Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.7 (acetylcholinesterase)
 28,390 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Biochemical studies of the actions of ethanol on the activity of acetylcholinesterase (AChE), isolated from electric eel (Electrophorus electricus) and purified by affinity chromatography, were performed to elucidate ethanol-enzyme-solvent interactions. 2. Ethanol at a low concentration [( EtOH] = 2.7-200 mM) was found to enhance AChE activity slightly and systematically. 3. This observation was consistent with the result from enzyme-kinetic studies that ethanol might noncompetitively activate AChE activity at this lower concentration range. 4. If ethanol alters the hydrophobic site interaction on the enzyme and subsequently induces a favorable conformation for the active center of the enzyme, then a slight increase in the AChE activity in the presence of a low concentration of ethanol will be observed. 5. This speculation was supported by the finding of ethanol's ability to perturb the inhibition of AChE activity by tetrabutylammonium bromide and to affect hydrophobic interaction between this salt and AChE, as investigated by enzyme activity and microcalorimetric measurements. 6. The ethanol effect on the activity of this soluble AChE was found to be distinguishable from that on a membrane-bound AChE. 7. Furthermore, to elucidate the effect of ethanol-solvent interaction on AChE activity, enzyme activity in the presence of much higher concentrations of ethanol was also examined. 8. At [EtOH] greater than 800 mM, ethanol can perturb the structure of water around hydrophobic areas of AChE, causing an instability in the enzyme conformation and subsequently decreasing AChE activity.
 ...
PMID:Biochemical studies of the actions of ethanol on acetylcholinesterase activity: ethanol-enzyme-solvent interaction. 199 62

Three distinct classes of membrane-bound acetylcholinesterases (AChEs) have been identified. A12 AChE is composed of 12 catalytic subunits that are linked to noncatalytic collagen-like subunits through intersubunit disulfide bonds. G2 AChE is localized in membranes by a glycoinositol phospholipid covalently linked to the C-terminal amino acid. Brain G4 AChE involves two catalytic subunits linked by a direct intersubunit disulfide bond while the other two are disulfide-linked to a membrane-binding 20-kDa noncatalytic subunit. Molecular cloning studies have so far failed to find evidence of more than one AChE gene in any organism although alternative splicing of torpedo AChE mRNA results in different C-terminal sequences for the A12 and G2 AChE forms. Support for a single bovine AChE gene is provided in this report by amino acid sequencing of the N-terminal domains from the G2 erythrocyte, G4 fetal serum, and G4 brain AChE. Comparison of the 38-amino acid sequences reveals virtually complete identity among the three AChE forms. Additional extensive identity between the fetal serum and brain AChEs was demonstrated by sequencing several brain AChE peptides isolated by high performance liquid chromatography after trypsin digestion of nitrocellulose blots of brain AChE catalytic subunits. Cysteines involved in intersubunit disulfide linkages in brain AChE were reduced selectively with dithiothreitol in the absence of denaturants and radioalkylated with iodoacetamide. The observed sequence of the major radiolabeled tryptic peptide was C*SDL, where C* was the radioalkylated cysteine residue. This sequence is precisely the same as that observed at the C terminus of fetal bovine serum AChE and shows close homology to the C-terminal sequence of torpedo A12 AChE. We conclude that the mammalian brain G4 AChEs utilize the same exon splicing pattern as the A12 AChEs and that factors other than the primary sequence of the AChE catalytic subunits dictate assembly with either the collagen-like or the 20-kDa noncatalytic subunits.
 ...
PMID:Bovine brain acetylcholinesterase primary sequence involved in intersubunit disulfide linkages. 201 79

