title: Overexpression of methyl parathion hydrolase and its application in detoxification of organophosphates.
abstract: The coding region of mpd gene corresponding to mature methyl parathion hydrolase (MPH) was heterologously overexpressed in Escherichia coli BL21 (DE3) by using pET expression system. The lactose-induced expression yield of MPH is increased 2-fold compared with IPTG as inducer. Furthermore, it was found that specific activity of MPH increased 48% by reducing the induction temperature to 22 degrees C. The addition of 25 mM lactose at 22 degrees C, the MPH activity of fermentation broth had a specific activity of 1.4 x 10(4) U/mg protein. Plasmid was no significant decrease in the modified medium. The optimal pH and temperature of MPH were 8.0 and 30 degrees C, respectively. Over a period of 5 months, the dried cells showed no significant decrease in the activity of the detoxifying enzymes. The crude enzymes in 50 mM citrate-phosphate buffer (pH 8.0) were able to degrade about 98% of the organophosphate pesticides sprayed on cabbage. The detoxification efficiency was superior to that of the treatments of water, detergent, and a commercially available enzyme product. Additionally, the products of pesticide hydrolysis generated by treatment with the enzyme extract were determined to be virtually nontoxic.
authors: State Key Laboratory of Integrated Management of Pest Insects & Rodents, Institute of Zoology, Chinese Academy of Sciences, Da Tun Lu, Beijing 100101, P.R. China.
authors: Jijian
authors: J
authors: Yang
authors: Chao
authors: C
authors: Yang
authors: Hong
authors: H
authors: Jiang
authors: Chuanling
authors: C
authors: Qiao
mesh_terms: D001483:Base Sequence; D001673:Biodegradation, Environmental; D001937:Brassica; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005285:Fermentation; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism*; D008658:Inactivation, Metabolic; D008743:Methyl Parathion / Q000378:metabolism* / Q000633:toxicity; D009943:Organophosphorus Compounds / Q000378:metabolism* / Q000633:toxicity; D010575:Pesticides / Q000378:metabolism / Q000633:toxicity; D010957:Plasmids / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013696:Temperature
chemical_list: D017931:DNA Primers; D009943:Organophosphorus Compounds; D010575:Pesticides; D011994:Recombinant Proteins; D008743:Methyl Parathion; D006867:Hydrolases