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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)

In chick retina, the tailed 20S molecular form of acetylcholinesterase (A12) is slowly degraded to globular forms after homogenization of the tissue in a buffer-salt-detergent solution, in the absence of EDTA. This process can be stopped by the addition of EDTA to the homogenate, prior to high speed centrifugation; however, longer delays in adding EDTA lead to lower recoveries of tailed enzyme. The rate of degradation of A12 is considerably enhanced by high speed centrifugation of this EDTA-less homogenate prior to addition of EDTA.
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PMID:Fate of collagen-tailed acetylcholinesterase upon extraction of chick retina with salt-detergent solutions in the absence of EDTA. 641 52

Several molecular forms of acetylcholinesterase were obtained from Schistosoma mansoni homogenates by extraction in either low-salt buffer, high-salt buffer or detergent buffer. The low-salt soluble form amounts to 25% of the total activity. By contrast, the extract obtained in the presence of Triton X-100 possessed almost almost 3-fold higher enzymatic activity, most of it (86%) being retained in the soluble extract (100 000 X g). High-salt concentration (1 M NaCl) also has a solubilizing effect, but to a lesser extent (50%). Acetylcholinesterase can also be solubilized by treatment with a solution of 1% methylmannoside (40%). In the presence of non-ionic detergents, the enzyme behaves as monodisperse 8 S form. In the absence of detergent the low-salt soluble extract is polydisperse: it contains a 10 S and a 32 S component, the latter could represent high polymers. The molecular form released from tissue homogenate by treatment with alpha-methylmannoside is polydisperse: it contains a major 10 S and a minor 32 S component. Differences in sedimentation coefficient were observed among the enzymes extracted with detergent from the various life cycle stages of the parasite. The enzyme from the cercarial stage sediments as a single 8 S peak. The adult worm exhibits an additional acetylcholinesterase peak of 18 S representing approx. 30% of the total enzymatic activity. The molecular weight of the major 8 S species, as determined by gel filtration, is 450 000.
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PMID:Acetylcholinesterase of Schistosoma mansoni. Molecular forms of the solubilized enzyme. 654 Oct 56

A dimeric form of acetylcholinesterase from the electric organ of Torpedo californica was solubilized by phosphatidylinositol-specific phospholipase C from Staphylococcus aureus. The solubilized enzyme had a sedimentation coefficient of 7.3S which was not modified by detergents. The high salt-soluble asymmetric forms of acetylcholinesterase were not solubilized by the phospholipase. Our data suggest that the hydrophobic dimer of acetylcholinesterase may be associated with the plasma membrane through a specific interaction involving phosphatidylinositol.
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PMID:A hydrophobic dimer of acetylcholinesterase from Torpedo californica electric organ is solubilized by phosphatidylinositol-specific phospholipase C. 663 70

[3H]Diisopropylfluorophosphate was used to label covalently the catalytic subunits of the acetylcholinesterase forms extracted using different solubilization media. The incorporation of radiolabel was specific for true acetylcholinesterase, and SDS-polyacrylamide gel electrophoresis revealed that differences in molecular size existed between low salt-soluble (mol. wt. approximately 76 000), detergent-soluble (69 000) and high salt-soluble (72 000) acetylcholinesterase. These differences could not be attributed solely to an unusual migration behaviour but appeared to reflect differences in primary structure. While the basic unit of the low salt-soluble esterase was a monomer, the detergent-soluble esterase was linked by disulphide bridges to form dimers. The high salt-soluble form existed in large aggregates, whereby disulphide bridges form covalent links between the catalytic and non-catalytic elements. Pronase treatment showed that the differences were confined to the 'outer' structure of these molecules. The active site peptide exhibited homologies indicating that this part is conserved in the different classes of acetylcholinesterase. The results suggest that one can discriminate between at least three distinct esterase classes in the electric organ of Torpedo marmorata.
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PMID:Structural differences in the catalytic subunits of acetylcholinesterase forms from the electric organ of Torpedo marmorata. 664 20

Muscarinic and nicotinic receptor site binding and the activity of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) in the forebrain and brainstem of Dahl salt-sensitive (DS) and salt-resistant (DR) rats was investigated. The DS line had a greater density of muscarinic sites in the cortex, hypothalamus, and medulla. Hypertensive DS rats had a greater density of sites than normotensive DS rats. ChAT activity was also higher in the cortex and hypothalamus of the DS line than the DR line. No significant differences were found in the activity of AChE or the concentration of nicotinic sites. These results suggest that the central muscarinic cholinergic system may participate in the pathogenesis of hypertension in the DS rat. The data indicate that central cholinergic activity is possibly greater in the DS than the DR rat and that this may help to explain the enhanced pressor response in the DS line after pharmacological activation of the central cholinergic system.
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PMID:Cholinergic receptor site binding, choline acetyltransferase, and acetylcholinesterase activity in the forebrain and brainstem of the Dahl rat model of essential hypertension. 666 56

