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Life Sciences Jan 1982A competitive inhibition enzyme immunoassay (EIA) was developed to detect and quantify levels of the organophosphate insecticide paraoxon in body fluids....
A competitive inhibition enzyme immunoassay (EIA) was developed to detect and quantify levels of the organophosphate insecticide paraoxon in body fluids. Protein-conjugated paraoxon served as an immunogen for the production of rabbit heteroantiserum, from which affinity purified IgG anti-paraoxon antibodies were isolated using a heterologous protein-paraoxon-conjugated immunoabsorbent. In the competitive inhibition EIA a standard curve was generated for the inhibition of binding of anti-paraoxon IgG to a solid-phase bound heterologous protein-paraoxon conjugate by various concentrations of free paraoxon. Binding was proportionate to the color change of an appropriate substrate generated by an enzyme-conjugated second antibody specific for the rabbit IgG anti-paraoxon. The assay detected paraoxon levels as low as 10(-10)M (28 pg/ml) in buffer, and serum paraoxon levels as low as 10(-9)M. In addition to its sensitivity, this technique is ideally suited to the simultaneous processing of large numbers of samples in less than 2 hr. The competitive inhibition EIA is cost effective and should facilitate environmental surveillance using sentinel animals, expand laboratory toxicology studies, and improve clinical detection capabilities.
Topics: Animals; Female; Humans; Immunoenzyme Techniques; Male; Paraoxon; Rabbits
PubMed: 7040891
DOI: 10.1016/0024-3205(82)90572-0 -
Pharmacology & Toxicology Jul 1995The effects of induction of various forms of cytochromes P450 by chemicals like phenobarbital on the hepatic oxidative desulfuration and acute toxicity of the...
The effects of induction of various forms of cytochromes P450 by chemicals like phenobarbital on the hepatic oxidative desulfuration and acute toxicity of the phosphorothioate insecticide parathion have been well-characterized. However, the effects of these chemicals on the metabolism and acute toxicity of the active metabolite paraoxon are less understood. In the present study, daily pretreatment of mice with phenobarbital (intraperitoneally 75 mg/kg) for up to eight days resulted in a transient increase in hepatic microsomal A-esterase activity, with a corresponding transient decrease in serum A-esterase activity (A-esterase was defined as hydrolysis of paraoxon which could be inhibited by EDTA). These alterations could be accounted for by a temporary decrease in the rate of secretion of A-esterase from liver. However, the same pretreatment resulted in a sustained protective effect against the acute toxicity of paraoxon. These data suggest that alterations in A-esterase activity as a result of phenobarbital pretreatment cannot account for the observed antagonism of the acute toxicity of paraoxon. Furthermore, these data demonstrate that the protective effect of phenobarbital pretreatment on phosphorothioate insecticides like parathion cannot be attributed exclusively to alterations in oxidative desulfuration of these compounds.
Topics: Analysis of Variance; Animals; Biotransformation; Carboxylic Ester Hydrolases; Cytochrome P-450 Enzyme System; Drug Interactions; Enzyme Induction; Hydrolysis; Injections, Intraperitoneal; Insecticides; Liver; Male; Mice; Microsomes, Liver; Paraoxon; Phenobarbital
PubMed: 8532607
DOI: 10.1111/j.1600-0773.1995.tb01908.x -
The Journal of Organic Chemistry Oct 2013Herein, the reactivity and selectivity of the reaction of O,O-diethyl 4-nitrophenyl phosphate triester (Paraxon, 1) with piperidine in ionic liquids (ILs), three...
Herein, the reactivity and selectivity of the reaction of O,O-diethyl 4-nitrophenyl phosphate triester (Paraxon, 1) with piperidine in ionic liquids (ILs), three conventional organic solvents (COS), and water is studied by (31)P NMR, UV-vis, and GC/MS. Three phosphorylated products are identified as follows: O,O-diethyl piperidinophosphate diester (2), O,O-diethyl phosphate (3), and O-ethyl 4-nitrophenyl phosphate diester (4). Compound 4 also reacts with piperidine to yield O-ethyl piperidinophosphate monoester (5). The results show that both the rate and products distribution of this reaction depend on peculiar features of ILs as reaction media and the polarity of COS.