As cortical reorganization in cat somatosensory cortex has been shown to be age-dependent and acetylcholinesterase and acetylcholine have been implicated in the shaping of sensory responses during the developmental process, we decided to investigate the biochemical changes that occur in acetylcholinesterase during postnatal development of the primary somatosensory cortex in normal cat. Somatosensory cortices were removed from cats at various ages between 4 and 144 postnatal days. Three fractions (total, membrane-bound and soluble) were analyzed for activity (esterase assay and sedimentation analysis) and amount of acetylcholinesterase (electrophoresis). Results indicated that both esterase activity levels and amounts were characterized by 4 distinct phases which included a large step increase in all fractions between postnatal days 10 and 12: a gradual rise between days 12 and 28: a 'dip' during the 42- to 82-day interval, and a subsequent recovery. Results may be attributed to concomitant developmental events. Furthermore, we suggest that the observed changes may relate to age-dependent differences in somatosensory cortex reorganization that occur after spinal cord transection.
 ...
PMID:Age-dependent changes in acetylcholinesterase activity in the primary somatosensory cortex of the cat. 226 81

In order to observe acetylcholinesterase (AChE) and its distribution into soluble and membrane-bound molecular forms in cholinergically denervated hippocampus, AChE was analyzed in the hippocampus of adult mice with and without bilateral fornix lesions made by stereotactically positioned knife cuts. Homogenates from lesioned mice contained an average of 3% of choline acetyltransferase-specific activity, 12% of AChE-specific activity and 98% of protein compared to homogenates from controls. After lesioning, the relative proportion of membrane-bound G4 decreased from 77% to 56% of total AChE while soluble G4, membrane-bound G1-G2, and soluble G1-G2 each increased in relative abundance.
 ...
PMID:Changes in membrane-bound and soluble molecular forms of acetylcholinesterase in mouse hippocampus after cholinergic denervation. 227 69

The effect of riboflavin deficiency on the fluidity and function of the red blood cell (RBC) membrane and on the activity of some enzymes involved in antioxidant defense mechanisms was studied. Growing male rats were fed an experimental (riboflavin-deficient) or a control (riboflavin-supplemented) diet. Following 7 wk of feeding, RBC from riboflavin-deficient rats contained higher levels of peroxidation products, most likely due to decreased glutathione reductase activity. An elevation in glutathione peroxidase activity was also observed whereas the activity of catalase and superoxide dismutase was not affected. Membrane fluidity was studied by fluorescence polarization, using 1,6-diphenyl-1,3,5 hexatriene (DPH) as a probe. The fluidity of RBC membranes isolated from riboflavin-deficient rats was significantly lower than that of the controls. This decreased fluidity was accompanied by an increase in the activity of the membrane-bound enzyme acetylcholinesterase. This study demonstrated that a decrease in cells' ability to cope with peroxidative damage as a result of riboflavin deficiency may lead to changes in the fluidity and function of membranes.
 ...
PMID:Riboflavin deficiency and the function and fluidity of rat erythrocyte membranes. 238 Jul 93

Acetylcholinesterase is a key enzyme in cholinergic neurotransmission for hydrolyzing acetylcholine and has been shown to possess arylacylamidase activity in addition to esterase activity. The enzyme is found at various loci, where its functional significance remains to be clarified, and it exists in multiple molecular forms. Sheep platelets have been shown to exhibit acetylcholinesterase activity associated with plasma membrane (Bp), endoplasmic reticulum (Cp), mitochondria granules (Dp), and soluble (As) fractions. These activities show differences in some physicochemical and kinetic properties. The soluble acetylcholinesterase is the most thermostable, and the enzyme from the Cp fractions shows the lowest affinity for the acetylthiocholine substrate and the strongest inhibition by fluoride. In all cases a noncompetitive inhibition of the enzyme by this ion is found. When membrane-bound acetylcholinesterases were assayed at temperatures between 12 degrees C and 33 degrees C, the Arrhenius plots of all activities exhibited a break point at about 17 degrees C. This discontinuity was abolished by addition of detergent to the assay medium (0.02% Triton X-100, final concentration). Their Hill coefficients were calculated in the presence of fluoride, showing unitary values in all cases, which points to a noncooperative effect and nonallosteric behavior in the particulate enzyme. These results suggest that the sheep platelet acetylcholinesterase associated with membrane-bound systems is modulated by the physical state of its environment, despite the fact that the enzyme might be lipid- or nonlipid-dependent.
 ...
PMID:Subcellular distribution and characterization of acetylcholinesterase activities from sheep platelets: relationships between temperature-dependence and environment. 238 54

