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)

Extraction of human caudate nucleus under high-ionic-strength conditions solubilized 20-30% of total acetylcholinesterase (AChE) activity. Density gradient centrifugation revealed monomeric (5.0 S) and tetrameric (11.0 S) enzyme species. The purified, tetrameric salt-soluble (SS) AChE sedimented at 10.6 S and did not bind detergents. It showed an immunochemical reaction of identity with the detergent-soluble (DS) AChE species from human caudate nucleus and human erythrocytes, but did not cross-react with antibodies raised against human serum cholinesterase. The remaining activity was solubilized under low-ionic-strength conditions in the presence of 1.0% Triton X-100. The purified tetrameric, DS-AChE sedimented at 10.0 S as detergent-protein mixed micelle and on extensive removal of the detergent this enzyme formed defined aggregates by self-micellarization. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis under nonreducing conditions revealed that the salt-soluble and detergent-soluble tetrameric enzyme species both contained a heavy and a light dimer; under reducing conditions mainly one band corresponding to the light subunit was seen. Molecular weights of 300,000 dalton and 280,000 dalton were calculated for SS-AChE and DS-AChE, respectively. Limited digestion of DS-AChE with proteinase K led to isolation of an enzyme that no longer bound detergents and lacked the intersubunit disulfide bridges.
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PMID:Molecular forms of acetylcholinesterase from human caudate nucleus: comparison of salt-soluble and detergent-soluble tetrameric enzyme species. 397 87

1. Acetylcholinesterase from human erythrocytes was solubilized with Triton X-100 in strong salt solution and partially purified by (NH(4))(2)SO(4) fractionation. This preparation showed three main bands of enzyme activity after electrophoresis on polyacrylamide gel and incubation with either alpha-naphthyl acetate or acetylthiocholine as enzyme substrate. Two of the multiple forms were completely inhibited by 10mum-eserine and one only partially. Treatment with neuraminidase had no effect on the electrophoretic pattern; therefore sialic acid does not appear to determine or affect the ratios of the acetylcholinesterase multiple forms, unlike those of the serum cholinesterase. 2. Chromatography of the preparation on Sephadex G-200 revealed one major peak of enzyme activity and a suggestion of two minor zones of mol.wt. 546000, 184000 and 93000 (i.e. in the proportion 6:2:1). The main peak was almost completely separated from the Triton X-100 and the overall purification was about 600-fold. Further attempts to purify the enzyme by absorption on calcium phosphate gels were unsuccessful. 3. Electrophoresis of the enzyme preparation on a polyacrylamide gradient for 24h revealed three main bands that corresponded to the three values for molecular weights obtained by column chromatography. After 70h of electrophoresis a further three zones of activity developed making six molecular entities, the molecular weights of which were simple multiples of a monomer, thus resembling the cholinesterase found in serum.
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PMID:Multiple forms of acetylcholinesterase from human erythrocytes. 473 38

Nine esterase fractions hydrolyzing 1-naphthylacetate were revealed in Triton X-100-solubilized extracts from aphides homogenates by polyacrylamide gel electrophoresis. The less mobile fractions 1-4 were identified as cholinesterases, using specific inhibitors--eserine and the cationic phosphoorganic inhibitor Gd-42; fractions 5-7 were related to carboxylesterases, using specific inhibition by triorthocresylphosphate and O,O-dimethyl (2,2-dichlorvinyl)phosphate. The most mobile fractions 8-9 which were resistant to the inhibitors, were classified as arylesterases. The aphis cholinesterase fractions revealed the highest mobility; the activity of carboxylesterase fractions was lower. Thiophosphonate--C8H17O(CH3)P(O)-SCH2SCH2COOCH3 was found to be a highly efficient selective inhibitor of aphis carboxylesterase, i. e. the kII values for carboxylesterase and cholinesterase were equal to 10(8) and 10(5) M-1 min-1, respectively. The thiophosphoorganic derivatives containing a beta-alanine residue in the cleaved part are more specific to acetylcholinesterase and carboxylesterase than those containing a valine residue. Studies with enanthiomers--C2H5O(CH3)P(O)SCH2CONHCH2CH2COOC2H5 and (C2H5O)2P(O)SCH2CONHCH(iC3H7)COOC2H5 have demonstrated that the asymmetry due to the central phosphorus atom is more essential for the acetylcholinesterase and carboxylesterase activities than that connected with the carbon atom in the cleaved part of the inhibitor molecule. During the interaction of the enanthiomers with the asymmetric phosphorus the stereospecificity of acetylcholinesterase is much higher than that of carboxylesterase. In terms of stereospecificity of the esterase site aphis acetylcholinesterase is is similar to its mammalian counterpart, while carboxylesterase from the same source is rather close to mammalian butyrylcholinesterase.
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PMID:[Multiple molecular forms of esterases from grass aphids inhibitory identification and stereospecificity]. 663 87

