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)

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

In the cerebellum there is scant evidence for cholinergic transmission but a large amount of acetylcholinesterase. Although it exists most commonly in a membrane-bound form, the release of a soluble form of this enzyme, within the cerebrum, has indicated that it may have a novel non-cholinergic role. In order to understand why the cerebellum is rich in acetylcholinesterase, the first step has been to investigate the possibility of its release in this structure. Following unilateral application of a depolarizing concentration of potassium ions, there was a large, sustained, calcium-dependent increase in release of acetylcholinesterase, specifically in the local cerebellar cortex; a marked enhancement of acetylcholinesterase release also occurred in the contralateral cerebellum, suggesting that the phenomenon reflected polysynaptic neuronal events. Indeed, systemic administration of harmaline, which modifies activity in certain cerebellar afferent pathways, induced a significant increase in acetylcholinesterase release in the cerebellar cortex. Local administration of the cholinomimetic, carbachol, had no effect. It is concluded that acetylcholinesterase is released from cerebellar neurons in association with physiological events, yet unrelated to cholinergic transmission.
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PMID:Release of acetylcholinesterase from the guinea-pig cerebellum in vivo. 339 74

This paper presents a formal procedure for the statistical analysis of data on the thermotropic behavior of membrane-bound enzymes generated using the Arrhenius equation and compares the analysis to several alternatives. Data is modeled by a bent hyperbola. Nonlinear regression is used to obtain estimates and standard errors of the intersection of line segments, defined as the transition temperature, and slopes, defined as energies of activation of the enzyme reaction. The methodology allows formal tests of the adequacy of a biphasic model rather than either a single straight line or a curvilinear model. Examples on data concerning the thermotropic behavior of pig brain synaptosomal acetylcholinesterase are given. The data support the biphasic temperature dependence of this enzyme. The methodology represents a formal procedure for statistical validation of any biphasic data and allows for calculation of all line parameters with estimates of precision.
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PMID:Nonlinear estimation of parameters in biphasic Arrhenius plots. 339 39

An improved method for assaying carbamylated acetylcholinesterase is described which has substantial benefits over current methods. Acetylcholinesterase was carbamylated with neostigmine and diluted extensively into buffer to allow decarbamylation to occur. At various times, phenyldichlorophosphate was added to the mixture of free and carbamylated enzyme, whereupon two very rapid, simultaneous reactions occurred: near total, and permanent, inactivation of free acetylcholinesterase by the organophosphate, and inactivation of phenyldichlorophosphate by hydrolysis. The carbamylated acetylcholinesterase was allowed to reactivate fully and then assayed for enzyme activity. The assay provided a measure of the amount of carbamylated enzyme present at the time of addition of phenyldichlorophosphate, thereby enabling the first-order rate constant for decarbamylation to be calculated. This new method of studying decarbamylation was applied to two systems of soluble acetylcholinesterase, where the half-life for decarbamylation was approximately 1/2 h or 4 min, respectively, and to membrane-bound acetylcholinesterase. The results agreed well with those determined by a conventional method; moreover, the standard error of the mean was lower for the new method. The advantages of the method using phenyldichlorophosphate over conventional methods are particularly evident when decarbamylation is rapid or when in vivo studies are being performed and it is not practical or desirable to run assays immediately on isolation of the tissue. The new method also has advantages over a published related technique using the organophosphate anticholinesterase soman.
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PMID:Phenyldichlorophosphate as an aid in studies of decarbamylation of carbamylated acetylcholinesterase. 339 43

The spiny mouse (Acomys cahirinus) is the only precocial murid species. It has some neuroanatomical peculiarities such as a relatively thin cerebral cortex and a large hippocampus. The levels of choline acetyltransferase, membrane-bound acetylcholinesterase and muscarinic receptor sites (measured as [3H]quinuclidynil benzilate binding) were assessed in the whole brain on days 1, 7, 14, 21, 28 and 80 (adult), and compared with those of Wistar rats of the corresponding ages. At birth choline acetyltransferase was significantly higher in spiny mice than in rats but the adult levels were similar, with an overall increase of about 5.2- and 14-fold for the former and the latter species, respectively. Membrane-bound acetylcholinesterase level and maximal density of muscarinic receptor sites in spiny mice were considerably higher at birth, in contrast adult levels were significantly lower than in rats with a respective overall increase of about 1.5- and over 4.5-fold. The high degree of maturity attained at birth by spiny mice partially depends on the long gestation period. However, if we consider postconception age, the maturation of choline acetyltransferase appears to be delayed at birth in the spiny mice, probably in relation to the lack of external stimulation during intrauterine life. In the cerebral cortex, hippocampus and striatum of adult spiny mice, when compared with the rats, there were similar levels of choline acetyltransferase but lower levels of membrane-bound acetylcholinesterase and, in the cerebral cortex, lower density of muscarinic receptor sites.
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PMID:Postnatal maturation of brain cholinergic systems in the precocial murid Acomys cahirinus: comparison with the altricial rat. 345 97

