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)

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

Serum stimulates both Ca2+ mobilization and colony growth of many small cell lung cancer (SCLC) cell lines, but the factors involved remain unknown. We demonstrate that 1-oleoyl-lysophosphatidic acid (LPA), like serum, induced a dose-dependent increase in intracellular Ca2+ in the H-510, H-345, and H-69 SCLC cell lines with half maximal concentrations of 18 nM, 22 nM, and 20 nM, respectively. Two lines of evidence revealed that LPA was the major factor in serum responsible for mobilizing Ca2+ in these SCLC cell lines: (a) both LPA and serum exhibited cross desensitization in the Ca2+ mobilization assay; and (b) phospholipase B pretreatment of either LPA or serum prevented the ability of these agents to stimulate Ca2+ mobilization. In marked contrast, LPA at concentrations between 2 nM and 20 microM, unlike serum, failed to stimulate colony formation. Furthermore, phospholipase B treatment of serum did not inhibit serum-induced colony formation. We therefore searched for growth factors which could induce colony growth through a Ca(2+)-independent pathway. We found that both human recombinant hepatocyte growth factor and stem cell growth factor increased colony growth, but failed to stimulate an increase in intracellular Ca2+ in the H-510, H-345, and H-69 SCLC cell lines. Our results indicate that LPA-depleted serum, hepatocyte growth factor, and stem cell growth factor stimulate colony formation in SCLC cells through a Ca(2+)-independent pathway.
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PMID:Lysophosphatidic acid-depleted serum, hepatocyte growth factor and stem cell growth factor stimulate colony growth of small cell lung cancer cells through a calcium-independent pathway. 752 56

A lysophospholipase-transacylase (h-LPTA) was purified to homogeneity from a clinical isolate of Candida albicans (C. albicans) that had high extracellular phospholipase activity (strain 16240). The purified enzyme was a glycoprotein with molecular mass of 84 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The specific activities of the enzyme were 117 mumol/min per mg protein for fatty acid release and 459 mumol/min per mg protein for phosphatidylcholine (PC) formation. An apparent Km of the hydrolase activity of the enzyme for 1-palmitoyl-sn-glycero-3-phosphocholine (1-palmitoyl-lyso-PC) was 60.6 microM. The enzyme had a pH optimum at 6.0. Transacylase activity of the enzyme was partially inhibited by palmitoylcarnitine (35% inhibition) and N-ethylmaleimide. In contrast, the hydrolase activity of the enzyme was stimulated by palmitoylcarnitine but was partially inhibited by N-ethylmaleimide. The enzyme exhibited broad specificity to lyso-phospholipids. The h-LPTA activity was not dependent on divalent cations (Ca2+ and Mg2+) and was not inhibited by addition of EDTA or EGTA. These results show that C. albicans strain 16240 with high extracellular phospholipase activity produced h-LPTA in large amount. This enzyme is biochemically distinct from the LPTA enzyme previously isolated from C. albicans 3125.
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PMID:Purification and characterization of lysophospholipase-transacylase (h-LPTA) from a highly virulent strain of Candida albicans. 761 59

The regulation of the lysophospholipase activity of the 85-kDa cytosolic phospholipase A2 (PLA2) was studied in vitro and in stimulated macrophages. Bovine serum albumin was found to inhibit lysophospholipase activity of the recombinant 85-kDa PLA2 when assayed at a relatively low substrate concentration. Inhibition could be reversed if the substrate concentration was increased or if Ca2+ was present in the assay. Incubation of recombinant enzyme with macrophage membranes and lipid extracts from macrophage membranes resulted in the release of arachidonic acid, as well as, stearic acid, which is enriched at the sn-1 position of macrophage phospholipids. This suggests that with a bilayer substrate the PLA2 can sequentially deacylate the sn-2 then sn-1 acyl groups. This was verified by demonstrating that the phospholipids, phosphatidylcholine and phosphatidylinositol, were hydrolyzed to glycerophosphocholine and glycerophosphoinositol by incubation with recombinant 85-kDa PLA2. The 85-kDa enzyme was identified as the main lysophospholipase activity in mouse peritoneal macrophage cytosols. Addition of Ca2+ to the assay enhanced activity, but this effect decreased as the substrate concentration was increased. Incubation of macrophages with zymosan increased the lysophospholipase activity of the 85-kDa PLA2 in cytosols. Phosphorylation of recombinant PLA2 with mitogen-activated protein kinase resulted in an increase in lysophospholipase, as well as, PLA2 activity. In macrophages stimulated with zymosan release of stearic acid (18:0) and palmitic acid (16:0) was observed in addition to arachidonic acid (20:4). These results are consistent with a role of the 85-kDa PLA2 in regulating lysophospholipid levels in macrophages during zymosan stimulation.
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PMID:Regulation of lysophospholipase activity of the 85-kDa phospholipase A2 and activation in mouse peritoneal macrophages. 765 19

