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)

We have recently shown that the anti-Parkinson-propargyl-containing monoamine oxidase B (MAO-B) inhibitor drug, rasagiline [N-propargyl-(1R)-aminoindan], and its cholinesterase inhibitor derivatives TV3326 and TV3279, regulate amyloid precursor protein (APP) processing by a protein kinase C (PKC)-dependent mechanism in SH-SY5Y neuroblastoma and PC12 cells. In the present study, we investigated the effect of rasagiline and its derivatives on the regulation of the PKC-dependent mechanism and APP processing under in vivo conditions. Administration of rasagiline (0.1 mg/kg) to male C57/BL mice for 14 days significantly decreased membrane-bound holoprotein APP levels in the hippocampus. Additionally, we observed that rasagiline up-regulated p-PKC levels and the expression of alpha and epsilon PKC isozymes in the hippocampus, indicating that the mechanism by which rasagiline affects APP processing may be related to PKC-associated signalling. The results also demonstrate that rasagiline treatment significantly elevated the levels of phosphorylated myristoylated alanine-rich C kinase substrate (p-MARCKS), a major substrate for PKC, as well as the levels of receptors for activated C kinase 1 (RACK1). Similar effects on APP and PKC levels were also demonstrated for the two cholinesterase inhibitor derivatives of rasagiline, TV3326 and TV3279. These results indicate that rasagiline and its derivatives regulate PKC-dependent mechanisms and APP processing. The activation and induction of PKC and MARCKS by these drugs may have a crucial role not only in their neuroprotective activity, but also in their ability to affect neuronal plasticity and spatial learning processes.
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PMID:Regulation of protein kinase C by the anti-Parkinson drug, MAO-B inhibitor, rasagiline and its derivatives, in vivo. 1514 4

The origins of human acetylcholinesterase (HuAChE) reactivity toward the lethal chemical warfare agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) and its stereoselectivity toward the P(S)-VX enantiomer (VX(S)) were investigated by examining the reactivity of HuAChE and its mutant derivatives toward purified enantiomers of VX and its noncharged isostere O-ethyl S-(3-isopropyl-4-methylpentyl) methylphosphonothioate (nc-VX) as well as echothiophate and its noncharged analogue. Reactivity of wild-type HuAChE toward VX(S) was 115-fold higher than that toward VX(R), with bimolecular rate constants of 1.4 x 10(8) and 1.2 x 10(6) min(-1) M(-1). HuAChE was also 12500-fold more reactive toward VX(S) than toward nc-VX(S). Substitution of the cation binding subsite residue Trp86 with alanine resulted in a 3 order of magnitude decrease in HuAChE reactivity toward both VX enantiomers, while this replacement had an only marginal effect on the reactivity toward the enantiomers of nc-VX and the noncharged echothiophate. These results attest to the critical role played by Trp86 in accommodating the charged moieties of both VX enantiomers. A marked decrease in stereoselectivity toward VX(S) was observed following replacements of Phe295 at the acyl pocket (F295A and F295A/F297A). Replacement of the peripheral anionic site (PAS) residue Asp74 with asparagine (D74N) practically abolished stereoselectivity toward VX(S) (130-fold decrease), while a substitution which retains the negative charge at position 74 (D74E) had no effect. The results from kinetic studies and molecular simulations suggest that the differential reactivity toward the VX enantiomers is mainly a result of a different interaction of the charged leaving group with Asp74.
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PMID:Stereoselectivity toward VX is determined by interactions with residues of the acyl pocket as well as of the peripheral anionic site of AChE. 1536 35