To study the effects of aromatic hydrocarbons, chlorinated aliphatic hydrocarbons, and alcohols on erythrocyte membrane, changes in the membrane-bound acetylcholinesterase (AchE) activity were tested after solvent treatment by the Ellman method. When the maximal effects of these solvents were tested at +37 degrees C, they diminished the AchE activity: benzene 75%, xylene 65%, styrene 80%, trichloroethylene 55%, tetrachloroethylene 60%, 1,1,1-trichloroethane 25%, and 1,1,2,2-tetrachloroethane 75%. Of the alcohols studied, only ethanol had a slight AchE inhibiting effect at +37 degrees C. The decrease in the incubation temperature increased the AchE inhibiting potency of aromatic hydrocarbons more than that of chlorinated aliphatic hydrocarbons and alcohols. The differences in inhibition may be due to the lipid solubility of the solvents, but also other factors, e.g. molecular structure, may determine it. Changes in the membrane-bound AchE may be one of the factors determining membrane fluidity.
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PMID:Effect of organic solvents on human erythrocyte membrane acetylcholinesterase activity in vitro. 346 11

A combination of direct fluorescence and indirect immunofluorescence microscopy has been used to compare the distribution of the acetylcholine receptor with the distribution of major cytoskeletal and extracellular matrix components during electrocyte differentiation in the electric organs of Torpedo marmorata. Laminin, fibronectin and extracellular matrix proteoglycan are always more extensively distributed around the differentiating cell than the acetylcholine receptor-rich patch that forms on the ventral surface of the cell. The distribution of acetylcholinesterase within the ventral surface of the differentiating electrocyte closely resembles the distribution of the acetylcholine receptor. Areas of apparently high acetylcholine receptor density within the ventrally forming acetylcholine receptor-rich patch are always areas of apparently high extracellular matrix proteoglycan density but are not always areas of high laminin or fibronectin density. Desmin levels appear to increase at the onset of differentiation and desmin initially accumulates in the ventral pole of each myotube as it begins to form an electrocyte. During differentiation F-actin-positive filament bundles are observed that extend from the nuclei down to the ventrally forming acetylcholine receptor-rich patch. Most filament bundles terminate in the acetylcholine receptor-rich region of the cell membrane. Electron-microscopic autoradiography suggests that the filament bundles attach to the membrane at sites where small acetylcholine receptor clusters are found. The results of this study suggest that, out of the four extracellular matrix components studied, only the distribution of acetylcholinesterase (which may be both matrix- and membrane-bound at this stage) closely parallels that of the acetylcholine receptor, and that F-actin filament bundles terminate in a region of the cell that is becoming an area of high acetylcholine receptor density.
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PMID:Development of the electromotor system of Torpedo marmorata: distribution of extracellular matrix and cytoskeletal components during acetylcholine receptor focalization. 356 8

The membrane-bound acetylcholinesterase (AchE) from human peripheral blood lymphocyte gives only one symmetrical peak on sucrose density gradient centrifugation in the presence of Triton X-100 detergent, with the calculated sedimentation coefficient of 6.5 S. However, this dimeric form of AchE was converted to a monomeric 3.8 S form when treated with 2-mercaptoethanol and iodoacetic acid. The results are consistent with studies which have shown by sodium dodecyl sulfate gel electrophoresis that the enzyme is built up of two identical monomers inter-linked by disulfide bond(s). Under reducing conditions, revealed a single species of 70,000 molecular weight, whereas under non-reducing conditions, another species of 140,000 molecular weight of the AchE was found. Polyacrylamide gel electrophoresis indicated a single band with AchE activity in the presence of Triton X-100. In contrast, in the absence of the same detergent multiple band pattern could be observed. These results suggest that membrane-bound AchE enzyme is present in homogenous dimeric form on human lymphocyte membrane.
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PMID:Molecular form of human lymphocyte membrane-bound acetylcholinesterase. 365 87

Kinetics of erythrocyte acetylcholinesterase activity alterations exposed to ultrasound of therapeutic intensities of 0.88 MHz and 0.05-1.5 W/cm2 was studied. The differences were studied between the mechanisms of the inactivation of membrane-bound and free enzyme: the diminution of active enzyme sites for membrane-bound acetylcholinesterase and the decrease of enzyme-substrate affinity for the free form during sonication. The combined mechanical stresses in the ultrasonic field did not produce inactivation of free enzyme, as compared to the membrane-bound enzyme. Exponential ultrasonic/acoustochemical inactivation curves were obtained for the soluted crystalline form of acetylcholinesterase.
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PMID:Comparative study on the therapeutic ultrasound effects on erythrocyte membrane-bound and free acetylcholinesterase. 365 74


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