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

---

Query: EC:3.1.1.7 (acetylcholinesterase)
28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Adult black ducks (Anas rubripes) were given freshwater or saltwater (1.5% NaCl) for 11 days and half of each group was also given an organophosphate (17 p.p.m. fenthion) in the diet on days 6-11. 2. After 11 days, ducks drinking saltwater had lost more weight and had higher plasma Na and uric acid concentrations and osmolalities than birds drinking freshwater. 3. Saltwater treatment stimulated the salt gland to increased weight and Na, K-ATPase activity. 4. Fenthion generally reduced plasma and brain cholinesterase activity and depressed cholinesterase and Na, K-ATPase activities in salt glands of birds drinking saltwater.
...
PMID:Organophosphate inhibition of avian salt gland Na, K-ATPase activity. 612 65

Calcium-membrane interactions have been studied in two animal models of hypertension using the erythrocyte membrane as a model system. The Okamoto-Aoki strain of spontaneously hypertensive rats (SHR) was the first examined, and the activities of the Ca++/Mg++-ATPases in the membrane of SHR erythrocytes were found to be consistently higher than those of the normotensive controls (WKY), while other membrane enzymes such as Na+/K+-ATPase and acetylcholinesterase were not detectably altered. Erythrocyte membranes of the SHR also have a higher passive permeability to calcium as well as other functional and compositional differences when compared to those of the WKY. These findings suggest that the membrane alterations in the SHR may be related to an increased passive permeability to calcium, and a possibly compensatory increase in Ca++/Mg++-ATPase activity in these animals. The second animal model examined was the deoxycorticosterone/salt-induced hypertension (DOCA) in uninephrectomized rats. In DOCA rats with comparable degree of blood pressure elevation, none of the erythrocyte membrane abnormalities observed in the SHR were present, suggesting that the latter alterations are probably genetically determined and not a consequence of elevated arterial pressure.
...
PMID:Erythrocyte membrane abnormalities in hypertension: a comparison between two animal models. 613 51

An enzyme immunoassay for acetylcholinesterase in amniotic fluid is described. Rabbit antiserum (IgG fraction) against human erythrocyte membrane acetylcholinesterase is first attached to microtitre plates. Samples containing acetylcholinesterase are added and the enzyme activity is then measured, with acetylthiocholine as substrate and Ellman's reagent as coupling salt. Results are comparable with those by qualitative determination of the enzyme after polyacrylamide gel electrophoresis, except for blood-contaminated amniotic fluids. One person can perform 200 enzyme analyses per day. Intra- and interassay coefficients of variation are less than 5% at concentrations from 15 to 450 arb. units/L. The mean catalytic concentration in 400 amniotic fluid samples was 21 arb. units/L (range 5 to 70 arb. units/L) with 1000 arb. units/L for a human serum pool as standard. All 39 cases of neural tube defects and two-thirds of cases with omphalocele and gastroschisis had abnormally high values, exceeding 75 arb. units/L.
...
PMID:Quantitative enzyme antigen immunoassay of acetylcholinesterase in amniotic fluid. 618 38

Nitroblue tetrazolium (NBT) has been used to stain motor nerve terminals and unmyelinated axons in vertebrate skeletal muscle, but undesirable background connective tissue coloration resulted. This procedure was improved by separation of the tetrazolium salt's binding from its subsequent reduction. By uncoupling the binding and reduction steps it was possible (1) to improve nerve terminal staining by using tetranitroblue tetrazolium (TNBT), (2) to counterstain and postfix in osmium tetroxide and (3) to enhance the overall tissue preservation. The separate binding and reduction procedure is compatible with postsynaptic acetylcholinesterase staining. Experimentally manipulated and diseased preparations can be successfully stained, and the requirements for optimal staining in each case are described.
...
PMID:Staining normal and experimental motor nerve terminals with tetrazolium salts. 619 50

In the original Karnovsky and Roots' method for the localization of acetylcholinesterase (AChE), thiocholine reduces the ferricyanide and cupric ions of this medium competitively, giving simultaneously cupric (Koelle's precipitate) as histochemical products. We modified the method in order to promote the true Karnovsky's reaction, and to slow down the secondary Koelle's reaction by increasing the concentration of the ferricyanide ion from 0.5 mM to 5.0 mM and by decreasing the concentration of the cupric ion from 3.0 mM to 2.5 mM. The cupric ion, complexed with 5 mM sodium citrate in the original method, was further stabilized by the use of 0.1 M citrate buffer in order to prevent the interaction of cupric ion with increased ferricyanide. In order to suppress completely the residual Koelle's precipitate, we used acetylthiocholine chloride as a substrate, instead of acetylthiocholine iodide. The chloride salt of cuprous thiocholine is soluble, contrary to the iodide salt. In addition, the pH of the medium was lowered from 6.0 to 5.0 to avoid artefactual nuclear staining, appearing at a pH beyond 5.5. In this modified medium, Karnovsky's cupric ferrocyanide becomes the sole precipitate at the enzymatic site and this provides fine localization of acetylcholinesterase activity.
...
PMID:A modification of thiocholine-ferricyanide method of Karnovsky and Roots for localization of acetylcholinesterase activity without interference by Koelle's copper thiocholine iodide precipitate. 619 86

