Subclinical Health Effects of Environmental Pesticide Contamination in a Developing Country: Cholinesterase Depression in Children

McConnell, Rob; Pacheco, F.; Wahlberg, K.; Klein, W.; Malespin, Omar; Magnotti, Ralph A.; Åkerblom, Malin; Murray, Douglas L.

doi:10.1006/enrs.1999.3958

Cited by 32 publications

(22 citation statements)

References 12 publications

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“…After having gained experience with the strengths and limitations of the Test-mate™ kit, McConnell et al (1999) studied the BChE activity of children potentially exposed to OP pesticides. Instead of using automated algorithms in the Test-mate™, the authors used a correction chart provided by the manufacturer to manually adjust BChE activity for ambient temperatures.…”

Section: Portabilitymentioning

confidence: 99%

An Evaluation of Blood Cholinesterase Testing Methods for Military Health

Knechtges¹

2008

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Section: Portabilitymentioning

confidence: 99%

An Evaluation of Blood Cholinesterase Testing Methods for Military Health

Knechtges¹

2008

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“…It has been estimated that more than 100 OPs are used, accounting for ~38% of the total pesticide usage in the world (Singh 2009). Continuous and excessive use of OPs has led to the contamination of many terrestrial and aquatic ecosystems (Cisar and Snyder 2000;McConnell et al 1999;Tse et al 2004). OPs are toxic to mammals and other nontarget animals, and the toxic effects of OPs on invertebrates, vertebrates, and wildlife are well documented.…”

Section: Introductionmentioning

confidence: 99%

An isofenphos-methyl hydrolase (Imh) capable of hydrolyzing the P–O–Z moiety of organophosphorus pesticides containing an aryl or heterocyclic group

Liu

Zhang

et al. 2011

Appl Microbiol Biotechnol

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Organophosphorus pesticide (OP) hydrolases play key roles in the degradation and decontamination of agricultural and household OPs and in the detoxification of chemical warfare agents. In this study, an isofenphos-methyl hydrolase gene (imh) was cloned from the isocarbophos-degrading strain of Arthrobacter sp. scl-2 using the polymerase chain reaction method. Isofenphos-methyl hydrolase (Imh) showed 98% sequence identity with the isofenphos hydrolase from Arthrobacter sp. strain B-5. Imh was highly expressed in Escherichia coli BL21 (DE3), and the His(6)-tagged Imh was purified (1.7 mg/ml) with a specific activity of 14.35 U/mg for the substrate isofenphos-methyl. The molecular mass of the denatured Imh is about 44 kDa, and the isoelectric point (pI) value was estimated to be 3.4. The optimal pH and temperature for hydrolysis of isofenphos-methyl were pH 8.0 and 35 °C, respectively. The secondary structure of Imh shows that Imh is a metallo-dependent hydrolase, and it was found that Imh was completely inhibited by the metalloprotease inhibitor 1,10-phenanthroline (0.5 mM), and the catalytic activity was restored by the subsequent addition of Zn(2+). Interestingly, Imh had a relatively broader substrate specificity and was capable of hydrolyzing 12 of the tested oxon and thion OPs with the P-O-Z moiety instead of the P-S(C)-Z moiety. Furthermore, it was found that the existence of an aryl or heterocyclic group in the leaving group (Z) is also important in determining the substrate specificity. Among all the substrates hydrolyzed by Imh, it was assumed that Imh preferred P-O-Z substrates still with a phosphamide bond (P-N), such as isofenphos-methyl, isofenphos, isocarbophos, and butamifos. The newly characterized Imh has a great potential for use in the decontamination and detoxification of agricultural and household OPs and is a good candidate for the study of the catalytic mechanism and substrate specificity of OP hydrolases.

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“…Organophosphorus compounds are usually esters or thiol derivatives of phosphoric, phosphinic, or phosphoramidic acids [6]. The excessive use of OPPs has impacted several ecosystems worldwide [7][8][9]. They are highly toxic also for mammals, representing a public health risk.…”

Section: Introductionmentioning

confidence: 99%

Substitution of the Catalytic Metal and Protein PEGylation Enhances Activity and Stability of Bacterial Phosphotriesterase

Perezgasga¹,

Sánchez-Sánchez²,

Águila³

et al. 2012

Appl Biochem Biotechnol

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Phosphotriesterase, a pesticide-degrading enzyme, from Flavobacterium sp. was cloned and expressed in Escherichia coli. The catalytic zinc ions were replaced by cobalt atoms increasing the catalytic activity of phosphotriesterase on different pesticides. This metal substitution increased the catalytic activity from 1.4 times to 4 times according to the pesticide. In order to explain this catalytic increase, QM/MM calculations were performed. Accordingly, the HOMO energy of the substrate is closer to the LUMO energy of the cobalt-substituted enzyme. The chemical modification of the enzyme surface with poly(ethylene glycol) increased the thermostability and stability against metal chelating agents of both metal phosphotriesterase preparations.

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Subclinical Health Effects of Environmental Pesticide Contamination in a Developing Country: Cholinesterase Depression in Children

Cited by 32 publications

References 12 publications

An Evaluation of Blood Cholinesterase Testing Methods for Military Health

An Evaluation of Blood Cholinesterase Testing Methods for Military Health

An isofenphos-methyl hydrolase (Imh) capable of hydrolyzing the P–O–Z moiety of organophosphorus pesticides containing an aryl or heterocyclic group

Substitution of the Catalytic Metal and Protein PEGylation Enhances Activity and Stability of Bacterial Phosphotriesterase

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