Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| hydrolysis of phosphatidylcholine liposomes by phospholipases a2. effects of the local anesthetic dibucaine. | (1) dibucaine evokes a downward shift in the phase transition temperature of saturated phosphatidylcholines, while it also affects the pretransition. (2) the binding of dibucaine to phosphatidylcholine liposomes increases sharply when the lipid is transformed from the gel phase to the liquid-crystalline phase. (3) the activity of naja naja phospholipase a2 towards dimyristoyl phosphatidylcholine liposomes is either stimulated or inhibited by dibucaine, depending on whether the substrate is in th ... | 1976 | 1260059 |
| possible relationship between membrane proteins and phospholipid asymmetry in the human erythrocyte membrane. | after incubation of human erythrocytes at 37 degrees c in the absence of glucose (a) for 24 h, (b) for 4 h with 8 mm hexanol or (c) for 3 h with sh reagents, phosphatidylethanolamine becomes partly susceptible to hydrolysis by phospholipase a2 from naja naja. the presence of glucose during the pretreatments suppresses this effect, except in the case of sh reagents that inhibit glycolysis. after incubation with tetrathionate, up to 45% of the phosphatidylethanolamine is degraded by the enzyme, an ... | 1976 | 1276220 |
| comparative characterization of two toxic phospholipases a2 from indian cobra (naja naja naja) venom. | indian cobra venom contains many phospholipase a2 (pla2) toxins. in the present study two toxic pla2s have been purified from the indian cobra (naja naja naja) venom by column chromatography. the nn-xia-and nn-xib-pla2s have mol. wts between 10,700 and 15,000. the nn-xia-pla2 induces myotoxic effects, oedema and neurotoxicity in mice and has an i.p. ld50 of 8.5 mg/kg body weight. the nn-xia-pla2 is also cytotoxic to ehrlich ascites tumour cells. the other pla2, nn-xib, in contrast has an i.p. ld ... | 1992 | 1279838 |
| toxicities, ld50 prediction and in vivo neutralisation of some elapid and viperid venoms. | toxicity levels of elapid (naja naja and naja oxiana) viperid (vipera lebetina and vipera russelli) venoms for mice and rat for intraperitoneal intravenous and intramuscular routes have been determined. the data have been analysed using a mathematical expression to calculate lethal venom concentrations in human snake bite cases. further, in vivo neutralisation of snake venom potency (after experimental injection) using high voltage-low current electric shock treatment has been attempted. this tr ... | 1992 | 1294479 |
| mapping the functional topography of a receptor. | photoactivatable derivatives of the alpha-neurotoxin ii from naja naja oxiana are useful tools for investigating the three dimensional architecture of the extra-membrane part of the nicotinic acetylcholine receptor from the electric tissue of torpedo californica. three derivatives, carrying an azidobenzoyl group in position lys-15, lys-26, and lys-46, respectively, are shown to react differently within the receptor's quaternary structure. especially the lys-26 and lys-46 derivatives can be used ... | 2007 | 1299215 |
| [pharmacokinetics of cytotoxin 14 from naja naja atra venom]. | the pharmacokinetics of cytotoxin 14 (ct 14) from naja naja atra venom was studied with biotin-avidin enzyme-linked immunosorbent assay. the plasma concentration-time curve of ct 14 after bolus i.v. 0.2 mg.kg-1 into rabbits was found to fit a two-compartment open model. t1/2 alpha was 5.8 +/- 0.6 min and t1/2 beta was 3.5 +/- 0.2 h. a rapid absorption was seen after im injection (0.5 mg.kg-1) to rabbits. the peak level was 260 +/- 90 ng.ml-1 and tpeak was 13.6 +/- 2.4 min. the absolute bioavaila ... | 1992 | 1302445 |
| alpha-cobratoxin: proton nmr assignments and solution structure. | the solution structure of alpha-cobratoxin, a neurotoxin purified from the venom of the snake naja naja siamensis, at ph 3.2 is reported. sequence-specific assignments of the nmr resonances was attained by a combination of a generalized main-chain-directed strategy and of the sequential method. the nmr data show the presence of a triple-stranded beta-sheet (residues 19-25, 36-41, and 52-57), a short helix, and turns. an extensive number of noe cross peaks were identified in the noesy nmr maps. t ... | 1992 | 1317211 |
| calcium ion independent membrane leakage induced by phospholipase-like myotoxins. | the two snake venom myotoxins ammodytin l and myotoxin ii, purified respectively from vipera ammodytes ammodytes and bothrops asper, have phospholipase-like structures but lack an asp-49 in the active site and are without normal phospholipase activity. the interaction of these proteins with different types of liposomes indicated that the myotoxins were able to provoke rapid and extensive release of the aqueous content of liposomes. leakage was measured by two different methods: fluorescence dequ ... | 1992 | 1334427 |
| immunochemical properties of naja naja atra (taiwan cobra) phospholipase a2 using polyclonal and monoclonal antibodies. | the immuno-chemical properties of naja naja atra phospholipase a2 (nna-pla2) were studied by using the chemically modified pla2 derivatives and the pla2 homologues toward anti-nna-pla2 polyclonal and monoclonal antibodies. anti-nna-pla2 polyclonal antibodies inhibited the enzymatic activity of nna-pla2 and hemachatus haemachatus de-i by 87% and 68%, respectively. however, the enzymatic activities of naja nigricollis cms-9 and notexin were not significantly affected by the polyclonal antibodies. ... | 1992 | 1373010 |
| antiflammins. anti-inflammatory activity and effect on human phospholipase a2. | two anti-inflammatory peptides (antiflammins) corresponding to a high amino acid similarity region between lipocortin i and uteroglobin were tested for their ability to inhibit purified human synovial fluid phospholipase a2 (hsf-pla2). no inhibitory activity was observed, even at such high concentrations of peptides as 50 microm. when antiflammins were preincubated with the enzyme and/or the substrate, no hsf-pla2 inhibition was detected. in vivo anti-inflammatory activity of these peptides was ... | 1992 | 1387313 |
| [specific killing of human leukemic t-cells by a monoclonal antibody coupled to the cytotoxin from chinese cobra]. | the immunotoxin (it) was prepared by conjugating cytotoxin from chinese cobra (naja naja atra) venom with monoclonal antibody (mcab) wu71 directed to human t-cells. first, calcium ions were used to suppress the cytolytic reaction while cell antigen was allowed to react with mcab. then magnesium ions and the chelating agent egta were used to abolish the calcium inhibition. with this treatment, the it showed high cytotoxicity for the leukemic cell line cem, which was antigen positive (82.4% of the ... | 1992 | 1394735 |
| lipopolysaccharide-induced stimulation of alveolar macrophage opsonin-independent phagocytosis. | alveolar macrophage (am) opsonin-independent phagocytosis may be an important process by which bacteria are cleared from the airspaces. although it has been shown that clearance of bacteria from the lung is altered in association with endotoxemia, the effect of endotoxemia on opsonin-independent phagocytosis is unknown. because alterations in am opsonin-independent phagocytosis could potentially influence bacterial clearance in the lung, we studied the effects of the intravenous injection of esc ... | 1992 | 1405605 |
| effects of snake venom phospholipase a2 toxins (beta-bungarotoxin, notexin) and enzymes (naja naja atra, naja nigricollis) on aminophospholipid asymmetry in rat cerebrocortical synaptosomes. | the effects of snake venom phospholipase a2 (pla2) toxins (beta-bungarotoxin, notexin) and pla2 enzymes (naja nigricollis, naja naja atra) on aminophospholipid asymmetry in rat cerebrocortical synaptic plasma membranes (spm) were examined. incubation of intact synaptosomes with 2 mm 2,4,6-trinitrobenzene sulfonic acid (tnbs) for 40 min, under non-penetrating conditions, followed by spm isolation, allowed us to calculate the percentage of phosphatidylethanolamine (pe) and phosphatidylserine (ps) ... | 1992 | 1417932 |
