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)

A comparison of the lipid content of normal and carrier-erythrocytes from cattle revealed no differences in phosphatidyl ethanolamine, sphingomyelin, phosphatidyl serine, or cholesterol. The ratio of membrane phospholipid to cholesterol and membrane-bound erythrocyte acetyl cholinesterase activity was unchanged. A microcytic tendency was observed for carrier-cells, however, this physical property of the cell cannot be related to measurable differences in lipid content of the cells.
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PMID:A comparison of membrane lipid content of normal and carrier-erythrocytes from cattle. 324 85

In the lichen Parmelia caperata (L.) Ach. the distribution pattern of membrane-bound Ca2+ is investigated in the symbionts by chlorotetracycline (CTC)-induced fluorescence during the development of propagative structures, the soredia. The results demonstrate that Ca2+ accumulation in the alga and the fungus is associated with this morphogenetic process; particularly, polarized hyphal growth involves a tip-to-base Ca2+ gradient. CTC fluorescence distribution is coincident with that of cholinesterase (ChE) activity during morphogenesis of soredia. A comparison is suggested with 'embryonic ChE' of animal cells, where developmental events are regulated by a cholinergic mechanism that also modulates Ca2+ levels.
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PMID:Membrane-bound Ca2+ distribution visualized by chlorotetracycline fluorescence during morphogenesis of soredia in a lichen. 339

The distribution of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) molecular forms and their solubility characteristics were examined, using density gradient centrifugation, in various regions of the postmortem human CNS. Total AChE activity varied extensively (50-fold) among the regions investigated, being highest in the telencephalic subcortical structures (caudate nucleus and nucleus of Meynert); intermediate in the substantia nigra, cerebellum, and spinal cord; and least in the fornix and cortical regions (hippocampus and temporal and parietal cortex). Total BChE activity was, in contrast, much more evenly distributed, with only a threefold variation between the regions studied. Although the patterns of molecular forms of each enzyme were broadly similar among the different areas, regional variations in the distribution and abundance of the various forms of AChE were much greater than those of BChE. Thus, although the tetrameric G4 form of AChE constituted the majority of the total AChE activity in all regions examined, the ratio of the G4 form to the monomeric G1 form, the latter of which constituted the majority of the remaining activity, varied markedly, ranging from 21 in the caudate nucleus to 1.7 in the temporal cortex. In addition to the G4 and G1 forms of AChE, the dimeric G2 form was observed in the nucleus of Meynert and a fast-sedimenting (16S) species was found in samples of both the parietal cortex and spinal cord. In contrast, the G4 and G1 forms of BChE were the only molecular species observed in the different areas and the G4:G1 ratio varied from 3.3 in the substantia nigra to 0.9 in the temporal cortex. Regarding the solubility characteristics of the individual AChE and BChE molecular forms, the majority of the G4 form of AChE was extractable only in the presence of detergent, indicating a predominantly membrane-bound localization of this species. The smaller AChE forms (G1 and G2) and both the G1 and G4 forms of BChE were all relatively evenly distributed between soluble and membrane-bound species. These findings are discussed in relation to neurochemical and neuroanatomical, particularly cholinergic, features of the regions examined.
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PMID:Molecular forms of acetylcholinesterase and butyrylcholinesterase in the aged human central nervous system. 371 2

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

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

Radiation inactivation was employed to measure the molecular size of calcium channels in guinea-pig skeletal muscle membranes, labelled by the potent 1,4-dihydropyridine calcium antagonist [3H]nimodipine. The molecular size was decreased when the membranes were preincubated and assayed with d-cis-diltiazem, a calcium channel blocker, which is structurally unrelated to the 1,4-dihydropyridines. d-cis-Diltiazem, which is a positive heterotropic regulator of 1,4-dihydropyridine calcium channel binding in vitro, reduced the molecular size from 178 000 to 111 500. 1-cis-Diltiazem, the diastereoisomer, which is devoid of calcium antagonistic action, did not decrease the molecular size of the 1,4-dihydropyridine binding site. Neither diastereoisomer affected the molecular size of the membrane-bound acetyl-cholinesterase, indicating that a stereospecific interaction with the calcium channel structure is the basis for these observations. It is concluded that this decrease in size is indicative of the oligomeric nature of the calcium channel and that calcium channel blockers, acting via different, but interacting drug receptor sites, induce different conformations of the channel structure, resulting in altered conductivity for ions.
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PMID:Calcium channels: evidence for oligomeric nature by target size analysis. 631 98

