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Chembiochem : a European Journal of... Mar 2021Quinone methide (QM) chemistry is widely applied including in enzyme inhibitors. Typically, enzyme-mediated bond breaking releases a phenol product that rearranges into...
Quinone methide (QM) chemistry is widely applied including in enzyme inhibitors. Typically, enzyme-mediated bond breaking releases a phenol product that rearranges into an electrophilic QM that in turn covalently modifies protein side chains. However, the factors that govern the reactivity of QM-based inhibitors and their mode of inhibition have not been systematically explored. Foremost, enzyme inactivation might occur in cis, whereby a QM molecule inactivates the very same enzyme molecule that released it, or by trans if the released QMs diffuse away and inactivate other enzyme molecules. We examined QM-based inhibitors for enzymes exhibiting phosphoester hydrolase activity. We tested different phenolic substituents and benzylic leaving groups, thereby modulating the rates of enzymatic hydrolysis, phenolate-to-QM rearrangement, and the electrophilicity of the resulting QM. By developing assays that distinguish between cis and trans inhibition, we have identified certain combinations of leaving groups and phenyl substituents that lead to inhibition in the cis mode, while other combinations gave trans inhibition. Our results suggest that cis-acting QM-based substrates could be used as activity-based probes to identify various phospho- and phosphono-ester hydrolases, and potentially other hydrolases.
Topics: Enzyme Inhibitors; Hydrolysis; Indolequinones; Organophosphates; Phosphoric Monoester Hydrolases
PubMed: 33105515
DOI: 10.1002/cbic.202000611 -
Chemico-biological Interactions Sep 2010The accepted target for organophosphorus agent (OP) binding to enzymes is the active site serine in the consensus sequence Gly X Ser X Gly. New motifs have been... (Review)
Review
The accepted target for organophosphorus agent (OP) binding to enzymes is the active site serine in the consensus sequence Gly X Ser X Gly. New motifs have been identified by using mass spectrometry to fragment OP-labeled peptides. It has been found that OP can make covalent bonds with tyrosine and lysine in proteins that have no active site serine. The OP-tyrosine bond is stable, and does not undergo the decay seen with OP-serine. Information on OP binding to tyrosine has been applied to diagnosis of OP exposure, through the use of mass spectrometry to detect OP-labeled albumin in human and animal plasma. It is expected that the new OP binding motif will aid in the search for a mechanism of low dose OP toxicity. It is hypothesized that proteins involved in axonal transport, especially proteins whose function depends on reversible phosphorylation, are prime candidates for a role in OP-induced neurodegeneration. Treatment of neurodegenerative disorders could be developed by identifying methods to reverse OP binding to tyrosine.
Topics: Animals; Catalytic Domain; Humans; Hydrolases; Lysine; Organophosphates; Protein Binding; Tyrosine
PubMed: 20211158
DOI: 10.1016/j.cbi.2010.03.002 -
Bioorganic Chemistry Jun 2017Based on the broad spectrum of biological activities associated with organophosphates, a novel type of this class of compounds was synthesized, bearing a nitrile group,...
Based on the broad spectrum of biological activities associated with organophosphates, a novel type of this class of compounds was synthesized, bearing a nitrile group, from the sodium alkoxide-catalyzed reaction of dialkylphosphites with γ-ketonitriles at 80°C under solvent-free conditions. A reaction mechanism involving a phospha-Brook type rearrangement is proposed. Eight title compounds were investigated for their in vitro inhibitory potency and selectivity against acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) using Ellman's spectrophotometric method. The synthesized derivatives exhibited mostly a moderate activity against both cholinesterases. The IC values for BChE were in a smaller concentration range (5.96-23.35µM) compared to those for AChE inhibition (9.61-53.74µM). The diethyl-3-cyano-1-p-tolylpropylphosphate which displayed the higher dual inhibitory potency towards both cholinesterases could be considered as a potential candidate for developing new drugs to treat Alzheimer's disease.
