Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.1.8 (cholinesterase)
 12,691 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Paraoxon and chlorpyrifos-oxon, the active metabolites of the organophosphorus insecticides parathion and chlorpyrifos, respectively, are hydrolyzed by an "A"-esterase, paraoxonase, which is present in the sera of several mammalian species. In this study, we investigated whether levels of serum paraoxonase activity in laboratory animals can influence the in vivo toxicity of paraoxon and chlorpyrifos-oxon. Paraoxonase was found to be 7-fold higher in rabbit serum than in rat serum. The dose of paraoxon required to produce similar signs of toxicity and similar degrees of cholinesterase inhibition in rats and rabbits (0.5 and 2.0 mg/kg, respectively) differed by 4-fold. Paraoxonase was then purified from rabbit serum and 8.35 units was injected in the tail veins of rats, increasing the peak hydrolytic activity of rat serum by 9-fold toward paraoxon and by 50-fold toward chlorpyrifos-oxon. The increase in serum paraoxonase/chlorpyrifos-oxonase activity was long-lasting, with a 2- and 10-fold increase, respectively, still present after 24 hr. Thirty minutes following enzyme injection, rats were challenged with an acute dose of paraoxon or chlorpyrifos-oxon given by the intravenous, intraperitoneal, dermal, or oral route. Cholinesterase activities were measured in plasma, red blood cells, brain, and diaphragm after 4 hr. Rats pretreated with paraoxonase exhibited less inhibition of cholinesterase than vehicle-treated controls following identical doses of paraoxon, particularly when the organophosphate was given iv or dermally. A very high degree of protection, particularly toward brain and diaphragm cholinesterase, was provided by paraoxonase pretreatment in animals challenged with chlorpyrifos-oxon by all routes. These results indicate that levels of serum paraoxonase activity can affect the toxicity of paraoxon and chlorpyrifos-oxon.
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PMID:Serum paraoxonase and its influence on paraoxon and chlorpyrifos-oxon toxicity in rats. 169 Apr 62

Various 4-arylthiomethyl-2-oxo-1,3-dioxole derivatives IIIa-o were synthesized. Their hydrolysis rates by arylesterase (EC 3.1.1.2) and cholinesterase (EC 3.1.1.8) in human serum were evaluated. Some of them were not hydrolyzed by cholinesterase, but were hydrolyzed easily by arylesterase. Among the substrates, sodium 4-((5-methyl-2-oxo-1,3-dioxol-4-yl)methylthio)benzenesulfonate (IIIg) was selected for its substrate reactivity toward arylesterase and its good water solubility. In addition, neither aliesterase (EC 3.1.1.1), acetylesterase (EC 3.1.1.6) nor cholesterol esterase (EC 3.1.1.13) hydrolyzed the compound. IIIg is thus concluded to be a specific substrate for arylesterase. Our assay system for serum arylesterase using IIIg can be readily applied to an automatic analyzer in the diagnosis of liver cirrhosis.
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PMID:2-Oxo-1,3-dioxoles as specific substrates for measurement of arylesterase activity. 193 62

In order to identify non-invasive, biochemical indicators of di(2-ethylhexyl)phthalate (DEHP) exposure, we have compared the effects in blood serum with biochemical effects in liver in rats fed a diet containing 0, 0.25, 0.75 and 2% DEHP for 2 weeks. After 3 days of treatment serum arylesterase activity levels and serum triglycerides were decreased to 60% and 20% of control values, respectively. After a 2-week treatment with DEHP the effects were generally stronger. Compared to a control group, serum arylesterase activity levels, serum triglycerides and serum cholesterol were decreased to 40%, 20% and 50%, respectively. Serum cholinesterase activity levels and serum albumin concentrations were increased by the DEHP treatment to 290% and 135% of control values, respectively. In the livers a hepatomegaly, an induction of cytochrome P-450 IVA1 and induction of the activity of palmitoyl-CoA oxidase and carnitine acetyl-CoA transferase was found to be 180%, 1080%, 1300% and 1700% of control values, respectively. The liver is a more sensitive target for DEHP exposure compared to the biochemical effects in serum, but determination of the serum parameters can be used to determine early biological effects of exposure to DEHP.
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PMID:Effect of di(2-ethylhexyl)phthalate on enzyme activity levels in liver and serum of rats. 227 65

