Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| [modulation of the m-cholinergic reaction by the venom of the central asian cobra (naja naja oxiana)]. | the effect of the central asian cobra's (naja naja oxiana) poison upon cholinergic response of isolated small intestine was studied in the wistar rats. the effect involved a significant activation by 30-70 per cent of m-cholinergic response in the type of "noncompetitive" interaction. the modulating effect of the poison is supposed to occur due to changes in cytoplasmatic membrane. | 1988 | 3181518 |
| purification and characterization of a lethal protein with phospholipase a1 activity from the hornet (vespa basalis) venom. | the hornet, vespa basalis, is one of the most dangerous species of wasps found in taiwan. the insect is aggressive and its venom is highly toxic. by gel filtration on a fractogel tsk hw 50 column followed by cation-exchange chromatography on cm-trisacryl m, a lethal protein was purified from the venom. it has a molecular mass of about 32 kda and an i.v. ld50 value of 0.32 micrograms/g mouse. the toxin is capable of catalyzing the hydrolysis of emulsified phospholipids but not sphingomyelin. anal ... | 1988 | 3196744 |
| antigenic relationships and relative immunogenicities of venom proteins from six poisonous snakes of thailand. | venoms from naja naja siamensis, ophiophagus hannah, bungarus fasciatus, vipera russelli, calloselasma rhodostoma and trimeresurus albolabris have been studied by means of sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting. the immunoblots were stained with rabbit homologous and heterologous antibodies. in general, the higher the mol. wt the protein the higher the immunogenicity although two proteins with mol. wts of 23,000 and 25,000 from o. hannah venom are extraordin ... | 1988 | 3201490 |
| edema-inducing activity of phospholipase a2 purified from human synovial fluid and inhibition by aristolochic acid. | a neutral-active, ca2+-dependent phospholipase a2 (pla2) purified 11,000-fold from human synovial fluid (hsf) induced edema when injected into the mouse foot pad. the edema produced by hsf-pla2 was dose-dependent and was positively correlated with the dose-dependent in vitro expression of pla2 activity. maximum edema was achieved within 45 min after the injection and persisted for at least 6 h. aristolochic acid [8-methoxy-6-nitrophenanthro(3,4-d)-1,3-dioxole-5-carboxylic acid], a major chemical ... | 1988 | 3220517 |
| lipid-induced aggregation of phospholipase a2: sucrose density gradient ultracentrifugation and crosslinking studies. | the aggregation behavior of cobra venom (naja naja naja) phospholipase a2 in the presence of lipids and ca2+ was examined using ultracentrifugation and crosslinking techniques. velocity sedimentation experiments were performed in sucrose gradients. the sedimentation coefficients of the cobra phospholipase a2 and various controls, including bovine serum albumin (bsa), malate dehydrogenase, carbonic anhydrase and pancreatic phospholipase a2, were calculated both in the presence and absence of liga ... | 1988 | 3382690 |
| a novel cleavage product of human complement component c3 with structural and functional properties of cobra venom factor. | the generation of two cleavage products of human c3, termed c3o and c3p, by incubation with a c3-cleaving protease isolated from cobra venom (naja naja siamensis) is described. the venom protease removes the c3p fragment (mr approximately 33,000) from the c3dg region of the c3 alpha-chain. the major cleavage fragment c3o (mr approximately 140,000) contains the unaltered beta-chain of c3 and two alpha-chain-derived polypeptides of mr approximately 29,000 and mr approximately 38,000, respectively. ... | 1988 | 3045125 |
| phospholipase a2 activity associated with synovial fluid cells. | high activity of phospholipase a2 (pla2) has been detected in synovial fluids (sf) in inflammatory arthritides. since the source(s) of sf pla2 has not been identified, we tested pla2 content in sf cells obtained from 11 sf. cell sonicates were prepared at 5 x 10(6) cells/ml. in the supernatants of the sonicated sf cells (n = 11), pla2 activity ranged from 38-755 u/ml, mean 368 +/- 243 (sd) u/ml, compared to 5-64 u/ml, mean 31 +/- 15 (sd) u/ml in sonicates of normal peripheral blood pmn (n = 5) ( ... | 1988 | 3050083 |
| lipid-induced changes in the secondary structure of snake venom cardiotoxins. | the secondary structures of three snake venom cardiotoxins (from hemachatus hemachatus, naja naja atra, and naja naja naja), in aqueous solution and in a lipid-bound form, were investigated by fourier-transform infrared spectroscopy. the conformation-sensitive protein infrared bands in the amide i region were analyzed using deconvolution and band-fitting procedures. the spectra of the three cardiotoxins in aqueous buffer are very similar; they indicate a high content of both antiparallel beta-sh ... | 1988 | 3335526 |
