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)

Membrane preparations of erythrocytes from normal and P. chabaudi-infected mice and membrane preparations of P. chabaudi-infected and uninfected erythrocytes from infected mice and separated by zonal centrifugation were characterized by the pattern of proteins and extracted glycoproteins obtained by SDS-polyacrylamide gel electrophoresis and by the specific activities of membrane associated enzymes. The protein pattern of the membrane preparation of infected erythrocytes showed similar differences from membrane preparations of normal erythrocytes as those described by Weidekamm et al. for P. berghei. The pattern of glycoproteins extracted by the chloroform-methanol method showed characteristic differences as compared to the controls. A new band (PASi) with a molecular weight of about 165,000 corresponds with the protein band IIa. In membrane preparations of normal erythrocytes and of nonparasitized erythrocytes separated from parasitized erythrocytes by zonal centrifugation was no difference in specific activities of ATPase, adenylate kinase and acetylcholinesterase. Adenylate kinase activity was markedly increased and acetyl-cholinesterase activity was slightly increased in membrane preparations of infected cells. Specific activities of ATPase of membrane preparations of normal and parasitized erythrocytes did not show significant differences. There was a decrease in enzyme activity of ATPase and an increase of acetylcholinesterase in Triton X 100 containing samples. Specific activities of an acid phosphatase were lower in membrane preparations of parasitized cells than in the controls.
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PMID:Plasmodium chabaudi-infection of mice: specific activities of erythrocyte membrane-associated enzymes and patterns of proteins and glycoproteins of erythrocyte membrane preparations. 19 21

When homogenates of cat or rat superior cervical ganglia in Krebs-Ringer solution were incubated at 37 degrees C, the ensuing decrease in acetylcholinesterase (acetylcholine acylhydrolase, EC 3.1.1.7) activity was increased significantly by prior administration in vivo of tetramonoisopropylpyrophosphotetramide at doses that produced selective alkylphosphorylation of butyrylcholinesterase or propionylcholinesterase. These findings are consistent with the proposal that the latter enzymes are posttranscriptional precursors of acetylcholinesterase. Results of similar studies with homogenates of ganglia in water or in M NaCl/1% Triton X-100 were inconclusive, as were those of heat-inactivation studies and immunoprecipitation of the enzymes.
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PMID:Interrelationships between ganglionic acetylcholinesterase and nonspecific cholinesterase of the cat and rat. 29 97

1. The cholinesterase (ChE) of frog brain and retina could be easily solubilized. About 10% of the brain and 20% of the retina ChE were found to be soluble in 0.05 M phosphate buffer. After treatment with 0.5% (v/v) Triton X-100, about 30% of the total ChE activity of the brain and only 10% for retina was left particle bound. NaCl by itself did not solubilize ChE. Use of higher NaCl concentrations in combination with Triton X-100 as well as higher detergent concentrations alone seemed to cause an inhibiting effect of the solubilized ChE from retina. 2. The solubilized ChE from brain as well as retina were electrofocused as one main activity peak, corresponding to isoelectric points of pH 6.1 and 6.0, respectively. A second molecular form at pH 5.9 was distinguishable for the brain, but not for retina ChE. 3. Sucrose gradient centrifugation indicated that the ChE solubilized from the brain and retina consists of two molecular forms exhibiting S values of 5.1 +/- 0.24, 10.9 +/- 0.33 and 6.1 +/- 0.30, 10.9 +/- 0.43, respectively. After solubilization by higher Triton X-100 concentrations the soluble extracts from brain and retina seemed to contain the activity of these forms in different proportions. 4. Polyacrylamide gel electrophoresis separated three molecular forms of the brain ChE. One of these forms was found to have a molecular weight of 394,000 +/- 20,000. The others were found to have an identical molecular weight of 550,000 +/- 10,000. Two molecular forms exhibiting molecular weights of 292,000 +/- 10,000 and 470,000 +/- 10,000, could be separated for retina.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Solubilization of frog brain and retina cholinesterase and studies of different molecular forms. 31 46

alpha-[125I]Bungarotoxin specifically binds to homogenates of Drosophila melanogaster head at levels of 0.3-0.8 pmol/mg protein. The dissociation constant calculated from rates of association and dissociation of toxin.receptor complex, is 0.6.10(-9) M. Ca2+, and to a lesser extent Na+, inhibit the reaction. alpha-[125I]Bungarotoxin binding is inhibited by low concentrations of unlabelled toxin, nicotinic ligands and eserine, but not by low concentrations of muscarinic ligands, decamethonium or an organophosphate. The receptor is membrane bound and can be partially released into 100 000 X g supernatant by combination of 1 M NaCl and 1% Triton X-100. Most of the activity in the supernatant sediments after further centrifugation at 200 000 X g for 2 h. Toxin binding sites are distinct from acetylcholinesterase molecules as revealed by pharmacological, biochemical and genetic techniques. The gene for the toxin-binding nicotinic receptor in Drosophila is apparently not located adjacent to the gene for acetylcholinesterase.
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PMID:Properties of an alpha-bungarotoxin-binding cholinergic nicotinic receptor from Drosophila melanogaster. 41 54

The mechanisms of activation of acetylcholinesterase (AChE) in the homogenates of rat and frog forebrains and medullae oblongatae under effects of non--ionic detergents (Triton X-100 and Tw-en 80) were studied. Titration of the active centers of enzyme by the highly selective phosphoorganic inhibitor HD-42 showed that the inhibitor-induced activation is due to the appearance of previously masked active sites of the enzyme. Activation of AChE in the homogenates of rat brain medulla oblongata was caused by lysis of the structural elements of nervous tissue which were not destroyed by homogenization. Another mechanism of AChE activation by the detergents (frog brain homogenate) is the destruction of the vesicular membrane structures present in the homogenate with AChE centers located on the inner surface of the vesicles.
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PMID:[Mechanism of activation of acetylcholinesterase in brain tissue homogenates by detergents]. 43 63