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.
...
PMID:Purification and properties of the membrane-bound form of acetylcholinesterase from chicken brain. Evidence for two distinct polypeptide chains. 620 93

Several pollutants like DDT, atrazine, PCP, and others induce changes of cortisol and glucose levels in serum, variations of the amount of liver glycogen and liver function, and exert changes of the activity of gill ATPase and acetylcholinesterase in brain and serum of carps. There is always a biphasic response, an increase of concentration or enzyme activity for a short time, and a decrease or inhibition of the enzymes after a longer exposure to the pollutants. The time scale, the duration of the period of increase and that of decrease, depends on the concentration and the toxicity of the pollutants. The influence of the pollutants in normal fresh water was compared with the effects occurring in carps acclimated to 1.2% salt water. This condition enables one to show that the carps are more sensitive to the pollutants under this condition. All responses are unspecific. Advice for the use of these tests as criteria for water quality are given.
...
PMID:Physiological changes in carps induced by pollution. 622 18

Molecular forms of acetylcholinesterase (AChE) in fresh electric organ tissue are elongated structures in which a multisubunit head containing the catalytic sites is attached to a fibrous tail. The principal form, 18S AChE, is of MW ca. 1,100,000 and aggregates reversibly at low ionic strength. Trypsin converts it to an 11S globular tetramer devoid of the tail and lacking the capacity to aggregate reversibly in low salt. Amino acid analysis, collagenase and pepsin digestion and immunological techniques were utilized to demonstrate that the fibrous tail of the elongated forms of AChE is a collagen triple helix. The distal portion of the tail contains a region responsible for the capacity for aggregation at low ionic strength. This latter property may be related to the postulated role of the tail in anchoring AChE to the fibrillar matrix of the basal lamina.
...
PMID:Electric eel acetylcholinesterase: a multisubunit enzyme containing a collagen tail. 626 36

We have extracted acetylcholinesterase from young chick retinas by homogenization in different solutions combining high salt concentration, ionic and nonionic detergents, and EDTA, looking for an optimum procedure for the solubilization of collagen-tailed, asymmetric structural forms of the enzyme. High salt and EDTA seem to be the only necessary requirements for the solubilization of acetylcholinesterase as the A12 form (20S), and the presence of detergent in the homogenization medium does not significantly improve the yield of tailed enzyme. Extraction in the absence of detergent has the potential advantage of a threefold enrichment of tailed enzyme, because only about one-third of the total retinal acetylcholinesterase activity is solubilized. Divalent cations, especially Ca2+, seem to be involved in the attachment of the tailed enzyme to the retinal membranes, at the tail level. High salt-EDTA-extracted 20S acetylcholinesterase (without detergent) aggregates in the presence of exogenous Ca2+ and becomes "insoluble." However, the aggregated 20S acetylcholinesterase can be completely recovered and brought back into solution by further addition of EDTA. Besides, the aggregation can be prevented by the inclusion of Triton X-100 in the homogenization buffer or by adding the detergent concurrently with Ca2+. It is postulated that the acetylcholinesterase collagenous tail is coated by acidic lipid molecules hydrophobically bound to the tail protein so that Ca2+ ionic bridges would actually link these lipid molecules (and consequently the tail) to the membrane matrix. Removal of the lipid coat (e.g., by Triton X-100) produces tailed acetylcholinesterase molecules that no longer aggregate in the presence of Ca2+ and are fully accessible to collagenase digestion.
...
PMID:Solubilization of collagen-tailed acetylcholinesterase from chick retina: effect of different extraction procedures. 627 24

We have examined the immunoreactivity of acetylcholinesterase from different vertebrate species with a rabbit antiserum raised against the purified rat brain hydrophobic enzyme (G4 form). We found no significant interaction with enzymes from Electrophorus, Torpedo, chicken, and rabbit. The antiserum reacted with acetylcholinesterases from the brains of the other mammalian species studied, with titers decreasing in the following order: rat = mouse greater than human greater than bovine. The serum was inhibitory with murine and human acetylcholinesterases, but not with the bovine enzyme. The inhibition was partially depressed in the presence of salt (e.g., 1 M NaCl). In those species whose acetylcholinesterase was recognized by the antiserum, both soluble and detergent-soluble fractions behaved in essentially the same manner, interacting with the same antibodies. The apparent immunoprecipitation titer was decreased in the presence of salt, and it did not make any difference whether NaCl was included in the solubilization procedure or added to the extracts. Both G1 and G4 forms of acetylcholinesterase in the soluble and detergent-soluble fractions were recognized by the antiserum, and in the case of the human enzyme, by monoclonal antibodies produced against human erythrocyte acetylcholinesterase. However, the monomer G1 showed a clear tendency to form smaller complexes and precipitate less readily than the tetramer G4. Although we cannot exclude the existence of significant differences between the various molecular forms of acetylcholinesterase, our results are consistent with the hypothesis that they all derive from the same gene or set of genes by posttranslational modifications.
...
PMID:An immunological study of rat acetylcholinesterase: comparison with acetylcholinesterases from other vertebrates. 637 38


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---