| tryptophan residue essential for activity of naja naja atra phospholipase a2. | when naja naja atra phospholipase a2, which contains three tryptophan residues at the 18th, 19th, and 61st positions, was oxidized with n-bromosuccinimide at ph 4.0, its activity decreased in a convex manner with increase in the extent of oxidation of tryptophan residues. the curve shape showed that the tryptophan residue oxidized last is most responsible for the activity. the order of accessibilities of the three tryptophan residues, which was analyzed according to the method reported previousl ... | 1988 | 3360757 |
| role of the n-terminal region in phospholipases a2 from naja naja atra (taiwan cobra) and naja nigricollis (spitting cobra) venoms. | the n-terminal alpha-amino groups of two phospholipases a2 (pla2) from naja naja atra and naja nigricollis venoms were selectively modified with trinitrobenzene sulfonic acid, and the modified derivatives were separated by high performance liquid chromatography (hplc). trinitrophenylated (tnp) derivatives contained only one tnp group in the alpha-amino group of asn-1 and showed a marked decrease in enzymatic activity. pla2 enzymes were cleaved with cnbr, and the n-terminal octapeptide was separa ... | 1988 | 3188062 |
| oral toxicity of central asian cobra (naja naja oxiana eichwald) venom and its fractions to adult blowflies parasarcophaga ruficornis fabricius. | 1988 | 3248836 | |
| bites by the philippine cobra (naja naja philippinensis): prominent neurotoxicity with minimal local signs. | we studied 39 patients envenomed by the philippine cobra (naja naja philippinensis). neurotoxicity occurred in 38 cases and was the predominant clinical feature. respiratory paralysis developed in 19 patients, and was often rapid in onset--in 3 cases apnea occurred within 30 min of the bite. there were 2 deaths, both in patients who were moribund upon arrival at the hospital. three patients developed necrosis, and 14 individuals with systemic symptoms had no local swelling. both cardiotoxicity a ... | 1988 | 3177741 |
| higher order structure of chloroplastic 5s ribosomal rna from spinach. | the secondary and tertiary structure of chloroplastic 5s ribosomal rna from spinach was investigated by the use of several chemical and enzymatic structure probes. the four bases were monitored at one of their watson-crick base-pairing positions with dimethyl sulfate [at a(n1) and c(n3)] and with 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-toluenesulfonate [at g(n1) and u(n3)]. position n7 of purines was probed with diethyl pyrocarbonate (adenines) and with dimethyl sulfate (guanines) ... | 1988 | 3167011 |
| amino-acid sequences of four cytotoxins (cytotoxins i, ii, iii and iv) purified from the venom of the thailand cobra, naja naja siamensis. | four cytotoxins, designated as cytotoxins i, ii, iii and iv, were isolated from the venom of the thailand cobra (naja naja siamensis) by gel filtration on sephadex g-75 followed by cm-cellulose chromatography. the amino-acid sequences were determined by a combination of conventional methods. cytotoxins i, ii, iii and iv were each composed of 60 amino-acid residues and their molecular weights were calculated to be 6693, 6646, 6709 and 6739, respectively. the amino-acid sequences were compared wit ... | 1988 | 3365434 |
| a role for acetylcholine receptors in the fusion of chick myoblasts. | the role of acetylcholine receptors in the control of chick myoblast fusion in culture has been explored. spontaneous fusion of myoblasts was inhibited by the nicotinic acetylcholine receptor antagonists alpha-bungarotoxin, naja naja toxin and monoclonal antibody mcab 5.5. the muscarinic antagonists qnb and n-methyl scopolamine were without effect. atropine had no effect below 1 microm, where it blocks muscarinic receptors; at higher concentrations, when it blocks nicotinic receptors also, atrop ... | 1988 | 3372592 |
| tourniquet application after cobra bite: delay in the onset of neurotoxicity and the dangers of sudden release. | the effects of tourniquet application were prospectively studied in 36 hospitalized patients who developed neurotoxic symptoms after bites by the philippine cobra (naja naja philippinensis). tourniquets had been applied in 94% of cases and delayed the onset of symptoms. four patients were asymptomatic prior to the release of their tourniquet and in 11 patients symptoms worsened precipitously. most importantly, 4 patients developed complete respiratory paralysis requiring artificial ventilation o ... | 1988 | 3275141 |
| purification and characterization of four monofluorescein cobra alpha-toxin derivatives. | we labeled cobra-alpha-toxin (naja naja siamensis 3) with near stoichiometric quantities of fluorescein isothiocyanate. to reduce labeling of the hyperreactive n epsilon-lysine 23, the alpha-toxin was modified reversibly with citraconic anhydride before fluorescein labeling. the citraconic anhydride was later removed with strong acid, and four of the six possible monofluorescein alpha-toxin derivatives were isolated by isoelectric focusing on an immobilized ph gradient. thermolysin digestion and ... | 1988 | 3125169 |