Topics: Ionic Liquids; Magnetic Resonance Spectroscopy; Nitrobenzenes; Paraoxon; Piperidines; Solvents; Water
PubMed: 24001321
DOI: 10.1021/jo401351v -
Life Sciences 1995Human serum A-esterase is a calcium-dependent enzyme that hydrolyzes the organophosphate paraoxon by an Ordered Uni Bi kinetic mechanism. Incubation of various...
Human serum A-esterase is a calcium-dependent enzyme that hydrolyzes the organophosphate paraoxon by an Ordered Uni Bi kinetic mechanism. Incubation of various concentrations of calcium chloride with human serum A-esterase resulted in corresponding changes in appk3 and appE for the reaction, while appk2 was unaffected. Carboxyglutamic acid (CAG) prevented calcium chloride from altering appk3, but not appE. Similarly CAG reduced the calcium-stimulated nonenzymatic hydrolysis of paraoxon, as well as the calcium-stimulated de-phosphorylation of chymotrypsin phosphorylated by paraoxon. These results suggest that calcium plays two roles in the hydrolysis of paraoxon by A-esterase. Firstly, calcium is required in order to maintain an active site. In this capacity calcium might participate directly in the catalytic reaction, or it might be required in order to maintain the appropriate confirmation of the active site. And secondly, free calcium (or calcium weakly associated with A-esterase) facilitates the removal of diethyl phosphate from A-esterase, probably by polarizing the P = O bond of the diethyl phosphate-A-esterase intermediate, thereby rendering phosphorus more susceptible to nucleophilic attack by hydroxide ions.
Topics: Adult; Aryldialkylphosphatase; Calcium; Esterases; Female; Humans; Hydrolysis; Kinetics; Male; Paraoxon
PubMed: 7823759
DOI: 10.1016/0024-3205(94)00422-o -
Applied and Environmental Microbiology Oct 2006Organophosphate compounds, which are widely used as pesticides and chemical warfare agents, are cholinesterase inhibitors. These synthetic compounds are resistant to...
Organophosphate compounds, which are widely used as pesticides and chemical warfare agents, are cholinesterase inhibitors. These synthetic compounds are resistant to natural degradation and threaten the environment. We constructed a strain of Pseudomonas putida that can efficiently degrade a model organophosphate, paraoxon, and use it as a carbon, energy, and phosphorus source. This strain was engineered with the pnp operon from Pseudomonas sp. strain ENV2030, which encodes enzymes that transform p-nitrophenol into beta-ketoadipate, and with a synthetic operon encoding an organophosphate hydrolase (encoded by opd) from Flavobacterium sp. strain ATCC 27551, a phosphodiesterase (encoded by pde) from Delftia acidovorans, and an alkaline phosphatase (encoded by phoA) from Pseudomonas aeruginosa HN854 under control of a constitutive promoter. The engineered strain can efficiently mineralize up to 1 mM (275 mg/liter) paraoxon within 48 h, using paraoxon as the sole carbon and phosphorus source and an inoculum optical density at 600 nm of 0.03. Because the organism can utilize paraoxon as a sole carbon, energy, and phosphorus source and because one of the intermediates in the pathway (p-nitrophenol) is toxic at high concentrations, there is no need for selection pressure to maintain the heterologous pathway.
Topics: Biodegradation, Environmental; Insecticides; Minerals; Paraoxon; Parathion; Pseudomonas putida
PubMed: 17021221
DOI: 10.1128/AEM.00907-06 -
Materials Science & Engineering. C,... Mar 2013In the present work, a paraoxon imprinted QCM sensor has been developed for the determination of paraoxon based on the modification of paraoxon imprinted film onto a...
In the present work, a paraoxon imprinted QCM sensor has been developed for the determination of paraoxon based on the modification of paraoxon imprinted film onto a quartz crystal combining the advantages of high selectivity of the piezoelectric microgravimetry using MIP film technique and high sensitivity of QCM detection. The paraoxon selective memories have formed on QCM electrode surface by using a new metal-chelate interaction based on pre-organized monomer and the paraoxon recognition activity of these molecular memories was investigated. Molecular imprinted polymer (MIP) film for the detection of paraoxon was developed and the analytical performance of paraoxon imprinted sensor was studied. The molecular imprinted polymer were characterized by FTIR measurements. Paraoxon imprinted sensor was characterized with AFM and ellipsometer. The study also includes the measurement of binding interaction of paraoxon imprinted quartz crystal microbalance (QCM) sensor, selectivity experiments and analytical performance of QCM electrode. The detection limit and the affinity constant (K(affinity)) were found to be 0.06 μM and 2.25 × 10(4) M(-1) for paraoxon [MAAP-Cu(II)-paraoxon] based thin film, respectively. Also, it has been observed that the selectivity of the prepared paraoxon imprinted sensor is high compared to a similar chemical structure which is parathion.
Topics: Hydrogen-Ion Concentration; Insecticides; Limit of Detection; Molecular Imprinting; Paraoxon; Quartz Crystal Microbalance Techniques; Reproducibility of Results; Spectroscopy, Fourier Transform Infrared
PubMed: 25427509
DOI: 10.1016/j.msec.2012.11.024 -
Chemico-biological Interactions Apr 2017Organophosphorus compounds (OP), which mainly penetrate via the percutaneous pathway, represent a threat for both military and civilians. Body surface decontamination is...
Organophosphorus compounds (OP), which mainly penetrate via the percutaneous pathway, represent a threat for both military and civilians. Body surface decontamination is vital to prevent victims poisoning. The development of a cost-effective formulation, which could be efficient and easy to handle in case of mass contamination, is therefore crucial. Metal oxides nanoparticles, due their large surface areas and the large amount of highly reactive sites, present high reactivity towards OP. First, this study aimed at evaluating the reaction of CeO nanoparticles, synthetized by microwave path and calcined at 500 or 600 °C, with Paraoxon (POX) in aqueous solution. Results showed that both nanoparticles degraded 60%-70% of POX. CeO calcined at 500 °C, owing to its larger specific area, was the most effective. Moreover, the degradation was significantly increased under Ultra-Violet irradiation (initial degradation rate doubled). Then, skin decontamination was studied in vitro using the Franz cell method with pig-ear skin samples. CeO powder and an aqueous suspension of CeO (CeO-W) were applied 1 h after POX exposure. The efficiency of decontamination, including removal and/or degradation of POX, was compared to Fuller's earth (FE) and RSDL lotion which are, currently, the most efficient systems for skin decontamination. CeO-W and RSDL were the most efficient to remove POX from the skin surface and decrease skin absorption by 6.4 compared to the control not decontaminated. FE reduced significantly (twice) the absorbed fraction of POX, contrarily to CeO powder. Considering only the degradation rate of POX, the products ranged in the order CeO > RSDL > CeO-W > FE (no degradation). This study showed that CeO nanoparticles are a promising material for skin decontamination of OP if formulated as a dispersion able to remove POX like CeO-W and to degrade it as CeO powder.
Topics: Aluminum Compounds; Animals; Cerium; Chromatography, High Pressure Liquid; Decontamination; Magnesium Compounds; Metal Nanoparticles; Paraoxon; Pesticides; Photolysis; Silicates; Skin; Skin Cream; Spectrophotometry, Ultraviolet; Swine; Ultraviolet Rays
PubMed: 27129420
DOI: 10.1016/j.cbi.2016.04.035 -
Drug Metabolism and Disposition: the... 1983
Topics: Animals; Chlorpyrifos; Hydrogen-Ion Concentration; Hydrolysis; In Vitro Techniques; Inactivation, Metabolic; Kinetics; Male; Mice; Microsomes, Liver; Paraoxon
PubMed: 6191937
DOI: No ID Found -
Langmuir : the ACS Journal of Surfaces... Jun 2013Amphiphilic peptides were designed to fold into a β-sheet monolayer structure while presenting the catalytic triad residues of the enzyme, acetylcholinesterase (Glu,...
Amphiphilic peptides were designed to fold into a β-sheet monolayer structure while presenting the catalytic triad residues of the enzyme, acetylcholinesterase (Glu, His, and Ser), to a solution containing the organophosphate, paraoxon. Three peptides, in which the catalytic triad residues were arranged in different orders along the strand, were generated to reveal potential differences in interactions with paraoxon as a function of the order of these amino acids. One additional peptide with amino acids introduced in random order was studied to highlight the contribution of the β-sheet secondary structure to any interactions with paraoxon. Langmuir isotherms, Brewster angle microscope at interfaces, and circular dichroism measurements in bulk showed that both the β-sheet conformation and the order of the amino acids along the strand influenced the interactions of paraoxon with the peptides. Compression isotherm curves as well as Brewster angle microscopy images provided evidence for enhanced adsorption of the paraoxon to the monolayers of peptides, which present neighboring Glu and Ser residues along the hydrophilic face of the β-strand. Circular dichroism revealed that the peptide most sensitive to interactions with paraoxon was that with the triad residues in the order Glu, Ser, and His, which appears to be appropriate for supporting a catalytic mechanism similar to that in the acetylcholinesterase enzyme. These rationally designed peptides may be further used for the development of technologies for organophosphate adsorption and detection.
Topics: Adsorption; Models, Molecular; Paraoxon; Particle Size; Peptides; Surface Properties; Surface-Active Agents
PubMed: 23631528
DOI: 10.1021/la401280e -
Molecules (Basel, Switzerland) May 2020We describe a patterned surface-enhanced Raman spectroscopy (SERS) substrate with the ability to pre-concentrate target molecules. A surface-adsorbed nanosphere...
Patterned Superhydrophobic SERS Substrates for Sample Pre-Concentration and Demonstration of Its Utility through Monitoring of Inhibitory Effects of Paraoxon and Carbaryl on AChE.
We describe a patterned surface-enhanced Raman spectroscopy (SERS) substrate with the ability to pre-concentrate target molecules. A surface-adsorbed nanosphere monolayer can serve two different functions. First, it can be made into a SERS platform when covered by silver. Alternatively, it can be fashioned into a superhydrophobic surface when coated with a hydrophobic molecular species such as decyltrimethoxy silane (DCTMS). Thus, if silver is patterned onto a latter type of substrate, a SERS spot surrounded by a superhydrophobic surface can be prepared. When an aqueous sample is placed on it and allowed to dry, target molecules in the sample become pre-concentrated. We demonstrate the utility of the patterned SERS substrate by evaluating the effects of inhibitors to acetylcholinesterase (AChE). AChE is a popular target for drugs and pesticides because it plays a critical role in nerve signal transduction. We monitored the enzymatic activity of AChE through the SERS spectrum of thiocholine (TC), the end product from acetylthiocholine (ATC). Inhibitory effects of paraoxon and carbaryl on AChE were evaluated from the TC peak intensity. We show that the patterned SERS substrate can reduce both the necessary volumes and concentrations of the enzyme and substrate by a few orders of magnitude in comparison to a non-patterned SERS substrate and the conventional colorimetric method.
Topics: Acetylcholinesterase; Carbaryl; Cholinesterase Inhibitors; Paraoxon; Spectrum Analysis, Raman
PubMed: 32397331
DOI: 10.3390/molecules25092223