The cDNA encoding human cytosolic phospholipase A2 (cPLA2) has been subcloned into a prokaryotic pET16b expression vector which also encodes an amino-terminal deca-histidine affinity tag to facilitate purification of the recombinant enzyme. Soluble, active fusion protein, designated His-cPLA2, has been obtained reproducibly from this expression system using the E. coli strain BL21 (DE3). The protein has been purified to homogeneity in four steps and the mass confirmed by electrospray mass spectrometry. His-cPLA2 was characterized by kinetic analysis which demonstrated that the enzyme is similar to native cPLA2 in all respects investigated. Specifically, the enzyme binds to anionic vesicles containing substrate, and acts processively on these vesicles. Enzymatic activity is supported by the presence of Ca2+ and several other divalent metal ions, and is inhibited by several transition metal ions. Finally, the enzyme demonstrates lysophospholipase activity and exhibits a high selectivity for sn-2 arachidonyl esters. This prokaryotic expression system yields moderate amounts of unmodified recombinant His-cPLA2 and is advantageous for rapid production of protein and mutational analyses.
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PMID:Active recombinant human cytosolic phospholipase A2 is expressed in Escherichia coli. 773 74

The lysophospholipase of human spermatozoa was purified to homogeneity by sequential ion-exchange, gel filtration, and hydrophobic chromatography. The final preparation exhibited a single protein band on SDS-PAGE. The molecular mass of the enzyme was estimated to be 51 kDa by SDS-PAGE and 52 kDa by gel filtration. The optimal pH of this enzyme is 8.0. Polyclonal antibodies against lysophospholipase were prepared by placing the enzyme adsorbed on nitrocellulose directly into the spleen of rabbits. These antibodies were purified by protein A-agarose and by affigel-lysophospholipase chromatography. The purified antibodies and enzyme were used to study the possible role of lysophospholipase in the acrosome reaction. The addition of these antibodies led to an increase in the acrosome reaction, thus suggesting that inhibition of lysophospholipase produces a higher lysophosphatidylcholine concentration and results in an acrosome reaction level similar to that obtained by the calcium ionophore A23187. Immunofluorescence localization of the enzyme indicated that the enzyme is located on the head of spermatozoa. The purified sperm lysophospholipase and its specific antibodies represent important tools for the study of the regulation of this enzyme in reproductive processes. Furthermore, the study of this enzyme will allow evaluation of the mechanisms underlying the acrosome reaction.
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PMID:Purification of lysophospholipase of human spermatozoa and its implication in the acrosome reaction. 775 55

Two lysophospholipases, named gastric lysophospholipases I and II (enzymes I and II), were purified 3730- and 2680-fold from pig gastric mucosa. The preparations showed 22 and 23 kDa single protein bands on SDS/PAGE respectively. Both enzymes lacked transacylase activity and appeared to exist as monomers. Their activities were not affected by Ca2+, Mg2+ or EDTA. Enzyme I was most active at pH 8.5 and hydrolysed a variety of lysophospholipids including acidic lysophospholipids and the acyl analogue of platelet-activating factor, whereas enzyme II was most active at pH 8 and its activity was confined to lysophosphatidylcholine and lysophosphatidylethanolamine. When 1-palmitoylglycerophosphocholine was used as substrate, enzymes I and II showed half-maximal activities at 11 and 12 microM respectively. The enzymes exhibited no phospholipase B, lipase or general esterase activity. Enzyme II was significantly inhibited by lysophosphatidic acid whereas enzyme I was only moderately inhibited. Peptide mapping with V8 protease and papain revealed structural dissimilarity between the two enzymes. Antiserum raised against enzyme I did not recognize enzyme II, but did recognize the small-sized lysophospholipase purified from rat liver. Anti-(enzyme II) consistently did not cross-react with enzyme I or the liver enzyme. These antisera specifically recognized neither the 60 kDa lysophospholipase transacylase purified from liver nor any peritoneal macrophage protein. Thus gastric mucosa contains two different small-sized lysophospholipases: one is closely related to the small-sized lysophospholipase of liver, but the other appears to be a novel isoform.
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PMID:Purification and properties of lysophospholipase isoenzymes from pig gastric mucosa. 777 41

