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 complete amino acid sequence of a mammalian acetylcholinesterase from fetal bovine serum (FBS AChE) is presented. This enzyme has a high degree of sequence identity with other cholinesterases, liver carboxyesterases, esterase-6, lysophospholipase, and thyroglobulin. The locations of 191 amino acids in 10 regions of the FBS enzyme were compared with corresponding sequences of Torpedo, human, and Drosophila AChEs and human serum butyrylcholinesterase (BChE). In one region there is a marked difference in both the number of amino acids and their sequence between mammalian AChE and other AChEs and the human serum BChE. The amino acid sequence of FBS AChE showed overall homologies of 90% with human AChE, 60% with T. california AChE, 50% with human serum BChE, and 39% with Drosophila AChE in these regions.
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PMID:Complete amino acid sequence of fetal bovine serum acetylcholinesterase and its comparison in various regions with other cholinesterases. 236 60

Studies have been made of the effect of several organophosphorus inhibitors, R1(R2)P(O) . SCH2CH2SR and R1(R2)P(O)SCH2CH2SRR . -O4SCH3 (or -I), which differ by the structure of split (R, P) and phosphoryl (R1, R2) parts of the molecule, on cholinesterase (ChE) from the brain of the fly Delia brassicae, acetylcholinesterase (AChE) of the bovine erythrocytes and butyrylcholinesterase (BuChE) from the blood serum of the horse. For fly ChE, higher values of a constant (kII) of the inhibition rate (at pH 7.5 and temperature 25 degrees C) were obtained both with thiophosphates and with thiophosphonates. This finding reveals higher reactivity of the active centre of this enzyme, as well as significantly lower selectivity of the latter to the structure of organophosphorus inhibitors. The data obtained suggest the existence of differences in the size of hydrophobic regions of anionic and esterase parts of the active centre in ChE of the fly and AChE of mammals, as well as the existence of some similarity between ChE of the fly and BuChE.
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PMID:[A comparative study of the interaction of the cholinesterase from the brain of the cabbage fly, the acetylcholinesterase from bovine erythrocytes and the butyrylcholinesterase from horse blood serum with organophosphorus inhibitors]. 237 93

Carbaryl and aldicarb, two carbamate pesticides used extensively throughout the United States, are known to act as acetylcholinesterase inhibitors. We have demonstrated previously that exposure to carbaryl and aldicarb in young chicks caused persistent locomotion alterations with no correlation to esterase inhibition. In this study, we investigated the effects of these carbamates when injected in ovo to chick embryos, at two time periods (days 5 and 15) during incubation. Carbaryl dosed at 45 mg kg-1 egg weight was extremely toxic to the embryos on day 5 of incubation. Hatchability was reduced to 0% as compared to 80% when carbaryl was injected on day 15 of incubation. Aldicarb at 1.5 mg kg-1 egg weight had no major effect on hatchability when injected either on day 5 or day 15 of incubation (hatchability = 90 and 100%, respectively). Plasma, liver and brain esterases were measured in the chick at different time points during incubation and after hatching. Brain acetylcholinesterase (AChE) and liver cholinesterase (ChE) were inhibited significantly during incubation in embryos dosed on day 15 with both carbaryl and aldicarb. Liver carboxylesterase was inhibited significantly during incubation with only the carbaryl treatment. All esterase enzyme activities returned to normal after hatching. Plasma ChE and carboxylesterase levels were not affected with either carbaryl or aldicarb treatment from 8 until 47 days after hatching. Neither carbamate had any effect on brain neuropathy target esterase (NTE) activity either during incubation or after hatching. The locomotion of chicks was affected in both treatment groups until 47 days after hatching. This study indicates that carbaryl and aldicarb may cause long-term delayed alterations in the chicks.
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PMID:Effects of in ovo injection of carbamates on chick embryo hatchability, esterase enzyme activity and locomotion of chicks. 238 Apr 82

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.
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PMID:Subcellular distribution and characterization of acetylcholinesterase activities from sheep platelets: relationships between temperature-dependence and environment. 238 54

When an automated counting instrument using an esterase stain was employed, decreased monocyte counts were observed in a group of process workers exposed to organophosphate esters. Their monocyte counts were not found to be depressed with manual counting or with an automated counter using another staining method. The apparent depression was transient. In these workers and a comparison group, theoretical adverse consequences of decreased monocyte esterase and also possible changes in other esterases were explored. No anergy was seen with mumps or staphylococcal phage lysate hypersensitivity skin tests. Histology of the mumps reaction was similar in both groups. The depressed monocyte counts were significantly associated with a mild reduction in erythrocyte cell acetylcholinesterase, but no reduction was seen in plasma pseudocholinesterase or lymphocyte neurotoxic esterase.
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PMID:Industrial exposure to organophosphorus compounds. Studies of a group of workers with a decrease in esterase-staining monocytes. 241 79

The purification and kinetic characterization of cholinesterase from blood plasma (pseudocholinesterase; butyrylcholinesterase: EC 3.1.1.8) is described. The hydrolysis of the artificial peptide substrate Lys-Pro-p-nitroanilide served as a model of the second step in degradation of substance P by dipeptidyl peptidase IV. The substrate is hydrolyzed by a gel-electrophoretic homogeneous cholinesterase preparation with a reaction rate of 5.8 mumol/min X mg and a KM value of 0.12 mmol/l. The proteolytic reaction could not be affected with typical cholinesterase inhibitors NaF and dibucain. On the other hand Lys (pNO2-Z)-Pro and a specific suicide substrate (diacylhydroxylamine derivative) inhibit the activity in a manner analogous to dipeptidyl peptidase IV. Though these active site-directed inhibitors also influenced the benzoylcholine hydrolyzing activity of serum cholinesterase, we conclude from the data that dipeptidyl peptidase IV was the true Lys-Pro-p-nitroanilide cleaving activity. Furthermore, the conclusion can also be drawn that hydrolysis of substance P reported by Lockridge 1982 is caused by the contamination that cannot be completely separated from the esterase during the purification method used.
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PMID:Contamination of highly purified human serum cholinesterase by dipeptidyl peptidase IV causing hydrolysis of substance P. 243 Mar 7

The effects of desbromoleptophos, fenitrothion, and fenthion on brain acetylcholinesterase (AChE), brain neurotoxic esterase (NTE), and walking were investigated in immature chicks, below the age of organophosphorus ester-induced delayed neurotoxicity (OPIDN). Seventy-five milligrams per kilogram of the delayed neurotoxicant desbromoleptophos (DBL) and 100 mg/kg of the nonneurotoxicant fenithrothion (FTR) were given orally to 8-d-old chicks. Five milligrams per kilogram of the suspected neurotoxicant fenthion (FEN) was administered topically for 7 d, in 4 different age groups. Behavioral testing was performed for treated and control chicks on various days after treatment. Brain NTE and AChE assays were carried out for treated and control chicks on each day of behavioral testing. NTE and AChE inhibition were around 80 and 50%, respectively, 24 h after treatment, for the chicks treated with DBL. NTE returned to normal levels by 20 d and AChE by 6 d after treatment. FTR caused 56% AChE inhibition but not NTE inhibition 24 h after treatment. NTE inhibition for the FEN-treated chicks never exceeded 25% during the whole period of the experiment, whereas 65 and 54% inhibition of AChE was seen in two age groups. DBL and FEN significantly altered the gait of treated chicks, but the non-OPIDN-inducing FTR did not. FEN-treated chicks developed an atypical ataxia at the normal age for onset of sensitivity to OPIDN. Minimal NTE inhibition, long latency for the development of ataxia, and immaturity of the chicks at treatment distinguish FEN-induced functional deficits from classical OPIDN.
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PMID:Acute and delayed effects of fenthion in young chicks. 243 99

The effects of multiple doses of desbromoleptophos, fenitrothion, and pure fenthion on brain acetylcholinesterase (AChE), brain neurotoxic esterase (NTE), and walking were investigated in immature chicks, below the age of sensitivity to organophosphorus ester-induced delayed neurotoxicity (OPIDN). Ten milligrams per kilogram per day of delayed neurotoxicant desbromoleptophos (DBL), 15 mg/kg.d of the non-neurotoxicant fenitrothion (FTR), and 3 mg/kg.d of the suspected neurotoxicant fenthion (FEN) were given orally for 7 d to 3-d-old chicks. Behavioral testing was performed for treated and control chicks on various days after treatment. Brain NTE and AChE assays were carried out for treated and control chicks on each day of behavioral testing. DBL altered gait and inhibited both NTE and AChE; FEN altered gait and inhibited AChE but not NTE; and FTR did not affect gait, while inhibiting AChE but not NTE. NTE and AChE inhibition were 70% and 55%, respectively, 24 h after the last treatment, for the chicks treated with DBL. NTE returned to normal levels by around d 25 and AChE by 20 d after the last treatment. FTR caused more than 50% AChE inhibition but no NTE inhibition, 24 h after last treatment. NTE inhibition for the FEN-treated chicks never exceeded 11% during the whole period of the experiment, whereas 54% inhibition of AChE was seen 1 d after last treatment. DBL and FEN significantly altered the gait of treated chicks, but the non-OPIDN-inducing FTR did not. This study confirms that alterations in the gait of young chicks are not direct consequences of either NTE or AChE inhibition, and that fenthion-induced functional deficits can be distinguished from classical OPIDN.
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PMID:Effects of multiple dosing of fenthion, fenitrothion, and desbromoleptophos in young chicks. 244 34

The effects of three irreversible anticholinesterase agents, echothiophate (217MI), tertiary methylamine analog of 217MI (217AO) and Tetram, on end plate currents (e.p.c.s) of Rana pipiens cutaneous pectoris muscle were studied using electrophysiological techniques. All three compounds (217MI, 1-10 microM; 217AO, 1-25 microM; and Tetram, 1-50 microM) decreased the rate of e.p.c. decay (alpha) to the same extent as neostigmine (10 microM), a reversible anticholinesterase agent. Decay remained a single exponential at all membrane potentials. 217MI and its derivatives greatly reduced the normal voltage dependence of alpha represented by the slope (H = mV-1) of log alpha vs. membrane potential, in contrast to neostigmine which had no effect on H. Suppression of Ach release by the addition of 4 mM Mg++ to end-plates did not alter the reduction of H by 217AO indicating that the anticholinesterase-induced decrease in H is not simply due to an increased interaction between Ach and its receptors. Additionally, the pretreatment of end-plates with methanesulfonyl fluoride, also an irreversible cholinesterase agent, did not modify the effects of 217AO and Tetram on H. 217MI and its derivatives, at low concentrations which altered H, did not affect [3H]PCP or [125I]alpha-bungarotoxin binding to Torpedo californica Ach receptor-rich membranes. It is concluded that these agents alter H by an effect on the Ach receptor ion channel complex unrelated to either esterase inhibition or channel block.
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PMID:Echothiophate and cogeners decrease the voltage dependence of end-plate current decay in frog skeletal muscle. 248 Oct 33

We and others have recently described 9-O-acetyl-sialic acid esterase (9-O-Ac-SA esterase) activities that appear to be specific for removal of O-acetyl esters from the 9-position of naturally occurring sialic acids. We have now examined a variety of species for such enzymes and found them in vertebrates and higher invertebrates, but not in plants or in lower invertebrates. This evolutionary distribution correlates well with that of the sialic acids themselves. All of the 9-O-Ac-SA esterase activities tested were inhibited by diisopropyl fluorophosphate (DFP) in a dose-dependent fashion. This indicates that each of these enzymes has a serine active site similar to the well known serine esterases and serine proteases. Methyl esterification of the carboxyl group of 9-O-acetyl-N-acetylneuraminic acid significantly reduced the activity of all of the 9-O-Ac-SA esterases against the O-acetyl group. This indicates that each of these enzymes may recognize the negatively charged carboxyl group of the sialic acid. Enzymes that recognize anionic substrates frequently have an essential arginine residue (Riordan, J. F., McElvany, K. D., and Borders, C. L., Jr. (1977) Science 195, 884-886). We therefore studied the effects of the arginine-specific modifying reagents 2,3-butanedione and phenylglyoxal on 9-O-Ac-SA esterase activities from influenza C virus, human erythrocytes, rat liver, starfish gonads, and sea bass brain. All of these enzymes were inhibited in a dose-dependent fashion by both reagents, under conditions previously known to avoid nonspecific modification. In contrast, the typical serine proteases trypsin and kallikrein and the serine esterase acetylcholinesterase were not significantly affected, even by the highest concentrations of these reagents used. These data indicate that five 9-O-Ac-SA esterase activities from evolutionarily distinct origins all have serine active sites and essential arginine residues. We postulate that the arginine residue is involved in substrate recognition via the negatively charged carboxyl group of the sialic acids. Thus, these 9-O-Ac-SA esterase activities may be members of a previously undescribed class of serine esterase.
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PMID:O-acetylation and de-O-acetylation of sialic acids. Sialic acid esterases of diverse evolutionary origins have serine active sites and essential arginine residues. 250 78


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