The reactivity of human acetylcholinesterase (HuAChE) toward the chemical warfare agent VX [O-ethyl S-[2-(diisopropylamino)ethyl] methyl-phosphonothioate] and its stereoselectivity toward the P(S)-enantiomer were investigated by examining the reactivity of HuAChE and its mutant derivatives toward purified enantiomers of VX and its noncharged isostere nc-VX [O-ethyl S-(3-isopropyl-4-methyl-pentyl) methylphosphonothioate]. Stereoselectivity of the wild-type HuAChE toward VX(S) is manifested by a 115-fold higher bimolecular rate constant (1.4 x 10(8) min(-1) M(-1)) as compared to that of VX(R). HuAChE was also 12,500-fold more reactive toward VX(S) than toward nc-VX(S), demonstrating the significance of the polar interactions of the ammonium substituent to their overall affinity toward VX. Indeed, substitution of the cation-binding subsite residue Trp86 by alanine resulted in a decrease of three orders of magnitude in HuAChE reactivity toward both VX enantiomers, with only a marginal effect on the reactivity toward the enantiomers of nc-VX. These results demonstrate that accommodation of the charged moieties of both VX enantiomers depends predominantly on interactions with the aromatic moiety of Trp86. Yet, these interactions seem to limit the stereoselectivity toward the P(S)-enantiomer, which for charged methylphosphonates is much lower than for the noncharged analogs, like sarin or soman. Marked decrease in stereoselectivity toward VX(S) was observed following replacements of Phe295 at the acyl pocket (F295A and F295A/F297A). Replacement of the peripheral anionic site (PAS) residue Asp74 by asparagine (D74N) practically abolished stereoselectivity toward VX(S) (a 130-fold decrease), while substitution which retained the negative charge at position 74 (D74E) had no effect. The results from kinetic studies and molecular simulations suggest that the differential reactivity toward the VX enantiomers originates predominantly from a different orientation of the charged leaving group with respect to residue Asp74. Such different orientations of the charged leaving group in the HuAChE adducts of the VX enantiomers seem to be a consequence of intramolecular interactions with the bulky phosphorus alkoxy group.
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PMID:The role of AChE active site gorge in determining stereoselectivity of charged and noncharged VX enantiomers. 1628 14

Methidathion (MD) phosphorodithioic acid S-[(5-methoxy-2-oxo-1,3,4-thiadiazol-3(2H)-yl)methyl] O,O-dimethyl ester is the organophosphate insecticide (OPI) most commonly used worldwide in the pest control of crops. Subchronic MD exposure was evaluated for its effects on lipid peroxidation, the serum activities of cholinesterase (ChE), and enzymes concerning liver damage, and the protective effects of combination of vitamins E and C in albino rats. Additionally, the histopathological changes in liver tissue were examined. Experimental groups were as follows: control group; a group treated with 5 mg/kg body weight MD (MD group); and a group treated with 5 mg/kg body wight MD plus vitamin E plus vitamin C (MD+AO group). The MD and MD+AO groups were treated orally with MD on five days a week for 4 weeks. The serum activities of cholinesterase (ChE), alanine transferase (ALT), aspartate amiotransferase (AST), lactate dehydrogenase (LDH), gamma-glutamyltransferase (GGT), alkaline phosphatase (ALP), and the concentration of malondialdehyde (MDA) and liver histopathology were studied. In serum samples, MD significantly increased MDA concentration and ALP, AST, GGT, LDH activities but decreased the ALT and ChE activities. In the MD+AO group, MDA level and ALP, AST, LDH activities were significantly decreased and ChE activity was increased compared to the MD group. Histopathological changes found in liver tissue of rats treated with MD included were infiltration with mononuclear cells in all portal areas, sinusoidal dilatation, and focal microvesicular steatosis and hydropic degenerations in parenchymal tissue. The severity of these lesions was reduced by administration of vitamins. From these results, it can be concluded that subchronic MD causes liver damage, and lipid peroxidation may be a molecular mechanism involved in MD-induced toxicity. Furthermore, the combination of vitamins E and C can reduce the toxic effects of MD on liver tissue of rats.
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PMID:The effects of subchronic methidathion toxicity on rat liver: role of antioxidant vitamins C and E. 1658 3

Given the effects of environmental pollution and different biotic factors on some important biochemical markers, as enzymes, two fish species inhabiting the Sariyar Dam Lake, Turkey have been investigated. Ethoxyresorufin O-deethylase, glutathion S-transferase, lactate dehydrogenase, alkaline phosphatase, acid phosphatase, and alanine and aspartate amino transferase activities have been measured in liver samples of Cyprinus carpio and Capoeta tinca. Also, brain acetylcholinesterase and carboxylesterase activities have been measured for the same samples. Selected enzymes confirmed that Sariyar basin is polluted by urban wastes and agricultural and industrial activities for many years. Organochlorine (OC) pesticide residues, caused by intensive agricultural activities, have also been observed in water, sediment samples, and adipose tissues of carp. Monitored results showed that SDL was polluted by different kinds of OC compounds such as DDT and its derivatives which are accumulated in adipose tissues of carp. Highest accumulation was found for beta-BHC in carp. The changes of enzyme activities in this study may be related to environmental pollution, while enzyme activity variations could be attributed to variable pollutants and variable concentrations of these pollutants. The results highlighted the potential convenience of these biomarkers to be used as components of environmental monitoring program in risk assessment studies in SDL. Since a seasonal variation in selected enzyme activities was found, the possible implications of such variability in the use of these enzymes as environmental biomarkers are also discussed. Hepatic cytosolic EROD did not show any significance according to the pollution factors in the lake which may be attributed to relatively less contamination by organic compounds such as PAH products.
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PMID:Ecotoxicological assessment of water pollution in Sariyar Dam Lake, Turkey. 1758 95

Cholinesterases are efficient scavengers of organophosphates and are currently being developed as drugs for treatment against poisoning by such compounds. Recombinant ChE bioscavengers have very short circular longevity, a limitation that can be overcome by complex post-translation manipulations or by chemical modification such as polyethylene glycol conjugation. Series of multiple Lys-Ala mutants of human acetylcholinesterase were prepared allowing the generation of homogenous and well defined polyethylene-glycol conjugated AChEs with either one, two, three, four, or five appended polyethylene glycol (PEG) moieties/molecule. The rank order of circulatory longevity of these molecules was dependent on the number of PEG appendages up to a certain threshold: 5 = 4 > 3 > 2 > 1 > 0. Hypolysine acetylcholinesterases (AChEs) carrying the same number of PEGs, and therefore with identical masses, allowed us to demonstrate that circulatory longevity correlates with the predicted extent of concealment of the AChE surface. Furthermore, circulatory profiles of high number and low number PEG-AChEs differing in their sialic acid contents demonstrate a direct relationship between PEG loading and the effective seclusion of AChE from the hepatic asialoglycoprotein receptor clearance system. Finally, an inverse relationship is found between the extent of PEG loading and the ability of the human acetylcholinesterase to elicit specific anti-HuAChE antibodies. In conclusion, these findings suggest that for the extension of circulatory longevity, protein surface domain concealment exerted by polyethylene glycol attachment is at least as important as its effect on size enlargement and highlights the role of PEG attachment in masking interactions between biomolecules and their cognate receptors.
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PMID:Controlled concealment of exposed clearance and immunogenic domains by site-specific polyethylene glycol attachment to acetylcholinesterase hypolysine mutants. 1793 38

Bambuterol is a chiral carbamate known as selective inhibitor of butyrylcholinesterase (BChE). In order to relate bambuterol selectivity and stereoselectivity of cholinesterases to the active site residues, we studied the inhibition of recombinant mouse BChE, acetylcholinesterase (AChE) and six AChE mutants, employed to mimic BChE active site residues, by bambuterol enantiomers. Both enantiomers selectively inhibited BChE about 8000 times faster than AChE. The largest inhibition rate increase in comparison to AChE w.t. was observed with the F295L/Y337A mutant, showing that leucine 295 and alanine 337 are crucial residues in BChE for high bambuterol selectivity. All studied enzymes preferred inhibition by the R- over the S-bambuterol. The enlargement of the AChE choline binding site and of the acyl pocket by single or double mutations (Y337A, F295L/Y337A and F297I/Y337A) increased, in comparison to w.t. enzymes, inhibition rate constants of R- bambuterol more than that of S- bambuterol resulting in four times higher stereoselectivity. Peripheral site mutations (Y124Q and Y72N/Y124Q/Y337A) increased inhibition rate by S- more than R-bambuterol and consequently diminished the stereoselectivity.
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PMID:Amino acid residues involved in stereoselective inhibition of cholinesterases with bambuterol. 1816 4

Although the primary function of AChE (acetylcholinesterase) is the synaptic hydrolysis of acetylcholine, it appears that the protein is also able to promote various non-cholinergic activities, including cell adhesion, neurite outgrowth and amyloidosis. We have observed previously that AChE is able to bind to mouse laminin-111 in vitro by an electrostatic mechanism. We have also observed that certain mAbs (monoclonal antibodies) recognizing AChE's PAS (peripheral anionic site) inhibit both laminin binding and cell adhesion in neuroblastoma cells. Here, we investigated the interaction sites of the two molecules, using docking, synthetic peptides, ELISAs and conformational interaction site mapping. Mouse AChE was observed on docking to bind to a discontinuous, largely basic, structure, Val(2718)-Arg-Lys-Arg-Leu(2722), Tyr(2738)-Tyr(2739), Tyr(2789)-Ile-Lys-Arg-Lys(2793) and Val(2817)-Glu-Arg-Lys(2820), on the mouse laminin alpha1 G4 domain. ELISAs using synthetic peptides confirmed the involvement of the AG-73 site (2719-2729). This site overlaps extensively with laminin's heparin-binding site, and AChE was observed to compete with heparan sulfate for laminin binding. Docking showed the major component of the interaction site on AChE to be the acidic sequence Arg(90)-Glu-Leu-Ser-Glu-Asp(95) on the omega loop, and also the involvement of Pro(40)-Pro-Val(42), Arg(46) (linked to Glu(94) by a salt bridge) and the hexapeptide Asp(61)-Ala-Thr-Thr-Phe-Gln(66). Epitope analysis, using CLiPS technology, of seven adhesion-inhibiting mAbs (three anti-human AChE, one anti-Torpedo AChE and three anti-human anti-anti-idiotypic antibodies) showed their major recognition site to be the sequence Pro(40)-Pro-Met-Gly-Pro-Arg-Arg-Phe(48) (AChE human sequence). The antibodies, however, also reacted with the proline-containing sequences Pro(78)-Gly-Phe-Glu-Gly-Thr-Glu(84) and Pro(88)-Asn-Arg-Glu-Leu-Ser-Glu-Asp(95). Antibodies that recognized other features of the PAS area but not the Arg(90)-Gly-Leu-Ser-Glu-Asp(95) motif interfered neither with laminin binding nor with cell adhesion. These results define sites for the interaction of AChE and laminin and suggest that the interaction plays a role in cell adhesion. They also suggest the strong probability of functional redundancy between AChE and other molecules in early development, particularly heparan sulfate proteoglycans, which may explain the survival of the AChE-knockout mouse.
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PMID:Interaction of acetylcholinesterase with the G4 domain of the laminin alpha1-chain. 1821 27

To test a product exit differing from the substrate entrance in the active site of acetylcholinesterase (EC 3.1.1.7), we enlarged a channel located at the bottom of the active site gorge in the Drosophila enzyme. Mutation of Trp83 to Ala or Glu widens the channel from 5 A to 9 A. The kinetics of substrate hydrolysis and the effect of ligands that close the main entrance suggest that the mutations facilitate both product exit and substrate entrance. Thus, in the wild-type, the channel is so narrow that the 'back door' is used by at most 5% of the traffic, with the majority of traffic passing through the main entrance. In mutants Trp83Ala and Trp83Glu, ligands that close the main entrance do not inhibit substrate hydrolysis because the traffic can pass via an alternative route, presumably the enlarged back channel.
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PMID:Insights into substrate and product traffic in the Drosophila melanogaster acetylcholinesterase active site gorge by enlarging a back channel. 1842 51

Under local practice of Egyptian conditions, the application of (14)C-fenitrothion on soybeans at a dose of 10mg insecticide/kg grains, led to the formation of 21% of (14)C-bound residues (non-extractable) after 24 weeks of storage. The external residues were 20% and the internal extracts were 55% of the applied dose. Feeding studies on rats revealed that bound residues were bioavailable. After feeding rats for three days with bound (14)C-fenitrothion residues, the main portion of radioactivity was eliminated via expired air (42%), urine (20%) and feces (11.5%). About 15% of the administered radioactivity was distributed among various organs as, liver, kidney, lung, fat, intestine, blood, heart, and brain. Toxicity of bound residues of (14)C-fenitrothion in stored soybeans was studied in mice through feeding experiments for three months at a concentration of 1.9 mg/kg. The maximum inhibition in plasma and erythrocyte cholinesterase activity was observed 22.5%, 18.9% and 8.6%, 9% after one and seven days, respectively. The obtained results showed a slight significant elevation after three months in the activity of liver enzymes alanine amino transferase, aspartate amino transferase and alkaline phosphatase. A moderate increase in blood urea nitrogen and creatinine concentration was observed in the treated groups at the end of the experimental period. The detected levels of albumin and total protein showed no significant compared to the control values, of controlled animals, after three months.
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PMID:Toxicological evaluation and bioavailability of (14)C-fenitrothion bound residues on soybeans towards experimental animals. 1863 7


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