Hydrolysis Of Parathion Research Articles

Zn(II)-complex-based hydrolytic nanozymes prepared by nanoprecipitation for the hydrolysis of carboxylic esters and methyl parathion

Zn(II)-complex-based nanozymes have been extensively used for the cleavage of carboxylic esters and phosphate esters. Cooperativity between neighboring Zn(II) complexes is of paramount importance for the development of Zn(II)-complex-based nanozymes with excellent efficiency. Here, we have developed a controllable synthetic strategy for the construction of Zn(II)-complex-based nanozymes by using the nanoprecipitation technique, which could bring Zn(II) complexes in close proximity and regulate their microenvironments. Linear copolymers containing di(2-picolyl)amine moieties were used for the preparation of Zn(II)-complex-based nanozymes by the coordination between di(2-picolyl)amine and Zn(II) ion. These Zn(II)-complex-based nanozymes displayed excellent catalytic performance in the hydrolysis of carboxylic esters. Moreover, hydrophobic Fe3O4 nanoparticles could be incorporated into Zn(II)-complex-based nanozymes via the one-step nanoprecipitation approach, enabling the recovery of nanozymes by using a permanent magnet. Such nanozymes effectively catalyzed the hydrolysis of methyl parathion, which is highly resistant to spontaneous hydrolysis and is extremely hazardous. These nanozymes may find application in the hydrolysis of hazardous carboxylic esters and phosphate esters.

The Investigation of Clone and Expression of Butyrylcholinesterase in Pichia pastoris for Parathion Hydrolysis

The Investigation of Clone and Expression of Butyrylcholinesterase in Pichia pastoris for Parathion Hydrolysis

Zwitterionic polymer-mediated immobilization of organophosphorus hydrolase enhances hydrolysis of methyl parathion by substrate enrichment

Organophosphorus pesticides (OPPs) degradation is highly demanded due to the toxic nature of the pesticides that have caused serious environmental concerns. Biocatalytic hydrolysis using organophosphorus hydrolase (OPH) is an important way to OPPs degradation, but the poor stability of OPH severely hindered its extensive applications in environmental bioremediation. It is well known that immobilization is an efficient way of enzyme stabilization, so this work has proposed to immobilize OPH onto mesoporous silica nanoparticles coated with a zwitterionic polymer containing short hydrophobic chains. It is found that the zwitterionic polymer coating significantly modified the microenvironment, leading to the stabilization of the immobilized enzyme while keeping its activity toward methyl parathion hydrolysis. More importantly, the coating resulted in the substrate enrichment onto the carrier (capacity, 49.7 mmol·g−1; dissociation constant, 11.7 μM), so the immobilized OPH presented a much lower Michaelis constant (0.09 mM) than its free counterpart (0.34 mM) as revealed by kinetic studies. Consequently, the catalytic efficiency (kcat/Km) of the immobilized OPH was 2.41 times higher than free OPH. Thus, this work demonstrated the promise of the zwitterionic polymer-mediated immobilization strategy for OPH in enhancing the enzyme performance for the hydrolysis of OPPs that are of low concentration in open environments.

Microbial degradation of organophosphorus pesticides using whole cells and enzyme extracts.

The use of microbial phosphotriesterases in the degradation of organophosphorus compounds employed as pesticides, plasticizers and petroleum additives is a sustainable alternative for bioremediation of water and soils, decontamination of particular foods and as poisoning antidote. Whole cells of six wild type microorganisms-Streptomyces phaeochromogenes, Streptomyces setonii, Nocardia corynebacterioides, Nocardia asteroides and two Arthrobacter oxydans-selected in our lab as phosphotriesterase sources, were further tested as biocatalysts in the hydrolysis of paraoxon, methyl paraoxon, methyl parathion, coroxon, coumaphos, dichlorvos and chlorpyrifos, highlighting 98% conversion of chlorpyrifos into its hydrolysis products using whole cells of S. phaeochromogenes at pH 8 and 40 °C. Immobilized whole cells and enzyme extracts were also assessed, observing as a general trend, that there is no significant variation in hydrolytic activity between them. These results suggest that according to the circumstances, immobilized whole cells (avoiding cellular disruption and centrifugation) or enzyme extracts (which can be handled more easily) could be used.