The activity of acetylcholinesterase in the rat striatum increased considerably during development, while activities in the cerebellum and midbrain increased only slightly. During maturation the activity of butyrylcholinesterase increased in all the brain regions examined except in cerebellum. The percentage of acetylcholinesterase extractable by isotonic sucrose solution from mature striatum was much smaller than those obtained for other regions of the rat brain. For the developing striatum, the percentage of isotonic sucrose extractable activity was almost three times that for adult striatum. Density gradient centrifugation showed that the membrane-bound particulate fraction of adult rat brain was mostly composed of the 10 S form of acetylcholinesterase with little activity of 4 S form of the enzyme. However, a much higher proportion of the 4S form was found in the isotonic sucrose soluble fraction. In contrast to the particulate fraction from adult brain, that from 6-day old rats contained a much higher proportion of the 4 S form of the enzyme. The sucrose soluble fraction from 6-day old rat brains contained in general much smaller proportion of 4S form as compared to those from adult rat brains.
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PMID:Molecular forms of sucrose extractable and particulate acetylcholinesterase in the developing and adult rat brain. 685 31

Extracts of the nematode Caenorhabditis elegans contain five molecular forms of acetylcholinesterase (AChE) activity that can be separated by a combination of selective solubilization, velocity sedimentation, and ion-exchange chromatography. These are called form IA (5.2s), form IB (4.9s), form II (6.7s), form III (11.3s), and form IV (13.0s). All except form III are present in significant amounts in rapidly prepared extracts and are probably native; form III is probably derived autolytically from form IV. Most of forms IA and IB can be solubilized by repeated extractions without detergent, whereas forms II, III, and IV require detergent for effective solubilization and may therefore be membrane-bound. High salt concentrations are not required for, and do not aid in, the solubilization of these forms. For all forms, molecular weights and frictional ratios have been estimated by a combination of gel permeation chromatography and velocity sedimentations in both H2O and D2O. The molecular weight estimates range from 83,000 to 357,000 and only form II shows extensive asymmetry. The separated forms have been characterized with respect to substrate affinity, substrate specificity, inhibitor sensitivity, thermal inactivation, and detergent sensitivity. Judging by these properties, C. elegans is like other invertebrates in that none of its cholinesterase forms resembles either the "true" or the "pseudo" cholinesterase of vertebrates. However, internal comparison of the C. elegans forms clearly distinguishes forms IA, III, and IV as a group from forms IB and II; the former are therefore designated "class A" forms, the latter "class B" forms. Genetic evidence indicates that separate genes control class A and class B forms, and that these two classes overlap functionally. Several factors, including kinetic properties, molecular asymmetry, molecular size, and solubility, all suggest that a molecular model of the multiple cholinesterase forms observed in vertebrate electric organs probably does not apply in C. elegans. Potential functional roles and subunit structures of the multiple AChE forms within each C. elegans class are discussed.
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PMID:Multiple molecular forms of acetylcholinesterase in the nematode Caenorhabditis elegans. 686 28

Organophosphorus compounds which cause delayed neurotoxic effects phosphorylate a characteristic nervous-tissue protein and inhibit its activity as an esterase. Studies with a variety of inhibitors reveal that the toxic effect does not occur because of the loss of esterase activity but depends on the chemistry of the inhibited enzyme. A process analogous to the 'aging' of inhibited cholinesterase occurs after neurotoxic esterase has been inhibited by neurotoxic agents which leaves a charged acidic group attached to the membrane-bound esterase. This charge could disrupt normal metabolism in the neurone. Protective compounds inhibit neurotoxic esterase but the 'aging' process cannot occur, so that there is no formation of a charged group. Neurotoxic esterase occurs widely in the brain. Attempts are being made to locate the enzyme intraneuronally. The present understanding is of great value in toxicology. However, it has not yet clarified the physiological processes which maintain long axons in normal health.
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PMID:Irreversible phosphorylation of brain neurotoxic esterase. The primary event leading to the delayed neuropathy caused by some organophosphorus esters. 723 40

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


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