To study the role of acetylcholine metabolism system in the mechanisms responsible for animals' resistance to emotional stress, the activity of acetylcholinesterase (AChE), butyrylcholinesterase and cholinacetyltransferase (CAT) was evaluated in brain structures and autonomous vegetative nervous system of rabbits after experimental emotional stress. In the course of experiments, arterial pressure and heart rate were recorded. The rabbits whose cardiovascular functions appeared to be resistant showed an increase in the activity of AChE and CAT in the perifocal area of the hypothalamus. It is suggested that the involvement of the perifocal area of the hypothalamus in the formation of the mechanisms responsible for the resistance is linked with the effects on water-salt metabolism.
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PMID:[Acetylcholinesterase and choline acetyltransferase in the nervous system of rabbits resistant to emotional stress]. 668 79

Evidence is presented that implicates brain acetylcholine (ACh) in the control of blood pressure (BP) and in hypertension. Central cholinergic stimulation by muscarinic agonists or inhibitors of acetylcholinesterase (AChE) evokes a hypertensive response in several animal species, including humans. The elevation in BP after injection of AChE inhibitors is mediated centrally by ACh acting on muscarinic receptors and peripherally through increased sympathetic nerve activity. The pressor response is accompanied by inhibition of reflex tachycardia and potentiation of both reflex bradycardia and the pressor reflex to carotid artery occlusion. Intracerebroventricular injection of hemicholinium 3 in doses that deplete brain ACh lowers BP in the spontaneously hypertensive and the deoxycorticosterone acetate-salt hypertensive rat. Little or no reduction occurs in the normotensive rat or in animals made hypertensive by aortic coarctation. In addition, atropine and the selective central muscarinic receptor antagonist N-(4-diethylamino-2-butynyl)-succinimide lower BP in the spontaneously hypertensive rat but not in the normotensive rat.
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PMID:Cardiovascular regulation by brain acetylcholine. 669 Mar 34

The density of muscarinic receptor sites, choline acetyltransferase (ChAT), and acetylcholinesterase (AChE) activity in the myocardium of the Dahl salt-sensitive (DS) and salt-resistant (DR) rat was investigated. Both normotensive and hypertensive (as a result of 8.0% NaCl added to the diet) DS rats displayed a lower concentration of muscarinic receptors and less ChAT and AChE activity in myocardial tissue than normotensive DR rats. Lower receptor site density and enzyme activity in the myocardial of the DS line may reflect decreased vagal tone. If true, this may produce dificits in the ability to appropriately adjust heart rate (HR) in response to elevations in blood pressure (BP). Therefore, the present results may be viewed as exacerbational factors in the pathogenesis of hypertension in the DS line.
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PMID:Myocardial cholinergic receptor sites and enzyme activity in the Dahl model of essential hypertension. 672 89

An assay capable of detecting tens-of-picomole quantities of choline and acetylcholine in milliliter volumes of a physiological salt solution has been developed. Silica column chromatography was used to bind and separate 10-3000 pmol [14C]choline and [14C]acetylcholine standards made up in 3 ml of a bicarbonate-buffered Krebs-Ringer solution. The silica columns bound 95-98% of both choline and acetylcholine. Of the bound choline 84-87% was eluted in 1.5 ml of 0.075 N HCl, whereas 95-98% of the bound acetylcholine was eluted in a subsequent wash with 1.5 ml of 0.030 N HCl in 10% 2-butanone. Vacuum centrifugation of the eluants yielded small white pellets with losses of choline and acetylcholine of only 1%. Dried pellets of unlabeled choline and acetylcholine standards were assayed radioenzymatically using [gamma-32P]ATP, choline kinase, and acetylcholinesterase. The net disintegrations per minute of choline[32P]phosphate product was proportional to both the acetylcholine (10-3000 pmol) and choline (30-3000 pmol) standards. The "limit sensitivity" was 8.5 pmol for acetylcholine and 11.4 pmol for choline. Cross-contamination of the choline assay by acetylcholine averaged 1.3%, whereas contamination of the acetylcholine assay by choline averaged 3.1%.
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PMID:Determination of picomole quantities of acetylcholine and choline in physiologic salt solutions. 673 54

2-Mercaptopropionylglycine (2-MPG) transformed normal red blood cells (RBCs) into paroxysmal nocturnal haemoglobinuria (PNH)-like RBCs in vitro, depending on the concentration, pH and time of incubation. The incorporation of radioactive choline in the presence of acetylcholine was reduced, as in RBCs treated with aminoethylisothiouronium salt (AET). In contrast, the uptake in the presence of choline differed when the RBCs were incubated with the two compounds, being reduced in AET-treated RBCs and increased in 2-MPG-treated ones. As true PNH RBCs incorporated to a higher extent the radioactivity in the presence of both acetylcholine and choline, 2-MPG-treated RBCs seemed to resemble the PNH RBCs better than the AET-treated ones. Present results suggest the possibility of modifying selectively the activity of acetylcholinesterase and the transport of choline through the cell membrane.
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PMID:In vitro production of PNH-like red blood cells by 2-mercaptopropionylglycine. 678 95


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