[Determination of the catalytic structures of methyl parathion hydrolase].
Methyl parathion hydrolase (MPH) is a novel member of organophosphorus hydrolase. In this study, mpd gene was expressed in Escherichia coli DH5alpha with its native promoter. MPH was purified to homogeneity. Results show that metal-chelating compounds cannot inhabit the enzyme activity. Inductively Coupled Plasma-Atomic Emission Spectrometry analysis showed that MPH is a zinc-containing enzyme, the Zinc to enzyme molar ratio is near 2:1. In order to investigate critical residues related to enzymatic activity of MPH, chemical modification reagents EDC, DEPC, butanedione and pyridoxal were tested. Experiment results suggested that aspartate, glutamate, arginine and lysine are not important for enzyme activity. But DEPC, which can modify histidine residue, inactivate the enzyme activity greatly, and the inactivation rate is 9.6 h(-1). This result reflects that histidine residues are essential for enzyme activity. All these results provide basic data for MPH structure and molecular evolution research.
Key Laboratory of Microbiological Engineering Agricultural Environment, Ministy of Agriculture, Nanjing Agricultural University, Nanjing 210095, China.
Xu-Ping
XP
Wu
Wei-Dong
WD
Liu
Hui
H
Cao
Shun-Peng
SP
Li
Zhong-Li
ZL
Cui
D043303:Aryldialkylphosphatase / Q000737:chemistry*; D004789:Enzyme Activation / Q000187:drug effects*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D006639:Histidine / Q000737:chemistry*; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics
D011993:Recombinant Fusion Proteins; D006639:Histidine; C495424:methyl parathion hydrolase, Pseudomonas; D010744:Phosphoric Monoester Hydrolases; D043303:Aryldialkylphosphatase