathion. MPH could rehabilitate soil and water resources contaminated by organophosphorus pesticides. However, natural MPHs generally exhibited a low tolerance to high temperatures and low catalytic efficiency. In this study, we improved the catalytic efficiency toward methyl-parathion and the thermal stability of the MPH from Pseudomonas sp. WBC-3 through saturation mutagenesis and fusion with self-assembling amphipathic peptides (SAP). The experimental characterization showed that compared to the wild-type enzyme, the k(cat)/K-m of the mutant T271S yielded by saturation mutagenesis was increased by 224.3% compared to the wild-type MPH. T-50 and T-m of SAP3-MPH with an SAP fused at the N-terminus were increased by 6.2 degrees C and 6.0 degrees C, respectively. Compared to the wild-type enzyme, T271S fused with SAP3 at the N-terminus (SAP3-T271S) exhibited a 2.1-fold increase in k(cat)/K-m without significantly affecting the thermal stability. The simultaneous improvement of the catalytic efficiency and thermal stability of MPH would be beneficial for its application in the degradation and detection of organophosphorus pesticides. Furthermore, our study provides a potential combination strategy for the design of the other enzyme preparations of pollutant degradation.

Automated summary

The study focuses on improving the catalytic efficiency and thermal stability of the MPH enzyme for its application in the degradation and detection of organophosphorus pesticides. By introducing mutations and fusing with self-assembling amphipathic peptides (SAP), the researchers achieved significant improvements in both aspects. This research has implications for the development of enzyme preparations for pollutant degradation.