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:3.1.1.5 (neuropathy target esterase)
1,070 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The delayed neurotoxic organophosphate [3H]diisopropylfluorophosphate ([3H]DFP) binds with high affinity to membrane-bound proteins from the chicken spinal cord. The DFP binding proteins were solubilized from membrane preparations, using a detergent (CHAPS). The protein(s) sites that labeled with a low concentration of [3H]DFP, e.g. 10(-10)-10(-9) M, were defined as the high-affinity binding sites. The density (or concentration) of the high-affinity binding sites in protein(s) was determined by the difference between total and non-specific binding. The high-affinity binding sites were saturable, and the maximal amount of binding sites was estimated at 400 fmol/mg protein. [3H]DFP binding to solubilized proteins was not completely reversible. Concentration-dependent curves suggested that the [3H]DFP binding sites differ from the active sites of acetylcholinesterase, butyrylcholinesterase, and neuropathy target esterase, as well as from muscarinic acetylcholine receptors. The amount of DFP binding sites after a neurotoxic dose of tri-o-cresyl phosphate (TOCP) decreased markedly in membrane preparations from the chicken spinal cord. These results indicate that a TOCP metabolite(s) interacts with the DFP binding sites in vivo. Gel filtration chromatography of the solubilized membranes indicated at least two major high-affinity DFP binding proteins with apparent molecular weights of 300 and 110 kDa. The DFP binding sites corresponding to the 110 kDa protein were insensitive to eserine, a potent anti-cholinesterase agent.
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PMID:Characterization of high-affinity binding sites for diisopropylfluorophosphate (DFP) from chicken spinal cord membranes. 780 97

Membrane-bound neuropathy target esterase (NTE) and associated phenyl valerate carboxylesterases were solubilized from chicken embryo brain by phospholipase A2. Phospholipase A2 from bee or cobra (Naja) venoms were the most effective preparations in solubilizing brain NTE and other phenyl valerate carboxylesterases. Phospholipase C and several proteinases (endoproteinase, pronase E, proteinase K, thermolysin, trypsin) did not solubilize brain membrane-bound carboxylesterases but reduced their activity. NTE solubilization by phospholipase A2 did not affect its apparent Km and Vmax for the substrate phenyl valerate or the susceptibility of phenyl valerate carboxylesterases to inhibition by paraoxon and mipafox. NTE thermal stability diminished after the treatment of brain membrane fragments with phospholipase A2.
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PMID:Solubilization of neuropathy target esterase and other phenyl valerate carboxylesterases from chicken embryonic brain by phospholipase A2. 788 4

A lysophosphatidic acid (LPA)-hydrolysing lysophospholipase was purified from rat brain and characterized. This membrane-bound lysophospholipase was solubilized by using n-octyl glucoside and purified by sequential cation, hydrophobic and gel-filtration chromatography. The purified protein has a mass of 80 kDa as assayed by SDS/PAGE. This lysophospholipase catalysed the hydrolysis of a variety of lysophosphatidic acids, but with different rates, depending on the length and degree of saturation of the sn-1 acyl group (1-oleoyl-LPA approximately 1-stearoyl-LPA > 1-palmitoyl-LPA > 1-myristoyl-LPA). This enzyme had no-measurable catalytic activity when other lysophospholipids, monoacylglycerol or phosphatidic acid were used as substrates. On the basis of its chromatographic properties, substrate specificity and cellular localization, we conclude that this lysophospholipase differs from those previously purified and speculate that it has an important function in terminating biological responses to LPA.
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PMID:Purification of a lysophosphatidic acid-hydrolysing lysophospholipase from rat brain. 800 51

NTE inhibitors cause different toxicological consequences (protection, induction or potentiation/promotion of neuropathy) depending on the order of dosing. These effects might be explained in terms of several phosphorylable sites with 'allosteric irreversible' behaviour. Brain neuropathy target esterase (NTE) has been preinhibited with phenylmethylsulphonyl fluoride (PMSF) (0, 5, 10, 15, 30 and 60 microM) or with diisopropylphoshoro fluoridate (DFP) (0, 0.2, 0.5, and 1 microM) at 37 degrees C for 30 min. After washing by centrifugation, tissues were then reinhibited with a range of PMSF (0 to 80 microM) or DFP (0 to 1 microM) concentrations. The slopes of the inhibition curves (log % activity vs. concentration) of pretreated tissues were identical to those of the non-pretreated tissues, with non-distinguishable I50 values. It is concluded that allosteric effects are not likely to be involved in membrane-bound NTE of hen brain.
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PMID:Properties of partly preinhibited hen brain neuropathy target esterase. 834 97