| effect of phospholipids on fluorescence polarization and lifetimes of fluorescein-labeled phospholipase a2. | phospholipids and divalent metal ions induce changes in the fluorescence polarization of fluorescein-labeled phospholipase a2 from the indian cobra (hazlett, t.l. and dennis, e.a. (1985) biochemistry 24, 6152-6158) which may be indicative of enzyme aggregation. lifetimes and rotational correlation times of the conjugate in the presence of these and other ligands are now reported. the correlation times of monomeric phospholipase a2 were shorter than expected for a hydrated, 13,000 molecular weigh ... | 1988 | 3337833 |
| toxicity of central asian cobra (naja naja eichwald) venom and its components to the larvae of blowfly parasarcophaga ruficornis fabr. | 1988 | 3397115 | |
| a comparative study of cobra (naja) venom enzymes. | 1. the l-amino acid oxidase, hyaluronidase, alkaline phosphomonoesterase, protease, phosphodiesterase, acetylcholinesterase, phospholipase a and 5'-nucleotidase activities of 47 samples of venoms from all the six species of cobra (naja), including five subspecies of naja naja, were examined. 2. the results demonstrated interspecific differences in the venom contents of phospholipase a, acetylcholinesterase, hyaluronidase and phosphodiesterase. these differences in venom enzyme contents can be us ... | 1988 | 2854766 |
| amino acid sequences of cytotoxin-like basic proteins derived from cobra venoms. | amino acid sequences of cytotoxin-like basic proteins (clbps), purified from the venoms of formosan cobra (naja naja atra) and indian cobra (naja naja), were reinvestigated. the determined sequences differed from those reported previously by takechi et al. [(1985) biochem. int. 11, 795-802; (1987) biochem. int. 14, 145-152]. the sequence of clbps at residues 25-30 was found to be hydrophilic as compared with those of cytotoxins. the difference in the hydrophobicity of this region might be respon ... | 1989 | 2583280 |
| studies on the status of lysine residues in phospholipase a2 from naja naja atra (taiwan cobra) snake venom. | phospholipase a2 (pla2) from naja naja atra (taiwan cobra) snake venom was subjected to lysine modification with trinitrobenzene sulphonic acid (tnbs), and two major trinitrophenylated (tnp) derivatives, tnp-1 and tnp-2, were separated by h.p.l.c. tnp-1 contained only one tnp group on lys-6 and showed a marked decrease in enzymic activity, but still retained 45% of the lethal toxicity. both lys-6 and lys-65 were modified in tnp-2, and modification of lys-65 caused a further reduction of the leth ... | 1989 | 2511834 |
| step-wise thermal denaturation of cobrotoxin, a snake venom neurotoxin from naja naja atra: a proton nuclear magnetic resonance study. | temperature dependence of proton nuclear magnetic resonance spectra has been followed for cobrotoxin, a postsynaptic neurotoxin from naja naja atra venom. several aromatic amino-acid residues, including the functionally essential trp-29 located at the tip of the central loop of the molecule, have been found to undergo a thermal structural transition above the global thermal denaturation temperature. it is suggested that a local structure around these residues behaves somehow independently of the ... | 1989 | 2803517 |
| assessment of the role of tryptophan residues in phospholipase a2 by fluorescence quenching. | tryptophan (trp) fluorescence of two phospholipases a2 (pla2) from naja naja atra and naja nigricollis snake venoms was quenched by acrylamide and iodide. trp residues in n. naja atra pla2 were equally accessible to acrylamide and iodide. iodide quenching studies indicate that there are two classes of trp fluorophores in n. nigricollis cms-9. the accessible class consists of trp-18 and trp-19. removal of the n-terminal octapeptide caused a perturbation of the micro-environment of the trp residue ... | 1989 | 2489051 |
| [major complement inhibiting factors from the venom of the central asian cobra naja naja oxiana]. | the properties of two anticomplementic factors isolated by cm-sepharose chromatography from the basic non-adsorbed on deae-sepharose fraction of the central asian cobra naja naja oxiana venom, were studied. of these three factors (cfb-i, cfb-ii and cfb-iii) the latter had been characterized earlier. cfb-i was shown to be a protein with an n-terminal asp and a molecular mass of about 39 kda (data from gel chromatography); its content in the venom is 3.6 mg/g of dry venom. the protein inhibits mai ... | 1989 | 2627558 |
| phospholipase a2 from cobra (naja naja naja) venom. primary structure and subspecies variation. | the primary structure of phospholipase a2 of the major race of indian cobra has been determined. together with previous data on other subforms, it establishes subspecies variations at no less than 20 of the 119 positions in the protein. these variations are large, not only in number but in several cases also regarding properties of the residues involved. nevertheless, all structures are compatible with largely unaltered enzyme properties. | 1989 | 2626425 |