Topics: Acetylcholinesterase; Cholinesterase Inhibitors; Dose-Response Relationship, Drug; Humans; Molecular Docking Simulation; Molecular Structure; Organophosphates; Structure-Activity Relationship
PubMed: 28500956
DOI: 10.1016/j.bioorg.2017.05.008 -
Journal of Chromatography. B,... Jul 2017Tabun has been shown to form phosphylated adducts on tyrosine residues in albumin in vivo and in vitro. However, in this work, tabun-labeled lysine adducts were found in...
Tabun has been shown to form phosphylated adducts on tyrosine residues in albumin in vivo and in vitro. However, in this work, tabun-labeled lysine adducts were found in albumin. Three types of albumin were treated with overdose of tabun in vitro and 17 tabun-labeled lysine residues were found: K4, K12, K224, K377, and K524 in bovine albumin, K186, K188, K212, K329, K414, and K525 in leporine albumin, and K79, K186, K188, K212, K376, and K525 in rat albumin. To investigate the modification of tabun in vivo, three leporines were injected with 0.8×LD dose of tabun. The results showed that the labeled lysine residues in vivo, were consistent with modified lysines in vitro. Structure characteristics and the binding mode of 6 tabun-labeled lysines of leporine albumin were further analyzed using theory simulation and molecular docking in Discovery Studio. For the first time, we show that tabun-labeled lysine peptides are found in vivo and in vitro. These modified lysine peptides are good biomarkers for exposure to tabun in albumin of leporine and rat.
Topics: Amino Acid Sequence; Animals; Biomarkers; Chromatography, High Pressure Liquid; Lethal Dose 50; Lysine; Molecular Docking Simulation; Organophosphates; Peptides; Rabbits; Rats; Serum Albumin; Serum Albumin, Bovine; Tandem Mass Spectrometry; Tyrosine
PubMed: 28500932
DOI: 10.1016/j.jchromb.2017.04.047 -
Chemosphere May 2011Tris(2-chloroethyl)phosphates (TCEP) is a widely used flame retardant in the US. It has recently been identified as one of the most frequently detected contaminants in...
Tris(2-chloroethyl)phosphates (TCEP) is a widely used flame retardant in the US. It has recently been identified as one of the most frequently detected contaminants in US streams. This contaminant is of toxicological concern in sensitive coastal ecosystems such as estuaries and salt marshes. It is likely that reactions with reduced sulfur species such as polysulfides (S(n)(2-)), bisulfide (HS(-)), and thiophenolate (PhS(-)) present in anoxic subregions of coastal water bodies could have a significant impact on rates of removal of such a contaminant. The kinetics of reaction of reduced sulfur species with tris(2-chloroethyl)phosphate have been determined in well-defined aqueous solutions under anoxic conditions. Reactions were monitored at varying concentrations of reduced sulfur species to obtain the second-order rate constants from the observed pseudo-first-order rate constants. The determined second-order rate constant for the reaction of TCEP with polysulfide at 25°C is 5.0 (±1.4)×10(-4) M(-1) s(-1), with thiophenolate at 50°C is 34 (±2)×10(-4) M(-1) s(-1) and with bisulfide at 50°C is 0.9×10(-4) M(-1) s(-1), respectively. In addition, the degradation products of hydrolysis and the reactions with polysulfides, thiophenolate, and bisulfide with TCEP were studied with GC-FID and LC-MS-MS and were quantified.
Topics: Flame Retardants; Hydrolysis; Kinetics; Organophosphates; Seawater; Sulfides; Sulfur; Water Pollutants, Chemical
PubMed: 21419471
DOI: 10.1016/j.chemosphere.2011.02.040 -
Molecules (Basel, Switzerland) Jul 2017The albumin molecule, in contrast to many other plasma proteins, is not covered with a carbohydrate moiety and can bind and transport various molecules of endogenous and...
The albumin molecule, in contrast to many other plasma proteins, is not covered with a carbohydrate moiety and can bind and transport various molecules of endogenous and exogenous origin. The enzymatic activity of albumin, the existence of which many scientists perceive skeptically, is much less studied. In toxicology, understanding the mechanistic interactions of organophosphates with albumin is a special problem, and its solution could help in the development of new types of antidotes. In the present work, the history of the issue is briefly examined, then our in silico data on the interaction of human serum albumin with soman, as well as comparative in silico data of human and bovine serum albumin activities in relation to paraoxon, are presented. Information is given on the substrate specificity of albumin and we consider the possibility of its affiliation to certain classes in the nomenclature of enzymes.
