Navegando por Palavras-chave "phospholipase A(2)"
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- ItemSomente MetadadadosBE-I-PLA2, a novel acidic phospholipase A(2) from Bothrops erythromelas venom: Isolation, cloning and characterization as potent anti-platelet and inductor of prostaglandin I-2 release by endothelial cells(Elsevier B.V., 2006-07-28) Albuquerque Modesto, Jeanne Claine de; Spencer, Patrick J.; Fritzen, Marcio; Valenca, Renata C.; Oliva, Maria Luiza Vilela [UNIFESP]; Bezerra da Silva, Marcia; Chudzinski-Tavassi, Ana Marisa; Camargo Guarnieri, Miriam; Universidade Federal de Pernambuco (UFPE); Inst Butantan; IPEN; Universidade Federal de São Paulo (UNIFESP)A novel acidic Asp49 phospholipase A(2) was isolated from Bothrops erythromelas (jararaca malha-de-cascavel) snake venom by four chromatographic steps. BE-I-PLA2 present a molecular weight of 13,649.57 Da as estimated by mass spectrometry. N-terminal and four internal peptides were sequenced, covering around one-third of the complete toxin sequence. the complete BE-I-PLA2 cDNA was cloned from a B. erythromelas venom-gland cDNA library. the cDNA sequence possesses 457 bp and encodes a protein with significant sequence similarity to many other phospholipase A(2) from snake venoms. When tested in platelet rich plasma, the enzyme showed a potent inhibitory effect on aggregation induced by arachidonic acid and collagen, but not ADP. On the other hand, BE-I-PLA2 did not modify aggregation in washed platelet. Furthermore, no action of BE-I-PLA2 on the principal platelets receptors was observed. Chemical modification with p-bromophenacyl bromide abolished the enzymatic activity of BE-I-PLA2, but its anti-platelet activity was only partially inhibited. in human umbilical-cord veins endothelial cells, BE-I-PLA2 was neither apoptotic nor proliferative but stimulated endothelial cells to release prostaglandin I-2, suggesting an increase of its potential anti-platelet activity in vivo. Further studies are required in order to determine the exact mechanism of action of BE-I-PLA2 in the inhibition of platelet aggregation. (c) 2006 Elsevier Inc. All rights reserved.
- ItemSomente MetadadadosHuman neutrophil migration in vitro induced by secretory phospholipases A(2): a role for cell surface glycosaminoglycans(Elsevier B.V., 2002-01-01) Gambero, A.; Landucci, ECT; Toyama, M. H.; Marangoni, S.; Giglio, JR; Nader, H. B.; Dietrich, C. P.; De Nucci, G.; Antunes, E.; Universidade Estadual de Campinas (UNICAMP); Universidade de São Paulo (USP); Universidade Federal de São Paulo (UNIFESP)The purpose of this study was to examine the ability of type I- (porcine pancreas and Naja mocambique mocambique venom), type II- (bothropstoxin-I, bothropstoxin-II, and piratoxin-I). and type III- (Apis mellifera venom) secretory phospholipases A(2) (sPLA(2)s) to induce human neutrophil chemotaxis, and the role of the cell surface proteoglycans, leukotriene B-4 (LTB4), and platelet-activating factor (PAF). in mediating this migration. the neutrophil chemotaxis assays were performed by using a 48-well microchemotaxis chamber. Piratoxin-I, bothropstoxin-I. N. m. mocambique venom PLA(2) (10-1000 mug/mL each), bothropstoxin-II (30-1000 mug/mL), porcine pancreas PLA(2) (0.3-30 mug/mL), and A. mellifera venom PLA(2) (30-300 mug/mL) caused concentration-dependent neutrophil chemotaxis. Heparin (10-300 U/mL) concentration-dependently inhibited the neutrophil migration induced by piratoxin-I, bothropstoxin-II, and N. in. mocambique and A. mellifera venom PLA(2)s (100 mug/mL each), but failed to affect the migration induced by porcine pancreas PLA(2). Heparan sulfate (300 and 1000 mug/mL) inhibited neutrophil migration induced by piratoxin-I, whereas dermatan sulfate and chondroitin sulfate (30-1000 mug/mL each) had no effect. Heparitinase I and heparinase (300 mU/mL each) inhibited by 41.5 and 47%. respectively, piratoxin-l-induced chemotaxis, whereas heparitinase 11 and chondroitinase AC failed to affect the chemotaxis. the PAF receptor antagonist WEB 2086 (3-[4-(2-chlorophenyl)-9-methyl-6H-thienol-[3,2-f] [1,2,4]-triazolo-[4.3-a] [1,4]-diazepine-2-yl]-1-(4-morpholynil)-1-propionate) (0.1-10 muM) and the LTB4 synthesis inhibitor AA-861 [2-(12-hydroxydodeca-5,10-diynyl)-3,5,6-trimethyl-1,4-benzoquinone] (0.1-10 muM) significantly inhibited the piratoxin-I-induced chemotaxis. Piratoxin-I (30-300 mug/mL) caused a concentration-dependent release of LTB4 Our results suggest that neutrophil migration in response to sPLA(2)s is independent of PLA activity, and involves an interaction of sPLA(2)s with cell surface heparin/heparan binding sites triggering the release of LTB4 and PAF. (C) 2002 Elsevier Science Inc. All rights reserved.
- ItemSomente MetadadadosPurification of a phospholipase A(2) from Lonomia obliqua caterpillar bristle extract(Elsevier B.V., 2006-04-21) Seibert, C. S.; Tanaka-Azevedo, A. M.; Santoro, M. L.; Mackessy, S. P.; Torquato, RJS; Lebrun, I; Tanaka, A. S.; Sano-Martins, I. S.; Inst Butanan; Univ No Colorado; Universidade Federal de São Paulo (UNIFESP)Lonomia obliqua caterpillar bristle extract induces both direct and indirect hemolytic activity on human and rat washed erythrocytes, and provokes intravascular hemolysis in Wistar rats. Indirect hemolytic activity is assumed to be caused by a phospholipase A(2) (PLA(2)) present in this extract, and this investigation was initiated in order to characterize this enzyme. Phospholipase A, activity of crude extract was inhibited by both a PLA(2)-specific inhibitor (pBpb) and the metal ion chelator EDTA. L. obliqua PLA(2) was purified by liquid chromatography from the crude bristle extract and had a molecular mass of 15 kDa and a pI of 5.9: its N-terminal sequence showed high homology to a sequence of a putative PLA(2) obtained from a cDNA library of L. obliqua bristles, and it is tentatively placed among Group III phospholipases A(2). This enzyme was stable at 4 degrees C sensitive to higher temperatures, and its maximum catalytic activity was at pH 8.0. L. obliqua PLA(2) induced hemolysis only when incubated with exogenous lecithin. Thus, the PLA(2) purified herein appears to be responsible for the indirect hemolytic activity of the crude bristle extract. (c) 2006 Elsevier Inc. All rights reserved.