A sensitive method for continuously monitoring the activity of the human cytosolic phospholipase A2 (cPLA2) is described. Recombinant cPLA2 efficiently hydrolyzes fatty acid esters of 7-hydroxycoumarin, producing the free fatty acid and the highly fluorescent 7-hydroxycoumarin. All of the observed 7-hydroxycoumarinyl ester hydrolase activity (7-HCEase) in a preparation of the purified recombinant cPLA2 was due to this enzyme since: (1) all of the ester hydrolase activity comigrated on nondenaturing polyacrylamide gel with a protein characterized as the cPLA2 by Western analysis; (2) the immunoreactive protein also possessed both phospholipase A2 and lysophospholipase activities; and (3) arachidonyl trifluoromethyl ketone, a potent inhibitor of the phospholipase A2 activity of cPLA2, also inhibited the 7-HCEase activity. A study of the 7-HCEase activity demonstrated that when 7-hydroxycoumarinyl gamma-linolenate was dispersed in a phospholipid matrix it was hydrolyzed by cPLA2 at a rate comparable to that of an arachidonyl-containing phospholipid substrate and with an identical reaction progress curve. In the presence of phospholipid vesicles, the cPLA2-catalyzed hydrolysis of hydrophobic 7-hydroxycoumarinyl esters was stimulated by submicromolar concentration of free calcium and showed a preference for polyunsaturated substrates. The cPLA2-catalyzed hydrolysis of the water-soluble substrate 7-hydroxycoumarinyl 6-heptenoate was catalyzed by cPLA2 in the absence of calcium and other lipids.
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PMID:A continuous fluorescence-based assay for the human high-molecular-weight cytosolic phospholipase A2. 785 35

We describe the purification and first biochemical characterization of an enzymatic activity in venom from the marine snail Conus magus. This enzyme, named conodipine-M, is a novel phospholipase A2 with a molecular mass of 13.6 kDa and is comprised of two polypeptide chains linked by one or more disulfide bonds. The amino acid sequence of conodipine-M shows little if any homology to other previously sequenced phospholipase A2 enzymes (PLA2s). Conodipine-M thus represents a new group of PLA2s. This is remarkable, since conodipine-M displays a number of properties that are similar to those of previously characterized 14-kDa PLA2s. The enzyme shows little, if any, phospholipase A1, diacyglycerol lipase, triacylglycerol lipase, or lysophospholipase activities. Conodipine-M hydrolyzes the sn-2 ester of various preparations of phospholipid only in the presence of calcium and with specific activities that are comparable to those of well known 14-kDa snake venom and pancreatic PLA2s. The Conus enzyme binds tightly to vesicles of the negatively charged phospholipid 1,2-dimyristoyl-sn-glycero-3-phosphomethanol and catalyzes the hydrolysis of this substrate in a processive fashion. Conodipine-M does not significantly discriminate against phospholipids with unsaturated versus saturated fatty acids at the sn-2 position or with different polar head groups. Linoleoyl amide and a phospholipid analog containing an alkylphosphono group at the sn-2 position are potent inhibitors of conodipine-M. We suggest that the functional resemblance of conodipine-M to other PLA2s might be explained by the utilization of similar catalytic residues.
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PMID:Conodipine-M, a novel phospholipase A2 isolated from the venom of the marine snail Conus magus. 787 86

The activity of lysophospholipase of human erythrocytes increased by about 3 orders of magnitude upon infection with Plasmodium falciparum. The apparent Km for hydrolysis of lysophosphatidylcholine by this enzyme was 50 +/- 7 microM and the apparent Vmax 6.8 +/- 0.6 nmol/h x 10(6) cells. The activity was Ca2+ independent and had a broad pH maximum at pH 8. The enzyme was insensitive to such anti-malarials as mefloquine and arteether and was only weakly inhibited by chloroquine, with a 50% inhibition concentration (IC50) of 70 mM. The anti-malarials quinine and quinacrine were more efficient inhibitors, with IC50s of 2.6 mM and 0.7 mM, respectively. The sulphydryl agents p-hydroxymercuribenzoate (pHMB) and thimerosal were considerably more potent, inhibiting the plasmodial lysophospholipase with IC50s of 18 microM and 10 microM, respectively. When present at 10 microM prior to invasion, both pHMB and thimerosal arrested the growth and reinvasion capacity of P. falciparum in culture. In a synchronized P. falciparum culture the continuous presence of 5 microM thimerosal dramatically decreased total parasitaemia and, within 4 days, totally abolished the capacity of the surviving parasites to reinvade. Thus the plasmodial lysophospholipase may represent a potential new target for anti-malarial chemotherapy.
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PMID:Inhibition of Plasmodium falciparum lysophospholipase by anti-malarial drugs and sulphydryl reagents. 802 53


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