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)

The conformation of the globular dimer (G2), the tailed asymmetric dodecamer (A12, also containing some tailed octamer A8) and the globular tetramer (G4, prepared by removing the collagen-like tail from A12) of acetylcholinesterase (acetylcholine acetylhydrolase, EC 3.1.1.7) was studied by circular dichroism (CD) in the ultraviolet region. The G2 and G4 forms had similar conformation with about 40% alpha-helix, 35% beta-sheets and 4% beta-turns; the tailed form had a lower helicity (about 34%) and beta-form (about 25%) content probably because of the presence of the tail whose CD spectrum resembles that of an unordered form, but it had about the same amount of beta-turns as the other two forms. All three forms also had similar CD spectra in the near-ultraviolet region due to their non-peptide chromophores. The pH, thermal and urea denaturation of the three acetylcholinesterase forms was also similar to each other. The pH-dependency of both the enzymatic activity and CD intensity of the three forms showed bell-shaped curves with a plateau at pH 7-8. The activity was completely lost at pH below 5 or above 10, but the corresponding CD spectra retained 70-80% of the original magnitudes. Thermal denaturation of the three forms at pH 7.5 showed a conformational transition and loss of activity between 30 and 40 degrees C, but the CD intensity of the helical band at 222 nm was reduced by only 20-30%. Urea denaturation of the three forms began at 1 M urea; it was protein concentration- and time-dependent. Again, the activity disappeared faster than the decreasing CD intensity. Thus, the overall conformation of the three acetylcholinesterase forms appears to be relatively stable, but their active site is easily perturbed by changing the environment. The loss of activity correlated well with the disappearance of the CD band of tryptophan(s) in the near-ultraviolet region, suggesting that the Trp residue(s) might be at or near the active center of the enzyme.
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PMID:Conformation similarities of the globular and tailed forms of acetylcholinesterase from Torpedo californica. 379 May 97

In order to determine whether a structural modification at the active center of cholinesterase may alter the conformational stability of the enzyme we compared the urea-induced unfolding of the tetrameric form of non-inhibited and irreversibly inhibited human plasma cholinesterase (acylcholine acylhydrolase, EC 3.1.1.8). We studied enzyme inhibited by methanesulfonyl fluoride, diisopropylfluorophosphonate (DFP) and racemic soman. DFP- and soman-inhibited cholinesterases are converted spontaneously into non-reactivable forms called 'aged' enzymes through a process involving dealkylation of the bound organophosphate residue. The unfolding was followed by transverse urea-gradient polyacrylamide electrophoresis at various temperatures ranging from 0 to 60 degrees C. Unfolding of cholinesterase appears to be a complex process. The denaturation patterns showed that partially unfolded states are thermodynamically unstable, but that several intermediates are involved; the lifetime of these depends on the temperature at which electrophoreses are carried out. Cholinesterase inhibited by methanesulfonyl fluoride behaved like the non-inhibited enzyme. On the other hand, small but significant differences in stability between non-inhibited and aged enzymes were observed. Whatever the temperature, the urea concentration at the mid-point of transition was always greater for aged enzyme than for the non-inhibited enzyme. In addition, aged enzymes showed more complex denaturation patterns at the lower temperatures (under 20 degrees C). These findings suggest that the overall stability of aged-cholinesterases is slightly increased as compared with the stability of non-inhibited or methanesulfonyl fluoride-inhibited enzymes. The denaturation pattern obtained at 0 degree C for soman-inhibited cholinesterase under non-aging conditions (inhibition at 0 degree C, pH 10.7) was similar to that of non-inhibited enzyme at this temperature, although splitting in two of the denaturation curve over the transition zone reflects the heterogeneity of soman-inhibited enzyme. The slight difference in denaturation behavior between these species may be due to stereoisomerism in soman. The differences in electrophoretic behavior and apparent stability observed between non-inhibited and aged enzymes were interpreted as the result of a conformational change induced by the dealkylation reaction of enzyme-inhibitor conjugates.
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PMID:Evidence that the conformational stability of 'aged' organophosphate-inhibited cholinesterase is altered. 394 40