| inhibition of phosphorylation of synapsin i and other synaptosomal proteins by beta-bungarotoxin, a phospholipase a2 neurotoxin. | some snake venom neurotoxins, such as beta-bungarotoxin (beta-butx), which possess relatively low phospholipase a2 (pla2) activity, act presynaptically to alter acetylcholine (ach) release both in the periphery and in the cns. in investigating the mechanism of this action, we found that beta-butx (5 and 15 nm) inhibited phosphorylation, in both resting and depolarized synaptosomes, of a wide range of proteins, including synapsin i. naja naja atra pla2, which has higher pla2 activity, also inhibi ... | 1992 | 1431893 |
| activation of bovine factor v by an activator purified from the venom of naja naja oxiana. | the crude venom of many elapid snakes appeared to contain proteins that activated blood coagulation factor v. the factor v activator present in the venom of naja naja oxiana was purified to homogeneity by chromatography on a mono-s column. the activator was a single chain protein with an apparent mol. wt of 48,000, as judged by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and by gel permeation chromatography on sephacryl s200. activation of bovine factor v by the ... | 1992 | 1440644 |
| sphingolipid metabolism and signal transduction: inhibition of in vitro phospholipase activity by sphingosine. | sphingosine inhibits protein kinase c activity in vitro and has been used to implicate this enzyme in signal transduction and cell function. we report that sphingosine directly inhibits phospholipases a2 and d. sphingosine inhibits ca(2+)-dependent phospholipases a2 from naja naja, porcine pancreas, crotalus adamanteus, human disc and neutrophil in a dose-dependent manner with ic50 values ranging from 5-40 microm using [1-14c]oleate-labelled autoclaved e. coli (20 microm) as substrate. inhibitio ... | 1992 | 1504102 |
| effect of calcium and phosphate ions on hemolysis induced by pyrularia thionin and naja naja kaouthia cardiotoxin. | pyrularia thionin is a strongly basic bioactive peptide of 47 amino acids isolated from nuts of pyrularia pubera. it is hemolytic, cytotoxic and activates an endogenous phospholipase a2 in 3t3 cells. earlier studies have shown that the cardiotoxin from naja naja kaouthia has similar activities and binds to the same site as pyrularia thionin. since the peptides appear to bind to the phospholipids of cell membranes to elicit their cellular responses, the effect of modifying the electrostatic envir ... | 1992 | 1509489 |
| binding properties of pyrularia thionin and naja naja kaouthia cardiotoxin to human and animal erythrocytes and to murine p388 cells. | pyrularia thionin and snake venom cardiotoxin are strongly basic peptides which induce hemolysis, depolarization of muscle cells and activation of endogenous phospholipase a2. an earlier study of the hemolysis reaction indicated that the two peptides bind to and compete for the same site on human erythrocytes. a recent study examined the hemolysis induced by both peptides as the phosphate and ca2+ content of the reaction mixture was varied. the results of the recent study (vernon, l. p. and roge ... | 1992 | 1509490 |
| mojave toxin affects fusion of myoblasts and viability of myotubes in cell cultures. | mojave toxin is a neurotoxic, heterodimeric phospholipase isolated from the venom of crotalus scutulatus scutulatus. responses of primary rat muscle cell cultures and clonal muscle cell lines to treatment with mojave toxin and its constituent subunits were examined. continuous exposure of cells to 0.5 microm or 1.0 microm mojave toxin or the basic subunit, added 24 hr after plating, prevented fusion of primary myoblasts and c2 myoblasts to multinucleate myotubes. under the same experimental cond ... | 1992 | 1509491 |
| a novel type of phospholipase a2 inhibitor, thielocin a1 beta, and mechanism of action. | thielocin a1 beta, a novel phospholipase a2 inhibitor, was isolated from thielavia terricola rf-143. it inhibited various phospholipase a2s in a dose-dependent manner. among these, group ii phospholipase a2 from rat was most sensitive to thielocin a1 beta (ic50 = 0.0033 microm). the inhibition of phospholipase a2 by thielocin a1 beta was independent of ca2+ and substrate concentration. in addition, the inhibition of rat group ii phospholipase a2 was noncompetitive (ki = 0.0068 microm) and revers ... | 1992 | 1517154 |
| investigation of ligand-binding sites of the acetylcholine receptor using photoactivatable derivatives of neurotoxin ii from naja naja oxiana. | several photoaffinity derivatives of neurotoxin ii from the venom of the central asian cobra naja naja oxiana have been prepared. after reaction of the 125i-labeled derivatives with the nicotinic acetylcholine receptor from electric organ, the alpha-subunit of the nachr is almost exclusively labeled by the derivative carrying the photoactivatable group in position lys46. in contrast to this, a reactive group at lys26 predominantly labels the gamma- and delta-subunits, while the alpha- and beta-s ... | 2006 | 1525162 |
| cinatrins, a novel family of phospholipase a2 inhibitors. ii. biological activities. | cinatrins a, b and c3 inhibited phospholipase a2 purified from rat platelets in a dose-dependent manner. cinatrin c3, the most potent component (ic50 70 microm), was noncompetitive with a ki value of 36 microm. cinatrins b and c3 also inhibited both porcine pancreas and naja naja venom phospholipase a2. inhibition of rat platelet phospholipase a2 by cinatrin c3 was independent of ca2+ and substrate concentration. comparison with duramycin, another phospholipase a2 inhibitor, displayed inhibition ... | 1992 | 1548189 |
| implications of a consensus recognition site for phosphatidylcholine separate from the active site in cobra venom phospholipases a2. | a model structure of naja naja kaouthia cobra venom phospholipase a2 has been constructed by utilizing molecular modeling techniques. analysis of the model and available biochemical data reveal the presence in this enzyme of a putative recognition site for choline derivatives in loop 57-70 made up of residues trp-61, tyr-63, phe-64, and lys-65, together with glu-55. the magnitude and shape of the electrostatic potential in this binding site are approximately 80% similar to that in the mcpc603 an ... | 1992 | 1550815 |
| preparation, characterization and immunogenicity of various polymers and conjugates of elapid postsynaptic neurotoxins. | seven polymeric forms and conjugates of purified principal postsynaptic neurotoxins of naja naja siamensis (nns), ophiophagus hannah (oh) and bangarus fasciatus (bf) have been synthesized by controlled polymerization in which only 29-60% of the toxins were allowed to react. a carbodiimide (ecdi) and glutaraldehyde (ga) were used as coupling agents while bsa and tetanus toxoid (tt) were used as carriers. the antigenic mosaic of these immunogens was: nns-ecdi, nns-bf-oh-ecdi, nns-bsa-ecdi, nns-tt- ... | 1992 | 1565098 |
| kinetics of the hydrolysis of micellar substrates catalyzed by snake venom phospholipases a2. | effects of ca2+ on the kinetic parameters for the hydrolysis of mixed micelles of 1,2-dipalmitoyl-sn-glycero-3-phosphorylcholine (dic16pc) with triton x-100, catalyzed by a cobra (naja naja atra) (group i) and a habu (trimeresurus flavoviridis) (group ii) pla2s, were studied and compared with the results reported for other group i and ii enzymes. the substrate bindings to group i enzymes were independent of the ca2+ binding, whereas the substrate bindings to group ii enzymes were facilitated mor ... | 1992 | 1569045 |