Several molecular forms of human erythrocyte membrane acetylcholinesterase have been studied after crosslinking with bifunctional diimidates. The crosslinked products were analysed by centrifugation on linear sucrose density gradients containing Triton X-100. Molecular weights of covalently linked oligomers were estimated by sodium dodecylsulfate gel electrophoresis. It was shown that acetylcholinesterase crosslinked in absence of Triton X-100 consists of molecular forms built up by dimeric protomers. These dimers were identical with the enzymatically active species sedimenting with 6.5S in linear sucrose density gradients.
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PMID:Molecular forms of purified human erythrocyte membrane acetylcholinesterase investigated by crosslinking with diimidates. 48 16

Detergents above their critical micellar concentration dissociate the aggregated forms of pure acetylcholinesterase from human erythrocyte membranes to a 6.5-S form, the protomer. This form is active only in presence of amphiphiles. 1. Uncharged (Triton X-100, Tweens, beta-D-octylglycoside), anionic (sodium dodecyl sulfate) and zwitterionic (lysophosphatidylcholine) detergents or bile salts (sodium cholate, deoxycholate) stabilize the 6.5-S enzyme at concentrations well below their critical micellar concentration. 2. Total erythrocyte lipids fully sustain catalytic activity of the 6.5-S form. 3. Protein-protein interactions stabilize the activity of the 6.5-S form of acetylcholinesterase. Above a critical acetylcholinesterase concentration (2.5 microgram/ml) enzyme activity no longer depends on the presence of an amphiphile as reaggregation to multiple molecular forms occurs. It is concluded that human erythrocyte membrane acetylcholinesterase is fully active only if the enzyme can undergo hydrophobic interactions with amphiphiles such as detergents, lipids or proteins.
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PMID:Effects of amphiphiles on structure and activity of human erythrocyte membrane acetylcholinesterase. 52 Mar 24

The effect of Triton X-100 on catalytic properties of acetylcholinesterase from human erythrocytes under acetylcholine hydrolysis, on sensitivity of acetylcholinesterase to specific phosphoorganic inhibitors and eserine, and on the mobility and isoenyme spectrum under analytical electrophoresis in polyacrylamide gel is investigated. Triton X-100, independently on its concentration within 0.05-1.0%, slightly changes V and [S]opt values and increases Km value in 2-3 times. The inhibitory effect of Triton X-100 is mainly competitive, 0.5% Triton X-100 decreases bimolecular constant (kII) of the interaction of acetylcholinesterase with phosphoorganic inhibitor and eserine in 2.5-4 times. In the presence of phosphoorganic inhibitor, kII sharply decreased when 0.02% Triton X-100 was added, and then it did not change under the increase of Triton X-100 concentration up to 1.0%. On the basis of these data, an analytical method of estimating Triton X-100 content in protein solution is proposed. The introduction of 0.1% Triton X-100 into polyacrylamide gel results in considerable quantitative redistribution of acetylcholinesterase isoenzyme fractions and in the change of the mobility of one fraction under electrophoresis.
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PMID:[Effect of Triton X-100 on properties of acetylcholinesterase from human erythrocytes]. 62 48

The active sites of acetylcholinesterase multiple forms from four widely different zoological species (Electrophorus, Torpedo, rat and chicken) were titrated using a stable, irreversible phosphorylating inhibitor (O-ethyl-S2-diisopropylaminoethyl methyl-phosphonothionate). In all cases, we found that within a given species, the molecular forms we examined were equivalent in their catalytic activity per active site. As pure preparations of the molecular forms of Electrophorus acetylcholinesterase were available, we were able to establish that one inhibitor molecule binds per monomer unit for each of them. This had already been shown by several authors for the tetrameric globular form, but not for the tailed molecules. Analysis of the phosphorylation reaction showed that they are equally reactive. Under our experimental conditions, their turnover number per site was 4.4 x 10(7) mol of acetylthiocholine hydrolysed . h-1 at 28 degrees C, pH 7.0. The corresponding value was less than half for Torpedo (1.64 x 10(7) mol . h-1), and again lower for rat (1.32 x 10(7) mol . h-1) and chicken (1.05 x 10(7) mol . h-1). In the case of rat acetylcholinesterase, the activity per active site of solubilized (with or without Triton X-100) and membrane-bound enzyme were identical. We discuss the implications of these findings with respect to the quaternary structure of acetylcholinesterase, and to the physico-chemical state and physiological properties of its molecular forms.
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PMID:Active-site catalytic efficiency of acetylcholinesterase molecular forms in Electrophorus, torpedo, rat and chicken. 64 23

Gel-filtration of 0,6 M NaCl and 0,6 M NaCl--0,1% Triton X-100 extracts of freshly isolated sarcolemma through Sepharose 2B (1,5 X 72 cm) has revealed one symmetric peak of acetylcholinesterase activity containing phospholipid and cholesterol, moving faster than fibrinogen and tyreoglobulin. The acetylcholinesterase fraction is substantially separated from other extract proteins. Gel-filtration of extracts from long-store, treated by ultrasound or high concentration of detergent sarcolemma has revealed some peaks of acetylcholinesterase activity, which may be suggested to be degraded forms of the complex high molecular weight structure. All species of acetylcholinesterase are converted by treatment with trypsin to a form moving upon gel-filtration with enzyme-marker catalase. The microsome extracts contain only the form moving with catalase.
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PMID:[Isolation of sarcolemma acetylcholinesterase fractions by gel-filtration through Sepharose 2B]. 65 88


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