Catalytic Chemosensing Assay for Selective Detection of Methyl Parathion Organophosphate Pesticide.

Herein, a catalytic chemosensing assay (CCA), based on a bimetallic complex, [RuII (bpy)2 (CN)2 ]2 (CuI I)2 (bpy=2,2'-bipyridine), is described. This complex integrates a task-specific catalyst (CuI -catalyst) and a signaling unit ([RuII (bpy)2 (CN)2 ]) to specifically hydrolyze methyl parathion, a highly toxic organophosphate (OP) pesticide. The bimetallic complex catalyzed the hydrolysis of the phosphate ester to generate o,o-dimethyl thiophosphate (DTP) anion and 4-nitrophenolate. Intrinsically, 4-nitrophenolate absorbed UV/Vis light at λmax =400 nm, creating the first level of the chemosensing signal. DTP interacted with the original complex to displace the chromophore, [RuII (bpy)2 (CN)2 ], which was monitored by spectrofluorometry; this was classified as the second level of chemosensing signal. By integrating both spectroscopic and spectrofluorometric signals with a simple AND logic gate, only methyl parathion was able to provide a positive response. Other aromatic and aliphatic OP pesticides (diazinon, fenthion, meviphos, terbufos, and phosalone) and 4-nitrophenyl acetate provided negative responses. Furthermore, owing to the metal-catalyzed hydrolysis of methyl parathion, the CCA system led to the detoxification of the pesticide. The CCA system also demonstrated its catalytic chemosensing properties in the detection of methyl parathion in real samples, including tap water, river water, and underground water.

Enhanced Degradation of Methyl Parathion in the Ligand Stabilized Soluble Mn(III)-Sulfite System

The ligand-stabilized soluble Mn(III) recognized as active intermediate can potentially mediate the attenuation of contaminants. In this study, the abiotic degradation behaviors of methyl parathion in the ligand stabilized Mn(III)-sulfite system were investigated. The results showed that the yield of soluble Mn(III) produced from the redox reaction of MnO2 and oxalic acid was dependent linearly on the dosage of MnO2 and caused the decomposition of methyl parathion up to 50.1% in Mn(III)-sulfite system after 30 minutes. The fitted pseudo-first-order reaction constants of methyl parathion degradation increased with the increasing of the amount of produced Mn(III) but was not effected linearly by the addition of sulfite. Other ligands, including pyrophosphate and oxalic acid, acted as effective complexing agents to stabilize soluble Mn(III), and exhibited competitive effect on methyl parathion degradation with sulfite. The formation of Mn(III)-sulfite complexes is the critical step in the system to produce abundant reactive oxygen species identified as SO3•- to facilitate methyl parathion degradation. The hydrolysis and oxidation of methyl parathion were acknowledged as two primary transformation mechanisms in Mn(III)-sulfite system. These findings indicate that naturally ligands-stabilized soluble Mn(III) can be generated and could oxidatively decompose organophosphate pesticides such as methyl parathion.

Carbon and hydrogen isotope analysis of parathion for characterizing its natural attenuation by hydrolysis at a contaminated site

The applicability of compound-specific isotope analysis (CSIA) for assessing in situ hydrolysis of parathion was investigated in a contaminated aquifer at a former pesticide wastes landfill site. Stable isotope analysis of parathion extracted from groundwater taken from different monitoring wells revealed a maximum enrichment in carbon isotope ratio of +4.9‰ compared to the source of parathion, providing evidence that in situ hydrolysis took place. Calculations based on the Rayleigh-equation approach indicated that the natural attenuation of parathion was up to 8.6% by hydrolysis under neutral and acidic conditions. In degradation experiments with aerobic and anaerobic parathion-degrading microbes, no carbon and hydrogen isotope fractionation of parathion were observed. For the first time, CSIA has been applied for the exclusive assessment of the hydrolysis of phosphorothioate-containing organophosphorus pesticides at a contaminated field site.

Non-photochemical catalytic hydrolysis of methyl parathion using core-shell Ag@TiO2 nanoparticles.

Highly water-dispersible core–shell Ag@TiO2 nanoparticles were prepared and shown to be catalytically active for the rapid degradation of the organothiophosphate pesticide methyl parathion (MeP). Formation of the hydrolysis product, p-nitrophenolate was monitored at pH 7.5 and 8.0, using UV-Vis spectroscopy. 31P NMR spectroscopy confirmed that hydrolysis is the predominant pathway for substrate breakdown under non-photocatalytic conditions. We have demonstrated that the unique combination of TiO2 with silver nanoparticles is required for catalytic hydrolysis with good recyclability. This work represents the first example of MeP degradation using TiO2 doped with AgNPs under mild and ambient conditions. Analysis of catalytic data and a proposed dark mechanism for MeP hydrolysis using core–shell Ag@TiO2 nanoparticles are described.

Characterizing chemical transformation of organophosphorus compounds by 13C and 2H stable isotope analysis

Continuous and excessive use of organophosphorus compounds (OPs) has led to environmental contaminations which raise public concerns. This study investigates the isotope fractionation patterns of OPs in the aquatic environment dependence upon hydrolysis, photolysis and radical oxidation processes. The hydrolysis of parathion (EP) and methyl parathion (MP) resulted in significant carbon fractionation at lower pH (pH2–7, εC=−6.9~−6.0‰ for EP, −10.5~−9.9‰ for MP) but no detectable carbon fractionation at higher pH (pH12). Hydrogen fractionation was not observed during any of the hydrolysis experiments. These results indicate that compound specific isotope analysis (CSIA) allows distinction of two different pH-dependent pathways of hydrolysis. Carbon and hydrogen isotope fractionation were determined during UV/H2O2 photolysis of EP and tris(2-chloroethyl) phosphate (TCEP). The constant δ2H values determined during the OH radical reaction of EP suggested that the rate-limiting step proceeded through oxidative attack by OH radical on the PS bond. The significant H isotope enrichment suggested that OH radical oxidation of TCEP was caused by an H-abstraction during the UV/H2O2 processes (εH=−56±3‰). Fenton reaction was conducted to validate the H isotope enrichment of TCEP associated with radical oxidation, which yielded εH of −34±5‰. Transformation products of OPs during photodegradation were identified using Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS). This study highlights that the carbon and hydrogen fractionation patterns have the potential to elucidate the transformation of OPs in the environment.

Kinetic Investigation of Micellar Promoted Pyridine based Oximate and Hydroxamate Catalysis on Phosphotriester Pesticides

The nucleophilic hydrolysis of paraoxon, parathion and fenitrothion by pyridine oximate (PyOx−) and hydroxamate (PyHA−) has been studied in aqueous and cationic micellar media. A noticeable kinetic changes has been observed at pH > pK a due to effective nucleophilicity of oximate (–CH=NO−) and hydroxamate (–CONHO−) functions. The Ox− nucleophile shows large reactivity than corresponding HA−. The reactivity of nucleophiles toward the electrophilic center of P=O and P=S bond of phosphate ester shows prominent effect in the presence of cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB) micelles than aqueous media. The adjacent lone pair of electron in nitrogen atom on the nucleophile moiety of 2-PyOx and 2-PyHA helps to augment the reactivity compared to presence in remote of 4-PyOx and 4-PyHA nucleophile. The application of the pseudophase model of micellar catalysis showed that the ratio k 2 m/k 2 w is higher for the reaction of esters.

Biotransformation of methyl parathion by marine-derived fungi isolated from ascidian Didemnum ligulum

Abstract This paper describes the biotransformation of methyl parathion by marine-derived fungi isolated from ascidian Didemnum ligulum. Seventeen strains were screened by their growth in solid culture medium containing different concentrations of methyl parathion (120 mg L −1 , 240 mg L −1 and 360 mg L −1 ). Three strains with potential to degrade methyl parathion were identified as Penicillium citrinum (DL4M3), P. citrinum (DL9M3) and Fusarium proliferatum (DL11A). When selected for experiments in liquid medium to quantify the biodegradation of methyl parathion, they were able to completely degrade it in 20 d. However, when comparing the hydrolysis of methyl parathion catalyzed by fungi with the chemical hydrolysis (abiotic control), there was no significant differences in the disappearance of the pesticide in both reactions. On the other hand, F. proliferatum DL11A strain was able to reduce the concentration of p -nitrophenol, the main metabolite of methyl parathion hydrolysis, promoting 90% of biodegradation/bioconjugation of p -nitrophenol in 30 d.

Kinetic analysis of the hydrolysis of methyl parathion using citrate-stabilized 10 nm gold nanoparticles.

"Ligand-free" citrate-stabilized 10 nm gold nanoparticles (AuNPs) promote the hydrolysis of the thiophosphate ester methyl parathion (MeP) on the surface of gold as a function of pH and two temperature values. At 50 °C, the active surface gold atoms show catalytic turnover ∼4 times after 8 h and little turnover of gold surface atoms at 25 °C with only 40% of the total atoms being active. From Michaelis-Menten analysis, k(cat) increases between pH 8 and 9 and decreases above pH 9. A global analysis of the spectral changes confirmed the stoichiometric reaction at 25 °C and the catalytic reaction at 50 °C and mass spectrometry confirmed the identity of p-nitrophenolate (PNP) product. Additional decomposition pathways involving oxidation and hydrolysis independent of the formation of PNP were also seen at 50 °C for both catalyzed and un-catalyzed reactions. This work represents the first kinetic analysis of ligand-free AuNP catalyzed hydrolysis of a thiophosphate ester.

Covalent fabrication of methyl parathion hydrolase on gold nanoparticles modified carbon substrates for designing a methyl parathion biosensor

A biosensor based on AuNP modified GC electrodes has been developed for direct detection of methyl parathion. AuNP can be introduced to mixed monolayers of aryldiazonium salt modified GC electrodes by Au–C bonding through aryldiazonium salt chemistry, which provides a stable interface showing efficient electron transfer between biomolecules and electrodes. PEG molecules were introduced to the interface to resist non-specific protein adsorption. AuNP surfaces were further modified with 4-carboxyphenyl followed by covalent immobilization of methyl parathion hydrolase (MPH), a specific biocatalytic enzyme to methyl parathion. Exposure of this interface to methyl parathion resulted in a change in amperometric signal due to the MPH catalytic hydrolysis of methyl parathion producing electroactive compound 4-nitrophenol. This biosensor shows high selectivity, specificity, reproducibility and stability, and is functional for the detection of methyl parathion in real samples. The linear range for detection of methyl parathion is 0.2–100ppb with a detection limit of 0.07ppb in 0.1M phosphate buffer at pH 7.0.

Bio-fabrication of gold nanoparticles using aqueous extract of red tomato and its use as a colorimetric sensor

In this work, we report a green method for the synthesis of gold nanoparticles (GNP) using the aqueous extract of red tomato (Lycopersicon esculentum). We believe that citric acid and ascorbic acid present in tomato juice are responsible for the reduction of gold ions. This biosynthesized GNP in the presence of sodium dodecyl sulfate has been used as a colorimetric sensor to detect and estimate the pesticide, methyl parathion. The GNP in the presence of methyl parathion shows a new peak at 400 nm due to the formation of 4-nitrophenolate ion by catalytic hydrolysis of methyl parathion in alkaline medium. A calibration curve between the absorption coefficients of the 400-nm peak versus the concentration of the pesticide allows the quantitative estimation of the 4-nitrophenolate ion, thereby enabling indirect estimation of methyl parathion present in the system.

Electronic effects on the reactivity of copper mono-bipyridine complexes

Electronic effects on the synthesis, structure and reactivity of copper 2,2′-bipyridine (bpy) complexes of formula [Cu(4,4′-R2-2,2′-bipyridine)]Cl2, where R=Cl, CH3, OCH3, and [Cu(4,4′-R2-2,2′-bipyridine)](NO3)2, where R=NO2, Cl, are reported. Pure complexes were formed, as shown by elemental analysis, for mono bpy Cu complexes when bpy ligands with groups R=Cl, CH3 or OCH3 were pre-dissolved in chloroform and added to methanol solution of CuCl2 in a 1:1 molar ratio (compounds 1–3). Mono bpy Cu complexes were obtained when bpy ligands with groups R=Cl and NO2 were pre-dissolved in THF and added to methanol solution of Cu(NO3)2 in a 1:1 molar ratio (compounds 4 and 5). Under the same conditions, for R=OCH3 the bis bipyridine complex [Cu(4,4′-(OCH3)2-2,2′-bipyridine)2(NO3)](NO3) (6) was formed. Suitable crystals of 4 and 6·CH3OH for X-ray analysis were formed by the slow evaporation of solvent. The main electronic effect for the catalytic hydrolysis of methyl parathion by Cu(4,4′-R2-2,2-bipyridine)2+(aq), where R=Cl, H and CH3, was a shift in the acid dissociation constant of coordinated water and a small increase in the second order rate constant, k2, measured at pH 9.1.

Accelerating the initial rate of hydrolysis of methyl parathion with laser excitation using monolayer protected 10 nm Au nanoparticles capped with a Cu(bpy) catalyst

Using a low power green laser, we have demonstrated a rate acceleration of ~2-fold for the hydrolysis of methyl parathion by irradiating the plasmon absorption band of Au nanoparticles capped with a Cu(bpy) catalyst.

Probing the simulant behavior of PNPDPP toward parathion and paraoxon: A computational study

The extreme toxicity of organophosphorus nerve agents and pesticides mandates to employ models or simulants in place of the actual compounds in the laboratory. The importance of simulants is known, however, their efficacy for direct comparison with the toxic organophosphorus compounds is not well documented. We have examined the potential energy surfaces (PES) for the alkaline hydrolysis of pesticides like paraoxon (diethyl 4-nitrophenyl phosphate), parathion (O,O-diethyl O-4-nitrophenyl phosphorothioate) and PNPDPP (4-nitrophenyl diphenyl phosphate), a simulant with MP2/6-311+G*//B3LYP/6-311+G*+ΔGsolv (HF/6-31+G*) level of theory. The effect of aqueous solvation was considered with the Integral Equation Formalism Polarizable Continuum Model (IEF-PCM). The alkaline hydrolysis of these organophosphorus compounds reveals that the reaction proceeds through the attack of hydroxide ion at the phosphorus center to form a pentacoordinate intermediate. The calculated free energies of activation for the alkaline hydrolysis of paraoxon and parathion are in good agreement with the available experimental activation free energies. The computed results show that the reaction profiles for the alkaline hydrolysis of paraoxon, parathion and PNPDPP are largely similar; however, the rate of hydrolysis of parathion may be higher than that of paraxon and PNPDPP. Such difference arises due to the less electrophilic nature of the phosphorus atom of parathion molecule as observed in the charge analysis study. The conceptual DFT analysis also showed the similar trend for the alkaline hydrolysis of paraoxon, parathion and PNPDPP with hydroxide anion. This computational study provides a quantitative support toward the use of PNPDPP as a simulant for organophosphorus compounds, which cannot be used directly for the laboratory purposes.

Phytoextraction et biodégradation dynamisée : une approche interdisciplinaire inventive au service de l'environnement

Human activities are the cause of dispersion of dangerous pollutants. Biocides, such as parathion, and heavy metals such as copper, are very demonstrative examples. Parathion and its derivatives are potent insecticides and fungicides. However, they are extremely toxic to all forms of animal life, and this because of their chemical nature, they are phosphorothioates. Copper salts are persistent and widespread polluants, which in high concentrations are harmful to mammals and highly toxic to marine organisms. For the first time, it is proposed to combine two innovative and sustainable strategies to remediate mineral and organic pollution. Aquatic hyperaccumulators of copper are used to phytoextract salts of Cu(II) in pools mimicking contaminated areas. Biomass loaded with metal salts is then transformed into a catalyst for hydrolysis of parathion. A 31P NMR study clearly shows that copper salts derived from vegetables accelerate the degradation of parathion unequivocally.

Microbial biosensor for detection of methyl parathion using screen printed carbon electrode and cyclic voltammetry

Whole cells of recombinant Escherichia coli were immobilized on the screen printed carbon electrode (SPCE) using glutaraldehyde. Recombinant E. coli was having high periplasmic expression of organophosphorus hydrolase enzyme, which hydrolyzes the methyl parathion into two products, p-nitrophenol and dimethyl thiophosphoric acid. Cells immobilized SPCE was studied under SEM. Cells immobilized SPCE was associated with cyclic voltammetry and cyclic voltammograms were recorded before and after hydrolysis of methyl parathion. Detection was calibrated based on the relationship between the changes in the current observed at +0.1 V potential, because of redox behavior of the hydrolyzed product p-nitrophenol. As concentration of methyl parathion was increased the oxidation current also increased. Only 20 μl volume of the sample was required for analysis. Detection range of biosensor was calibrated between 2 and 80 μM of methyl parathion from the linear range of calibration plot. A single immobilized SPCE was reused for 32 reactions with retention of 80% of its initial enzyme activity.

Zinc(II) tweezers containing artificial peptides mimicking the active site of phosphotriesterase: The catalyzed hydrolysis of the toxic organophosphate parathion

Two new ligand-containing histidine based on N, N′, N″-tris(N-benzyl- l-histidinyl)tri(2-aminoethyl)amine, L 1 , namely N, N′, N″-tris[(1S)-2-methoxy-2-oxy-1-(1-benzylimidazol-4-ylmethyl)]nitrilotriacetamide L 2 and N, N′, N″-tris{N-benzyl-N-[N-benzyl-N-(N-benzyl- l-histidinyl)- l-histidinyl]- l-histidinyl}tri(2-aminoethyl)amine L 3 were prepared. Zinc(II) binding studies by these ligand systems were analyzed by means of potentiometric and 1H NMR titrations in aqueous methanol (33 % v/ v). Subsequently their zinc(II) complexes [ L 1 Zn(H 2O)](ClO 4) 2·HClO 4 ( 1), [ L 2 Zn(OH 2)](ClO 4) 2·H 2O ( 2), and ([ L 3 Zn 3(H 2O) 3](ClO 4) 6·3HClO 4·5H 2O ( 3), respectively were synthesized and characterized. The reactivity of the trinuclear complex ( 3) toward the hydrolysis of the toxic organophosphate parathion was investigated and compared with that of the mononuclear reference complex ( 1). From the pH dependence of the apparent rate constants, and the deprotonation constant (p K a) of the coordinated water molecules in ( 1), the active species were confirmed to be {[H L 1 Zn(OH)] 2+/[ L 1 Zn(H 2O)] 2+} at pH 8.5. The trizinc complex ( 3) effects hydrolysis of parathion, with three times rate enhancement over the mononuclear ( 1), indicating that cooperative action of the three zinc centers is limited.