The cholinesterase activity of Xenopus laevis oocytes was assessed using [3H]acetylcholine in a simple radiometric procedure. The cholinesterase activity of mature (stage V-Vl) oocytes was very sensitive to inhibition by the specific acetylcholinesterase inhibitor, BW284-C5l, and relatively insensitive to an inhibitor of non-specific, or butyrylcholinesterase. The Km and Vmax of the acetylcholinesterase measured in homogenates of oocytes were 312 microM and 4.6 nmol-oocyte 1-h 1, respectively. Triton X-100 increased the enzyme activity of homogenates four- to five-fold while collagenase treatment displaced into the medium none of the acetylcholinesterase activity from either homogenates or intact oocytes. Cations were found generally to diminish the acetylcholinesterase activity of oocyte homogenates, and lanthanum ions inhibited acetylcholine hydrolysis with an IC50 of 0.63 mM. Subcellular fractionation of oocytes revealed that the bulk of enzyme activity was associated with particulate fractions. Acetylcholinesterase activity was also detected on the surface, and in homogenates, of immature oocytes. Peak enzyme activity resided in stage IV oocytes. Eggs obtained from females induced to spawn were found to have acetylcholinesterase activity in homogenates but little or no hydrolytic activity was detected on the egg surface. These results provide a point of departure for further investigations of the functional significance of this enzyme in Xenopus oocytes.
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PMID:Acetylcholinesterase activity of Xenopus laevis oocytes. 666 98

Acetylcholinesterase (AChE) activity was measured in cholinergic and non-cholinergic neurons in the central nervous system of the leech. Intracellular AChE was assayed by pretreating intact ganglia with echothiophate to inhibit selectively extracellular enzyme. The concentration of intracellular AChE in cholinergic neurons was 3- to 24-fold higher than that in non-cholinergic cells. The properties of AChE in extracts of leech ganglia were similar to those of "true" acetylcholinesterase, although butyrylthiocholine was almost as good a substrate as acetylthiocholine. There was also cholinesterase activity in leech blood; this enzyme resembled butyrylcholinesterase. Sucrose gradient velocity sedimentation of Triton X-100 extracts of leech ganglia revealed a major peak of AChE activity at 6.5 S and a small peak at 4.3 S. The pattern of activity in the gradient was the same when intact ganglia were pretreated with echothiophate, although the total activity was reduced by 98%. Intact leech ganglia were stained for AChE activity with and without echothiophate pretreatment. In ganglia that had not been exposed to echothiophate, cholinesterase reaction product was deposited primarily on the ganglionic sheath. In pretreated ganglia, on the other hand, cholinesterase activity was concentrated within neuronal cell bodies. Electrophysiological identification and intracellular injection of the fluorescent dye Lucifer Yellow prior to staining were used to confirm that most AChE-positive cells were cholinergic motoneurons. Two previously unidentified neurons staining for AChE were shown to be motoneurons. These results demonstrate that cholinergic motoneurons can be differentiated from other cells in the leech nervous system by their high intracellular concentration of AChE.
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PMID:Characterization of acetylcholinesterase in individual neurons in the leech central nervous system. 710 85