Clinically normal Nubian goats were given the antiprotozoal drug imidocarb at single intramuscular doses of 6, 12, 18 and 24 mg/kg, and the various clinical, biochemical and pathological manifestations were recorded. At a dose of 6 mg/kg the drug produced no change in any of the parameters studied. At higher doses, the drug produced dose dependent changes which included increased heart and respiratory rates, increased defaecation, urination, depression, incoordination of movement, weakness of the hindlegs, recumbency, and finally death. Just prior to death, there was a significant decrease in the number of erythrocytes, and in packed cell volume, and haemoglobin concentration. In plasma there was an increase in the activity of aspartate transaminase, urea and creatinine concentrations and inhibition of cholinesterase activity. The main histopathological changes were associated with hepatic and renal damage. Three goats were pre-treated with atropine sulphate (1 mg/animal) and after one hour given imidocarb intramuscularly at a dose of 12 mg/kg. The changes were similar but much less severe when compared with those in animals given imidocarb alone at the same dose.
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PMID:Some effects of imidocarb in goats. 408 55

Eight hematologic parameter values, 16 serum biochemical constituents, serum protein fractions and albumin-globulin ratios were determined in blood samples obtained from 879 normal, healthy Beagle dogs of both sexes which had been reproduced and bred in our laboratories. The blood samples were collected from the Beagles that ranged in monthly ages from 1 to 12 and in monthly ages from 13 to 121, which were classified as the adult class. As a result, red blood cell counts, hemoglobin concentrations and packed cell volumes increased with growth. Red blood cell parameters of normal Beagles in our laboratories were rather higher than those in literatures presented by many other researchers. MCV decreased and MCHC increased gradually with age. Total serum protein concentrations increased with growth. alpha 1-1 and alpha 1-2 Globulin fractions descended, but beta 2 and gamma globulin fractions ascended in serum proteins. Alkaline phosphatase activities, inorganic phosphorus concentrations and glucose concentrations decreased conspicuously with growth. Leucine aminopeptidase activities and calcium concentrations decreased slightly. Serum cholinesterase and LDH activities showed a tendency to diminish similarly. Blood urea nitrogen and creatinine concentrations multiplied gradually. Hematologic parameters became almost steady in our 7-month-old dogs or older ones and serum biochemical constituents had a tendency to be stable in our 7- to 9-month-old dogs or older ones in the blood. White blood cell counts, alkaline phosphatase activities, inorganic phosphorus concentrations, glucose concentrations, leucine aminopeptidase activities and calcium concentrations were lowest in the adult class.
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PMID:[Successive changes in the blood composition of experimental normal beagle dogs associated with age]. 408 64

1. A number of methods of solubilization of pig brain acetylcholinesterase (EC 3.1.1.7) were studied. The multiple enzymic forms of the resultant preparations were examined by polyacrylamide-gel electrophoresis. 2. Butanol extraction, Nagarase treatment and ultrasonication proved unsuitable as preparatory methods, but detergent treatment (Triton X-100, Triton X-100-KCl and lysolecithin) gave good yields. 3. Separation of soluble enzyme in three systems of polyacrylamide-gel electrophoresis were compared and the relative advantages are discussed. 4. By using a 6% (w/v) gel and continuous buffer system two forms of acetylcholinesterase were detected in Triton X-100-solubilized enzyme, but the incorporation of a sample and spacer gel and a discontinuous buffer system resolved this into four components. The forms of the soluble enzyme extracted by different methods differed in mobility. 5. With gradient polyacrylamide-gel electrophoresis between two and six forms were detected, depending on the method used for extraction. The average molecular weights of the five forms most frequently found were 60000, 130000, 198000, 266000 and 350000. 6. Treatment of the Triton X-100-extracted enzyme with 2.5m-urea altered the pattern and evidence of dissociation was observed. 7. The results are discussed in the light of present theories on the molecular structure of acetylcholinesterase.
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PMID:Multiple forms of acetylcholinesterase from pig brain. 474 27