| the anticoagulant activity of malayan cobra (naja naja sputatrix) venom and venom phospholipase a2 enzymes. | malayan cobra (naja naja sputatrix) venom was found to exhibit an in vitro anticoagulant activity that was much stronger than most common cobra (genus naja) venoms. the most potent anticoagulants of the venom are two lethal phospholipase a2 enzymes with pi's of 6.15 and 6.20, respectively. the anticoagulant activity of the venom is due to the synergistic effect of the venom phospholipase a2 enzymes and polypeptide anticoagulants. bromophenacylation of the two phospholipase a2 enzymes reduced the ... | 1989 | 2619749 |
| interaction of central asian cobra (naja naja oxiana eichwald) venom cytotoxins with phospholipase d. | effect of cytotoxins from the venom of naja naja oxiana eichwald on the hydrolytic function of phospholipase d has been further analysed. cytotoxins in the absence of ca2+ activated the enzyme, whereas in its presence they inhibited it. inhibition is shown to be related to the interaction of cytotoxins with the enzyme which blocks the absorption of the enzyme at the surface of the substrate phase. synergism in the action of cytotoxin and phospholipase d was not noticed. | 1989 | 2628264 |
| isolation and characterization of an acidic lethal phospholipase az from malayan cobra (naja naja sputatrix) venom. | an acidic, lethal phospholipase az was purified to electrophoretic homogeneity from the venom of the malayan cobra (naja naja sputatrix). the enzyme has an isoelectric point of 5.58, a molecular weight of 12000, and a medium lethal dose (ld50) of 0.86 micrograms/g in mice by intravenous injection. the enzyme also exhibited weak anticoagulant and edema-forming activities. the amino acid composition of the enzyme is similar to those of other cobra venom phospholipases az. | 1989 | 2764979 |
| induction of alveolar epithelial injury by phospholipase a2. | severe damage to the alveolar type i epithelial cell is a characteristic morphological feature of lung injury due to numerous cases. it is postulated that excess phospholipase a2 (pla2) activity might be responsible for these changes, as one of the naturally occurring products of this enzyme, lysophosphatidylcholine (lysopc) has been shown to cause selective injury to the type i pneumonocyte when it is instilled into the lower air spaces of the lung. to further investigate this potential mechani ... | 1989 | 2917929 |
| pharmacological study of phospholipase a2-induced histamine release from rat peritoneal mast cells. | the effect of some drugs on phospholipase a2 (pla2)-induced histamine release from rat peritoneal mast cells was investigated. 1. pla2 (naja naja) caused the release of histamine from rat peritoneal mast cells in a dose related fashion. 2. the release of histamine by pla2 was decreased by the removal of each of calcium and glucose from the reaction medium (tyrode's solution). 3. p-bromophenacyl bromide and mepacrine, pla2 inhibitors, inhibited the release of histamine caused by pla2. 4. cinnariz ... | 1989 | 2482349 |
| neutrophil-dependent, oxygen-radical mediated lung injury associated with acute pancreatitis. | cerulein-induced acute pancreatitis in rats is associated with a reversible lung injury that is characterized by alveolar capillary endothelial-cell injury, increased microvascular permeability, interstitial edema formation, and intraalveolar hemorrhage and fibrin deposition. the role of mediators in this injury was analyzed using gravimetric data, microvascular permeability indices, electron microscopy, and a quantitative morphometric analysis. neutrophil depletion induced by a specific antibod ... | 1989 | 2589887 |
| pulmonary responses to phospholipase a2 in the perfused guinea pig lung. | we examined the effect of phospholipase a2 (pla2; naja naja) challenge on pulmonary hemodynamics, airway constriction, and fluid filtration in isolated ringer-perfused guinea pig lungs. intratracheal pla2 (10-100 u) produced dose-dependent increases in pulmonary arterial pressure, intratracheal pressure, and lung weight, although intravenous pla2 administration had no effect on monitored variables. morphological features indicative of airway constriction and pulmonary edema were observed by ligh ... | 1989 | 2606858 |
| amino acid sequence of nerve growth factor purified from the venom of the formosan cobra naja naja atra. | nerve growth factor (ngf) was isolated from the venom of the formosan cobra (naja naja atra). the amino acid sequence was determined by a combination of conventional methods. the total number of amino acid residues was 116, giving a molecular mass of 13,057 da. the sequence was identical with that deduced from the nucleotide sequence of an ngf cdna from the venom gland of naja naja siamensis, reported by selby et al. [j. neurosci. res., 18, 293-298 (1987)]. | 1989 | 2619756 |
| effects of divalent cations on snake venom cardiotoxin-induced hemolysis and 3h-deoxyglucose-6-phosphate release from human red blood cells. | at a low concentration of naja naja kaouthia cardiotoxin (3 microm) ca2+, sr2+ and ba2+ (2 mm), had little to no effect on 3h-deoxyglucose-6-phosphate (3h-dglu-6-p) or hemoglobin release. at higher concentrations of n. n. kaouthia cardiotoxin (greater than or equal to 10 microm), ca2+ (2 mm), but not sr2+ or ba2+, significantly enhanced 3h-dglu-6-p and hemoglobin release. mn2+ (2 mm) almost completely inhibited 3h-dglu-6-p release and hemolysis at both the 3 microm and 10 microm concentrations o ... | 1989 | 2629171 |