Neural carboxylesterases can be discriminated by differential inhibition assays with organophosphorus compounds (OPs), paraoxon (O,O'-diethyl p-nitrophenyl phosphate) and mipafox (N,N'-diisopropyl phosphorodiamidofluoridate) being the ones used to discriminate esterases that should be either irrelevant or candidates as targets of the mechanism of induction of the organophosphorus-induced delayed polyneuropathy (OPIDP). The brain membrane-bound phenyl valerate esterase (PVase) defined by Dr Johnson in 1969 as neuropathy target esterase (NTE) and recently cloned by Dr Glynn and coworkers is termed here as particulate NTE due to its association to the membrane particulate fraction. It is considered as the target of OPIDP and is the activity measured in standard NTE assays and toxicity tests. Following the same operational criteria in the soluble fraction of sciatic nerve a paraoxon-resistant but mipafox-sensitive PVase activity was described and termed as S-NTE, with an apparent lower sensitivity to some inhibitors than particulate NTE. Two isoforms (S-NTE1 and S-NTE2) were subsequently separated by gel filtration chromatography. In a partly purified S-NTE2 preparation polypeptides were identified in western blots by labelling with S9B [1-(saligenin cyclic phospho)-9-biotinyldiaminononane], the same biotinylated OP used to label and isolate particulate NTE, but not with anti-particulate NTE antibodies. From sequential inhibition protocols, inhibitor washing-out and time course inhibition studies it is deduced that reversibility of inhibition is a new factor introducing a higher complexity in the identification of the esterases that could be candidates as targets of the mechanisms of induction and/or promotion of neuropathy. We have evidences that in sciatic nerve soluble fraction a high proportion (about 70%) of the activity that is inhibited by paraoxon in the usual concurrent assay is quickly reactivated after removing paraoxon and it is permanently inhibited by mipafox. Under this improved sequential paraoxon/mipafox inhibition procedure S-NTE represents about 50% of total PVases while in the usual concurrent assay it was only apparently about 1-2%. Moreover with such criteria, S-NTE2 isoform(s) represents about 97-99% of total S-NTE, and S-NTE1 is only a marginal amount probably resulting of a partial solubilization from particulate NTE. Fixed time inhibiton curves with variable mipafox concentration failed to discriminate more than one component. However kinetic behaviour of the time progressive inhibition cannot be explained by a simple model with a single exponential mathematical component, indicating that either the possibility of more than one component or a more complex mechanistic model should be considered. Consequently both particulate NTE and S-NTE assay protocols and their role in induction and promotion of neuropathies will need to be reviewed. Data published by Drs Lotti, Moretto and coworkers suggest that particulate NTE cannot be the target of promotion of axonopathies. The proposal that S-NTE2 could be such a target is suggestive and under collaborative biochemical and toxicological studies.
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PMID:NTE soluble isoforms: new perspectives for targets of neuropathy inducers and promoters. 1042 92

The neuropathy target esterase is a membrane-bound enzyme linked to organophosphate-induced distal neuropathy. Here we report a tentative mechanism of its solubilization from chicken embryo brains by using phospholipase A2. The enzyme was released from brain membranes after degradation of their structural phospholipids initiated by phospholipase A2. L-A inverted exclamation mark-lysophosphatidylcholine, tested as a representative product of phospholipid hydrolysis, was identified as a new efficient detergent for solubilization of the neuropathy target esterase.
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PMID:A tentative mechanism of solubilization of neuropathy target esterase from chicken embryo brain by phospholipase A2. 1866 Oct 50