1. Alkylation of acetylcholinesterase and butyrylcholinesterase by 2-chloro-N-(chloroethyl)-N-methyl-2-phenylethylamine was observed. This alkylating agent was more potent than related compounds previously described, and less stable (half-life 8.5min. at 23 degrees ). 2. Alkylation had effects on hydrolysis of substrates varying from activation for indophenyl acetate to inhibition for acetylcholine, and intermediate effects with five other substrates. The effects were on V(max.) and not K(m). 3. Alkylation caused a variety of changes in sensitivity to inhibition by five carbamates, five organophosphates and four other inhibitors, varying from total protection against tetraethylammonium to mildly enhanced sensitivity to urea. 4. The findings suggested the existence of three binding sites, one of which was anionic and another hydrophobic, in addition to the esteratic site.
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PMID:Binding sites of cholinesterases. Alkylation by an aziridinium derivative. 538 94

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

Sixty male workers in a lindane (gamma-hexachlorocyclohexane)-producing factory were examined with regard to health in comparison with an external control group of 20 clerks. Case history, physical examination, neurologic status, and ECG revealed no significant differences between groups. However, the following significant differences in clinical-chemical blood tests were ascertained: higher polymorphonuclear leukocyte count, lower lymphocyte count, higher reticulocyte count, lower prothrombin (Quick's) test, and lower blood concentrations of creatinine and uric acid. No significant differences were observed in total red and white blood cell as well as platelet counts, hemoglobin content, the other counts of differential blood picture, gamma-GT, GOT, GPT, LDH, cholinesterase, triglycerides, cholesterol, and urea. In spite of a pronounced exposure to the alpha-, beta-, and gamma-isomers of hexachlorocyclohexane, no signs of severe impairment of health were observed; only small deviations in some laboratory tests were found having no pathologic significance. However, biological monitoring and health supervision of HCH-exposed workers should be carried out.
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PMID:Occupational exposure to hexachlorocyclohexane. II. Health conditions of chronically exposed workers. 616 31

Six Beagle dogs were orally intubated with mixtures of a urea-based fertilizer, 2,4-D, mecoprop (MCPP), dicamba, and either bensulide or chlorpyrifos. The mixtures were formulated as they are used in liquid application to lawns. The dogs were given volumes of 10 ml/kg of body weight, delivering the following quantities of each ingredient: urea--623 mg/kg, inorganic phosphorus (P2O5)--24 mg/kg, potassium (K2O)--66 mg/kg, 2,4-D--6.5 mg/kg, MCPP--3.26 mg/kg, dicamba--0.55 mg/kg, and either bensulide--60.93 mg/kg or chlorpyrifos--6.77 mg/kg. The dogs were given 3 consecutive daily doses of the mixture containing bensulide (round 1) or the mixture containing chlorpyrifos (round 2). The dogs did not exhibit any clinical signs of illness associated with the treatments. Effects on hematologic values or routine clinical chemical analyses did not occur with the round 2 mixture. Serum lactic dehydrogenase activity decreased by approximately 50% after a single dose of the round 1 mixture was given. Plasma cholinesterase decreased to approximately 50% of control values following either the round 1 or the round 2 mixture; this decrease was not accompanied by cholinergic signs of intoxication.
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PMID:Oral intubation of dogs with combinations of fertilizer, herbicide, and insecticide chemicals commonly used on lawns. 620 Oct 92

A clinical and serological study was performed on 267 of 636 volunteers vaccinated against Argentine hemorrhagic fever with the XJCl3 attenuated strain of Junin virus seven to nine years earlier, in order to determine their long-term evolution. This study included a clinical examination, a chest roentgenogram, an electrocardiogram, and the following laboratory determinations: white and red cell count, number of platelets, hematocrit, hemoglobin, sedimentation rate (Katz index), urea, nitrogen, glucose concentration, cholesterol, GOT, GPT, gamma GT, alkaline phosphatase, cholinesterase, and total bilirubin. Neutralization reactions were performed to determine presistence of antibody levels. All clinical and laboratory findings were within normal limits, excluding a long-term pathology attributable to the virus. Of 165 tested sera, 153 (90.3%) had detectable levels of neutralizing antibodies, and the rest had no antibodies after this time. Although these people live in the endemic area, it is considered that only the 9% that had increased antibody levels had suffered a reinfection during the seven- to nine-year period, which acted as a booster. This figure aproximately coresponds to the subclinical infection value found in the region. In the rest, the persistence of antibodies is attributed to the immunization achieved with the vaccine employed.
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PMID:Immunogenicity of A/USSR (H1N1) subunit vaccine in unprimed young adults. 627 Feb 79


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