| continuous spectrophotometric assay of phospholipase a2 activity hydrolyzing plasmalogens using coupling enzymes. | we developed a continuous spectrophotometric assay of the phospholipase a2 activity specific for choline plasmalogen using rat liver lysoplasmalogenase and horse liver alcohol dehydrogenase as coupling enzymes and naja naja venom phospholipase a2 as a source of the phospholipase a2 activity. in these coupling reactions, choline lysoplasmalogen is hydrolyzed by lysoplasmalogenase to glycerophosphocholine and free aldehyde. the free aldehyde is quantitatively converted to alcohol by alcohol dehydr ... | 1989 | 2712287 |
| do chemical modifications dissociate between the enzymatic and pharmacological activities of beta bungarotoxin and notexin? | we have measured enzymatic, hemolytic and anticoagulant activities, lethal potencies and effects on contractions of the phrenic nerve-diaphragm preparation, by chemically modified derivatives of beta bungarotoxin (beta butx) and notexin, two presynaptically acting toxins which have pla2 activity. the following chemical modifications of beta butx were tested: alkylation and methylation of histidine 48, alkylation of tryptophan 19, sulfonylation of tyrosine 68, oxidation of methionines 6 and 8, se ... | 1989 | 2718187 |
| factors influencing the hemolysis of human erythrocytes by cardiotoxins from naja naja kaouthia and naja naja atra venoms and a phospholipase a2 with cardiotoxin-like activities from bungarus fasciatus venom. | the effects of red blood cell age and incubation conditions (temperature, divalent cation type and concentration, ph and glucose) on hemolysis induced by cardiotoxin fractions from naja naja atra and naja naja kaouthia venoms, a phospholipase a2 with cardiotoxin-like activities from bungarus fasciatus venom and bee venom phospholipase a2 were examined. hemolysis by the snake venom toxins was dependent on red blood cell age (aged more susceptible than fresh) and the temperature of incubation (37 ... | 1989 | 2718193 |
| roles of mast cells and pmn leukocytes in cardiotoxin-induced rat paw edema. | cardiotoxin, isolated from the venom of naja naja atra, was found to cause rat hind-paw edema in a dose-dependent manner. this edematous response was significantly suppressed by pretreatment with diphenhydramine, methysergide or compound 48/80, which reduced the tissue histamine content. polymorphonuclear (pmn) leukocyte infiltration appeared within 1 h and had accumulated markedly in the rat paw 3-6 h after subplantar injection of cardiotoxin. methotrexate pretreatment significantly reduced not ... | 1989 | 2721549 |
| hemolytic activity of thionin from pyrularia pubera nuts and snake venom toxins of naja naja species: pyrularia thionin and snake venom cardiotoxin compete for the same membrane site. | pyrularia thionin (p. thionin) is a strongly basic peptide of 47 amino acids which is hemolytic, cytotoxic and neurotoxic. it shows the greatest hemolytic activity toward human erythrocytes. rabbit, guinea pig and pig erythrocytes show decreasing activity in that order, and little or no activity is shown with sheep, horse, cow or mouse erythrocytes. crotalus venoms are inactive, but the venoms from naja naja atra, naja naja ceylonicus and naja naja melanoleuca and, more specifically, cardiotoxin ... | 1989 | 2749751 |
| a prostaglandin oligomeric derivative inhibits activities of phospholipase and protease: a possible mechanism of membrane protection during ischemia. | a prostaglandin oligomeric derivative was synthesized by alkaline treatment of prostaglandin e1. this compound protected the perfused rat heart from global ischemia. this compound was found to inhibit several lipolytic and proteolytic enzymes in vitro. when phospholipase a2 from naja naja venom was used as an enzyme and phosphatidylcholine was used as a substrate, 50 per cent inhibition was achieved at 50 microm of the prostaglandin derivative. when trypsin and casein were used as enzyme and sub ... | 1989 | 2752536 |
| [a factor from the venom of the central asiatic cobra naja naja oxiana, which inactivates component c4 of human complement]. | an acid glycoprotein (mol. m. 60 kda) containing 6 sialic acid residues and n-terminal thr was isolated from the venom of the central asian cobra naja naja oxiana. the protein has an anticomplementary activity selectively inactivating of the c4 component of the human complement. this factor (cfa-ib) binds c4 with ki = 0.27 +/- 0.13 microm and then irreversible inactivates it with a rate constant k = 0.75 +/- 0.25 min-1. membrane bound c4b restores its ability of cfa-ib binding. this binding hind ... | 1989 | 2770721 |