The biotinylated organophosphorus compound 1-(saligenin cyclic phospho)-9-biotinyldiaminononane (S9B) has been used for the detection, labeling and isolation of the membrane-bound neuropathy target esterase (NTE) as it was considered a specific inhibitor of NTE. After incubation with the soluble fraction of chicken peripheral nerve, most of the soluble esterase activity was highly sensitive to S9B, indicating NTE-like esterases. A kinetic model equation was used to assume a multi-enzymatic system with three different simultaneously occurring molecular phenomena; (1) inhibition; (2) simultaneous spontaneous reactivation; and (3) ongoing inhibition (inhibition during the substrate reaction); to fit the data to analyze kinetic behavior. A high "ongoing inhibition" effect was observed in an enzymatic component. A three-dimensional fit of the model was applied. The best fitting model is compatible with three sensitive enzymatic entities (33, 52 and 15%), and only one spontaneously reactivate. The second-order rate constants of inhibition (k(i)=116 x 10(6), 4.6 x 10(6) and 0.28 x 10(6)M(-1)min(-1), respectively) and the spontaneous reactivation constant for the first sensitive component (k(r)=0.0054 min(-1)) were simultaneously estimated. These parameters are similar to those deduced in spontaneous reactivation experiments of the preinhibited samples with S9B. The estimated proportions of enzymatic components are similar to those previously observed in inhibition experiments with mipafox, demonstrating that this kinetic approach offers consistent results.
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PMID:Inhibition with spontaneous reactivation and the "ongoing inhibition" effect of esterases by biotinylated organophosphorus compounds: S9B as a model. 2049 77

Phospholipase A1 (PLA1) has been described in the infective stages of Trypanosoma cruzi as a membrane-bound/secreted enzyme that significantly modified host cell lipid profile with generation of second lipid messengers and concomitant activation of protein kinase C. In the present work we determined higher levels of PLA1 expression in the infective amastigotes and trypomastigotes than in the non-infective epimastigotes of lethal RA strain. In addition, we found similar expression patterns but distinct PLA1 activity levels in bloodstream trypomastigotes from Cvd and RA (lethal) and K98 (non-lethal) T. cruzi strains, obtained at their corresponding parasitemia peaks. This fact was likely due to the presence of different levels of anti-T. cruzi PLA1 antibodies in sera of infected mice, that modulated the enzyme activity. Moreover, these antibodies significantly reduced in vitro parasite invasion indicating the participation of T. cruzi PLA1 in the early events of parasite-host cell interaction. We also demonstrated the presence of lysophospholipase activity in live infective stages that could account for self-protection against the toxic lysophospholipids generated by T. cruzi PLA1 action. At the genome level, we identified at least eight putative genes that codify for T. cruzi PLA1 with high amino acid sequence variability in their amino and carboxy-terminal regions; a putative PLA1 selected gene was cloned and expressed as a recombinant protein that possessed PLA1 activity. Collectively, the results presented here point out at T. cruzi PLA1 as a novel virulence factor implicated in parasite invasion.
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PMID:Phospholipase A1: a novel virulence factor in Trypanosoma cruzi. 2327 96

Legionella pneumophila is an intracellular pathogen and the main causative agent of Legionnaires' disease, a potentially fatal pneumonia. The bacteria infect both mammalian cells and environmental hosts, such as amoeba. Inside host cells, the bacteria withstand the multifaceted defenses of the phagocyte and replicate within a unique membrane-bound compartment, the Legionella-containing vacuole (LCV). For establishment and maintenance of the infection, L. pneumophila secretes many proteins including effector proteins by means of different secretion systems and outer membrane vesicles. Among these are a large variety of lipolytic enzymes which possess phospholipase/lysophospholipase and/or glycerophospholipid:cholesterol acyltransferase activities. Secreted lipolytic activities may contribute to bacterial virulence, for example via modification of eukaryotic membranes, such as the LCV. In this review, we describe the secretion systems of L. pneumophila, introduce the classification of phospholipases, and summarize the state of the art on secreted L. pneumophila phospholipases. We especially highlight those enzymes secreted via the type II secretion system Lsp, via the type IVB secretion system Dot/Icm, via outer membrane vesicles, and such where the mode of secretion has not yet been defined. We also give an overview on the complexity of their activities, activation mechanisms, localization, growth-phase dependent abundance, and their role in infection.
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PMID:Secreted phospholipases of the lung pathogen Legionella pneumophila. 2910 10


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