A method for the determination of cholinesterases [1] has been adapted to monitor these enzymes in the presence of anti-cholinesterase insecticides. The cholinesterases in blood samples, which were dried on filter papers, could be eluted with water (plasma cholinesterase) and with 1% Triton X-100 (erythrocyte acetylcholinesterase) with complete recovery of the enzyme activity. The samples could be stored at room temperature for at least two weeks and in a refrigerator more than six weeks without a decreased efficiency of elution from the filter paper. It was found that if blood samples to which the two insecticides, used to test the validity of the method, had been added, were stored on filter paper at room temperature or deep frozen for at least one week, there was the same inhibition of the cholinesterases as at the start of the experiment. The samples stored at room temperature in tubes, recovered maximally within a day. This modified method of cholinesterase determination will be especially suitable when samples have to be mailed to laboratories making the analysis.
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PMID:A reliable way of estimating cholinesterases from whole blood in the presence of anti-cholinesterases. 735 Oct 88

Amphiphilic monomers and dimers of acetylcholinesterase (AChE) and hydrophilic tetramers of butyrylcholinesterase (BuChE) were released by extracting human meningioma with Tris-saline and Tris-saline-Triton X-100 buffers. The amphiphilic or hydrophilic behavior of the AChE and BuChE forms was assessed by sedimentation analysis, hydrophobic chromatography and Triton X-114 phase-partitioning. A significant fraction of the amphiphilic AChE species was converted into hydrophilic components by incubation of the soluble enzyme with phosphatidylinositol-specific phospholipase C (PIPLC) from Bacillus thuringiensis, this fraction being increased by a double treatment with PIPLC and alkaline hydroxylamine. A significant amount of the membrane-bound AChE was released by incubation with PIPLC. These results demonstrate that AChE forms in meningioma are attached to the membrane via glycosylphosphatidylinositol, although part of the enzyme forms are resistant to PIPLC.
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PMID:Monomers and dimers of acetylcholinesterase in human meningioma are anchored to the membrane by glycosylphosphatidylinositol. 747 60

The acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities in the neural retina and retinal pigment epithelium (RPE) of adult rats were determined. The tissues were extracted with a saline buffer to release the soluble enzymes (S1) and the pellet re-extracted with Triton X-100 to detach the membrane-bound enzymes (S2). Less than 5% of the cholinesterase activity measured in retina and almost 30% of that assayed in RPE was due to BChE. About 20% and 10% of the AChE in retina and RPE was brought into solution with a saline buffer and the rest with a detergent-containing buffer. Main AChE molecular forms of 10.5S (hydrophilic G4H), 9.5S (amphiphilic G4A) and 3.0S (amphiphilic G1A) were identified in retina by subjecting the supernatant S1 to sedimentation analysis in sucrose gradients made with Brij 96. Amphiphilic G4 and G1 AChE were found in S2. Analysis of the soluble fractions obtained from RPE in the gradients made with Brij 96 revealed 16.0S (asymmetric A12), 10.5-10.0S (globular G4H + G4A), 4.5S (G2A), and 3.0S (G1A) AChE forms in S1, whereas G4A, G2A, and G1A enzyme molecules predominated in S2. Our results show that amphiphilic tetramers and monomers of AChE are abundant in neural retina, and enzyme tetramers, dimers, and monomers in RPE. The AChE in the neural retina might be involved in cholinergic actions. The enzyme function in the retinal pigment epithelium remains to be established.
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PMID:Acetyl- and butyrylcholinesterase activities in the rat retina and retinal pigment epithelium. 756 46

