Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The inhibition of cholinesterase of human serum by paraoxon can be predicted by a mathematical model which considers two competing reactions for paraoxon: one, the direct interaction with cholinesterase, and the other, enzymatic hydrolysis by paraoxonase. On the basis of the residual cholinesterase activity at various times during the incubation with paraoxon, it is possible to determine the rate constants for the reaction of paraoxon with cholinesterase (k1), and the reaction with paraoxonase (k2), the latter being directly proportional to paraoxonase activity. The percentage of initial activity remaining as residual cholinesterase depends primarily upon the paraoxonase level; it is influenced only slightly by variations in initial cholinesterase levels within the normal range. From these results, we conclude that the residual cholinesterase activity test is, in fact, an indirect measure of serum paraoxonase activity; it has the same limitations and is no more reliable a means of differentiating individual paraoxonase genotypes than measuring the level of serum paraoxonase activity directly. Our model suggests that there are conditions where paraoxonase genotype may alter the clearance of paraoxon and in turn the reaction of paraoxon with target sites. Whether similar results would be obtained in vivo is unknown. Since this model predicts the degradation of paraoxon well in vitro, it may be possible to extend the model and predict the effect of paraoxonase genotype on the clearance of paraoxon in vivo.
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PMID:A mathematical model for evaluating the reaction of paraoxon with human serum cholinesterase and with polymorphic forms of paraoxonase. 614 13

The esterase activity of the mitochondrial fraction from cortical renal cells was studied in guinea pigs aged 15, 21, 30, and 120 days. The rate of hydrolysis of beta-naphthyl acetate was measured by incubating aliquots of mitochondrial preparations with physostigmine, diisopropylfluorophosphate, HgCl2, and p-hydroxymercuribenzoate. Enzyme activity was mainly due to the heterogeneous aliesterase group: some aliesterases were sensitive to physostigmine, others to organophosphorus compounds and/or to HgCl2; a C-esterase stimulated by organomercurials and similar to that described by Bergmann et al. in hog kidney was detected (F Bergmann, R Segal, S Rimon. Biochem J 67:481-486, 1957); arylesterase activity was very weak. Acetylthiocholine used as substrate showed there was no cholinesterase activity in the mitochondrial fraction.
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PMID:Characterization of the esterases of the mitochondrial fraction of guinea pig cortical renal cells. 646 57

The multiplicity of soluble esterases in Raillietina tetragona, R. echinobothrida and R. cesticillus was studied by use of slab polyacrylamide gel electrophoresis. Five fractions of esterase activity were observed in R. tetragona, seven in R. echinobothrida and three in R. cesticillus. The various fractions of esterase activity of closely related species of Raillietina showed differential behaviour towards various chemicals. Based on the inhibitory effect of inhibitors p-CMB, EDTA, malathion, silver nitrate and eserine sulphate, the various esterases have been classified into arylesterase, carboxylesterase, acetylesterase and cholinesterase.
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PMID:A comparative study on esterases from three species of Raillietina. 654 Feb 80

The effects of pregnancy and lactation on the toxicity and distribution of parathion and paraoxon were examined. Signs of cholinergic stimulation were more intense in pregnant mice when compared to virgin controls after administration of parathion or its active metabolite, paraoxon. Cholinesterase activity and tissue levels of parathion and paraoxon were determined in mice at 19 days of gestation or Day 19 postpartum after administration of a single dose of 5 mg/kg parathion or 0.58 mg/kg paraoxon. Plasma (pseudo) cholinesterase activity was consistently lower in treated pregnant mice. Total brain cholinesterase was also suppressed to a greater degree in pregnant mice after treatment with parathion or paraoxon when compared with virgin animals treated similarly. In addition, when equal quantities of paraoxon (32 micrograms) were administered to both pregnant and virgin animals, total brain cholinesterase was significantly less in pregnant mice. Administration of parathion to lactating mice on Day 19 postpartum did not result in any significant differences in plasma or brain cholinesterase activity when compared to that in virgin animals. Pregnant mice treated with 5 mg/kg parathion demonstrated higher concentrations of both parathion and paraoxon in blood and brain than similarly treated virgin controls which correlated with the enhanced cholinesterase inhibition. Decreased ability to detoxify paraoxon was also demonstrated by a significant reduction in serum paraoxonase activity during pregnancy.
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PMID:Influence of pregnancy on parathion toxicity and disposition. 663 86

A high heritability estimate was obtained for serum arylesterase activity level in a series of 40 male twin pairs (23 MZ, 17 DZ) aged 33-39 years. The heritability estimated for cholinesterase activity was strikingly lower. In unrelated individuals a positive correlation between arylesterase, cholinesterase, and various lipoprotein parameters appeared to support the suggestion that these enzymes interact with various lipoproteins at the molecular level. The nature of these associations is not known. It is, however, tempting to speculate that some of the hereditary influence on lipoprotein levels in man may be mediated through the genetic control of one or both of these enzymes.
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PMID:Cholinesterase, arylesterase, and lipoprotein parameters in twins. 719 53