We are interested in the expression of synapse-specific macromolecules and its correlation with the appearance of neuronal types and synaptogenesis during development of the mammalian brain. We report here studies showing that the appearance of acetylcholinesterase (AChE) at layer IV of the rat somatosensory cortex is correlated with the expression of a membrane-bound AChE. Both its electrophoretic mobility and its sedimentation coefficient remain unaltered during maturation; however, its kinetics parameters, the heat and fixative sensitivities and the substrate inhibition changed through development. Our results suggest that an adult form of membrane-bound AChE is expressed postnatally.
 ...
PMID:Membrane-bound form of acetylcholinesterase activated during postnatal development of the rat somatosensory cortex. 241 18

A 30-day ingestion of gamma-hexachlorocyclohexane (lindane) by carp (Cyprinus carpio) induced hypoglycemia without activation of two hepatic gluconeogenesis enzymes (fructose diphosphatase, EC 4.1.2.13, and glucose-6-phosphatase, EC 3.1.3.9) and hyponatremia and variations in muscle plasmic membrane-bound enzymes (especially cholinesterases, EC 3.1.1.7). After 109 days carps exhibited a decrease in natremia but no significant hypoglycemia. There was an activation of gluconeogenesis enzymes. Important changes were observed in the activities of muscle plasmic membrane enzymes (especially 5'-nucleotidase, EC 3.1.3.5, and ATPases, EC 3.6.1.3). Lindane, a lipophilic substance, especially disturbed the activity of membrane-bound enzymes enclosed in a phospholipid matrix.
 ...
PMID:Effect of gamma-hexachlorocyclohexane (lindane) on carp (Cyprinus carpio). II. Effects of chronic intoxication on blood, liver enzymes, and muscle plasmic membrane. 244 Jun 61

The fast axonal transport of acetylcholinesterase (AChE) and the slow transport of choline acetyltransferase (ChAT) were measured by the stop-flow ligation technique in the sciatic nerve of rabbits 6 and 24 h after ischemia performed by the occlusion of the abdominal aorta which lasted 40 min. Activities of these enzymes were also measured in punched samples of the spinal cord (L5-6). Results were correlated with those obtained from the sham-operated control group. Six h after ischemia, its only apparent effect was a different distribution of accumulated enzymes in the central nerve segments. Twenty-four h after ischemia, the transport of AChE was markedly depressed; proximodistal accumulation decreased by 68%, whereas enzyme activity in the intact contralateral nerve and in the ventral horns of the spinal cord was preserved. No effect of ischemia on the retrograde axonal transport of AChE was observed in this experimental model. Cytoplasmic ChAT is much more susceptible to necrotic degeneration than membrane-bound AChE; 24 h after ischemia its activity decreased significantly in all investigated parts of the sciatic motoneurones but the rate of slow axonal transport did not seem to be affected.
 ...
PMID:Effect of spinal cord ischemia on axonal transport of cholinergic enzymes in rabbit sciatic nerve. 246 95

The possible mechanism of the depressive effect of organic solvents on the central nervous system (CNS) was studied with synaptosome membranes as a model. The changes in the activities of the membrane-bound integral enzymes acetylcholinesterase, total adenosinetriphosphatase, and magnesium-activated adenosinetriphosphatase were determined after treatment with different concentrations of organic solvents in vitro. Aromatic hydrocarbons and chlorinated aliphatic hydrocarbons inhibited all the enzyme activities concentration dependently. Alcohols had no significant effect at the same dose levels. The results of the present study suggest that the CNS depressive effect of organic solvents may be based on their interaction with membrane integral proteins.
 ...
PMID:Inhibition of synaptosome membrane-bound integral enzymes by organic solvents. 252 39


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