Topics: Animals; Cattle; Enzyme Activation; Esterases; Humans; Hydrolysis; Ligands; Models, Molecular; Molecular Conformation; Organophosphates; Protein Binding; Serum Albumin; Substrate Specificity
PubMed: 28718803
DOI: 10.3390/molecules22071201 -
Biotechnology Letters Sep 2021An aptamer specifically binding to diethyl thiophosphate (DETP) was constructed and incorporated in an optical sensor and electrochemical techniques to enable the...
OBJECTIVE
An aptamer specifically binding to diethyl thiophosphate (DETP) was constructed and incorporated in an optical sensor and electrochemical techniques to enable the specific measurement of DETP as a metabolite and a biomarker of organophosphate exposure.
RESULTS
A DETP-bound aptamer was selected from the library using capillary electrophoresis-systematic evolution of ligands by exponential enrichment (CE-SELEX). A colorimetric method revealed that the aptamer had the highest affinity for DETP, with a mean K value (± SD) of 0.103 ± 0.014 µM. The docking results and changes in resistance showed that the selectivity of the aptamer for DETP was higher than that for the similar structures of dithiophosphate (DEDTP) and diethyl phosphate (DEP). The altered amplitude of cyclic voltammetry showed a linear range of DETP detection covering 0.0001-10 µg/ml with a limit of detection of 0.007 µg/ml. The recovery value of a real sample of pH 7 was 97.2%.
CONCLUSIONS
The current method showed great promise in using the DETP-specific aptamer to detect the exposure history to organophosphates by measuring their metabolites, although degradation of organophosphate parent compounds might occur.
Topics: Aptamers, Nucleotide; Biosensing Techniques; Calorimetry; Electrochemical Techniques; Humans; Molecular Docking Simulation; Organophosphates; Phosphates; SELEX Aptamer Technique; Sensitivity and Specificity
PubMed: 34231090
DOI: 10.1007/s10529-021-03158-2 -
Indoor Air Sep 2001The chlorinated organo-phosphate triesters, tris(2-chloroethyl)-phosphate (TCEP) and tris(monochloroisopropyl)-phosphate (TCPP), are employed in consumer articles for... (Comparative Study)
Comparative Study
The chlorinated organo-phosphate triesters, tris(2-chloroethyl)-phosphate (TCEP) and tris(monochloroisopropyl)-phosphate (TCPP), are employed in consumer articles for indoor usage, e.g. flame retardants and plasticizers in foam material as well as in paints, varnishes and wallpapers. As a result of this widespread usage, employing domestic dust as a matrix, both chemicals have been detected in the indoor environment. TCEP was present in 85% of a total of 983 samples, whereas TCPP was found in 60-90% of 436 cases (with levels ranging from 0.1 to 375 mg/kg). Since TCEP and TCPP residues in domestic dust are assumed to be condensates arising from primary sources, spot check analysis of various indoor materials was performed. The results show that soft foams, paints and wallpapers contained mainly TCEP, whereas in insulation and sealant foams high levels of TCPP were found. Moreover, TCEP can also be detected in indoor air in concentrations up to 6,000 ng/m3. On the basis of this data, we estimated the levels of indoor exposure via oral and inhalative ingestion.
Topics: Air Pollution, Indoor; Dust; Flame Retardants; Housing; Humans; Inhalation Exposure; Organophosphates; Paint; Plasticizers; Public Health
PubMed: 11521497
DOI: 10.1034/j.1600-0668.2001.011003145.x -
Tuning the Envelope Structure of Enzyme Nanoreactors for In Vivo Detoxification of Organophosphates.International Journal of Molecular... Oct 2023Encapsulated phosphotriesterase nanoreactors show their efficacy in the prophylaxis and post-exposure treatment of poisoning by paraoxon. A new enzyme nanoreactor...
Encapsulated phosphotriesterase nanoreactors show their efficacy in the prophylaxis and post-exposure treatment of poisoning by paraoxon. A new enzyme nanoreactor (E-nRs) containing an evolved multiple mutant (L72C/Y97F/Y99F/W263V/I280T) of phosphotriesterase (PTE) for in vivo detoxification of organophosphorous compounds (OP) was made. A comparison of nanoreactors made of three- and di-block copolymers was carried out. Two types of morphology nanoreactors made of di-block copolymers were prepared and characterized as spherical micelles and polymersomes with sizes of 40 nm and 100 nm, respectively. The polymer concentrations were varied from 0.1 to 0.5% (/) and enzyme concentrations were varied from 2.5 to 12.5 μM. In vivo experiments using E-nRs of diameter 106 nm, polydispersity 0.17, zeta-potential -8.3 mV, and loading capacity 15% showed that the detoxification efficacy against paraoxon was improved: the LD shift was 23.7xLD for prophylaxis and 8xLD for post-exposure treatment without behavioral alteration or functional physiological changes up to one month after injection. The pharmacokinetic profiles of i.v.-injected E-nRs made of three- and di-block copolymers were similar to the profiles of the injected free enzyme, suggesting partial enzyme encapsulation. Indeed, ELISA and Western blot analyses showed that animals developed an immune response against the enzyme. However, animals that received several injections did not develop iatrogenic symptoms.
Topics: Animals; Organophosphates; Paraoxon; Phosphoric Triester Hydrolases; Nanotechnology
PubMed: 37958742
DOI: 10.3390/ijms242115756 -
The Science of the Total Environment Jan 2023Evidence from in vitro and rodent studies suggests that organophosphate esters (OPEs) may disrupt sex steroid hormone homeostasis, but no human studies, to date, have...
BACKGROUND
Evidence from in vitro and rodent studies suggests that organophosphate esters (OPEs) may disrupt sex steroid hormone homeostasis, but no human studies, to date, have examined the effects of in utero exposure to OPEs on offspring reproductive development.
OBJECTIVE
Anogenital distance (AGD) is a sensitive biomarker of fetal hormonal milieu and has been used to assess reproductive toxicity. We evaluated the longitudinal effects of prenatal exposure to OPEs on the AGD of offspring from birth to 4 years.
METHODS
Based on Shanghai-Minhang Birth Cohort Study, pregnant women provided urine samples at a gestational age of 12-16 weeks, which were analyzed for eight OPE metabolites. AGD was measured in offspring at birth and 0.5, 1, and 4 years of age. We used generalized estimating equations (GEE) and Bayesian kernel machine regression (BKMR) models to estimate the associations of prenatal exposure to individual OPE metabolites and OPE mixtures with AGD stratified by sex.
RESULTS
A total of 733 mother-infant pairs were analyzed. Prenatal exposure to diphenyl phosphate and bis-(2-ethylhexyl) phosphate was associated with decreased AGD in boys in GEE models. Bis-(1-chloro-2-propyl) phosphate (BCIPP) showed a similar but marginally significant effect. Prenatal exposure to most OPE metabolites was associated with decreased AGD in girls, with the most profound association observed for bis (2-butoxyethyl) phosphate (BBOEP) and alkyl-OPEs. The OPE mixture was also inversely associated with AGD in both sexes. The single-exposure effects of BKMR models were largely consistent with those observed in the GEE models. In addition, alkyl-OPEs, particularly BBOEP, contributed the most to the decreased AGD in girls, while BCIPP contributed the most to the decreased AGD in boys.
CONCLUSIONS
This study provides the first human evidence that prenatal exposure to OPEs is associated with decreased AGD in offspring. The magnitude of these effects may vary depending on the structure of OPEs.
Topics: Male; Infant; Infant, Newborn; Humans; Female; Pregnancy; Prenatal Exposure Delayed Effects; Cohort Studies; Bayes Theorem; China; Organophosphates; Phosphates
PubMed: 36174683
DOI: 10.1016/j.scitotenv.2022.159050