| differential hydrolysis of 1-alkyl-2-acyl and diacylglycerophosphocholines by human and non-human phospholipases a2. | the activity of two human phospholipases a2, purified from synovial fluid and lumbar disc herniations, was tested using alkylacyl- and diacylglycerophosphocholines and the influence of the chemical link at the sn-1 position of glycerol was investigated. both enzymes exhibited 2.5-3-fold selectivity for 1-ester-linked compared to 1-ether-linked phosphatidylcholine. no significant selectivity was observed with pancreatic phospholipase a2 while naja naja naja venom enzyme was more efficient against ... | 1992 | 1576169 |
| use of hplc to demonstrate variation of venom toxin composition in the thailand cobra venoms naja naja kaouthia and naja naja siamensis. | the composition of the venoms of naja naja kaouthia and naja naja siamensis from different commercial sources has been investigated using both ion-exchange and reverse-phase high-pressure liquid chromatography (rp-hplc) in order to investigate variation in toxin contents. the venoms contained identical major toxin components, although in different relative concentrations. the venom collected separately from the left and right glands of individual snakes were virtually the same as judged by rp-hp ... | 1992 | 1595079 |
| direct effects and augmentation of airway smooth muscle contraction caused by phospholipase a2. | we examined the effect of phospholipase a2 (pla2; naja naja) on isometric tracheal smooth muscle force generation in guinea pig trachealis in situ. direct application of pla2 to the surface of the trachea caused dose-related contraction of tracheal smooth muscle. in seven guinea pigs, a dose/density of 100 micrograms/cm2 pla2 caused active tension (at) that began immediately and was maximum (1.32 +/- 0.13 g/cm) at 5 min (p less than 0.01 versus baseline tension). pla2 also augmented the contract ... | 1992 | 1596019 |
| [biotin-avidin-elisa for cytotoxin purified from cobra venom]. | a technique combining the biotin-avidin amplifying system with sandwich enzyme-linked immunosorbent assay (b-a-elisa) was developed for the microassay of the cytotoxin from naja naja atra venom. the horse-peroxidase was used as the marker and polystyrene microhemagglutination plates as solid carrier. the sensitivity was 0.5 ng.ml-1. the assay range was 1.25-320 ngml-1 with coefficient of variation of 4.9% (intragroup) and 8.1% (intergroups), respectively. | 1992 | 1598840 |
| [pharmacological study on naja naja kaouthia lesson. iii. effects of 50% ethanolic extracts from liver and gall bladder on phagocytic activity of mouse reticuloendothelial system]. | effects of 50% ethanolic extracts from the liver and the gall bladder of naja naja kaouthia lesson (cob-l or cob-g) were studied on the phagocytic activity of a mouse reticuloendothelial system. the clearance-rate of carbon was shortened by the oral administration of cob-l or cob-g (50 or 200 mg/kg). cob-l or cob-g promoted the phagocytosis of latex by peritoneal macrophages (m phi). furthermore, effects of these extracts on the peritoneal m phi were biochemically investigated using in vitro exp ... | 1992 | 1608042 |
| structural analysis and comparison of cobrotoxin and cardiotoxins by near-ir fourier transform raman spectroscopy. | venom toxins were isolated from formosan cobra (naja naja atra) by cation-exchange chromatography. the near-ir ft-raman analytical method has been applied to the characterization and classification of the toxin components in their lyophilized forms. structural analysis and comparison of various purified toxin fractions were made with respect to their amino acid compositions and near-ir fourier-transform raman spectra. the results indicate that the major secondary structure of cobra toxins includ ... | 1992 | 1610379 |
| purification and properties of the l-amino acid oxidase from monocellate cobra (naja naja kaouthia) venom. | 1. the l-amino acid oxidase of the monocellate cobra (naja naja kaouthia) venom was purified to electrophoretic homogeneity. the molecular weight of the enzyme was 112,200 as determined by sephadex g-200 gel filtration chromatography, and 57,400 as determined by sds-polyacrylamide gel electrophoresis. 2. the enzyme had an isoelectric point of 8.12 and a ph optimum of 8.5. it showed remarkable thermal stability, and, unlike many venom l-amino acid oxidase, was also stable in alkaline medium. the ... | 1992 | 1612186 |
| reversibility of the activation of soluble phospholipase a2 on lipid bilayers: implications for the activation mechanism. | the time-courses of hydrolysis of large vesicles of dipalmitoylphosphatidylcholine were compared using four species of phospholipase a2 (agkistrodon piscivorus piscivorus, crotalus adamanteus and naja naja venoms and porcine pancreatic). in all four cases, the hydrolysis rate suddenly increases 10 to 100-fold at the time (tau) when a specific mole fraction of reaction products has accumulated. the intrinsic fluorescence emission of the three venom enzymes also increases suddenly at time tau. bot ... | 1992 | 1643108 |
| comparative effects of phospholipase a2 neurotoxins and enzymes on membrane potential and na+/k+ atpase activity in rat brain synaptosomes. | beta-bungarotoxin (beta-butx) and notexin are phospholipase a2 (pla2) neurotoxins which cause an irreversible blockade of neurotransmitter release through specific and potent effects at the presynaptic nerve terminal; however, their mechanism of action is uncertain. we examined the effects of beta-butx and notexin on na+/k+ atpase activity using sprague-dawley rat brain synaptosomes in order to determine if alterations in activity might modulate neurotoxin-induced depolarization. treatment of sy ... | 1991 | 1648801 |
| comparison of group i and ii soluble phospholipases a2 activities on phagocytic functions of human polymorphonuclear and mononuclear phagocytes. | soluble phospholipase a2 (pla2) purified from rheumatoid synovial fluid (group ii) and repurified naja naja venom pla2 (group i) were compared for their influence on phagocytic activity of human polymorphonuclear (pmn) and mononuclear (mo) phagocytes. group ii pla2 reduced chemotaxis, adhesiveness, and intracellular bactericidal activity (icba) and induced release of muramidase from pmns. group i pla2 suppressed chemotaxis, and enhanced icba but had no influence on other phagocytic functions. gr ... | 1991 | 1649131 |
| comparative enzymatic composition of brazilian coral snake (micrurus) venoms. | 1. venoms of 11 coral snake taxa, including micrurus albicinctus, m. corallinus, m. frontalis altirostris, m. f. brasiliensis, m. f. frontalis, m. fulvius fulvius, m. ibiboboca, m. lemniscatus ssp., m. randonianus, m. spixii spixii, and m. surinamensis surinamensis, were examined for 13 enzymatic activities. 2. these were compared with venoms of three outgroup taxa: naja naja kaouthia, bungarus multicinctus, and bothrops moojeni. 3. enzyme activity levels in micrurus venoms were highly variable ... | 1991 | 1662592 |
| effects of a cardiotoxin from naja naja kaouthia venom on skeletal muscle: involvement of calcium-induced calcium release, sodium ion currents and phospholipases a2 and c. | snake venom cardiotoxin (ctx) fractions induce contractures of skeletal muscle and hemolysis of red blood cells. the fractions also contain trace amounts of venom-derived phospholipase a2 (pla2) contamination and activate tissue phospholipase c (plc) activity. the present study examines the mechanisms of action of a ctx fraction from naja naja kaouthia venom in skeletal muscle. sphingosine competitively antagonized ctx-induced red blood cell hemolysis, but not skeletal muscle contractures. ctx r ... | 1991 | 1666202 |
| effects of anti-inflammatory drugs on rat hind-paw swelling caused by phospholipase a2 from naja naja atra venom. | rat hind-paw swelling was induced dose-dependently by subplantar injection of acidic phospholipase a2 (nnavpla2) from naja naja atra venom. diphenhydramine and methysergide pretreatment greatly reduced the swelling effect caused by nnavpla2. several doses of compound 48/80 given to deplete the histamine content of rat hind paw, also greatly suppressed nnavpla2-induced paw swelling. the paw swelling caused by nnavpla2 was reduced following pretreatment with bw 755c, a dual inhibitor of cyclooxyge ... | 1991 | 1683689 |
| antiallergic and anti-inflammatory action of tioxamast in rats. i. antiallergic activity in vivo and in vitro. | tioxamast (f 1865) is an antiallergic drug that, administered systemically, reduces anaphylaxis in various models in rats. this action is due mainly to the inhibition of the synthesis and release of certain mediators. orally or intraduodenally administered tioxamast inhibits ige-dependent passive cutaneous anaphylaxis (ed50 = 0.8 mg/kg), ige-dependent passive pulmonary anaphylaxis (ed50 = 0.5 mg/kg), and igg-dependent passive cutaneous anaphylaxis (ed50 = 0.6 mg/kg). it has little or not effect ... | 1990 | 1700967 |
| primary structure and functional properties of cobra (naja naja naja) venom kunitz-type trypsin inhibitor. | a trypsin inhibitor from the venom of the cobra naja naja naja has been isolated by a single step of reverse-phase high-performance liquid chromatography. the protein strongly inhibits trypsin (ki = 3.5 pm). the primary structure was determined by peptide analysis of the [14c]carboxymethylated inhibitor. the 57-residue polypeptide chain belongs to the family of kunitz-type inhibitors, and exhibits 42% residue identity with bovine pancreatic trypsin inhibitor. the structure shows only 70% identit ... | 1990 | 1702708 |
| comparison of the enzymatic and edema-producing activities of two venom phospholipase a2 enzymes. | the edema-producing activity of nnavpla2, an acidic phospholipase a2 (pla2) enzyme from naja naja atra venom (nnav), was less potent than that of tmvpla2 ii, a basic pla2 from trimeresurus mucrosquamatus venom (tmv). these edema-forming effects were greatly suppressed by pretreatment of rats with diphenhydramine/methysergide or compound 48/80, which reduced the tissue content of histamine and serotonin. heparin abolished and suppressed the paw edema caused by protamine and tmvpla2 ii, respective ... | 1990 | 1703083 |
| intracellular mechanisms involved in short-term regulation of net protein synthesis in pancreatic acini. | the mechanisms regulating the net synthesis of digestive enzymes during short-term stimulation by agonists were examined in pancreatic acini isolated from the rat. dispersed pancreatic acini were stimulated for up to 60 min with various concentrations of cholecystokinin octapeptide (cck-op), carbachol, a23187, 4 beta-phorbol 12-myristate 13-acetate (pma). the effects of these agonists on net protein synthesis was determined by measuring the incorporation of [3h]leucine or [35s]methionine into pr ... | 1991 | 1708286 |
| production and characterization of monoclonal antibodies against naja naja atra cobrotoxin. | twelve monoclonal antibodies against cobrotoxin from naja naja atra venom were tested for cross-reactivity with eight different snake toxins, binding to linear epitopes, prevention of cobrotoxin binding to acetylcholine receptor (achr) in vitro, and protection in mice concomitantly given a lethal dose of cobrotoxin. the antibodies were highly specific, as evidenced by little reactivity with other snake toxins. none of the monoclonal antibodies bound to reduced cobrotoxin or synthesized 8-mer reg ... | 1991 | 1724806 |
| extracellular phospholipase a2 and histamine release from rat peritoneal mast cells. | phospholipase a2 (pla2) from cobra (naja naja) venom and pla2 from porcine pancreas accelerated ige antibody-mediated histamine release from rat peritoneal mast cells. these enhancements were clearly abrogated by heating the enzymes and pretreatment with parabromophenacyl bromide, mepacrine and antiflammin. indomethacin (cyclooxygenase inhibitor) and aa-861 (lipoxygenase inhibitor) did not affect the enhancement by pla2. these results indicate that extracellular pla2 enhances the ige antibody-me ... | 1991 | 1725674 |
| renaturation of cobra venom phospholipase a2 expressed from a synthetic gene in escherichia coli. | cobra venom (naja naja naja) phospholipase a2 (pla2) contains 14 cysteines in the form of 7 disulfide bonds amongst its 119 amino acids. a gene encoding the pla2 was synthesized and inserted into a bacterial expression vector containing the phage lambda pl promoter. in order to obtain protein without the initiating methionine at the n-terminus, a factor xa site was engineered upstream from the pla2 gene. upon heat-induction of the cells transformed with the expression plasmid, the protein is pro ... | 1992 | 1730025 |
| structural features of carbohydrate moieties in snake venom glycoproteins. | the structures of the carbohydrate moieties of glycoproteins in snake venoms are largely unknown. in the present study, we have analyzed venoms of several species of snakes as well as plasma and tissue glycoproteins from one species of cobra (naja naja kaouthia) by lectin affinity staining of western blots. the data demonstrate that glycoproteins in cobra venom invariably contain terminal alpha-galactosyl residues with negligible proportions of sialic acids. interestingly, however, terminal alph ... | 1992 | 1731789 |
| absence of lung reactions after complement depletion during dialysis: an experimental study in pigs. | sequestration of 111in-labeled neutrophils (polymorphonuclear leukocytes--pmns) in the lungs during sham dialysis was studied dynamically using a gamma camera. five animals were pretreated with cobra venom factor, naja naja (cvf), to achieve depletion of the complement system, mainly c5a. seven animals were studied without pretreatment with cvf. central hemodynamics and gas exchange were studied as well as neutrophil function using luminescence and aggregation. in the control group there was a s ... | 1991 | 1741685 |
| comparative chromatography of brazilian coral snake (micrurus) venoms. | 1. elution profiles of 11 coral snake venoms, including those of micrurus albicinctus, m. corallinus, m. frontalis altirostris, m. f. brasiliensis, m. f. frontalis, m. fulvius fulvius, m. ibiboboca, m. lemniscatus ssp., m. rondonianus, m. spixii spixii and m. surinamensis surinamensis, were compared using high performance gel filtration and reverse phase media. 2. micrurus venom profiles were compared with those of "outgroup" taxa bothrops moojeni, naja naja kaouthia and bungarus multicinctus. 3 ... | 1991 | 1756614 |
| isolation and fundamental characteristics of a phospholipase b inhibitor from autolyzed torulaspora delbrueckii. | phospholipase b inhibitor was found in the autolyzate of yeast cells, torulaspora delbrueckii. the inhibitor was purified to homogeneity by ethanol precipitation, gel filtration with sephadex g-10, ion-exchange chromatography with deae-sephacel, and gel filtration with asahipak gs-320. on thin-layer chromatography the purified inhibitor was detected with the hanes-isherwood reagent, which is used to detect phosphorus. the activity of the inhibitor was not affected by heat treatment at 100 degree ... | 1991 | 1760134 |
| interleukin-1 alpha stimulates the release of prostaglandin e2 and phospholipase a2 from fetal rat calvarial cells in vitro: relationship to bone nodule formation. | we have shown previously that interleukin-1 (il-1) has biphasic effects on the formation of bone nodules in long-term cultures of fetal rat calvarial (rc) cells (ellies and aubin, cytokine 2:430-437, 1990). to determine the role of arachidonic acid metabolism in this process, we have examined the release of prostaglandin e2 (pge2) and phospholipase a2 (pla2) from rc cells under conditions that allowed concomitant analysis of the formation of bone nodules. recombinant human il-1 alpha (rhil-1 alp ... | 1991 | 1785374 |
| the involvement of polymorphonuclear leukocytes in the pathogenesis of bronchopneumonia in calves. ii. granulocyte-induced changes in erythrocyte membrane phospholipid topology. | phospholipid topology in erythrocyte membranes of bronchopneumonic calves and changes in phospholipid asymmetry induced by incubation of erythrocytes with neutrophils of diseased calves were examined. using aminophospholipid tracing by non-penetrating probe, trinitrobenzenesulfonic acid, and phospholipid hydrolysis by specific phospholipase a2 from naja naja venom and sphingomyelinase from staphylococcus aureus it was stated that in erythrocytes from diseased calves phosphatidylserine and, to so ... | 1991 | 1785438 |
| structural analysis of phospholipase a2 by near-ir fourier transform raman spectroscopy. | venom toxins were isolated from formosan cobra (naja naja atra) by cation-exchange chromatography. most toxin components could be obtained in relatively pure forms by single-step ion-exchange chromatography whereas an extra step of gel permeation was needed for the separation of phospholipase a2 (pla2) from the major neurotoxic component, i.e. cobrotoxin. the newer near-ir ft-raman analytical method has been applied to the characterization of pla2 in their lyophilized forms. structural analysis ... | 1991 | 1789801 |
| effects of chemical modification on enzymatic and toxicological properties of phospholipases a2 from naja naja naja and vipera russelli snake venoms. | the effects of chemical modification with 4-nn-dimethyl amino azo benzene-4'-isothiocyanate on various biological activities of phospholipases a2, nn-xiii-pla2 from naja naja naja and vrv-pl-viiia from vipera russelli snake venoms were investigated. modification of the enzymes resulted in significant reduction of lethal, hemolytic, anticoagulant and enzymatic activities. the km value of the modified enzymes was increased. the modified enzymes failed to induce edema in the foot pads of mice and w ... | 1991 | 1801318 |
| characterization and immunological comparison of isoenzymes of phospholipases a2 from snake venoms of different genera and families. | phospholipases a2 (pla2) were isolated and purified from the taiwan cobra (naja naja atra) and several snake species of the same or different genera by semipreparative cation-exchange and reversed-phase hplc. they were shown to possess different enzymatic activity toward the synthetic substrate l-alpha-lecithin by the fatty-acid titration method. the immunological cross-reactivity of these structurally similar isotoxins was investigated using immunodiffusion, precipitin reaction and enzyme-linke ... | 1991 | 1810246 |
| isolation and characterization of a lethal phospholipase a2 (nn-ivb1-pla2) from the indian cobra (naja naja naja) venom. | indian cobra (naja naja naja) venom is reported to contain multiple forms of phospholipase a2. only a couple of them have been isolated and characterized. a lethal phospholipase a2 (nn-ivb1-pla2) from naja naja naja venom has been purified in three steps involving cm-sephadex c-25, sephadex g-50 and rechromatography on cm-sephadex c-25 columns. it is a basic protein with pl value between 7-7.5 and has molecular weight between 11,000-11,500. the ld50 of nn-ivb1-pla2 is 1.2 mg/k g body weight. it ... | 1991 | 1810247 |
| purification and characterization of a neurotoxic phospholipase a2 from indian cobra (naja naja naja) venom. | snake venoms contain multimolecular forms of phospholipase a2 which are diverse with respect to their pharmacological properties. a neurotoxic pla2 from naja naja naja venom has been purified in two steps. (1) the whole venom was fractionated on cm-sephadex c-25 column; 4.6% of the total pla2 activity recovered was found in the nn-v fraction. (2) the nn-vb-pla2 fraction was purified to homogeneity by gel filtration of fraction nn-v on sephadex g-50. it is a basic protein with a mol. wt between 1 ... | 1991 | 1814010 |
| procoagulant activities in venoms from central asian snakes. | the venoms from central asian snakes (echis carinatus, echis multisquamatus, vipera ursini, vipera lebetina, agkistrodon halys halys and naja naja oxiana) contain several enzymes with amidolytic- and procoagulant activity. we have characterized the activities and the mol. wts of the venom enzymes that are able to convert a number of commercially available chromogenic substrates for activated coagulation factors. the chromogenic substrate cleavage patterns obtained for the crude venoms may be hel ... | 1991 | 1830705 |
| synthesis and characterization of a heterobifunctional mercurial cross-linking agent: incorporation into cobratoxin and interaction with the nicotinic acetylcholine receptor. | the heterobifunctional organomercurial reagents 3-(acetoxymercurio)- and 3-(chloromercurio)-5-nitrosalicylaldehyde were prepared, characterized in model studies, and used to probe the interaction between cobratoxin, purified from the venom of the thailand cobra (naja naja siamensis), and the affinity-purified nicotinic acetylcholine receptor (acchr) from torpedo california electroplax. these reagents may also be useful in introducing chemically well-defined heavy metal atoms into proteins contai ... | 1991 | 1854732 |
| interfacial catalysis by phospholipase a2: substrate specificity in vesicles. | the binding equilibrium of phospholipase a2 (pla2) to the substrate interface influences many aspects of the overall kinetics of interfacial catalysis by this enzyme. for example, the interpretation of kinetic data on substrate specificity was difficult when there was a significant kinetic contribution from the interfacial binding step to the steady-state catalytic turnover. this problem was commonly encountered with vesicles of zwitterionic phospholipids, where the binding of pla2 to the interf ... | 1991 | 1854740 |
| a non-radioactive receptor assay for snake venom postsynaptic neurotoxins. | a non-radioactive assay was developed for detecting the binding of postsynaptic neurotoxins to acetylcholine receptor (achr) from torpedo californica. enzyme linked immunosorbent assay (elisa) wells coated with long or short chain neurotoxins specifically bound to purified achr while crotamine or two different cardiotoxins did not. bound receptor was detected by antibody against achr. specificity was determined by dose-response experiments and competition studies using carbamylcholine chloride, ... | 1991 | 1862522 |
| [1-14c]oleate-labeled autoclaved yeast: a membranous substrate for measuring phospholipase a2 activity in vitro. | radiolabeled, autoclaved yeast were tested as a substrate for mammalian phospholipase a2 activity because the only other membranous substrate used for this purpose, autoclaved escherichia coli, totally lacks a major mammalian phospholipid, phosphatidylcholine. candida albicans were grown in the presence of [1-14c]oleate and then autoclaved. sixty three percent of the incorporated label was in yeast phospholipid, and more than 95% of that was in the 2-acyl position. the distribution of label in t ... | 1991 | 1872466 |
| comparison of the catalytic properties of phospholipase a2 from pancreas and venom using a continuous fluorescence displacement assay. | phospholipases a2 from pig pancreas and the venoms from bee, naja naja and crotalus atrox have been studied by using a new continuous fluorescence displacement assay that utilizes normal phospholipid substrates [wilton (1990) biochem. j. 266, 435-439]. with limiting amounts of substrate, the assay demonstrated stoichiometric conversion into products with both pancreatic and venom enzymes, and thus would allow phospholipid determination at concentrations down to about 0.1 microm. the substrate sp ... | 1991 | 1898370 |
| acute lung injury induced by phospholipase a2. structural and functional changes. | on the basis of the observation that serum levels of phospholipase a2 (pla2) are elevated in pancreatitis and systemic sepsis, and the association of these conditions with the subsequent development of acute lung injury, the present investigation examined the structural and physiologic consequences of intratracheal administration of pla2 to adult male rats. rats received direct intratracheal instillation of either control vehicle or 40,000 units/kg of pla2 repurified from naja naja venom. animal ... | 1991 | 1902636 |
| kinetic characterization of phospholipase a2 modified by manoalogue. | manoalogue, a synthetic analogue of the sea sponge-derived manoalide, has been previously shown to partially inactivate the phospholipase a2 from cobra venom (reynolds, l. j., morgan, b. p., hite, e. d., mihelich, e. d., & dennis, e. a. (1988) j. am. chem. soc. 110, 5172) by reacting with enzyme lysine residues. in the present study, the inactivation of the phospholipases a2 from pig pancreas, bee venom, and cobra (naja naja naja) venom by manoalogue was studied in detail. manoalogue-treated enz ... | 1991 | 1911741 |
| critical role of a hydrogen bond in the interaction of phospholipase a2 with transition-state and substrate analogues. | the inhibition of phospholipase a2 by an amide substrate analogue, 1-hexadecylthio-2-hexadecanoyl-amino-1,2-dideoxy-sn-glycero-3-phos phocholine, and a phosphonate transition-state analogue, 1-hexadecylthio-1-deoxy-2-hexadecylphosphono-sn-glycero-3-ph osphocholine, is dramatically influenced by ph. however, these two inhibitors show opposite ph dependencies. the amide analogue acts more potently under basic conditions, whereas the phosphonate acts more potently under acidic conditions. in both c ... | 1991 | 1924395 |
| the refined crystal structure of alpha-cobratoxin from naja naja siamensis at 2.4-a resolution. | the crystal structure of the "long" alpha-neurotoxin alpha-cobratoxin was refined to an r-factor of 19.5% using 3271 x-ray data to 2.4-a resolution. the polypeptide chain forms three loops, i, ii, iii, knotted together by four disulfide bridges, with the most prominent, loop ii, containing another disulfide close to its lower tip. loop i is stabilized by one beta-turn and two beta-sheet hydrogen bonds; loop ii by eight beta-sheet hydrogen bonds, with the tip folded into two distorted right-hande ... | 1991 | 1939183 |
| a convenient method to differentiate the monoclonal antibodies with differing immunochemical properties. | three monoclonal antibodies (mabs) against naja naja atra phospholipase a2 (pla2) were prepared by hybridoma technique. of which two mabs, 1e531 and 5f92 inhibited the enzymatic activity of pla2, but 5f6f10 did not. 1e531 and 5f92 nearly exhibited the same binding patterns which was different from that observed with 5f6f10 toward the chemically modified derivatives and homologous variants of pla2 as revealed by enzyme immunoassay. this suggests that, based on the results of comparative analysis ... | 1991 | 1953802 |
| effect of anti-inflammatory drugs on the cardiotoxin-induced hind-paw oedema in rats. | cardiotoxin, isolated from naja naja atra venom, induced rat hind-paw oedema. this effect was suppressed by the pretreatment with dexamethasone or bw 755c, or subplantar co-injection with fpl 55712. pretreatment with aspirin alone did not affect this response, while a significant reduction of cardiotoxin-induced paw oedema was achieved with aspirin in combination with diphenhydramine and methysergide. subplantar co-injection of paf antagonist, bn 52021 or l 652731, with cardiotoxin had no effect ... | 1990 | 1983146 |
| fusion of sphingomyelin vesicles induced by proteins from taiwan cobra (naja naja atra) venom. interactions of zwitterionic phospholipids with cardiotoxin analogues. | egg sphingomyelin vesicles were used to assay aggregation/fusion activities of proteins from taiwan (naja naja atra) venom to avoid the problem of phospholipase a2 contamination during protein purification. it led to the identification of a new cardiotoxin (ctx) analogue protein (ctx v) with major aggregation/fusion, but few hemolysis, activities. on the contrary, cardiotoxin (ctx iii) induced significant hemolysis of human red blood cells but exhibited few aggregation/fusion activities. to stud ... | 1991 | 1993698 |
| amino acid sequences of nerve growth factors derived from cobra venoms. | amino acid sequences of nerve growth factors (ngfs), purified from the venoms of indian cobra (naja naja) and thailand cobra (naja naja siamensis) were determined. the sequence of n. naja ngf differed from that reported previously by hogue-angeletti et al. [(1976) biochemistry 15, 26-34]. the sequence of n. naja siamensis ngf was identical to that of formosan cobra naja naja atra ngf, determined previously by oda et al. [(1989) biochem. int. 19, 909-917] and to that deduced from the nucleotide s ... | 1991 | 1995338 |
| development of an elisa to assess the potency of horse therapeutic antivenom against thai cobra venom. | an elisa for the quantitation of antibodies against naja naja siamensis venom proteins has been developed for use as a possible replacement for the in vivo neutralization assay of antivenom potency. comparison was made with three preparations of venom proteins as antigens of elisa: these were the crude venom, a toxin fraction and the purified principle postsynaptic neurotoxin of the thai cobra. eight batches of horse monovalent therapeutic anti-cobra antivenom, one of which served as positive re ... | 1991 | 1995711 |
| in vivo anti-complementary activities of the cobra venom factors from naja naja and naja haje. | the kinetics of complement (c) depletion and recovery of c levels upon injection of balb/c mice with cobra venom factors (cvf), from n. naja (c3- and c5-depleting) and n. haje (selectively c3-depleting) were studied. the animals received i.p. or i.v. injections of either of the two preparations. ch50 and hemolytic c3 and c5 levels were followed as parameters of residual complement activity. n. naja cvf turned out to be as efficient in depleting total complement activity as n. haje cvf. decreased ... | 1991 | 1999656 |
| suicide-inhibitory bifunctionally linked substrates (siblinks) as phospholipase a2 inhibitors. mechanistic implications. | novel phospholipids that function as mechanism-based inhibitors for phospholipase a2 (pla2) are described. pla2-catalyzed hydrolysis of the sn-2 ester of these suicide-inhibitory bifunctionally linked substrates (siblinks) followed by a cyclization reaction generates a cyclic anhydride at the active site of the enzyme which leads to inhibition. structure/activity relationships for the siblinks substituents in the sn-1 and sn-2 position are delineated. time courses and efficiency of siblinks inhi ... | 1991 | 2002046 |
| structure-function relationships among neurotoxic phospholipases: nn-xiii-pla2 from indian cobra (naja naja naja) and vrv pl-v from russell's viper (vipera russelli) venoms. | though venom phospholipases induce various pharmacological effects their mechanism of action is in some cases unclear. there may be separate pharmacological sites on the venom phospholipase molecule. in order to understand the structure-function relationships among venom phospholipases, studies on interaction of venom phospholipases with its antibodies and various alkaloids were carried out. the alkaloids aristolochic acid, ajmaline and reserpine were incapable of inhibiting the phospholipase a2 ... | 1991 | 2028476 |
| cobra venom phospholipase a2: naja naja naja. | 1991 | 2051932 | |
| snake venom cardiotoxins and bee venom melittin activate phospholipase c activity in primary cultures of skeletal muscle. | the effects of cardiotoxin fractions from naja naja kaouthia and naja naja atra snake venoms and synthetic melittin peptide were examined on lipolytic activity in red blood cells and primary skeletal muscle cultures. both native cardiotoxin fractions caused considerable production of free fatty acids in red blood cells. this production was abolished when the fractions were first treated with p-bromophenacyl bromide to reduce the venom phospholipase a2 activity contamination. in equine and human ... | 1991 | 2054159 |
| preliminary crystallographic analysis of cardiotoxin v with major fusion activity from taiwan cobra (naja naja atra) venom. | crystals of a cardiotoxin from taiwan cobra venom have been obtained by the vapor diffusion method using methyl pentanediol as precipitant. the crystals belong to the hexagonal space group p6(1)22 (or p6(5)22), with cell dimensions a = b = 47.5 a, c = 111.3 a, alpha = beta = 90 degrees and gamma = 120 degrees and diffract to a resolution of 2.2 a. there is one molecule per asymmetric unit and the solvent content is estimated to be 53%. | 1991 | 2056526 |
| extensive multiplicity of the miscellaneous type of neurotoxins from the venom of the cobra naja naja naja and structural characterization of major components. | a multiplicity of miscellaneous type neurotoxins were detected in the venom of the cobra naja naja naja by use of reverse-phase hplc and fplc. the primary structures of major forms were determined, giving 4 novel structures. all four contain 62-65 residues, with 10 half-cystine residues and resemble the miscellaneous type of toxins from other naja species. differences within the species are extensive, exchanges occur at 27 positions, giving only 58% residue identity between all forms. however, t ... | 1991 | 2060629 |
| lipopolysaccharide-induced pulmonary vascular sequestration of polymorphonuclear leukocytes is complement independent. | lipopolysaccharide (lps) injected intravenously produces leukopenia and sequestration of polymorphonuclear leukocytes (pmn) in the pulmonary vascular bed. to evaluate the role of complement in this process, we used c5-sufficient (b10.d2/nsn) and c5-deficient (b10.d2/osn) mice and sprague-dawley rats depleted of complement with naja naja cobra venom factor (cvf). we found a comparable increase in the number of pmn in lung tissue of c5-sufficient and c5-deficient mice given escherichia coli lps (0 ... | 1991 | 2064126 |
| [spatial structure of the basic chain of the neurotoxin i molecule from the venom of cobra naja naja oxiana and its crystal packing]. | the structure of the alpha-carbon chain was solved by molecular replacement method at 2.7 a resolution. neurotoxin i (ntx-i) is one of the main protein components purified from the venom of the central asian cobra naja naja oxiana. ntx-i is known to bind specifically to acetylcholine receptors thus preventing the transmission of the neuroconductivity signal from synapses to muscles. ntx-i crystals were grown either by vapour diffusion or dialysis methods using specially prepared microdialysis ce ... | 1991 | 2064629 |
| anionic subsites of the catalytic center of acetylcholinesterase from torpedo and from cobra venom. | a peptide of acetylcholinesterase (acchoease; acetylcholine acetylhydrolase, ec 3.1.1.7) from the venom of the cobra naja naja oxiana labeled by the affinity reagent n,n-dimethyl-2-phenylaziridinium (dpa) has been identified. the sequence is gly-ala-glu-met-trp-asn-pro-asn. in acchoease from torpedo californica, a homologous peptide was labeled and isolated. its sequence is ser-gly-ser-glu-met-trp-asn-pro-asn, representing positions 79 through 87. in both cases labeling can be prevented by 0.1 m ... | 1991 | 2068091 |
| phospholipid hydrolysis and loss of membrane integrity following treatment of rat brain synaptosomes with beta-bungarotoxin, notexin, and naja naja atra and naja nigricollis phospholipase a2. | the effects of the phospholipase a2 (pla2) toxins, beta-bungarotoxin and notexin, and the pla2 enzymes from naja naja atra and naja nigricollis snake venoms on the plasma membrane integrity of synaptosomes were examined. synaptosomes were isolated from rat brain cerebral cortex, corpus striatum and hippocampus. osmotic activity, lactate dehydrogenase leakage, and leakage of 2-deoxy-d-(1-3h)-glucose-6-phosphate were monitored (37 degrees c, 10-120 min) following incubation with 0.5, 5 and 50 nm c ... | 1990 | 2080518 |
| rapid activation of the non-toxic basic isoform of phospholipase a2 from naja mossambica mossambica (spitting cobra) by long-chain fatty acylation. | purified phospholipase a2 from naja naja (common indian cobra) venom, a basic non-toxic isoform and a toxic isoform from naja mossambica mossambica venom were treated with an equimolar amount of oleoyl imidazolide, a known activator of bee venom phospholipase a2. the ability of the first two enzymes to induce erythrocyte lysis was strongly activated while hydrolysis of dioctanoyl phosphatidyl choline was only weakly activated. the toxic enzyme showed little change in either assay. the susceptibl ... | 1990 | 2080519 |
| inhibition of phosphorylation of rat synaptosomal proteins by snake venom phospholipase a2 neurotoxins (beta-bungarotoxin, notexin) and enzymes (naja naja atra, naja nigricollis). | some snake venom neurotoxins, such as beta-bungarotoxin (beta-butx) and notexin, which inhibit the release of neurotransmitter at both peripheral and central presynaptic terminals possess phospholipase a2 activity. in contrast, most snake venom phospholipase a2 enzymes such as those isolated from naja naja atra and naja nigricollis are structurally homologous to these neutrotoxins but do not have any specific or potent presynaptic action although they have higher enzymatic activities than the ne ... | 1990 | 2089738 |
| orientation of cobra alpha-toxin on the nicotinic acetylcholine receptor. fluorescence studies. | four flourescein isothiocyanate (fitc) derivatives of naja naja siamemsis 3 neurotoxin (alpha-toxin), labeled at the epsilon-amino groups of lys-23, lys-35, lys-49, or lys-69, and a tetramethylrhodamine isothiocyanate (tritc) derivative, labeled at epsilon-amino group of lys-23, were prepared and used to analyze the orientation of cobra alpha-toxin on the nicotinic acetylcholine receptor (acchr) relative to both the plane of the membrane and the central ion channel. fluorescence-quenching studie ... | 1990 | 2110165 |
| inhibitory effect of edta.ca2+ on the hydrolysis of synaptosomal phospholipids by phospholipase a2 toxins and enzymes. | phospholipases a2 (pla2) are ca2(+)-dependent enzymes that are inhibited by edta; this inhibition would be expected to be reversed by restoring the ca2+ concentration. by examining the hydrolysis of synaptosomal phospholipids by pla2 enzymes, naja naja atra and naja nigricollis, and by toxins with pla2 activity, beta-bungarotoxin (beta-butx) and notexin, we demonstrated a novel inhibitory action of edta manifested in the presence of excess ca2+. we postulate the formation of an edta.ca2+ complex ... | 1990 | 2123106 |
| a guanine nucleotide-binding protein participates in ige receptor-mediated activation of endogenous and reconstituted phospholipase a2 in a permeabilized cell system. | activation of phospholipase a2 (pla2) by the aggregation of receptors for immunoglobulin e (ige) can be studied in streptolysin o-permeabilized rat basophilic leukemia cells. under these conditions, 40 microm guanosine 5'-o-(3-thio)triphosphate (gtp gamma s) stimulates pla2 activity 5-6-fold when free ca2+ concentrations are buffered at 10(-7)-10(-5) m. antigen-mediated cross-linking of receptors for ige synergizes with low concentrations of gtp gamma s (0.1 microm) to cause similar stimulation. ... | 1990 | 2136853 |
| binding and inhibition studies on lipocortins using phosphatidylcholine vesicles and phospholipase a2 from snake venom, pancreas, and a macrophage-like cell line. | studies are reported on the inhibition of phospholipase a2 (pla2) from porcine pancreas, cobra (naja naja) venom, and the p388d1 macrophage-like cell line by human recombinant lipocortin i and bovine lung calpactin i. membrane vesicles prepared from 1-stearoyl,2-arachidonoyl phosphatidylcholine (pc) and other pcs were utilized as substrate. binding studies using sucrose flotation gradients showed that both lipocortin i and calpactin i bind to these vesicles although less tightly than to vesicles ... | 1990 | 2138608 |
| selective inhibition of receptor-coupled phospholipase c-dependent processes in human platelets and polymorphonuclear neutrophils. | aggregation of human platelets induced by a variety of agonists was inhibited by 1-[6-[[17 beta-3-methoxyestra-1,3,5(10)-trien-17-yl] amino]hexyl]-1h-pyrrole-2,5-dionel (u-73122) (ic50 values 1-5 microm), but not by the close analog 1-[6-[[17 beta-3-methoxyestra- 1,3,5(10)-trien-17-yl]amino]hexyl]-2,5-pyrrolidine-dione (u-73343) in which pyrrolidinedione was substituted for pyrroledione. inhibition by u-73122 was not mediated by an increase in intracellular cyclic amp. in contrast, the productio ... | 1990 | 2147038 |
| lack of the blocking effect of cobrotoxin from naja naja atra venom on neuromuscular transmission in isolated nerve muscle preparations from poisonous and non-poisonous snakes. | neuromuscular transmission in the chinese cobra naja naja atra was not affected by its own toxin (cobrotoxin) at a concentration of as high as 100 microm, while in the frog a concentration of less than 0.1 microm cobrotoxin depressed the amplitude of the end-plate potential to less than 10% of its original value within 30 min or directly blocked the nerve-evoked muscle action potential. the lack of effect of cobrotoxin was also observed in the nerve-muscle preparations from a pit viper (agkistro ... | 1990 | 2175458 |
| [preparation of toxoid from taiwan cobra (naja naja atra) venom]. | potency of sixty antitoxic unit was reached after two immunizations in 2-week intervals of rabbits and horses with 10-25 mg taiwan cobra (naja naja atra) venom which was detoxified by 0.125% glutaraldehyde. now this procedure has become a routine antivenine-producing method by which snake bivalent neurotropic antivenine is produced. the stability test showed that taiwan cobra toxoid kept at 37 degrees c for 40 days, the antigenicity increased by 24% and toxicity decreased by 10% as compared to t ... | 1990 | 2176918 |
| phospholipase a2-induced pulmonary and hemodynamic responses in the guinea pig. effects of enzyme inhibitors and mediators antagonists. | the effect of phospholipase a2 (naja naja) pla2) on mean arterial blood pressure and intratracheal pressure was examined in anesthetized guinea pigs. intracheally administered pla2 (1 to 10 u) produced acute, dose-dependent increases in mean arterial blood pressure and intracheal pressure. however, intravenously administered pla2 (doses as large as 1,000 u) did not alter monitored variables. acute pla2-induced morphologic alterations were characterized by airway constriction, airway/alveolar cel ... | 1990 | 2240843 |
| hemolysis of erythrocytes and fluorescence polarization changes elicited by peptide toxins, aliphatic alcohols, related glycols and benzylidene derivatives. | hemolysis rates of human erythrocytes induced by c2 and c8-c14 straight chain 1-alkanols, 1,2-alkanediols and the corresponding benzylidene derivatives (benzaldehyde acetals) have been studied and compared with hemolysis rates obtained by three peptide toxins. the peak of activity occurs at c12 for the alkanols and glycols and at c10 for the benzylidene derivatives. the most active compound is 1-dodecanol, followed by 1,2-dodecanediol and the c10 benzylidene acetal, which show 50% hemolysis at 1 ... | 1990 | 2245210 |
| two-dimensional nmr studies and secondary structure of cobrotoxin in aqueous solution. | the 1h-nmr spectra of cobrotoxin, a neurotoxic protein isolated from formosan cobra naja naja atra, have been studied by two-dimensional nmr techniques. of 62 amino acid residues in cobrotoxin, the complete assignments of 58 residues have been made. the resonances from several of the remaining residues have been identified but not yet specifically assigned. the secondary structure of an antiparallel triple- and double-stranded beta-sheet has also been determined by observing the noe. | 1990 | 2249693 |
| purification and characterization of a chymotrypsin kunitz inhibitor type of polypeptide from the venom of cobra (naja naja naja). | a chymotrypsin kunitz inhibitor type of polypeptide has been isolated from the venom of naja naja naja by reverse phase hplc and cation exchange fplc. it is present in a considerably lower amount than that of the corresponding trypsin inhibitor. the primary structure, determined by sequence analysis of the whole molecule and its tryptic peptides, has 57 residues with an apparent molecular mass of 6.2 kda. the main contact site with the protease (p1) has a phe, showing the specificity of the inhi ... | 1990 | 2262001 |
| in vivo interactions between neurotoxin, cardiotoxin and phospholipases a2 isolated from malayan cobra (naja naja sputatrix) venom. | the in vivo interactions between alpha-neurotoxin, cardiotoxin and two phospholipases a2 (sputa-phospholipase a2-1 and 3) isolated from malayan cobra venom were assessed by examining the effects of simultaneous injection of sub-ld50 dose of one toxin on (i) i.v. ld50 s of the other toxins in mice; and (ii) mean survival times of mice injected with lethal doses of the other toxins. while ld50 measurements did not reveal any interaction between the toxins in vivo, survival time measurements sugges ... | 1990 | 2264068 |
| the effect of cholinergic manipulations on the analgesic response to cobrotoxin in mice. | intracerebroventricular (i.c.v.) injection of cobrotoxin (ct), a neurotoxin isolated from the venom of naja naja atra, produced an antinociceptive response in mice as measured by the tail-flick test. this effect of ct was blocked by systemic administration of atropine, but not by methylatropine or naloxone. depletion of central acetylcholine (ach) by hemicholinium-3 (hc-3) blocked the antinociceptive action of cobrotoxin. these results suggest that central cholinergic neurons are important for t ... | 1990 | 2266778 |
| interfacial catalysis: the mechanism of phospholipase a2. | a chemical description of the action of phospholipase a2 (pla2) can now be inferred with confidence from three high-resolution x-ray crystal structures. the first is the structure of the pla2 from the venom of the chinese cobra (naja naja atra) in a complex with a phosphonate transition-state analogue. this enzyme is typical of a large, well-studied homologous family of pla2s. the second is a similar complex with the evolutionarily distant bee-venom pla2. the third structure is the uninhibited p ... | 1990 | 2274785 |
| crystal structure of cobra-venom phospholipase a2 in a complex with a transition-state analogue. | the crystal structure of a complex between a phosphonate transition-state analogue and the phospholipase a2 (pla2) from naja naja atra venom has been solved and refined to a resolution of 2.0 angstroms. the identical stereochemistry of the two complexes that comprise the crystal's asymmetric unit indicates both the manner in which the transition state is stabilized and how the hydrophobic fatty acyl chains of the substrate are accommodated by the enzyme during interfacial catalysis. the critical ... | 1990 | 2274787 |
| [comparison of two elapidae venoms: naja naja and naja nigricollis]. | in our study on the identification of snake venoms by electrofocusing technics, the protein profiles of naja naja naja, naja nigricollis pallida and naja nigricollis west africa were compared. the typical profile of venoms of elapidae was easily identified in this comparison. the two species could easily be differentiated, whereas the differences between the two sub-species were more difficult to evidence, since they are geographic variants of the same type. | 1990 | 2291604 |