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)

1. Breakdown of phosphatidylinositol was studied in homogenates and subcellular fractions of rat cerebral cortex by using both membrane-bound and externally added [(32)P]phosphatidylinositol as substrate. 2. In the presence of deoxycholate breakdown followed first-order kinetics at low substrate concentrations ([unk]1mm) and zero-order kinetics at higher concentrations (6-9mm). 3. Maximum breakdown by cerebral-cortex homogenates was approximately 0.5mumol/h per mg of protein and occurred at pH7.0 in the presence of 8mm-phosphatidylinositol, 2mm-CaCl(2) and 2mg of deoxycholate/ml. Activity was abolished by 1mm-ethanedioxybis(ethylamine)tetra-acetate. 4. The products of phosphatidylinositol breakdown were 1,2-diacylglycerol and a mixture of d-myoinositol 1:2-cyclic phosphate (55%) and d-myoinositol 1-phosphate (45%). The two phosphate esters appeared to be produced together and in constant proportions. 5. Some 51% of the activity was particle-bound, with the highest activities in small nerve endings, microsomal material and two synaptic membrane fractions (fractions Mic(20), Mic(100), M(1) 1.0 and M(1) 0.9 respectively), all of which were also rich in acetylcholinesterase and which have been shown to be rich in other surface-membrane enzymes. Much of the particle-bound activity therefore appears to be present in cerebral-cortex plasma membranes. 6. The results are discussed in relation to previously described soluble activities that catalyse the same reaction, and to a possible role of the membrane-bound enzyme in enhanced phosphatidylinositol turnover in externally stimulated cells.
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PMID:A membrane-bound activity catalysing phosphatidylinositol breakdown to 1,2-diacylglycerol, D-myoinositol 1:2-cyclic phosphate an D-myoinositol 1-phosphate. Properties and subcellular distribution in rat cerebral cortex. 435 17

The effects of putrescene, spermidine and spermine on membrane-bound acetylcholinesterase from human erythrocyte ;ghosts' and the solubilized enzyme of the electric organ of the electric eel were studied by kinetic methods. Measurements were made by using a photometric method which made it possible to record the enzyme reaction in the steady-state phase. Substrate-concentration-dependent activation and inhibition of acetylcholinesterase by polyamines is similar to that by Na(+), K(+), Ca(2+), Mg(2+) and certain quaternary and bisquaternary amines. The kinetics suggest an allosteric reaction mechanism. On the basis of the kinetic results a role for the polyamines as modulators of synaptic acetylcholinesterase is proposed.
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PMID:Regulatory effects of polyamines on membrane-bound acetylcholinesterase. 446 73

The molecular size of acetylcholinesterase (EC 3.1.1.7) from the electric organ of Electrophorus electricus and erythrocyte ;ghosts' was estimated in both membrane-bound and purified preparations by irradiation inactivation. Results suggest that the form of the enzyme in the membrane is a monomer of molecular weight approx. 75000 and that multiple forms of the enzyme observed in solubilized preparations are aggregates of this monomer.
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PMID:The molecular form of acetylcholinesterase as determined by irradiation inactivation. 482 94

The study of toxicology and other related fields has been largely based on in vitro techniques. These methods have provided quantitative information on the effects of inhibitors on enzymes, but none on the localized effects of inhibitors on selected sites of action within the animal. Histochemical study of frozen sections does provide data on the site of action of toxicants. The utility of histochemistry in conjunction with in vitro methods is discussed.The substrates acetylthiocholine and phenyl thioacetate were utilized in demonstrating cholinesterase. Neither substrate penetrated well into freshly dissected nerve cord preparations, but both compounds were hydrolysed by sectioned tissue. The leaving group of phenyl thioacetate was demonstrated to be benzenethiol. In general, acetylthiocholine was hydrolysed slightly more rapidly by insect cholinesterases. A unique cholinesterase was found in motor end-plates of cricket muscle, which hydrolyses acetylthiocholine and which was inhibited by physostigmine. No other insect muscle preparation showed this activity. Topical application of insecticides showed that a vital site of action in flies is the peripheral area of the thoracic ganglia and that in crickets the brain and nerve cord are involved at knock-down. Kinetic data indicate that acetylthiocholine has a greater affinity than does phenyl thioacetate for a variety of enzyme sources. Ultrastructural evidence shows that cholinesterases that hydrolyse acetylthiocholine are membrane-bound. Phenyl thioacetate was found to be useful as a model in designing new insecticides.
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PMID:Distribution of cholinesterases in insects. 531 59

Treatment of isolated electroplax with physiological solutions supplemented with either 1 molar sodium chloride, 2 molar urea, or 2 molar sucrose renders the cell insensitive to carbamylcholine, phenyltrimethylammonium, or decamethonium even at high concentrations. The treated cells have a residual resting potential of -20 +/- 10 millivolts (negative inside) and are depolarized by acetylcholine at concentrations larger than 10(-3) mole per liter. This response is not affected by d-tubocurarine but is blocked by physostigmine, diisopropylphosphorofluoridate, or strong buffers and thus depends on the catalytic activity of the membrane-bound acetylcholinesterase.
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PMID:Electrical phenomena associated with the activity of the membrane-bound acetylcholinesterase. 603 74

Some enzymatic parameters of neuronal transmission as well as the occurrence and the properties or carboxylic ester hydrolases in the hippocampal region of the wistar rat are investigated by histochemical and comparable biochemical methods. The acetylcholinesterase-, the monoamine oxidase- and the GABA-transaminase reaction are found at fibre structures, the course of which is seen more or less clearly. The histochemical picture of these enzymes is very different in each hippocampal layer and mainly limited by the corresponding number of reacting fibres. The origin and attribution of the fibres to the afferent and efferent systems are discussed. The occurrence of the acetylcholinesterase, the monoamine oxidase and the GABA-transferase as well as of the biogenic amines and the GABA are hints for the existence of cholinergic as well as aminergic and GABA-ergic processes of transmission in the hippocampal region. In the hippocampal region, the cingular and the optic cortex carboxylic ester hydrolases acetylcholinesterase, unspecific cholinesterase and the A-, B- and C-esterase could be demonstrated. The acetylcholinesterase of the hippocampal region is for the most part firmly membrane-bound and exists at least in two multiple, formalin-sensitive forms which are histochemically located in fibre structures. The unspecific cholinesterase, localized in the hippocampal region within vessel and capillary walls, exists in an electrophoretic mobile, formalin-sensitive form. Nearly half of the enzymes is soluble. A preferred binding to definite cell organelles was not demonstrable. In the hippocampal region the 3 multiple forms of the A-esterase are formalin-instable lyoenzymes. Good solubility and high formalin-sensitivity are the reason, why A-esterases are not demonstrable with usually histochemical methods. In the hippo ampal region the B-esterase is tightly bound to n electrophoretic mobile formalin-sensitive form in the microsomal fraction. In the cytoplasm of the neurones the desmoenzyme appears more or less granular. The 3 multiple forms of the C-esterase are formalin-sensitive to a different degree. Good solubility and low formalin-sensitivity, compared to the A-esterases are responsible for the fact, that the C-esterases can be shown histochemically only after en-bloc-fixation. The reaction products are granular. The similar behaviour of C-esterase and acid phosphatase, stated by many tests, suggests the C-esterases of the B- and C-type results in the same reactivity of pyramidal and granular cells of the hippocampal region. Some small, very strongly reacting cells belong to other cell types (probably basket cells or polymorphic cells).
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PMID:[Histochemical and biochemical investigations of the hippocampus and neocortex of the Wistar rat. I. Carboxylic ester hydrolases, transmitter enzymes and transmitters of the normal animal (author's transl)]. 610 39

The action of electroacupuncture (EA) may be similar to analgesia by electrode stimulation or transcutaneous nerve stimulation. Since EA may directly stimulate nerve activity or indirectly enhance the release of opiate peptides and other neurotransmitter substances, we have used (Na+ + K+)-ATPase as a model to study the mechanism of action of EA. The membrane-bound (Na + K)-ATPase from purified synaptic plasma membranes inhibited slightly by high concentration of endorphin (30 microM), but not by met-enkephalin up to 6 X 10(-4) M. A single EA treatment for 30 min did not alter the (Na+ + K+)-ATPase activity in the cerebral cortex. However, when rats were treated with low (4 Hz) or high (200 Hz) frequency EA 30 min daily for 3 weeks, both (Na+ + K+)-ATPase and acetylcholinesterase were significantly elevated. The enhanced (Na+ + K+)-ATPase activity after high frequency EA was only partially blocked by i.p. injection of naloxone prior to EA during the last week of the EA treatment program. The results indicated that EA treatment may involve some other neurotransmitter pathways besides opiate peptides.
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PMID:Effect of electroacupuncture on synaptosomal (Na+ + K+)-ATPase. 614 70

The major molecular form of acetylcholinesterase (AChE) from chicken brain is a membrane-bound glycoprotein with an apparent sedimentation coefficient of 11.4 S. Analysis of the purified protein by gel filtration, velocity sedimentation, and sodium dodecyl sulfate-gel electrophoresis shows that the solubilized enzyme is a globular tetramer with an apparent Mr = 420,000. This membrane-bound form of AChE is hydrophobic and readily aggregates in the absence of detergent. These aggregates are concentration-dependent, relatively stable in the presence of high salt concentrations, yet readily dissociate upon addition of detergent to the 11.4 S form, indicating that the interactions are hydrophobic. Polyclonal and monoclonal antibodies raised against chicken brain AChE purified by ion exchange chromatography, affinity chromatography, and preparative gel electrophoresis precipitate AChE enzyme activity. However, these antibodies do not cross-react with the enzyme from chicken muscle which preferentially hydrolyses butyrylcholine. Immunoprecipitation of isotopically labeled enzyme molecules from tissue cultured brain cells and analysis by sodium dodecyl sulfate-gel electrophoresis shows that AChE consists of two polypeptide chains with apparent Mr = 105,000 (alpha) and 100,000 (beta) in a 1:1 ratio. Immunoblotting of brain AChE with either the polyclonal or monoclonal antibodies indicates that the alpha and beta chains share antigenic determinants. Furthermore, both polypeptide chains can be labeled with [3H]diisopropyl fluorophosphate, indicating that they each contain a catalytic site. This is the first indication that globular forms of AChE may consist of multiple polypeptide chains.
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PMID:Purification and properties of the membrane-bound form of acetylcholinesterase from chicken brain. Evidence for two distinct polypeptide chains. 620 93

Electron spin resonance, enzymatic, and SDS-polyacrylamide gel electrophoretic investigations of erythrocyte membranes from patients with Alzheimer's disease were performed. Alterations in the physical state of membrane proteins in Alzheimer's disease erythrocytes were found by spin labeling studies. However, no alterations in membrane lipid fluidity or in the activities of membrane-bound sodium plus potassium-stimulated, magnesium-dependent adenosine triphosphatase or acetylcholinesterase could be demonstrated. Also, no changes in staining profiles of AD erythrocyte membrane proteins subjected to electrophoresis were observed. The altered conformation and/or organization of extraneural membrane proteins in Alzheimer's disease suggests the possibility that this disorder may have more widespread membrane involvement than was originally thought.
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PMID:Spin label and biochemical studies of erythrocyte membranes in Alzheimer's disease. 624 87

The activity of Na+, K+ATPase (EC 3.6.1.3) and acetylcholinesterase (EC 3.1.1.7) as well as the content of masked and exposed SH-groups in sealed and unsealed erythrocyte ghosts were studied as affected by single rapid freezing-thawing. The freezing-thawing procedure resulted in different reactions of membrane-bound enzymes: Na+, K+-ATPase activity is doubled in sealed ghosts and unchanged in unsealed ones. In both types of ghosts the equal decrease in the AChE activity was found to be parallel with the diminution in the content of masked SH-groups but this cannot be referred to exposed SH-groups. The obtained results seem to suggest that the changes in the native conformation of membrane catalytic proteins resulted from cryodamage are responsible for the lowered aChE activity; the primary cause of increase Na+, K+-ATPase activity is due to the changes in the permeability and integrity of erythrocyte membrane, which are followed by the greater accessibility of the substrate (ATP) to the enzyme.
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PMID:[Changes in Na+, K+-ATPase and acetylcholinesterase activity in red cell membranes after freezing-thawing]. 626 9


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