The blood esterase mediating the hydrolysis of esmolol was characterized in several different species including man. In contrast to most ester-containing drugs, hydrolysis of esmolol was mediated by an esterase in the cytosol of red blood cells (RBC) in man and dogs and not in plasma or RBC membrane. Species differences in the esterase activity existed. Guinea pig and rat blood esterase activities were much greater than those in the dog followed by those in man. In addition, the esterase activity in rat and guinea pig blood was localized in plasma and not in RBC. Purified human serum cholinesterase, human RBC membrane acetylcholinesterase, human hemoglobin, human carbonic anhydrases A and B, and human and dog serum albumin were all inactive against esmolol. Esmolol esterase activity in human and dog blood was inhibited by sodium fluoride, EDTA, and p-hydroxymercuribenzoate, but not by echothiophate, eserine, and acetazolamide. In contrast, echothiophate and sodium fluoride, but not eserine, inhibited the esterase activity in rat and guinea pig plasma. Metabolic interaction studies indicated that acetylcholine, succinylcholine, procaine, and chloroprocaine did not interfere with the metabolism of esmolol by human and dog blood. Based on the results, it appeared that an arylesterase in human and dog RBC cytosol mediated the hydrolysis of esmolol while an aliphatic esterase mediated the hydrolysis of esmolol in guinea pig and rat plasma.
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PMID:Biochemical properties of blood esmolol esterase. 286 4

Paraoxon, 0,0-diethyl-0-p-nitrophenylphosphate is the highly toxic metabolite of parathion. The activity of paraoxonase, the enzyme which hydrolyses paraoxon in human serum shows a genetically influenced polymorphism with strong interethnic differences. The serum paraoxonase genotype has a significant influence on the paraoxon clearance and consequently on the toxic action of paraoxon and some related organophosphates and definitively protects the serum cholinesterase. Persons with low paraoxonase activity seem to be more endangered when handling parathion and related insecticides. More than 50% of all Europeans can be included in this group. The distribution of paraoxonase activity in human serum will be shown for samples which were collected from all over the world. As one moves from Europe in the direction of Africa and Asia the percentage of the low activity group decreases and was not even demonstrable in some tribes.
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PMID:Interethnic differences in the detoxification of organophosphates: the human serum paraoxonase polymorphism. 302 23

The effect of dietary exposures to peroxisome-proliferating, hypolipidemic agents on serum esterases was determined in rats and mice. Four genotypes of mice were fed nafenopin (1000 ppm) for six weeks and clofibrate (5000 ppm) was fed to young and aged rats for three weeks. The exposures significantly increased serum cholinesterase activity levels and decreased serum arylesterase activity levels in all groups of both species.
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PMID:Effect of peroxisome proliferating hypolipidemic agents on serum activity levels of arylesterase and cholinesterase in rats and mice. 338 Oct 6

The trichothecene T-2 toxin was rapidly hydrolyzed by rat liver microsomal fraction into HT-2 toxin which was the main metabolite. The metabolism was completely blocked by paraoxon, a serine esterase inhibitor, but not affected by EDTA or 4-hydroxy mercury benzoate, inhibitors of arylesterase and esterases containing SH-group in active site, respectively. Among the serine esterases carboxylesterase (EC 3.1.1.1), but not cholinesterase (EC 3.1.1.8) hydrolysed T-2 toxin to HT-2 toxin. Carboxylesterase activity from liver microsomes was separated into at least five different isoenzymes by isoelectric focusing, and only the isoenzyme of pI 5.4 was able to hydrolyse T-2 toxin to HT-2 toxin. The toxicity of T-2 toxin in mice was enhanced by pre-treatment with tri-o-cresyl phosphate (TOCP), a specific carboxylesterase inhibitor. This confirms the importance of carboxylesterase in detoxification of trichothecenes.
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PMID:Metabolism of T-2 toxin by rat liver carboxylesterase. 370 11

Ten different nonspecific esterases in both mouse (Mus musculus) and rat (Rattus norvegicus) testis were identified following the analysis of electrophoretic patterns using genetic, developmental, and biochemical criteria. None of the enzymes were unique to testis, although the pattern of activity was testis specific. The enzymes comprised, in each species, six carboxylesterases (EC 3.1.1.1), one arylesterase (EC 3.1.1.2), one acetylesterase (EC 3.1.1.6), and two butyrylesterases (tentative designation). Cholinesterase (EC 3.1.1.8) was not detected. Individual homology relationships were recognized between the two species for all of these activities, except three of the carboxylesterases; however, these were coded for by homologous gene clusters. Similarities between the two species extended to the developmental course of expression and the modulation of the pattern of activity by the testicular feminization (Tfm) mutation. We describe the effects of the sex reversal (Sxr) mutation in the mouse, as well as the distribution of individual activities between Leydig cells and seminiferous tubules. The results of earlier histochemical studies are interpreted in the light of the present investigation. The correspondence between mouse- and rat-testis esterases suggests that the results could serve as a basis for mammalian testis esterase systems in general.
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PMID:Nonspecific esterases of mammalian testis. Comparative studies on the mouse (Mus musculus) and rat (rattus norvegicus). 389 53

Patients with reactive systemic amyloidosis have a reduced ability to degrade amyloid A protein fibrils in vitro. The amyloid A degrading activity in serum has been attributed to a neutral serine protease or proteases. Our results show that patients with reactive systemic (amyloid A) amyloidosis have low activities of two serum esterases, namely, arylesterase and paraoxonase, whereas the activity of a third esterase, cholinesterase, is normal. The combination of reduced arylesterase (less than 55 kU/L) plus reduced paraoxonase activity (less than 35 U/L) was found in 32% of patients with rheumatoid arthritis complicated by amyloidosis, but in only 5% of a control nonamyloid patient group, including patients with rheumatoid arthritis, liver disease, and hypoalbuminemia (p less than 0.001). A significant correlation between serum arylesterase and amyloid A degrading activity was found (patients with rheumatoid arthritis plus amyloidosis, n = 31, r = 0.51, p less than 0.01; all patients, n = 95, r = 0.34, p less than 0.001). Our results suggest that the amyloid A degrading activity may be closely related to the esterase activity in serum.
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PMID:Serum esterase activity in reactive systemic amyloidosis and its relation to amyloid A degrading activity. 609 1

We estimated the concentrations, multiple forms, and lectin binding of five microsomal enzymes in particle free extracts from human kidney, pancreas, jejunal mucosa, and normal and cancerous liver. While arylesterase markedly reacted only with concanavalin A, arylamidase, alkaline phosphatase, gamma-glutamyltransferase, and cholinesterase were intensely precipitated by lectins from Ricinus communis 120, Canavalia ensiformis, Triticum vulgare and Phaseolus vulgaris S. Agglutinins from Glycine max, Arachis hypogaea and Ulex europaeus proved less effective. The reaction mainly depended on the origin of enzymes not on their species. Desialylation always decreased precipitation, and in extracts of normal liver parenchyma it even totally abolished precipitation, by Triticum vulgare lectin. Sialoenzymes therefore appear to be normal intracellular constituents. Differences between enzymes from normal and cancerous liver were not reflected by variant properties of the corresponding activities in sera. The same held true for multiple forms. The reasons for these differences are discussed.
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PMID:[Catalytic concentration, multiple forms, and lectin affinity of microsomal enzymes from human tissues: lectins as reagents, II (author's transl)]. 612 Feb 6


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