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Proteins Jan 2024Methyl parathion hydrolase (MPH) is an enzyme of the metallo-β-lactamase superfamily, which hydrolyses a wide range of organophosphates (OPs). Recently, MPH has...
Methyl parathion hydrolase (MPH) is an enzyme of the metallo-β-lactamase superfamily, which hydrolyses a wide range of organophosphates (OPs). Recently, MPH has attracted attention as a promising enzymatic bioremediator. The crystal structure of MPH enzyme shows a dimeric form, with each subunit containing a binuclear metal ion center. MPH also demonstrates metal ion-dependent selectivity patterns. The origins of these patterns remain unclear but are linked to open questions about the more general role of metal ions in functional evolution and divergence within enzyme superfamilies. We aimed to investigate and compare the binding of different OP pesticides to MPH with cobalt(II) metal ions. In this study, MPH was modeled from Ochrobactrum sp. with different OP pesticides bound, including methyl paraoxon and dichlorvos and profenofos. The docked structures for each substrate optimized by DFT calculation were selected and subjected to atomistic molecular dynamics simulations for 500 ns. It was found that alpha metal ions did not coordinate with all the pesticides. Rather, the pesticides coordinated with less buried beta metal ions. It was also observed that the coordination of beta metal ions was perturbed to accommodate the pesticides. The binding free energy calculations and structure-based pharmacophore model revealed that all the three substrates could bind well at the active site. However, profenofos exhibit a stronger binding affinity to MPH in comparison to the other two substrates. Therefore, our findings provide molecular insight on the binding of different OP pesticides which could help us design the enzyme for OP pesticides degradation.
Topics: Methyl Parathion; Organophosphates; Hydrolases; Ochrobactrum; Phosphoric Monoester Hydrolases; Pesticides; Metals; Ions
PubMed: 37646471
DOI: 10.1002/prot.26579 -
The Journal of Pharmacology and... Jan 2024Organophosphate (OP) compounds are highly toxic and include pesticides and chemical warfare nerve agents. OP exposure inhibits the acetylcholinesterase enzyme, causing...
Organophosphate (OP) compounds are highly toxic and include pesticides and chemical warfare nerve agents. OP exposure inhibits the acetylcholinesterase enzyme, causing cholinergic overstimulation that can evolve into status epilepticus (SE) and produce lethality. Furthermore, OP-induced SE survival is associated with mood and memory dysfunction and spontaneous recurrent seizures (SRS). In male Sprague-Dawley rats, we assessed hippocampal pathology and chronic SRS following SE induced by administration of OP agents paraoxon (2 mg/kg, s.c.), diisopropyl fluorophosphate (4 mg/kg, s.c.), or O-isopropyl methylphosphonofluoridate (GB; sarin) (2 mg/kg, s.c.), immediately followed by atropine and 2-PAM. At 1-hour post-OP-induced SE onset, midazolam was administered to control SE. Approximately 6 months after OP-induced SE, SRS were evaluated using video and electroencephalography monitoring. Histopathology was conducted using hematoxylin and eosin (H&E), while silver sulfide (Timm) staining was used to assess mossy fiber sprouting (MFS). Across all the OP agents, over 60% of rats that survived OP-induced SE developed chronic SRS. H&E staining revealed a significant hippocampal neuronal loss, while Timm staining revealed extensive MFS within the inner molecular region of the dentate gyrus. This study demonstrates that OP-induced SE is associated with hippocampal neuronal loss, extensive MFS, and the development of SRS, all hallmarks of chronic epilepsy. SIGNIFICANCE STATEMENT: Models of organophosphate (OP)-induced SE offer a unique resource to identify molecular mechanisms contributing to neuropathology and the development of chronic OP morbidities. These models could allow the screening of targeted therapeutics for efficacious treatment strategies for OP toxicities.
Topics: Rats; Male; Animals; Rats, Sprague-Dawley; Mossy Fibers, Hippocampal; Organophosphates; Acetylcholinesterase; Status Epilepticus; Epilepsy; Seizures; Disease Models, Animal
PubMed: 37643794
DOI: 10.1124/jpet.123.001739 -
Micromachines Aug 2023The ongoing advancement in the synthesis of new nanomaterials has accelerated the rapid development of non-enzymatic pesticide sensors based on electrochemical...
Development and Characterization of Nano-Ink from Silicon Carbide/Multi-Walled Carbon Nanotubes/Synthesized Silver Nanoparticles for Non-Enzymatic Paraoxon Residuals Detection.
