Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.1.5 (neuropathy target esterase)
 1,070 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. A pure lipid acyl-hydrolase was prepared from potato tubers by acetone precipitation, Sephadex G-100 and DEAE-Sephadex A-50 column chromatography, and by electrofocusing. 2. The purified enzyme was an acidic protein of pI 5.0 and molecular weight of about 70 000. Km values were 0.38 mM for monogalactosyldiacylglycerol and 1.7 mM for phosphatidylcholine. 3. The hydrolytic activity of the enzyme on different substrates was determined. The relative rates were acylsterylglucoside greater than monogalactosyldiacylglycerol greater than monogalactosylmonoacylglycerol greater than digalactosyldiacylglycerol greater than diagalactosylmonoacylglycerol, while the rates for phospholipids were lysophosphatidylcholine greater than phosphatidylcholine greater than lysophosphatidylethanolamine greater than phosphatidylethanolamine. 4. Analyses of enzymatic hydrolysis products suggested that a single enzyme had both galactolipase and phospholipase activities, and for the phospholipids it showed activities similar to phospholipase B and glycerylphosphorylcholine diesterase. 5. A competitive relation was found between monogalactosyldiacylglycerol and phosphatidylcholine as substrates of the enzyme, indicating that the active sites for both substrates may be the same. 6. It was suggested that histidine and probably serine residues were important to the enzymic activity, and that a tyrosine residue might be involved in the activity as an accessory component.
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PMID:Purification and properties of a lipid acyl-hydrolase from potato tubers. 23 65

The bases of using blood enzyme activity measurements [e.g. AChE, non-specific cholinesterase (BChE), carboxylesterase] as markers of organophosphate ester (OP) exposure are inhibition of activity by the binding of OPs to serine active sites in the enzymes, and the accessibility of the enzymes in RBCs and serum. The methods used to determine esterases in the blood of humans, experimental animals, and wildlife are outlined with emphasis on the acetylcholinesterase (AChE) of the red blood cell. Adaptations of an acetylthiocholine ester assay of Ellman et al. (1961) are common, but other colorimetric procedures, radiometric assays, and pH methods are also in use. Optimized, standardized methods are needed to assess exposures and provide a solid basis for risk assessment analyses. Useful adjuncts to ChE measurements are oxime reactivation tests and assay of neuropathy target esterase, an enzyme associated with organophosphate-induced delayed neuropathy. Determination of urinary metabolites compliments, but does not substitute for, the information obtained from blood ChE studies. Future assays are likely to involve antibodies to OP-protein complexes. Improvements in techniques permit the detection of small decreases in ChE activities. Whether or not such small decreases in ChE activities can, by themselves, constitute an adverse effect for input into risk assessment analyses is a controversial matter.
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PMID:Blood esterase determinations as markers of exposure. 141 Jun 89

The serine/cysteine hydrolase inhibitor phenylmethylsulfonyl fluoride (PMSF) markedly intensifies the clinical expression of organophosphorus-induced delayed neurotoxicity (OPIDN) in adult chickens when administered after organophosphate exposure. In this study, we have examined the ability of PMSF post-treatment to affect sensitivity to OPIDN in developing animals at ages normally showing resistance. Chickens (35, 49 or 70 days of age) were treated with diisopropylphosphorofluoridate (DFP, 2 mg/kg, sc) and then treated four hours later with PMSF (90 mg/kg, sc) or vehicle only and examined for clinical signs of ataxia and incoordination. Chickens treated with DFP alone showed a marked age-related increase in the severity of motor deficits. Birds treated with DFP followed by PMSF showed more extensive clinical deficits relative to those treated with DFP only, but relatively similar degrees of motor dysfunction among the age groups. Cervical spinal cord samples processed by the Fink-Heimer degeneration method indicated that PMSF post-treatment induced more extensive axonal degeneration in all age groups relative to treatment with DFP only. As the DFP treatment alone caused greater than or equal to 90% inhibition of neurotoxic esterase activity (NTE, the putative molecular target site for OPIDN), interaction with NTE by PMSF does not appear to be involved in potentiation. We hypothesize that PMSF potentiates OPIDN through impairment of a physiological process which normally imparts resistance to young animals and which regresses during development.
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PMID:Phenylmethylsulfonyl fluoride alters sensitivity to organophosphorus-induced delayed neurotoxicity in developing animals. 143 55