Necator americanus (Nematoda: Strongyloidea), a human hookworm parasite, is known to release considerable amounts of acetylcholinesterase (AChE) [Pritchard, D. I., Leggett K. V., Rogan, M. T., McKean, P. G. & Brown, A. (1991) Necator americanus secretory acetylcholinesterase and its purification from excretory/secretory products by affinity chromatography, Parasite Immunol. 13, 187-199]. The present study deals with AChE activity recovered in sequential somatic extracts, and excretory/secretory products, of the adult stage of the parasite. 97% of AChE was extractable in low-salt and high-salt detergent-free buffers, and only 3% was solubilised by a further extraction in the presence of Triton X-100. AChE in all three extracts was affected by the AChE inhibitors eserine, bis(4-allyldimethylammoniumphenyl)pentan-3-one dibromide and edrophonium chloride, but was resistant to the effects of tetramonoisopropylpyrophosphortetramide, a butyrylcholinesterase inhibitor. Sucrose density centrifugation revealed that AChE in all somatic extracts (low-salt, high-salt and detergent) resolved almost exclusively as a single peak between 6.9-7.5 S, while excretory/secretory products resolved at 8.2 S. These values are all compatible with dimers of catalytic subunits and no evidence was found for the presence of higher oligomers such as asymmetric forms. The only sample to show a shift in sedimentation following the inclusion of detergent (Triton X-100, Brij 96) in the gradient was a component of the detergent-soluble extract, indicating the existence of a minor amphiphilic form. In low-salt-soluble and high-salt-soluble extracts, AChE was solubilised as a hydrophilic globular form, probably a dimeric G2. The analysis of diisopropylfluorophosphate-labelled extracts by SDS/PAGE, and unlabelled extracts by immunoblotting using a polyvalent antiserum to N. americanus AChE, indicated that the AChE isolated in each extract was biochemically and immunologically similar. The banding patterns obtained were comparable to that seen when purified AChE was analysed by SDS/PAGE and immunoblotted. This suggests that the basic catalytic subunit has a mass of 66-70 kDa with the active site being located in a 30-kDa domain. All experimental data indicate the existence of only one AChE class in Necator homologous to AChE of class B from Caenorhabditis elegans. The solubility characteristics and globular nature of this hookworm AChE suggest that its major function is as an excretory or secretory product. This again raises the question of the true biological function of this 'non-cholinergenic' nematode secretion.
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PMID:The molecular forms of acetylcholinesterase from Necator americanus (Nematoda), a hookworm parasite of the human intestine. 830 98

Differences in glycosylation between molecular forms of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) in muscle and serum of normal and dystrophic mice have been studied by means of their adsorption to immobilized lectins. Application of a two-step extraction procedure, first with saline buffer, and second with saline buffer and Triton X-100, brought into solution most of the muscle AChE and BuChE activities. The AChE activity was five times greater than that of BuChE in normal (NM) and dystrophic muscle (DM). The AChE activity in the serum of dystrophic mice was twice that measured in control animals, but the BuChE activity remained almost unchanged. Both AChE and BuChE in muscle and serum bound completely to concanavalin A (Con A) and Lens culinaris agglutinin (LCA). A12, A8 and G4 AChE, but not the light G2 and G1 AChE forms, in NM and DM were completely adsorbed to wheat germ agglutinin (WGA). Similarly, G4 BuChE, but not the G2 and G1 forms, were associated to WGA. A high proportion of G4 and G1 AChE and G4 BuChE forms in mouse serum were fixed to WGA. Asymmetric AChE in NM and DM reacted with Ricinus communis agglutinin (RCA) but the light AChE and BuChE forms in muscle and serum did not bind to the lectin. G4 AChE and G4 BuChE in NM were not recognized by RCA, but the isoforms in DM bound fully to the lectin. Serum G4 AChE from control or dystrophic mice did not react with RCA, but G4 BuChE was fixed to the lectin. Since RCA is specific for galactose, the results suggest that in dystrophic muscle galactose is incorporated early in G4 AChE and this affects the level of the functional tetramers destined for insertion in the plasma membrane.
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PMID:G4 forms of acetylcholinesterase and butyrylcholinesterase in normal and dystrophic mouse muscle differ in their interaction with Ricinus communis agglutinin. 831 75


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