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:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Heparan sulfate and heparin, two sulfated glycosaminoglycans (GAGs), extracted collagen-tailed acetylcholinesterase (AChE) from the extracellular matrix (ECM) of the electric organ of Discopyge tschudii. The effect of heparan sulfate and heparin was abolished by protamine; other GAGs could not extract the esterase. The solubilization of the asymmetric AChE apparently occurs through the formation of a soluble AChE-GAG complex of 30S. Heparitinase treatment but not chondroitinase ABC treatment of the ECM released asymmetric AChE forms. This provides direct evidence for the vivo interaction between asymmetric AChE and heparan sulfate residues of the ECM. Biochemical analysis of the electric organ ECM showed that sulfated GAGs bound to proteoglycans account for 5% of the total basal lamina. Approximately 20% of the total GAGs were susceptible to heparitinase or nitrous acid oxidation which degrades specifically heparan sulfates, and approximately 80% were susceptible to digestion with chondroitinase ABC, which degrades chondroitin-4 and -6 sulfates and dermatan sulfate. Our experiments provide evidence that asymmetric AChE and carbohydrate components of proteoglycans are associated in the ECM; they also indicate that a heparan sulfate proteoglycan is involved in the anchorage of the collagen-tailed AChE to the synaptic basal lamina.
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PMID:Anchorage of collagen-tailed acetylcholinesterase to the extracellular matrix is mediated by heparan sulfate proteoglycans. 316

An estimate of the amplitude of respiratory sinus arrhythmia (V) has been proposed as a noninvasive measure of parasympathetic activity. This experiment monitored V in response to a subclinical dose of pyridostigmine bromide (PYR) and a pharmacological challenge of atropine sulfate (ATR). Twelve male rhesus macaques received 200 micrograms/kg of PYR 30 min prior to an injection of 0, 14, 44, or 140 micrograms/kg ATR. The decrease in V after both the 44 and 140 micrograms/kg ATR doses was similar to the response to ATR alone in a previous experiment. The 14 micrograms/kg dose of ATR did not significantly decrease V in this experiment, which is in contrast with the large decrease of V after ATR alone in a previous experiment. Neither drug affected respiration. The dose of ATR which would be effective in causing a 30% decrease of V in the presence of PYR was estimated to be 18.3 micrograms/kg of ATR. This is twice the dose of ATR calculated to have the same effect without PYR. The attenuated response of V after a pharmacological challenge of ATR may be used to quantify the latent muscarinic effects from exposure to anticholinesterase agents. The attenuated response to ATR may also be useful for evaluating the return of normal cholinergic function after disruption by cholinesterase inhibitors.
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PMID:Quantifying the altered cardiac response to atropine following pyridostigmine in rhesus macaques. 324 15

An original immunoenzymatic screening method, based on the use of antigens labeled with the stable enzyme acetylcholinesterase (AChE, EC 3.1.1.7), is described. The high turnover of this enzyme results in a very sensitive detection of antibodies. In this method, monoclonal antibodies from the supernatants of hybridoma cultures are immobilized on a solid phase coated with anti-mouse immunoglobulins and react simultaneously with the appropriate antigen labeled with biotin molecules. In a second step, biotinylated acetylcholinesterase is in turn associated to the system via avidin interactions and subsequently detected by a colorimetric assay. The method appears more sensitive and easier to use than either the corresponding radioimmunological test using a 125I-iodinated antigen or the same type of enzymatic immunoassay performed with biotinylated horseradish peroxidase instead of biotinylated AChE. The combined use of microtiter plates, solid-phase separation, and colorimetric detection allows a high level of automation of the method which makes it very efficient to process a large number of samples. This technique has been successfully applied to the screening of monoclonal antibodies directed against peripheral proteins of the photosystem 1 (PS1) membrane complex in photosynthesis. A complete set of antibodies recognizing these PS1 components was selected. The same technique was also tested in competition immunoassays and appears to be a very precise and useful tool for quantifying PS1 polypeptides in different biological extracts, including sodium dodecyl sulfate-denatured membranes. This can be of special interest for studying the biogenesis of membrane complexes.
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PMID:Screening of monoclonal antibodies using antigens labeled with acetylcholinesterase: application to the peripheral proteins of photosystem 1. 328 14

A dialysis cannula was implanted into rat striatum while the animals were anesthetized, and after at least one day following the surgery the area was perfused with Ringer solution under the unrestrained and unanesthetized conditions. Concentration of acetylcholine (ACh) in the perfusate was determined by high-performance liquid chromatography (HPLC)-electrochemical detection (ECD) with the enzyme-column on which acetylcholine esterase and choline oxidase were immobilized. ACh in the dialysate was only detectable when the Ringer solution containing eserine, an inhibitor of acetylcholinesterase, was perfused. ACh peak on HPLC-ECD could be detected at least for 4 h under these conditions. The level of ACh increased 2-3 fold with the perfusion of 1 mM atropine sulfate, a blocker of ACh receptor. These data indicate that brain dialysis in the presence of eserine is useful for study on the neurochemical activity of ACh neurons in the brain.
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PMID:Brain dialysis: detection of acetylcholine in the striatum of unrestrained and unanesthetized rats. 332 Aug 17

A factor that stimulates the incorporation of 75Selenomethionine into the newly formed platelets of recipient mice (thrombopoietin, TPO) has been partially purified from the plasma of thrombocytopenic patients. The activity was precipitated at 60-80% ammonium sulfate saturation and further purified with hydrophobic interaction chromatography. Thrombopoietin was retained by concanavalin-A-Sepharose. Using HPLC size-exclusion chromatography, an approximate molecular weight of 40,000 dalton was calculated. The overall purification factor was about 2,100-fold. TPO was stable in a pH range from 5 to 9 and was heat-sensitive, and the biological activity was destroyed by trypsin treatment and by dithiothreitol. The partially purified molecule did not stimulate the proliferation of megakaryocyte progenitors in vitro and had no effect on the growth of erythroid or granulocyte-macrophage colonies; when administered in-vivo, TPO significantly affected the mean platelet volume and increased the number of small acetylcholinesterase cells in the bone marrow. TPO appears to be specific for the megakaryocytic lineage and active on the postmitotic compartment of megakaryocytes.
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PMID:Partial purification and biochemical characterization of human plasma thrombopoietin. 336 51

In addition to its ability to hydrolyze acetylcholine, purified eel acetylcholinesterase possesses a trypsin-like endopeptidase activity. The tryptic activity is associated with a serine residue at a site that is distinct from the esteratic site. To label both the esteratic and tryptic sites, the enzyme was incubated with the serine hydrolase inhibitor [3H]diisopropyl fluorophosphate. This compound labelled the protein in a biphasic manner, with both slow and rapid labelling kinetics. The time course of the rapid phase was similar to the time course of inactivation of the esteratic activity. The time course of the slow phase was similar to the time course of inactivation of the tryptic activity. Labelling of the nonesteratic site was inhibited by the trypsin inhibitor N alpha-p-tosyl-L-lysine chloromethyl ketone. The total number of sites labelled by [3H]diisopropyl fluorophosphate on eel acetylcholinesterase was 2.6 mol/280,000 g protein, whereas the number of tryptic sites was less (0.52 mol/280,000 g). The results suggest that a subpopulation of acetylcholinesterase molecules may possess tryptic activity. Extensive chromatography of the purified enzyme by ion-exchange and gel filtration failed to separate the labelled tryptic component from acetylcholinesterase. On sodium dodecyl sulfate-polyacrylamide gels, the labelled tryptic component comigrated with a polypeptide of 50,000 molecular weight, which is a major proteolytic digestion product derived from the intact acetylcholinesterase monomer. Because of its localization in many noncholinergic peptide-containing cells, acetylcholinesterase could act as a neuropeptide processing enzyme in these cells.
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PMID:Identification of a trypsin-like site associated with acetylcholinesterase by affinity labelling with [3H]diisopropyl fluorophosphate. 337 13

A 20% fenthion (0,0-dimethyl-0-(3-methyl-4-(methylthio)-phenyl) phosphorothionate) formulation was applied topically to dogs at 8 mg/kg, 2 treatments at 14-day intervals, and 33 mg/kg, 4 treatments at 7-day intervals. Control dogs received 4 treatments at 7-day intervals of the proprietary vehicle. Following the last dose, the dogs were observed for a 14-day period. Plasma cholinesterase (ChE) exhibited a significant dose-related response with maximum inhibition to 52% and 24% of pre-dose activity occurring 4 days after the final fenthion treatment of 8 and 33 mg/kg, respectively. Erythrocyte ChE activity showed a downward trend to 32% of normal activity measured 9 days following the last treatment of fenthion at 33 mg/kg. No cholinomimetic effects were observed. All dogs were challenged with atropine sulfate (0.02 mg/kg, sc) on the last day of the observation period. A 5 min electrocardiogram was analyzed to estimate V as that portion of the variance in the R-R intervals corresponding with the normal respiratory frequency band for dogs. The mean heart period, mean heart period variance, and mean of V had significant change when measured across time in the atropine challenge (0, 25, 70, and 100 min) with a pronounced decrease at 25 min. An attenuation of the V measure in the fenthion-treated groups indicated an altered muscarinic response to atropine from prior subacute fenthion exposure.
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PMID:Effects of topical fenthion on blood cholinesterase and vagal tone in dogs. 338 51

Plasma cholinesterase activity levels were studied in 15 pregnant patients with preeclampsia before and after the administration of therapeutic doses of magnesium sulfate. Plasma cholinesterase activity was also studied in 15 healthy nonpregnant and 15 healthy pregnant women. The mean plasma cholinesterase activity level in pregnant patients with preeclampsia before and after the administration of magnesium sulfate was 179 +/- 26 and 176 +/- 39 units/ml, respectively. The healthy nonpregnant patients and healthy pregnant patients had a plasma cholinesterase activity level of 426 +/- 85 and 264 +/- 24 units/ml, respectively. Our data demonstrated that magnesium has no significant effect on plasma cholinesterase activity. Our data also confirm that there is a significant reduction in plasma cholinesterase activity in pregnant patients with preeclampsia compared with either healthy nonpregnant or healthy pregnant patients. We conclude that the low level of plasma cholinesterase activity is probably responsible for the prolonged action of succinylcholine in pregnant patients with preeclampsia receiving magnesium sulfate.
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PMID:Effect of magnesium on plasma cholinesterase activity. 260 42

The hydrophobic, membrane-binding domain of purified human erythrocyte acetylcholinesterase was labeled with the photoactivated reagent 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine. The radiolabel was incorporated when the enzyme was prepared in detergent-free aggregates, in detergent micelles, or in phospholipid liposomes, but the highest percentage of labeling occurred in the detergent-free aggregates. Papain digestion of the enzyme released the hydrophobic domain, and polyacrylamide gel electrophoresis in sodium dodecyl sulfate or gel exclusion chromatography demonstrated that the label was localized exclusively in the cleaved hydrophobic domain fragment. This fragment was purified in a three-step procedure. Digestion was conducted with papain attached to Sepharose CL-4B, and the supernatant was adsorbed to acridinium affinity resin to remove the hydrophilic enzyme fragment. The nonretained fragment associated with Triton X-100 micelles was then chromatographed on Sepharose CL-6B, and finally detergent was removed by chromatography on Sephadex LH-60 in an ethanol-formic acid solvent. The fragment exhibited an apparent molecular weight of 3100 on the Sephadex LH-60 column when compared with peptide standards. However, amino acid analysis of the purified fragment revealed only 1 mol each of histidine and glycine per mole of fragment in contrast to the 25-30 mole of amino acids expected on the basis of the molecular weight estimate. This result suggests a novel non-amino acid structure for the hydrophobic domain of human erythrocyte acetylcholinesterase.
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PMID:Selective radiolabeling and isolation of the hydrophobic membrane-binding domain of human erythrocyte acetylcholinesterase. 352 70

We have previously communicated that heparin released asymmetric acetylcholinesterase (AChE) from cholinergic synapses. Here we report studies showing that heparin, besides releasing asymmetric AChE from the skeletal muscle extracellular matrix (ECM), specifically solubilizes a dermatan sulfate proteoglycan (DSPG) which accounts for more than 95% of the 35S-released material. The co-solubilization of AChE and the proteoglycan opens up the possibility that both macromolecules could be involved in the formation of the soluble AChE complex observed after incubation of muscle homogenate with heparin. Our results suggest a possible association between asymmetric AChE and DSPG at the muscle ECM, moreover this work is the first report of the existence of DSPG at the skeletal muscle cell surface.
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PMID:Co-solubilization of asymmetric acetylcholinesterase and dermatan sulfate proteoglycan from the extracellular matrix of rat skeletal muscles. 355 75


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