| immunological relationships of phospholipase a2 neurotoxins from snake venoms. | polyclonal rabbit antisera were raised against ten snake phospholipase a2 neurotoxins and one snake phospholipase a2 cytotoxin. immunological cross-reactivities between these toxins, two other snake phospholipase a2 enzymes and pancreatic phospholipase a2 were studied using elisa technology. all snake phospholipase a2 neurotoxins fell into two main antigenic classes. one antigenic class was composed of all the elapid toxins tested (textilotoxin, taipoxin, notexin, pseudexin and beta-bungarotoxin ... | 1989 | 2799839 |
| sequence characterization of venom toxins from thailand cobra. | several toxins with distinct pharmacological properties were isolated from the venom of thailand cobra (naja naja siamensis) by cation-exchange chromatography. two neurotoxins and one basic toxin with cardiotoxic activity were further purified and sequenced. the neurotoxins characterized were closely similar to the previously reported long- and short-chain neutrotoxins. the complete sequences of one minor neurotoxin and one cardiotoxin analogue were determined with the automatic protein sequence ... | 1989 | 2807733 |
| the role of phospholipase in host cell penetration by toxoplasma gondii. | phospholipase a2 (pla2) plays an important pathogenic role in infections caused by several microorganisms and has been implicated in host cell invasion. the mechanism of host cell penetration by the intracellular protozoan toxoplasma gondii involves several steps; we have investigated the role of pla2 in cellular invasion by the tachyzoite stage of this parasite. we assayed t. gondii invasion of human fibroblast monolayers by measurement of the selective incorporation of 3h-uracil into growing i ... | 1989 | 2919724 |
| role of ca2+ in the substrate binding and catalytic functions of snake venom phospholipases a2. | phospholipases a2 are classified into two groups, i and ii, according to differences in the polypeptide-chain length and the intramolecular-disulfide bondings. the effects of ca2+ on the kinetic parameters for the hydrolysis of monodispersed and micellar phosphatidylcholines, catalyzed by a cobra (naja naja atra) enzyme (group i) and by mamushi (agkistrodon halys blomhoffii) and habu (trimeresurus flavoviridis) enzymes (group ii), were studied by the ph-statassay method at 25 degrees c, ph 8.0-8 ... | 1989 | 2606904 |
| identification of a locality in snake venom alpha-neurotoxins with a significant compositional similarity to marine snail alpha-conotoxins: implications for evolution and structure/activity. | alpha-neurotoxins from elapid snake venoms and alpha-conotoxins from marine snails bind specifically and with high affinity to nicotinic cholinoceptors. although both types of toxin are polypeptides, there is more than a fourfold difference in size between the two and no clear sequence homology is evident. a systematic computer search of the three-dimensional structure of erabutoxin b (an alpha-neurotoxin from the false sea snake laticauda semifasciata) was performed to identify the locality tha ... | 1989 | 2514275 |
| [complement-inhibiting acidic factors from the venom of central asian cobra naja naja oxiana]. | two anticomplementic factors isolated from the venom of the central asian cobra naja naja oxiana by chromatography on deae-sepharose cl-6b and subsequent gel filtration on sephacryl s-200 were studied. of these, five factors (cfa-ia, cfa-ib, cfa-ic, cfa-iia and cfa-iib), cfa-ib had been characterized earlier, while cfa-ia was assigned to a previously identified h-cof factor. it was shown that cfa-ic has a molecular mass of 3900 da; its content in the venom amounts to 2.6 mg/g of dry venom. this ... | 1989 | 2633805 |
| factors in snake venoms that increase capillary permeability. | capillary permeability increasing (cpi) activity is a phenomenon of the microvasculature caused by many agents such as snake venoms, histamine, 5-hydroxytryptamine (5-ht), prostaglandins and leukotrienes. since no systematic study has been done to determine what components of snake venom cause cpi activity, a cpi factor from naja naja atra (taiwan cobra) venom was isolated using intravenous injections of evan's blue dye as the indicator of increased permeability and the factor's properties were ... | 1989 | 2576052 |
| 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 |
| 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 |
| azidophenantridinium compounds as photoaffinity labels of cholinergic proteins. | the synthesis of diazidopropidium and diazidoethidium is described. the applicability of these compounds as photoaffinity labels for cholinergic proteins has been investigated: diazidopropidium inhibits neuromuscular transmission. this inhibition is reversible if the compound is applied in the dark but becomes irreversible after irradiation with white light. inhibition is accompanied by a disappearance of miniature endplate potentials. electrophysiological analysis of this effect indicates that ... | 1990 | 208646 |
| 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 |
| 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 |
| 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 |
| 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 |
| [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 |