The substrate specificity of a calcium-independent, 97-kDa phospholipase B purified from guinea pig intestine was further investigated using various natural and synthetic lipids. The enzyme was equally active toward enantiomeric phosphatidylcholines under conditions allowing a strict phospholipase A activity. The lysophospholipase activity declined with the following substrates: 1-acyl-sn-glycero-3-phosphocholine greater than 1-palmitoyl-propanediol-3-phosphocholine greater than 1-palmitoyl-glycol-2-phosphocholine, suggesting some influence of the polar residue vicinal to the cleavage site. The enzyme also acted on various neutral lipids including triacylglycerol, diacylglycerol, and monoacylglycerol, whereas cholesteryl oleate remained refractory to enzymatic hydrolysis. The lipase hydrolyzed sequentially the sn-2 and sn-1 acyl ester bonds of diacylglycerol, although some direct cleavage of the external acyl ester bond could also occur, as shown with diacylglycerol analogues bearing a nonhydrolyzable alkyl ether or amide bond in the sn-1 or sn-2 position. The three main activities of the enzyme (phospholipase A2, lysophospholipase, and diacylglycerol lipase) were resistant to 4-bromophenacyl bromide, but they were inhibited by N-ethylmaleimide, 5,5'-dithiobis-(2-nitrobenzoic acid), and diisopropyl fluorophosphate, suggesting the possible involvement of both cysteine and serine residues in a single active site. It is concluded that guinea pig intestinal phospholipase B, which was also detected in rat and rabbit, is actually a glycerol ester lipase with broad substrate specificity and some unique enzymatic properties.
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PMID:Substrate specificity of phospholipase B from guinea pig intestine. A glycerol ester lipase with broad specificity. 161 44

We have isolated and sequenced cDNA clones covering the entire coding sequence of human-milk bile-salt-stimulated lipase, as well as 996 nucleotides of the 3' end of the pancreatic enzyme carboxylic ester hydrolase. The deduced amino acid sequence of the lipase starts with a 23-residue leader peptide. The open reading frame continues with 722 amino acid residues. The sequence contains in the C-terminal part a proline-rich repeat, 16 repeats of 11 amino acid residues each. The mRNA was estimated to be approximately 2500 nucleotides from Northern blot and of similar size in mammary and pancreatic tissues. Data obtained indicate that the lipase and the carboxylesterase are identical and coded for by the same gene. The cDNA is 2428 bases long, which indicates that a near full-length copy of the transcript has been isolated. Comparisons with other enzymes show that the lipase is a new member of the supergene family of serine hydrolases. It is not only closely related (and in its N-terminal half virtually identical) to lysophospholipase from rat pancreas and cholesterol esterase from bovine pancreas, but also shows a high degree of similarity to several esterases, e.g. acetylcholine esterase. In contrast, no such similarity could be found to typical lipases.
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PMID:cDNA cloning of human-milk bile-salt-stimulated lipase and evidence for its identity to pancreatic carboxylic ester hydrolase. 169 25

To determine the active site residue, human milk bile-salt stimulated lipase (BSSL) was labelled with [3H]diisopropyl fluorophosphate (DFP). Partial sequence analysis of cyanogen bromide fragments (a total of 146 residues from 6 peptides) revealed 84% sequence identity with a putative rat lysophospholipase. Sequence analysis of a [3H]DFP-labelled peptide indicated that the active site serine was contained in the sequence Gly-Glu-Ser-Ala-Gly. In addition to similarity with rat lysophospholipase, this sequence showed homology with regions of human butyrylcholinesterase and electric ray acetylcholinesterase (68% identity). It is concluded that these proteins are members of a new supergene family.
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PMID:Human milk bile-salt stimulated lipase. Sequence similarity with rat lysophospholipase and homology with the active site region of cholinesterases. 199 11

About 30% of the primary structure of acetylcholinesterase (AchE) from the cobra Naja naja oxiana has been determined. The sequence around the serine residue labeled by diisopropylfluorophosphate (DFP) was found to be TVTLFGESAGAASVGM which is similar to the active sites of AChE from other tissues. The part of the primary structure determined shows 76% identity with AChE from Torpedo and 42% identity with the Drosophila enzyme. A surprisingly large identity (42% in the sequence determined) was found with lysophospholipase from rat.
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PMID:The active site and partial sequence of cobra venom acetylcholinesterase. 234 76

The biosynthesis of phospholipids is extensive in Plasmodium knowlesi-infected simian erythrocytes due to the synthesis of membranes by this single-cell eukaryote in a host erythrocyte devoid of any pathway for lipid biosynthesis. In the present paper, we show that the incorporation of [3H]glycerol, which reflects de novo biosynthesis, is better studied at 300 microM-1 mM than at the trace doses, since this non-physiological precursor does not modify the amount of phosphatidylcholine biosynthesis from [3H]choline. Time-course incorporation of radioactive glycerol, oleate, lysophosphatidylcholine, choline, and inositol in RPMI 1640 medium containing nutrients for lipid synthesis showed that the optimum incubation time for phospholipid studies is 60-90 min, after which radioactive incorporation slows considerably. On the other hand, studies with [14C]serine revealed that incubation for 2-3 h is necessary for isotopic labelling of phosphatidylcholine via phosphatidylserine decarboxylation and phosphatidylethanolamine N-methylation. Incorporation of the various fatty acids into individual lipids was related to the molecular species composing each of them. Studies with [14C palmitoyl] lysophosphatidylcholine showed a very fast intracellular release of radioactive fatty acids, which indicates a potent lysophospholipase activity. Taken together, these data define the indispensable conditions for an experimental system suitable for further studies.
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PMID:Phospholipid metabolism in Plasmodium-infected erythrocytes: guidelines for further studies using radioactive precursor incorporation. 250 13

Lysophospholipase released from rat platelets upon activation with thrombin has been purified to near homogeneity by sequential column chromatography on heparin-Sepharose, CM-Sephadex C-50, and TSK gel G2000SW. The final preparation showed a single band with a molecular mass of 32,000 daltons in sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by silver staining. The purified enzyme was heat-labile and inactivated after 5 min at 60 degrees C. It showed a broad pH optimum (pH 6-10) and required a divalent cation, such as Ca2+, for the optimal activity. Appreciable activity, however, was observed in the presence of EDTA. Lysophospholipase activity was inhibited by diisopropylfluorophosphate and dithiothreitol. This enzyme activity was retained by a concanavalin A-Sepharose column and eluted with methyl-alpha-D-mannoside. Treatment of lysophospholipase with peptide: N-glycosidase F gave degraded products, suggesting that this protein contain N-linked carbohydrate chains. The purified enzyme was specific to 1-acyl-sn-glycero-3-phospho-L-serine; none of lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylinositol, and 1-acyl-sn-glycero-3-phospho-D-serine was hydrolyzed appreciably.
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PMID:Purification and characterization of lysophospholipase released from rat platelets. 339 99

An "A1 type" phospholipase activity with serine-phospholipid preference was released by rat activated platelets. It was distinct from the secretory type II phospholipase A2 [Horigome, K., Hayakawa, M., Inoue, K., and Nojima, S. (1987) J. Biochem. 101, 625-631] and co-purified with the secretory lysophosphatidylserine-selective lysophospholipase activity [Higashi, S., Kobayashi, T., Kudo, I., and Inoue, K. (1988) J. Biochem. 103, 442-447]. Several lines of evidence indicated that a single protein was responsible for the phospholipase A1 and lysophospholipase activities. Marked accumulation of lysophospholipids was observed in rat calcium ionophore-activated washed platelets and both phospholipase A1/lysophospholipase and type II phospholipase A2 were shown to contribute to this phospholipid degradation. A selective inhibitor of type II phospholipase A2 reduced the phospholipid degradation and enhanced the clotting time and prothrombinase activity. These results indicate that secretory platelet phospholipases may play a role in regulation of blood clotting.
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PMID:Phospholipid degradation in rat calcium ionophore-activated platelets is catalyzed mainly by two discrete secretory phospholipase As. 749 Feb 72


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