The ongoing advancement in the synthesis of new nanomaterials has accelerated the rapid development of non-enzymatic pesticide sensors based on electrochemical platforms. This study aims to develop and characterize Nano-ink for applying organophosphorus pesticides using paraoxon residue detection. Multi-walled carbon nanotubes, silicon carbide, and silver nanoparticles were used to create Nano-ink using a green synthesis process in 1:1:0, 1:1:0.5, and 1:1:1 ratios, respectively. These composites were combined with chitosan of varying molecular weights, which served as a stabilizing glue to keep the Nano-ink employed in a functioning electrode stable. By using X-ray powder diffraction, Raman spectroscopy, energy dispersive X-ray spectroscopy, and a field emission scanning electron microscope, researchers were able to examine the crystallinity, element composition, and surface morphology of Nano-ink. The performance of the proposed imprinted working electrode Nano-ink was investigated using cyclic voltammetry and differential pulse voltammetry techniques. The Cyclic voltammogram of Ag NPs/chitosan (medium, 50 mg) illustrated high current responses and favorable conditions of the Nano-ink modified electrode. Under the optimized conditions, the reduction currents of paraoxon using the DPV techniques demonstrated a linear reaction ranging between 0.001 and 1.0 µg/mL (R = 0.9959) with a limit of detection of 0.0038 µg/mL and a limit of quantitation of 0.011 µg/mL. It was concluded that the fabricated Nano-ink showed good electrochemical activity for non-enzymatic paraoxon sensing.
PubMed: 37630149
DOI: 10.3390/mi14081613 -
Toxics Aug 2023Organophosphate pesticides (OPs) are toxic substances that contaminate aquatic environments, interfere with the development of the nervous system, and induce...
Organophosphate pesticides (OPs) are toxic substances that contaminate aquatic environments, interfere with the development of the nervous system, and induce Neurodevelopmental Toxicity (NDT) in animals and humans. The canonical mechanism of OP neurotoxicity involves the inhibition of acetylcholinesterase (AChE), but other mechanisms non-AChE are also involved and not fully understood. We used network toxicology and molecular docking to identify molecular targets and toxicity mechanisms common to OPs. Targets related to diazinon-oxon, chlorpyrifos oxon, and paraoxon OPs were predicted using the Swiss Target Prediction and PharmMapper databases. Targets related to NDT were compiled from GeneCards and OMIM databases. In order to construct the protein-protein interaction (PPI) network, the common targets between OPs and NDT were imported into the STRING. Network topological analyses identified EGFR, MET, HSP90AA1, and SRC as hub nodes common to the three OPs. Using the Reactome pathway and gene ontology, we found that signal transduction, axon guidance, cellular responses to stress, and glutamatergic signaling activation play key roles in OP-induced NDT.
PubMed: 37624215
DOI: 10.3390/toxics11080710 -
Mutation Research. Genetic Toxicology... 2023We tested the hypothesis that the pesticides paraoxon and glyphosate cause DNA double-strand breaks (DSB) by poisoning the enzyme Type II topoisomerase (topo II)....
We tested the hypothesis that the pesticides paraoxon and glyphosate cause DNA double-strand breaks (DSB) by poisoning the enzyme Type II topoisomerase (topo II). Peripheral lymphocytes in G0 phase, treated with the pesticides, plus or minus ICRF-187, an inhibitor of Topo II, were stimulated to proliferate; induced cytogenetic damage was measured. Micronuclei, chromatin buds, nucleoplasmic bridges, and extranuclear fragments were induced by treatments with the pesticides, irrespective of the pre-treatment with ICRF-187. These results indicate that the pesticides do not act as topo II poisons. The induction of DSB may occur by other mechanisms, such as effects on other proteins involved in recombination repair.
Topics: Dexrazoxane; Paraoxon; Topoisomerase II Inhibitors; Poisons; DNA Topoisomerases, Type II; DNA; Pesticides; Glyphosate
PubMed: 37567644
DOI: 10.1016/j.mrgentox.2023.503657 -
Indian Journal of Pharmacology 2023Human paraoxonase 1 (PON1) enzyme protects against atherosclerosis by preventing low-density lipoprotein from oxidative modification. Upregulation of PON1 enzymatic...
Human paraoxonase 1 (PON1) enzyme protects against atherosclerosis by preventing low-density lipoprotein from oxidative modification. Upregulation of PON1 enzymatic activity is suggested to contribute to atheroprotective potential of statins. Glutamine (Q) to arginine (R) at site 192 and leucine (L) to methionine (M) substitution at site 55 polymorphisms influence the PON1 activity. The study assessed the role of PON1 polymorphisms on lipid-lowering and PON1-modulating activity of statins in a Western Indian cohort of patients with dyslipidemia. Lipid profile and PON1 activity were determined at baseline and 3 months after initiation of statin treatment. PON1 genotypes (QQ, QR, RR; LL, LM, and MM) were determined by PCR-RFLP. Paraoxon was used as a substrate for assessing PON1 activity by spectrophotometry. A total of 140 statin-naïve patients were enrolled; of them, 116 were available for final analysis. Fifty-seven (50%) had QQ, 39 (35%) had QR, and 17 (15%) had RR genotypes. Seventy-six (67%) patients had LL, 35 (31%) had LM, and 2 (2%) had MM genotypes. We observed no impact of PON1 polymorphisms on lipid parameters posttreatment. A significant increase was observed in the serum PON1 activity from a median (range) of 47.92 U/L (9.03-181.25) to 72.22 U/L (7.64-244.44) (P < 0.05) following statin treatment, which was independent from high-density lipoprotein (HDL) concentration. This increase was significantly greater in QQ compared to QR and RR genotypes (P = 0.01). To conclude, the important antioxidant properties of statins are exerted via the rise in serum PON1 activity, independent of HDL cholesterol concentrations. The increase was greater in individuals with QQ genotype. Future large-scale studies will validate the premise that QQ homozygotes see added benefits from statin treatment compared to R carriers. In the meantime, PON1 enzymatic activity remains an important marker to be measured while assessing pleotropic effects of statins in CAD.
Topics: Humans; Aryldialkylphosphatase; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Antioxidants; Prospective Studies; Genotype; Lipoproteins, HDL; Phenotype
PubMed: 37555413
DOI: 10.4103/ijp.IJP_215_20 -
Talanta Jan 2024A novel colorimetric biosensor for the sensitive and selective detection of an organophosphate pesticide, paraoxon ethyl (POE), was developed based on its inhibitory...
A novel colorimetric biosensor for the sensitive and selective detection of an organophosphate pesticide, paraoxon ethyl (POE), was developed based on its inhibitory effect on the acetylcholine esterase (AChE) enzyme. The bis-neocuproine copper (II) complex ([Cu(Nc)]) known as the CUPRAC reagent, was used as a chromogenic oxidant in the AChE inhibition-based biosensors for the first time. To initiate the biosensor, an enzymatic reaction takes place between AChE and its substrate acetylthiocholine (ATCh). Then, enzymatically produced thiocholine (TCh) reacts with the light blue [Cu(Nc)] complex, resulting in the oxidation of TCh to its disulfide form. On the other hand, [Cu(Nc)] reduces to a yellow-orange cuprous complex ([Cu(Nc)]) which gives maximum absorbance at 450 nm. However, the absorbance of [Cu(Nc)] proportionally decreased with the addition of POE because the inhibition of AChE by the organophosphate pesticide reduced the amount of TCh that would give a colorimetric reaction with the CUPRAC reagent. Based on this strategy, the linear response range of a colorimetric biosensor was found to be between 0.15 and 1.25 μM with a detection limit of 0.045 μM. The fabricated biosensor enabled the selective determination of POE in the presence of some other pesticides and metal ions. The recovery results between 92% and 104% were obtained from water and soil samples spiked with POE, indicating that the determination of POE in real water and soil samples can be performed with this simple, accurate, sensitive, and low-cost colorimetric biosensor.
Topics: Acetylcholinesterase; Oxidants; Indicators and Reagents; Copper; Colorimetry; Paraoxon; Pesticides; Insecticides; Organophosphorus Compounds; Water; Biosensing Techniques; Soil
PubMed: 37499364
DOI: 10.1016/j.talanta.2023.124962 -
Talanta Jan 2024Most of covalent organic frameworks (COFs) are non or weakly emissive due to either the molecular thermal motion-mediated energy dissipation or the aggregation-caused...
Most of covalent organic frameworks (COFs) are non or weakly emissive due to either the molecular thermal motion-mediated energy dissipation or the aggregation-caused quenching (ACQ) effect. Herein, we synthesize an imine-linked COF (TFPPy-TPh-COF) with high electrochemiluminescence (ECL) emission and the capability of eliminating the ACQ effect and further construct an ECL sensor for malathion detection. The imine-linked COF is obtained by the condensation reaction of (1,1':3',1″-terphenyl)-4,4″-diamine (TPh) and 1,3,6,8-tetrakis(p-formylphenyl)pyrene (TFPPy), and it has higher ECL efficiency than TFPPy aggregates due to the separation of ACQ luminophores (i.e., TFPPy) from each other by TPh and the restriction of intramolecular motions of TFPPy and TPh to reduce the nonradiative decay. The efficient quenching of ECL is achieved by electrochemiluminescence resonance energy transfer (ERET) from the excited state of the TFPPy-TPh-COF to zeolite imidazolate framework-8 (ZIF-8) and the steric hindrance of ZIF-8. Acetylcholinesterase (AChE) can enzymatically hydrolyze acetylcholine (ACh) to generate acetic acid. The resultant acetic acid can trigger the dissolution of ZIF-8 to produce an enhanced ECL signal. Malathion as an organophosphorus pesticide serves as an AChE inhibitor to prevent the production of acetic acid, inducing the decrease of ECL signal. This sensor displays a limit of detection (LOD) of 2.44 pg/mL and a wide dynamic detection range of 0.01-1000 ng/mL. Furthermore, it can be used to detect other organophosphates pesticides (e.g., methidathion, chlorpyrifos, and paraoxon) and measure malathion in real samples (i.e., pakchoi, lettuce, and apples).
Topics: Metal-Organic Frameworks; Pesticides; Organophosphorus Compounds; Malathion; Acetylcholinesterase; Luminescent Measurements; Biosensing Techniques; Electrochemical Techniques
PubMed: 37481885
DOI: 10.1016/j.talanta.2023.124964 -
The Journal of Rheumatology Jul 2023This posthoc analysis investigated the relationship between paraoxonase-1 (PON1) genotype and activity, and risk of major adverse cardiovascular events (MACE) and...
Relationship Between Paraoxonase-1 Genotype and Activity, and Major Adverse Cardiovascular Events and Malignancies in Patients With Rheumatoid Arthritis Receiving Tofacitinib.
OBJECTIVE
This posthoc analysis investigated the relationship between paraoxonase-1 (PON1) genotype and activity, and risk of major adverse cardiovascular events (MACE) and malignancies in clinical studies of tofacitinib in patients with rheumatoid arthritis (RA).
METHODS
Data were pooled from 9 phase II/III studies and the associated long-term extension studies (all completed by October 2017). PON1 activities in plasma were measured using paraoxon (paraoxonase activity), dihydrocoumarin (lactonase activity), and phenylacetate (arylesterase activity) as substrates. PON1 Q192R genotype effect on baseline PON1 activity was assessed using linear regression for each study, with fixed-effects metaanalysis across studies. MACE and malignancy risk by time-varying enzyme activity was determined using Cox proportional hazards regression.
RESULTS
The analysis included 1969 patients with RA. Compared with the QQ genotype, the RR genotype had a significant positive association with baseline paraoxonase activity and a significant negative association with baseline lactonase and arylesterase activity (all < 0.001). Time-varying models demonstrated a significant association of increased paraoxonase activity over time with lower risk of MACE ( < 0.001) and malignancies (excluding nonmelanoma skin cancer [NMSC]; ≤ 0.05), even after controlling for risk factors identified in univariate analysis and RA disease activity. A similar trend was observed for lactonase and arylesterase for MACE.
CONCLUSION
Higher paraoxonase activity over time was associated with significantly reduced risk of future MACE and malignancies (excluding NMSC), but not NMSC, in patients with RA receiving tofacitinib. Further investigation of PON1 as a novel functional lipid biomarker of MACE/malignancy risk in patients with RA is warranted. (ClinicalTrials.gov: NCT01059864, NCT00550446, NCT00687193, NCT00960440, NCT00814307, NCT00856544, NCT00853385, NCT00847613, NCT01039688, NCT00413699, NCT00661661).
PubMed: 37453736
DOI: 10.3899/jrheum.2023-0112 -
ACS Applied Materials & Interfaces Jul 2023The development of bio-MOFs or MOF biocomposites through the combination of MOFs with biopolymers offers the possibility of expanding the potential applications of MOFs,...
The development of bio-MOFs or MOF biocomposites through the combination of MOFs with biopolymers offers the possibility of expanding the potential applications of MOFs, making use of more environmentally benign processes and reagents and giving rise to a new generation of greener and more bio-oriented composite materials. Now, with the increasing use of MOFs for biotechnological applications, the development of new protocols and materials to obtain novel bio-MOFs compatible with biomedical or biotechnological uses is needed. Herein, and as a proof of concept, we have explored the possibility of using short-peptide supramolecular hydrogels as media to promote the growth of MOF particles, giving rise to a new family of bio-MOFs. Short-peptide supramolecular hydrogels are very versatile materials that have shown excellent in vitro and in vivo biomedical applications such as tissue engineering and drug delivery vehicles, among others. These peptides self-assemble by noncovalent interactions, and, as such, these hydrogels are easily reversible, being more biocompatible and biodegradable. These peptides can self-assemble by a multitude of stimuli, such as changes in pH, temperature, solvent, adding salts, enzymatic activity, and so forth. In this work, we have taken advantage of this ability to promote peptide self-assembly with some of the components required to form MOF particles, giving rise to more homogeneous and well-integrated composite materials. Hydrogel formation has been triggered using Zn salts, required to form ZIF-8, and formic acid, required to form MOF-808. Two different protocols for the in situ MOF growth have been developed. Finally, the MOF-808 composite hydrogel has been tested for the decontamination of water polluted with phosphate ions as well as for the catalytic degradation of toxic organophosphate methyl paraoxon in an unbuffered solution.
Topics: Metal-Organic Frameworks; Hydrogels; Salts; Peptides; Drug Delivery Systems
PubMed: 37390355
DOI: 10.1021/acsami.3c06943