| proteinaceous inhibitors of phospholipase a2 purified from inflammatory sites in rats. | we have purified two phospholipase a2 inhibitory proteins (37 and 33 kda) from peritoneal fluid of dexamethasone-treated rats. the extracellular phospholipase a2 found in inflammatory sites differed from the exocrine phospholipase a2 in susceptibility to these endogenous inhibitors; both proteins inhibited the activity of the extracellular phospholipase a2 purified from sites of inflammation but did not affect appreciably the activity of either porcine pancreatic or naja naja venom phospholipase ... | 1990 | 2320562 |
| the active site and partial sequence of cobra venom acetylcholinesterase. | 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 f ... | 1990 | 2340076 |
| identification of a crotoxin-binding protein in membranes from guinea pig brain by photoaffinity labeling. | crotoxin is a neurotoxic phospholipase a2 capable of blocking synaptic transmission by inhibiting the release of neurotransmitters. the photoaffinity labeling technique was used to identify the neural membrane molecules involved in the binding of crotoxin. a photoactivatable, radioactive derivative of crotoxin was synthesized by reacting crotoxin with n-hydroxysuccinimidyl-4-azidobenzoate and with na[125i]. photoirradiation of synaptosomes from guinea pig brains in the presence of the crotoxin d ... | 1990 | 2341382 |
| leukotriene and prostaglandin production in rat brain synaptosomes treated with phospholipase a2 neurotoxins and enzymes. | beta-bungarotoxin (beta-butx) and notexin cause an irreversible blockade of neurotransmitter release through specific and potent effects at the presynaptic nerve terminal, however, the mechanism of action is uncertain. we examined the effects of beta-butx and notexin on lt and pg production in rat cerebrocortical synaptosomes in order to determine if eicosanoid production might mediate or regulate the pharmacological actions of these phospholipase a2 (pla2) neurotoxins. the effects of the pla2 e ... | 1990 | 2343144 |
| [the effect of calmodulin and chlorpromazine on the activity of phospholipases a2 from various sources]. | the effects of calmodulin and chlorpromazine on purified phospholipase a2 preparations from snake venoms: cobra (naja naja oxiana), echis (ehis multisquamatus) and agkistrodon halys halys, as well as on phospholipases a2 from rat liver mitochondria and human platelets were studied. it was shown that within the concentration range of 1-5 microm calmodulin stimulates the phospholipase activity. chlorpromazine inhibits the activity of these enzymes, the degree of inhibition being different for vari ... | 1990 | 2344456 |
| selective cytolysis by a protein toxin as a consequence of direct interaction with the lymphocyte plasma membrane. | two lines of evidence support the concept that cardiotoxin from naja naja siamensis interacts directly with the plasma membrane to produce selective cytolysis of lymphocytes. toxin adsorbed to the wells of microtiter plates retained the ability to lyse murine t-lymphocytes, but lost the ability to destroy natural killer cells, whereas soluble toxin obliterated both cell types. second, toxin covalently coupled to 100-microns-diameter agarose beads, such that endocytosis would be precluded, effect ... | 1990 | 2363180 |
| purification of plasmalogens using rhizopus delemar lipase and naja naja naja phospholipase a2. | bovine heart chogpl (choline glycerophospholipid) and bovine brain etngpl (ethanolamine glycerophospholipid) contain diacyl, alkenylacyl and alkylacyl analogs. purification of plasmalogens was achieved using r. delemar lipase and n. naja naja phospholipase a2 digestion. the r. delemar lipase hydrolyzes the acyl bond at the 1-position of 1,2-diacyl glycerophospholipids. the n. naja naja phospholipase a2 has greater activity with diacyl and alkylacyl than with alkenylacyl glycerophospholipids. the ... | 1990 | 2366631 |
| kinetic and inhibition studies of phospholipase a2 with short-chain substrates and inhibitors. | the action of the phospholipases a2 (pla2s) from naja naja naja, naja naja atra, and crotalus atrox venoms as well as the enzyme from porcine pancreas on a number of short-chain, water-soluble substrates was studied. the inhibition of these enzymes by short-chain phosphonate- and thiophosphonate-containing phospholipid analogues was also examined. the kinetic patterns observed for the action of the venom pla2s on substrates containing phosphocholine head groups all deviated from a classical mich ... | 1990 | 2383571 |
| interactions in red blood cells between fatty acids and either snake venom cardiotoxin or halothane. | phospholipase a2 (pla2) activity enhances snake venom cardiotoxin (ctx)-induced and general anesthetic (halothane)-induced hemolysis of red blood cells. in the case of halothane-induced hemolysis, this effect appears to be related primarily to free fatty acids. in the present study, the interaction between ctxs and halothane and the effects of different free fatty acids on cardiotoxin and halothane-induced hemolysis were examined. the hemolytic actions of halothane and a ctx from naja naja kaout ... | 1990 | 2402762 |
| 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 |