A simple direct spectrophotometric method for the determination of butyrylcholinesterase (EC 3.1.1.8) and arylesterase (EC 3.1.1.2) activities has been developed. New chromogenic substrates, (3-carboxypropyl)trimethylammonium iodide o-nitrophenyl ester (I) and (3-carboxypropyl)trimethylammonium iodide p-nitrophenyl ester (II), as well as new fluorogenic substrate, (3-carboxypropyl)trimethylammonium iodide 4'-methylumbelliferyl ester (III), were used in this study. Horse serum butyrylcholinesterase equally catalyzed hydrolysis of the compounds, I, II and III. Hydrolysis of these compounds by trypsin, chymotrypsin, acetylcholinesterase and carboxylesterase was negligible or quite slow. By human serum butyrylcholinesterase, however, only the compound I was preferentially hydrolyzed. The compound III, by contrast, was found to be a specific substrate for arylesterase of human serum without being affected by the butyrylcholinesterase. All these measurements were carried out readily and efficiently, by analyzing highly colored products with I and II, and highly fluorescent product with III.
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PMID:New chromogenic and fluorogenic substrates for the determination of butyrylcholinesterase and arylesterase activities. 720 43

Electrophoretic pattern of the blood serum proteins from 8 chicks of 1, 7, 14, and 21 days of age was determined by crossed immunoelectrophoresis. The chicks at 1 day of age had low levels of albumin and high levels of IgG, beta-lipoprotein, and transferrin. The albumin increased gradually to attain high levels by 21st day. The IgG levels, however, showed a considerable decline up to the 14th day. The beta-lipoprotein levels also decreased considerably on the 7th day. The transferrin levels showed a gradual decline. The IgM appeared as a faint precipitate on the 7th day. The cholinesterase showed transition from an initial low level at 1 day to a subsequent relatively high level at 7 to 21 days. The arylesterase in day-old chicks was higher than in chicks of 7 to 21 days of age.
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PMID:The serum protein pattern of chickens during the early growing period using crossed immunoelectrophoresis. 730 32

Serum arylesterase isozyme patterns were studied in 184 normal healthy individuals, 290 cancer patients and 466 patients with various diseases. No abnormal patterns were seen in the normal healthy subjects. Several abnormal patterns found in the group of cancer patients and patients with various diseases are described. In the majority of patients with cancer of the liver there is an abnormal additional cathodal band. The most cathodal band in normals or the two most cathodal bands in the patients with hepatoma with double cathodal bands stained for cholinesterase as well as for arylesterase. We also studied serum arylesterase activity on the basis of the kinetic release of beta-naphthol in these groups. The mean activity in normal healthy individuals agrees with that reported earlier. In patients with cancer and with miscellaneous other diseases, the mean activity is lower but the range of values in the two groups is very wide.
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PMID:Arylesterase isoenzymes and activity in normal healthy adults and in patients with cancer and with other diseases. 741 94

The enzyme in human serum that rapidly hydrolyzes diacetylmorphine (heroin) to 6-acetylmorphine is identified in this report as serum cholinesterase (EC 3.1.1.8, acylcholine acylhydrolase; also called pseudocholinesterase or butyrylcholine esterase). The rate of heroin hydrolysis was measured spectrophotometrically at 245 nm using highly purified serum cholinesterase. The turnover number was 500 mumol of heroin hydrolyzed per min per mumol active site. The product was identified spectrophotometrically and by thin-layer chromatography to be 6-acetylmorphine. There appeared to be marked product inhibition of heroin hydrolysis, as 6-acetylmorphine (Ki = 0.015 mM) bound 7 times more tightly than heroin (Ki = 0.11 mM). Purified human serum arylesterase did not hydrolyze heroin. Purified serum cholinesterase accounted for all the observed heroin hydrolysis by whole serum. The genetic variants of human serum cholinesterase, silent and atypical cholinesterase, were also tested. Serum from a person identified as having silent cholinesterase did not hydrolyze heroin. Purified atypical cholinestearase hydrolyzed heroin, but the binding was less tight (Km = 0.45 mM) than with usual cholinesterase (Km = 0.11 mM). The possibility that heroin potency may be influenced by serum cholinesterase genotype or activity level remains to be investigated.
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PMID:Hydrolysis of diacetylmorphine (heroin) by human serum cholinesterase. 745 76

Species differences in the hydrolysis of isocarbacyclin methyl ester (TEI-9090) in whole blood and in its separated components were studied in rats, dogs and human. Esterase activity in rat whole blood was approximately 100 and 400 times higher than that in dog and human whole blood, respectively, and was attributed to high plasma activity. In contrast, TEI-9090 hydrolysis activities in dog and human blood were due to red blood cells (RBC), whose activity in humans was slightly suppressed by albumin. In dogs, activity in RBC membranes was 10 times greater than in the cytosol, while in human membrane and cytosol activity was virtually the same. The effects of the esterase inhibitor diisopropylfluorophosphate, bis-p-nitrophenylphosphate (BNPP), eserine, 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) and p-chloromercuribenzoate showed that the rat plasma and RBC cytosol esterases hydrolysing TEI-9090 were carboxylesterase (CarbE) and arylesterase (ArE), respectively. The esterases in dog plasma and RBC membrane were CarbE, and RBC cytosol esterase was ArE. In humans, the esterase activities in plasma, RBC membrane and cytosol were butyrylcholinesterase, CarbE and ArE, respectively.
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PMID:Species differences in hydrolysis of isocarbacyclin methyl ester (TEI-9090) by blood esterases. 776 77


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