PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “ACETYLCHOLINESTERASE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1984

Chemical modification of acetylcholinesterase from eel and basal ganglia: effect on the acetylcholinesterase and aryl acylamidase activities.

The effect of chemical modification on the acetylcholinesterase and the aryl acylamidase activities of purified acetylcholinesterase from electric eel and basal ganglia was investigated in the presence and absence of acetylcholine, the substrate of acetylcholinesterase, and 1,5-bis[4-(allyldimethylammonium)phenyl]pentan-3-one dibromide (BW284C51), a reversible competitive inhibitor of acetylcholinesterase. Trinitrobenzenesulfonic acid, pyridoxal phosphate, acetic anhydride, diethyl pyrocarbonate, and 2-hydroxy-5-nitrobenzyl bromide under specified conditions inactivated both acetylcholinesterase and aryl acylamidase in the absence of acetylcholine and BW284C51. Chemical modifications in the presence of acetylcholine and BW284C51 by all the above except diethyl pyrocarbonate selectively prevented the loss of acetylcholinesterase but not aryl acylamidase activity; modification by diethyl pyrocarbonate in the presence of acetylcholine and BW284C51 prevented the loss of both acetylcholinesterase and aryl acylamidase activities. Treatment with N-acetylimidazole resulted in the inactivation of acetylcholinesterase and the activation of aryl acylamidase. These changes in both the activities could be prevented by acetylcholine and BW284C51. Modification by phenylglyoxal, 2,4-pentanedione, or N-ethylmaleimide did not affect the enzyme activities. Indophenylacetate hydrolase activity followed a pattern similar to that of acetylcholinesterase in all the above modification studies. The results suggested essential lysine, tyrosine, tryptophan, and histidine residues for the active center of acetylcholinesterase and essential lysine, histidine, and tryptophan residues for the active center of aryl acylamidase.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗
PubMed1984

An immunological study of rat acetylcholinesterase: comparison with acetylcholinesterases from other vertebrates.

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.

Acetylcholinesterase↗
PubMed2004

Acetylcholinesterase-based biosensor electrodes for organophosphate pesticide detection. I. Modification of carbon surface for immobilization of acetylcholinesterase.

Screen-printed carbon electrodes modified with the dialdehydes, glutaraldehyde and terephthaldicarboxaldehyde, and then polyethyleneimine have been utilized for production of pesticide biosensors based on acetylcholinesterase. To improve the extent of dialdehyde modification, the electrodes were NH2-derivatized, initially by electrochemical reduction of 4-nitrobenzenediazonium to a nitroaryl radical permitting attachment to the carbon surface. Subsequent reduction of the 4-nitrobenzene yields a 4-aminobenzene modified carbon surface. Drosophila melanogaster acetylcholinesterase was immobilized either covalently onto dialdehyde modified electrodes or non-covalently onto polyethyleneimine modified electrodes. Internal diffusion limitations due to the dialdehyde and polyethyleneimine modifications increased the apparent Km of the immobilized enzyme. The thiocholine sensitivity was about 90% for dialdehyde modified electrodes and about 10% for polyethyleneimine modified electrodes as compared with non-modified carbon electrodes. The detection limit of the biosensors produced by non-covalent immobilization of acetylcholinesterase onto polyethyleneimine modified carbon electrodes was found to be about 10(-10) M for the organophosphate pesticide dichlorvos.

Acetylcholinesterase↗
PubMed1991

The effect of elimination of intersubunit disulfide bonds on the activity, assembly, and secretion of recombinant human acetylcholinesterase. Expression of acetylcholinesterase Cys-580----Ala mutant.

Site-directed mutagenesis was used to study the cysteine residue involved in the assembly of human acetylcholinesterase (HuAChE) catalytic subunits. Substitution of the cysteine at position 580 by alanine resulted in impairment of interchain disulfide bridge formation; the mutagenized enzyme (C580A) was secreted from recombinant cells in the monomeric form and failed to assemble into dimers. The mutant monomeric HuAChE did not differ from the native oligomeric enzyme neither in rate of catalysis nor in affinity to acetylthiocholine. Mutant monomers were also shown to retain the acetylcholinesterase characteristic sensitivity to high substrate concentrations. The mutation did not seem to affect the efficiencies of either synthesis or secretion of recombinant HuAChE polypeptides, as was demonstrated in cell lines derived from human embryonic kidney (293 cells) as well as from a human neuroblastoma (SK-N-SH). Furthermore, the mutation did not lead to an increase in accumulation of intracellular HuAChE polypeptides, suggesting that export of acetylcholinesterase from cells may not be coupled to subunit assembly.

Acetylcholinesterase↗
PubMed1990

Different levels of acetylcholinesterase and choline acetyltransferase activities in C57Bl/6 and DBA/2 mice are not accompanied with different density of cortical acetylcholinesterase reactive fibers.

Mice of the inbred strains C57B1/6 and DBA/2 show strain-dependent behavioural differences which have been correlated with variations in the organization of brain cholinergic systems. The aim of our study was to analyse the extent of cholinergic interstrain differences in circumscript brain regions of C57B1/6 and DBA/2 mice. The biochemical determination of choline acetyltransferase and acetylcholinesterase in cortical areas, basal forebrain and striatum showed significantly lower enzyme activities in most of the regions of C57B1/6 mice. The deficit was most pronounced in the basal forebrain/diagonal band, in the piriform cortex, and striatum. The density of acetylcholinesterase-stained cortical fibres did not reflect the biochemical interstrain differences. This may be due to a different enzyme content in the nerve fibers of the two mice strains. The previous findings are discussed in terms of brain cholinergic disorders in which the extent of damage but also the proportions of regional deficits may influence the pattern of behavioural dysfunctions.

Acetylcholinesterase↗
PubMed1975

Immobilized electric eel acetylcholinesterase. I. Kinetics of acetylcholinesterase trapped in polyacrylamide membranes.

Techniques are described for the trapping of electric eel acetylcholinesterase in polyacrylamide gel. The activity of the trapped enzyme was substantially reduced, the effect being due to inhibition by acrylamide, but the emzyme immobilized in polyacrylamide was considerable more stable than that in free solutionma kinetic study was made of the hydrolysis of acetylthiocholine, covering a range of membrane thicknesses, enzyme concentrations, substrate concentrations and temperatures. The results were interpreted with reference to the theoretical treatment of Sundaram, Tweedale and Laidler, and of Kobayaski and Laidler, and provided support for those treatments; Clear evidence was obtained for diffusion control with the thicker membranes. An activation energy was obtained for the diffusion of the substrate within the membrane, by combining the temperature results for thick and thin membranes at low substrate concentrations. The results lead to the conclusion that the in vivo kinetics of acetylcholinesterase are largely diffusion-free in muscle filaments, but are substantially diffusion-controlled in fibrils and fibers.

Acetylcholinesterase↗
PubMedDate not supplied

Indirect detection of anti-acetylcholinesterase compounds in microcolumn liquid chromatography using packed bed reactor with immobilized human red blood cell acetylcholinesterase and choline oxidase.

The inhibiting compounds were separated by micro-column liquid chromatography in the mobile phase containing the natural substrate acetylcholine. A home-made packed bed microbioreactor system containing immobilized enzyme acetylcholinesterase (ACHE) in human red blood cell membrane and choline oxidase (CHO) from alcaligenes was used for the post-column conversion of acetylcholine to hydrogen peroxide which was detected by an electrochemical detector. The inhibition effect of the solutes caused a decrease in the acetylcholinesterase activity, a decrease in the formation of hydrogen peroxide and also a decrease in the response corresponding to the concentration of the solutes. The rate of the enzyme regeneration was also recorded. The micro-system was compared with a conventional LC system comprising commercially prepared enzyme reactor. The stability of the enzymes is at least 3 weeks at ambient temperature. The limit of detection depends on biological activity of inhibition and for galanthamine was 1 pmol.

Acetylcholinesterase↗
PubMed1998

Functional expression of a mammalian acetylcholinesterase in Pichia pastoris: comparison to acetylcholinesterase, expressed and reconstituted from Escherichia coli.

The mature rat brain acetylcholinesterase gene (T subunit, AChE) was subcloned downstream of the temperature-inducible lambda promoter PL and fused to the signal peptide of the OmpA protein. Three different expression vectors were constructed: (i) pCompmA containing the mature AChE, (ii) pComp delta TA containing a truncated AChE and (iii) pComp delta TAH containing the truncated AChE C-terminal fused to a 6xHis-tag. With all expression vectors the overexpression of AChE in Escherichia coli resulted mainly in cytoplasmic inclusion bodies (IB). However, some activity was found in the periplasmic space. The inclusion bodies were refolded in vitro, yielding up to 1.42 U/mg IB of active AChE. The refolded AChE was partially purified (approx. 300-fold) by affinity chromatography with a specific activity of approx. 250 U/mg. Removing the cysteine residue near the C-terminus (truncated AChE, delta TAChE) assuming to affect the refolding, did not increase the amount of active enzyme obtained after refolding. Purification of denatured delta TAChE-6xHis prior to refolding by Ni-NTA-chromatography increased the refolding efficiency by a factor of 1.5. Functional expression and secretion of rat brain acetylcholinesterase into the medium was achieved in Pichia pastoris. By optimizing the culture conditions, 100 mU/ml AChE in the medium was produced. In this work we are describing the functional expression of a mammalian AChE in a microbial host in good yields for the first time. The physico-chemical properties of both, the bacterial and yeast expressed AChE were compared with those of the native AChE. The properties of the yeast expressed AChE and the native AChE were similar, whereas the E. coli expressed enzyme was found to be less stable and had different inhibition properties.

Acetylcholinesterase↗
PubMed1987

Acetylcholinesterase from bovine caudate nucleus is attached to membranes by a novel subunit distinct from those of acetylcholinesterases in other tissues.

Acetylcholinesterase extracted with Triton X-100 from bovine brain caudate nuclei was purified by affinity chromatography to apparent homogeneity. The purified enzyme was labeled with [3H]diisopropyl fluorophosphate at the active sites and with the photoactivated reagent 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine, a compound which has been shown to be selective for the hydrophobic membrane-binding domains of several other proteins. The subunit structure was analyzed by polyacrylamide gel electrophoresis in sodium dodecyl sulfate before and after disulfide reduction. After reduction, a single 3H-labeled band at 70 kDa was stained by silver, but most of the 125I label corresponded to a 20-kDa species. Prior to reduction, five 3H-labeled and silver-stained bands were apparent at 70, 140, 160, 260, and greater than 360 kDa. These species were presumed to represent monomer and disulfide-linked oligomers of 70-kDa catalytic subunits. 125I label was selectively associated with the 160-, 260-, greater than 360-, and a 90-kDa species. Quantitative gel slicing of 3H- and 125I-labeled nonreduced enzyme supported a structural model in which the tetrameric enzyme is a dimer of nonidentical catalytic subunit dimers, one of which involves a direct intersubunit disulfide linkage between two 70-kDa catalytic subunit monomers and the second of which contains two disulfide linkages through an intervening 125I-labeled 20-kDa noncatalytic subunit. This 20-kDa subunit is proposed to contain the membrane attachment site. The brain enzyme did not contain components characteristic of the glycolipid anchors of erythrocyte acetylcholinesterases. However, part of the 125I label was associated with fatty acids, indicating that at least a portion of the brain enzyme membrane anchor is composed of nonamino acid components.

Acetylcholinesterase↗
PubMed1998

Acetylcholinesterase antibody treatment results in neurite detachment and reduced outgrowth from cultured neurons: further evidence for a cell adhesive role for neuronal acetylcholinesterase.

Data from our laboratory and others demonstrate that acetylcholinesterase (AChE) is expressed transiently by neurons during periods of neurite outgrowth preceding synaptogenesis, suggesting an extrasynaptic function for this molecule. These findings, along with reports that AChE shares amino acid sequence homology and structural similarities with known cell adhesion molecules, have led to the theory that, during development, AChE may exert a morphogenic effect through cell adhesion. To further test this hypothesis, we have examined the effects of an AChE monoclonal antibody (MAB304) on neurite outgrowth in primary cultures of rat dorsal root ganglion (DRG) neurons. Short-term, high-concentration antibody treatment produced a rapid detachment of established DRG neurites, which was followed by regrowth upon removal of the antibody from the culture medium. This effect appeared to be site-specific, because other AChE antibodies that were able to detect AChE immunocytochemically failed to produce this disadhesion. Long-term, low-concentration antibody exposure produced a 50% reduction in total area of outgrowth, in which neurites were more densely packed and interlaced compared with the neurites in control cultures. These results extend our previous observations on the outgrowth perturbing effects of AChE inhibitor treatment and provide further evidence that AChE may support neurite outgrowth through a cell adhesive role.

Acetylcholinesterase↗
PubMed1989

Amniotic fluid acetylcholinesterase measurement in the prenatal diagnosis of open neural tube defects. Second report of the Collaborative Acetylcholinesterase Study.

Seventeen centres from Australia, Britain, France, and the United States collaborated in a study to compare amniotic fluid acetylcholinesterase (AChE) determination by gel electrophoresis and amniotic fluid alpha-fetoprotein (AFP) measurement as diagnostic tests for open neural tube defects. The study was based on 32,642 women with singleton pregnancies (including 428 with open spina bifida and 238 with anencephaly) who had an amniocentesis at 13-24 weeks' gestation. The AChE test yielded a detection rate for open spina bifida of 99 per cent (95 per cent confidence interval 98-100 per cent), 98 per cent for anencephaly (95 per cent confidence interval 96-100 per cent), and a false-positive rate of 0.34 per cent (95 per cent confidence interval 0.28-0.40 per cent) excluding miscarriages, intrauterine death, and serious fetal abnormalities. The false-positive rate was 0.30 per cent among the 13 centres that used a specific AChE inhibitor in the test. Comparable rates for the AFP test were less favourable. (For example, the open spina bifida detection rate was 90 per cent and the false-positive rate was 0.46 per cent using the cut-off levels specified in the U.K. Collaborative AFP Study.) The AChE false-positive rate was lower in samples that were not bloodstained (0.16 per cent) than in those that were (2.4 per cent). It was higher in women who had an amniocentesis on account of a raised maternal serum AFP level (0.56 per cent) than in those who had one for other reasons (0.29 per cent). The best results were obtained by a combination of the two tests, an effective and economical policy being to perform the AFP measurement on all amniotic fluid samples and an AChE test on samples with AFP levels greater than or equal to 2.0 multiples of the normal median (about 5 per cent of all samples). Using this policy, the open spina bifida detection rate was 96 per cent and the false-positive rate was 0.14 per cent (0.06 per cent for samples that were not bloodstained and 1.2 per cent for those that were; 0.40 per cent for women with raised serum AFP levels and 0.09 per cent for other women). This policy offers a useful improvement to the prenatal diagnosis of open spina bifida.

Acetylcholinesterase↗
PubMed1992

Occurrence of acetylcholinesterase activity closely associated with amyloid beta/A4 protein is not correlated with acetylcholinesterase-positive fiber density in amygdala of Alzheimer's disease.

To investigate the possible relationship between acetylcholinesterase (AChE)-containing fiber density and senile plaque density and between AChE-positive plaques and beta/A4 protein deposition, AChE histochemistry, the modified Bielschowsky's method and beta/A4 protein immunohistochemistry were performed on the amygdala of Alzheimer's disease (AD) and aged control cases. Abundant AChE-positive senile plaques were found in the amygdala and related structures in AD. These AChE-positive plaques were mainly of the primitive or diffuse type. In addition to senile plaques of typical morphologies a variety of AChE-positive structures were observed in the amygdala and related regions in AD. A comparison of serial sections stained alternatively with AChE histochemistry and beta/A4 protein immunohistochemistry has revealed that these AChE-positive structures with variable morphological appearances displayed beta/A4 protein immunoreactivity, indicating that AChE is localized in a variety of beta/A4 protein deposition including the diffuse plaque. Thus, it is suggested that AChE is present in some senile plaques at the earliest stage. However, there was no apparent correlation between the numerical density of AChE-positive fibers and senile plaque density. These findings suggest that the degeneration of cholinergic neurons is not attributed to the occurrence of AChE activity in beta/A4 protein.

Acetylcholinesterase↗
PubMed1986

Identical N-terminal peptide sequences of asymmetric forms and of low-salt-soluble and detergent-soluble amphiphilic dimers of Torpedo acetylcholinesterase. Comparison with bovine acetylcholinesterase.

We have determined partial N-terminal sequences of acetylcholinesterase (AChE) catalytic subunits from Torpedo marmorata electric organs and from bovine caudate nucleus. We obtain identical sequences (23 amino acids) for the soluble ('low-salt-soluble' or LSS fraction) and particulate ('detergent-soluble', or DS fraction) amphiphilic dimers (G2 form) and for the asymmetric, collagen-tailed forms ('high-salt-soluble', or HSS fraction, A12 + A8 forms). There are two amino acid differences, at position 3 (Asp/His) and 20 (Ile/Val), with the sequences obtained for T. californica by MacPhee-Quigley et al. [(1985) J. Biol. Chem. 260, 12185-12189] for the soluble G2 form and the lytic G4 form which is derived from asymmetric AChE. The bovine sequence (12 amino acids) presents an identity of 4 amino acids (Glu-Leu-Leu-Val) with that of Torpedo, at positions 5-8 (Torpedo) and 7-10 (bovine). There is also a clear homology with the sequence of human butyrylcholinesterase [(1986) Lockridge et al. J. Biol. Chem., in press] indicating that these enzymes probably derive from a common ancestor.

Acetylcholinesterase↗
PubMed1996

Structure-activity relationships in platelet-activating factor (PAF). 8. Tetrahydrofuran derivatives as dual PAF antagonists and acetylcholinesterase inhibitors: anti-acetylcholinesterase activity and comparative SAR.

2,5-disubstituted tetrahydrofuran derivatives display a dual functionality: they are PAF antagonists and acetylcholinesterase (AChE) inhibitors. In vitro anti-AChE activity and in vivo trials are presented herein. These compounds are competitive and potent AChE inhibitors. Structure-activity relationships are described and compared with PAF-antagonist results. The presence of an onium group, a suitable distance supplied by a chain of 7 or 10 carbon atoms separating the function from the polar head and an appreciable chain hydrophobicity (4 < sigma f < 7) are the main features required for a dual activity. The derivatives are evaluated in a mouse passive avoidance model. Only compounds with both activities are able to reverse scopolamine-induced amnesia. In addition, they display a very weak toxicity.

Acetylcholinesterase↗
PubMed2005

Delivery of human acetylcholinesterase by adeno-associated virus to the acetylcholinesterase knockout mouse.

The purpose of this work was to develop a gene delivery system that expressed acetylcholinesterase (AChE) for prolonged periods. An adeno-associated virus (AAV) expressing human AChE was constructed by co-transfecting three plasmids into HEK 293T cells. The purified vector expressed 0.17 microg AChE per 1 million viral particles in culture medium in 23 h, or 0.8 U/ml. The AAV/hAChE was injected into muscle of adult AChE knockout mice and into the brains of 3-6 week old AChE knockout mice. Intramuscular injection yielded plasma AChE levels approaching 50% of the AChE activity of wild-type mouse plasma. The highest AChE activity was found on day 3 post-injection. AChE activity declined thereafter to a constant 7% of normal. The decreased level was accompanied by the appearance of anti-human AChE antibodies, suggesting partial clearance of AChE from plasma by antibodies. Intrastriatal injection resulted in AChE expression in the striatum. No antibodies were detected in animals treated intrastriatally. Motor coordination was improved and the lifespan of intrastriatally-treated AChE knockout mice was prolonged. Human AChE was expressed in mouse brain for up to 7 months after intrastriatal injection of an AAV/hAChE construct. Gene-therapy to supply AChE to the striatum improved motor coordination and prolonged the life of mice genetically deficient in AChE, probably by reducing their susceptibility to spontaneous seizures. This supports the hypothesis that their seizures are induced by excess acetylcholine.

Acetylcholinesterase↗
PubMed2005

Differential effects of TAK-802, a selective acetylcholinesterase inhibitor, and carbamate acetylcholinesterase inhibitors on contraction of the detrusor smooth muscle of the guinea pig.

The aim of this study was to compare the effects of TAK-802, a novel acetylcholinesterase (AChE) inhibitor, and carbamate AChE inhibitors on the detrusor smooth muscle contractility in vitro using isometric tension measurements. The effects of drugs on the nicotine-induced contractions and basal tone of the isolated detrusor muscle of the guinea pig were examined. All of the drugs, namely, TAK-802, distigmine, neostigmine and pyridostigmine, enhanced the nicotine-induced contractions of the muscle strips in a concentration-dependent manner. On the other hand, while neostigmine and pyridostigmine markedly increased the basal tone, and distigmine slightly but significantly increased the basal tone, TAK-802 had no influence on the basal tone of the muscle strips at all. However, following co-treatment with tetraisopropyl pyrophosphoramide, a selective butyrylcholinesterase (BuChE) inhibitor, TAK-802 also did increase the basal tone. The increase of the basal tone by all of the above treatments was completely abolished by atropine. These results reveal that while all the four AChE inhibitors enhanced endogenous acetylcholine-induced contractions, their effects on the basal tone were clearly different. The effect of carbamate AChE inhibitors of increasing the basal tone could be partly attributed to their dual inhibition of both AChE and BuChE, because both cholinesterases may play a critical role in maintaining the resting tension of the urinary bladder. TAK-802, however, did not increase the basal tone of the detrusor muscle strips, probably because of its selective inhibitory effect against AChE. The effect of carbamate AChE inhibitors on the basal tone of the detrusor muscle may explain the decrease of bladder compliance observed in our previous study on guinea pigs as well as the deterioration of the bladder-storage function reported with their clinical use.

Acetylcholinesterase↗
PubMed2004

A peptide derived from the C-terminal region of acetylcholinesterase modulates extracellular concentrations of acetylcholinesterase in the rat substantia nigra.

It is well established that acetylcholinesterase (AChE) has 'non-classical' functions independent of cholinergic transmission. A region of AChE distinct from the catalytic site may be responsible for these actions via a 14-residue peptide located between residues 586-599 at the C-terminus of human AChE. This AChE-peptide possesses a high amino acid sequence homology with a region of amyloid precursor protein and shares many biophysical and physiological characteristics. In this study, the effect of AChE-peptide (AEFHRWSSYMVHWK) on the extracellular levels of endogenous AChE was examined in rat substantia nigra in vitro. A chemiluminescent assay was used to continuously measure the soluble AChE concentration from tissue punches of the substantia nigra. Application of NMDA evoked an increase in extracellular AChE levels consistent with previous results obtained from in vivo models. AChE-peptide, when applied alone, had no effect on AChE release: however, when co-applied with NMDA, AChE-peptide reduced the effectiveness of NMDA to evoke release of AChE. These results indicate, in a region of the brain central to the aetiology of Parkinson's disease, that an AChE-peptide fragment derived from AChE displays a bioactivity that could involve regulation of Ca(2+) availability and hence the release of AChE.

Acetylcholine↗