| 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 |
| crystallization and preliminary x-ray diffraction study of neurotoxin-i from naja naja oxiana venom. | crystals of the neurotoxin-i (ntx-i) from the venom of the middle asian cobra naja naja oxiana have been grown by vapour diffusion and dialysis methods. the crystals belong to space group p2(1)2(1)2 with dimension of a = 25.19 a, b = 75.59 a, c = 36.09 a and diffract to 1.9 a resolution. the asymmetric unit contains one molecule (vm = 2.2 a/da). using the molecule of alpha-cobratoxin (ctx) as a starting model for ntx-i structure determination coordinates of c alpha atoms of the ntx-i molecule we ... | 1990 | 2387409 |
| 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 |
| characterization of a cytotoxin-like basic protein from the cobra (naja naja naja) venom. | a cytotoxin-like basic protein has been isolated from the venom of the nominate race of cobra (naja naja naja from pakistan) by a single step of high-performance liquid chromatography. the primary structure was determined and consists of 62 amino acid residues in a single polypeptide chain. it is highly similar to that of the cytotoxin-like basic proteins isolated from other naja species, but differs in two of the ss-loop structures from that of cytotoxins. | 1990 | 2311757 |
| the interaction of phospholipase a2 with phospholipid analogues and inhibitors. | a series of structurally modified phospholipids have been used to delineate the structural features involved in the interaction between cobra venom (naja naja naja) phospholipase a2 and its substrate. special emphasis has been placed on sn-2 amide analogues of the phospholipids. these studies have led to a very potent, reversible phospholipase a2 inhibitor. a six-step synthesis of this compound, 1-palmitylthio-2-palmitoylamino-1,2-dideoxy-sn-glycero-3- phosphorylethanolamine (thioether amide-pe) ... | 1990 | 2303420 |
| nonequivalence of alpha-bungarotoxin binding sites in the native nicotinic receptor molecule. | in the native, membrane-bound form of the nicotinic acetylcholine receptor (m-acchr) the two sites for the cholinergic antagonist alpha-bungarotoxin (alpha-bgt) have different binding properties. one site has high affinity, and the m-acchr/alpha-bgt complexes thus formed dissociate very slowly, similar to the complexes formed with detergent-solubilized acchr (s-acchr). the second site has much lower affinity (kd approximately 59 +/- 35 nm) and forms quickly reversible complexes. the nondenaturin ... | 1990 | 2340276 |
| amino acid sequence and circular dichroism of indian cobra (naja naja naja) venom acidic phospholipase a2. | the full amino acid sequence of the acidic phospholipase a2 from indian cobra (naja naja naja) venom was determined and its tertiary structure examined by circular dichroism (cd). the sequence was aligned with other sequences of secreted phospholipase a2 from snakes of the genus naja, using the progressive alignment method of feng and doolittle (j. mol. evol. (1987) 25, 351-360). the primary sequence of naja naja naja phospholipases a2 shows up to 85% identity with the other acidic naja phosphol ... | 1990 | 2294972 |
| pattern of acetylcholinesterase activity in the hypothalamus of the cobra, naja naja. | application of acetylcholinesterase (ache) method to the hypothalamus of the cobra naja naja revealed a clearly discernible pattern of activity in the nuclear groups. the magnocellular neurons distributed in various subdivisions showed strong reaction. among the parvocellular groups, intense enzyme activity was observed in the cells of nucleus subfornicalis, nucleus hypothalamicus medialis, dorsal and ventral subdivisions of the nucleus hypothalamicus lateralis and the nucleus mamillaris. the pa ... | 1990 | 2358653 |
| effect of modification of tyrosine residues in cytotoxin-1 from indian cobra venom. (naja naja naja). | the role of tyrosine residues in the biological activity of cytotoxin-1 was evaluated using n-bromo succinimide. n-bromo succinimide effected the oxidation of tyrosine residues in cytotoxin-1 with an increase in absorption at 260 nm. n-chloro succinimide was ineffective in the oxidation of tyrosine residues in the toxin. oxidation of a single tyrosine residue (at 3.50 equivalents of n-bromo succinimide/mole of the toxin) resulted in complete loss of lethal activity of the toxin. the lytic activi ... | 1990 | 2350359 |
| ablation of natural killer cell function by soluble cardiotoxin. | a one-hour preincubation of nonadherent murine spleen cells with a soluble membrane-active cardiotoxin purified from the venom of the thailand cobra naja naja siamensis results in the destruction of natural killer (nk) cell activity against yac-1 target cells in a dose-dependent manner. prior in vivo induction of interferon production by polyinosinic/polycytidylic acid does not avert the cardiotoxin inhibition of nk function. loss of complement-mediated lysis of cells capable of binding an nk-1. ... | 1990 | 2329017 |
| [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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |