Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| functional properties of human factor va lacking the asp683-arg709 domain of the heavy chain. | a protease purified from the venom of the elapid snake naja naja oxiana converts human blood coagulation factor va into a molecule (factor vano) with greatly reduced cofactor activity. polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed that the venom protease cleaved a small peptide from the heavy chain of factor va and reduced the apparent m(r) from 105,000 to 101,000. this peptide was isolated by high performance liquid chromatography on a reversed-phase colu ... | 1994 | 8051166 |
| a comparison of ovine and equine antivenoms. | commercial antivenoms produced in horses were compared with monospecific antivenoms raised in sheep against crotalus durissus terrificus, crotalus atrox, crotalus adamanteus, micrurus fulvius fulvius, naja naja, naja kaouthia, echis ocellatus, vipera lebetina deserti, vipera berus berus and vipera ammodytes ammodytes venom. antibodies raised by immunizing sheep with c. d. terrificus venom were more effective than their equine counterparts in preventing lethal toxicity in mice (ed50), in inhibiti ... | 1994 | 8052997 |
| comparison of refolding patterns of erabutoxin b and cardiotoxin 3.10.2 from snake venom. | the refolding patterns of erabutoxin b (a neurotoxin) and cardiotoxin 3.10.2 (from naja naja siamensis venom) have been studied by reducing both the proteins by treatment with reduced dithiothreitol followed by renaturation by treatment with oxidised dithiothreitol. isoelectric focusing of the samples trapped at varying time intervals during renaturation of the proteins reveals formation of intermediates in the folding pathway with cardiotoxin 3.10.2. having fewer intermediates than erabutoxin b ... | 1994 | 8076968 |
| a comparative study of three vehicles on antibody responses against elapid snake neurotoxin immunogens. | a study was undertaken to compare the effects of three vehicles (incomplete freund's adjuvant, ifa; bentonite and squalene/arlacel a) on the antibody responses to various elapid neurotoxin immunogens. three neurotoxin immunogens were prepared using purified principal postsynaptic neurotoxin(s) of naja naja siamensis (nns), ophiophagus hannah (oh) and bungarus fasciatus (bf). glutaraldehyde (ga) or a carbodiimide (ecdi) was used as a coupling agent while diphtheria toxoid (dt) was used as a prote ... | 1994 | 8079368 |
| groups i, ii and iii extracellular phospholipases a2: selective inhibition of group ii enzymes by indomethacin but not other nsaids. | the three types (groups i, ii and iii) of stable extracellular 14 kda phospholipase a2 enzymes differ in their primary amino acid sequences and their properties. it may thus be possible to design low-molecular weight inhibitors targeted to the secretory form of mammalian pla2. this enzyme has been implicated in inflammatory disorders. we have studied the inhibition of four distinct pla2 enzymes by a range of nsaids, using 3h-oleate release from prelabelled membranes of e. coli for assay. the enz ... | 1994 | 8079814 |
| effects of systemic complement activation on renal circulation of rats. | in a variety of immunopathological diseases activation of the complement cascade occurs either systemically or localized in the kidney. to elucidate the functional impact of complement activation upon the renal microcirculation, we administered cobra venom factor of naja naja kaouthia (cvf) i.v. into thiobarbital anaesthetized female rats. cvf is a potent activator of the alternative pathway of complement by forming the c3-convertase cvf, bb which cannot be downregulated by the natural inhibitor ... | 1994 | 8088308 |
| cardiotoxin ii from taiwan cobra venom, naja naja atra. structure in solution and comparison among homologous cardiotoxins. | the three-dimensional structure in solution of cardiotoxin ii, a membrane toxin from the venom of taiwan cobra, naja naja atra, was determined using 1h nuclear magnetic resonance spectroscopy and molecular modeling based on the hybrid distance geometry/dynamic simulated annealing technique. a complete sequence-specific proton assignment was obtained, and the secondary structures of the protein were determined from information on nuclear overhauser effect connectivities, coupling constants, and h ... | 1994 | 8089116 |
| interactions of n-terminal fragments of groups i and ii phospholipases a2 with phospholipid bilayers and their surface recognition properties. | in order to elucidate the roles of the n-terminal segments of groups i and ii phospholipases a2 (pla2s) which have been known to have alpha-helical structure and have been assumed to be involved in the water/lipid interface recognition site, the peptides corresponding to the n-terminal moieties of group i pla2 (naja naja atra) and group ii pla2s (trimeresurus flavoviridis and crotalus atrox) were synthesized and their interactions with model membranes were studied. circular dichroism spectra sho ... | 1994 | 8117749 |
| both neurotoxin ii from venom of naja naja oxiana and its endogenous analogue induce apoptosis in tumor cells. | both neurotoxin ii (nt ii from venom of naja naja oxiana) and 20-30 kda proteins partially purified from pig brain (ntlm) cross-reacting with antibodies to nt ii were cytotoxic for l929 and k562 tumor cells at concentrations of 10(-6)-10(-8) m. modification of cys residues significantly reduced cytotoxicity of nt ii. both nt2 and ntlm induced apoptosis in l929 and k562 cells. | 1994 | 8119402 |
| inhibition of trimeresurus flavoviridis phospholipase a2 by lung surfactant protein a (sp-a). | a marked sequence homology has been noted between lung surfactant protein a (sp-a) and an inhibitor of phospholipase a2 (pla2) isolated from the serum of trimeresurus flavoviridis (habu snake). this study evaluated the effect of sp-a on pla2 activity from several sources. sp-a was isolated from bovine or rat lung surfactant by extraction with 1-butanol and octyl beta-d-glucopyranoside. the addition of sp-a produced a concentration-dependent inhibition of t. flavoviridis pla2 that indicated non-c ... | 1994 | 8130257 |
| structural determinants of the intrinsic fluorescence emission in notexin and phospholipase a2 enzymes. | fluorescence measurements of the homologous proteins, notexin and pla2 enzymes from naja naja atra, naja nigricollis, and hemachatus haemachatus venoms, showed that the wave-length of maximum emission and the quantum yield of their intrinsic fluorescence emission spectra were different. to verify the factors which affected their fluorescence characteristics, the dynamics of tryptophan residues in those homologous proteins were studied by quenching with acrylamide, iodide, and cesium. the degrees ... | 1993 | 8142000 |
| a sensitive fluorogenic enzyme linked immunosorbent assay for the detection of vipera russelli venom. | a highly sensitive fluorogenic enzyme-linked immunosorbent assay (felisa) has been adapted for the detection of vipera russelli venom. the assay sensitivity was observed to be 0.1 pg/ml (1 x 10(-13) g/ml). venoms from snakes of the vipera group exhibited a high degree of cross-reactivity when tested with the antibody raised against v. russelli venom. with the exception of venom from naja naja, all the tested venoms from unrelated families also showed cross-reactivity. this procedure is useful fo ... | 1993 | 8167946 |
| micellar bolaform and omega-carboxylate phosphatidylcholines as substrates for phospholipases. | a series of mixed-chain diacyl-pcs which contain an omega-cooh on the sn-2 chain [1-cx-2-cy-(cooh)-pc] and bolaform (1-cx-2,2'-cy-1'-cx-pc) phosphatidylcholines were synthesized and examined as substrates for phospholipase a2 (naja naja naja) and c (bacillus cereus). there is very little detectable phospholipase a2 activity toward pure micellar 1-acyl-2-acyl-(omega-cooh) species. in addition, when these same omega-cooh species are present at concentrations above their cmcs, they are potent inhib ... | 1994 | 8172875 |
| isolation and characterization of a phospholipase a2 inhibitor from the blood plasma of the thailand cobra naja naja kaouthia. | a phospholipase a2 (pla2) inhibitory protein was purified from the blood plasma of the thailand cobra naja naja kaouthia by sequential chromatography on sephadex g-200, deae affi-gel blue, and protein-pak g-butyl columns. the purified inhibitor was a glycoprotein with an apparent molecular mass of about 90 kda and contained 25- and 31-kda subunits with a molar ratio of 1:2. the 31-kda subunit contained a glycosidic chain and the molecular mass was reduced to 28 kda by n-glycosidase f treatment. ... | 1994 | 8179612 |
| two distinct types of cardiotoxin as revealed by the structure and activity relationship of their interaction with zwitterionic phospholipid dispersions. | cardiotoxins (ctxs) are a group of homologous proteins found in cobra snake venom and consist of 60-62 amino acid residues. although ctxs are known to consist of three extended beta-sheet loops similar to neurotoxins, the target and interaction of ctxs with membranes unlike those of neurotoxins are not well understood. herein, we report comparative studies of 10 ctxs purified from taiwan cobra (naja naja atra) and mozambique spitting cobra (naja mossambica mossambica) snake venoms with respect t ... | 1994 | 8182052 |
| effects of flavonoids on naja naja and human recombinant synovial phospholipases a2 and inflammatory responses in mice. | six flavonoid derivatives were tested for their influence on naja naja and human recombinant synovial phospholipase a2. they showed a selectivity for the last enzyme with ic50 = 14.3, 17.6, 12.2 and 28.2 microm for quercetagetin, kaempferol-3-o-galactoside, scutellarein and scutellarein-7-o-glucuronide, respectively, while reduced effects were observed for hispidulin and hibifolin. after topical application all the flavonoids inhibited 12-o-tetradecanoylphorbol-13-acetate-induced ear oedema in m ... | 1994 | 8190018 |
| sequence characterization of cardiotoxins from taiwan cobra: isolation of a new isoform. | cardiotoxins (or called cytotoxins) are a group of very basic polypeptides present in some snake venoms, which are especially abundant in formosan cobras. several cardiotoxins with distinct pharmacological and biochemical properties were isolated and purified from the taiwan cobra venom (naja naja atra) by employing sequentially preparative-scale cation-exchange chromatography on tsk cm-650 coupled with the improved separation of toxin components on reversed-phase hplc based on their hydrophobic ... | 1993 | 8193587 |
| acetylcholine receptor binding characteristics of snake and cone snail venom postsynaptic neurotoxins: further studies with a non-radioactive assay. | the binding of postsynaptic neurotoxins from snake and marine cone snail (conus sp.) venoms to nicotinic acetylcholine receptor (achr) was investigated with an elisa-based, non-radioactive assay. three snake postsynaptic toxins from the long-chain group (naja naja kaouthia cobratoxin, naja oxiana neurotoxin i, bungarus multicinctus alpha-bungarotoxin) and short-chain group (naja naja atra cobrotoxin, naja oxiana neurotoxin ii, and laticauda semifasciata erabutoxin b) were studied. both types of ... | 1993 | 8212028 |
| oedema formation and degranulation of mast cells by phospholipase a2 purified from porcine pancreas and snake venoms. | phospholipase a2 is ubiquitous in nature, with the highest concentrations occurring in pancreatic juice and in the venom of snakes. local oedema formation is a common feature of the effects caused by snakebite, and indicates an increase in vascular permeability that could be produced by lipid mediators such as lysophospholipids, eicosanoids or paf release by the enzymatic activity of pla2. desalted porcine pancreatic pla2 exhibited strong oedema-inducing activity in a similar form to pla2 venom ... | 1993 | 8212047 |
| [purification and anticancer activity of cytotoxin-14 from venom of naja naja atra]. | ion-chromatography of lyophilized cobra (naja naja atra) venom on sp-sephadex c-50 yielded 14 fractions, of which 7, 8, 9, and 10 possessed neurotoxic actions and 11, 12, 13, and 14 had cytotoxic activities. chromatography of fraction 14 on sp-sephadex c-25 gave cytotoxin-14. it was homogeneous on polyacrylamide gel electrophoresis with m = 7448 da. it was a typical cytotoxin without phospholipase a2 activity and had a selective cytotoxic action on human cancer cell lines. | 1993 | 8237412 |
| chemical modification of amino groups in cardiotoxin iii from taiwan cobra naja naja atra) venom. | cardiotoxin iii (ctx iii), a major cardiotoxin analogue isolated from the taiwan cobra (naja naja atra) venom was modified, either with trinitrobenzene sulfonate (tnbs) or 4-chloro-3,5-dinitrobenzoate (cdnb). under the conditions of limited reagent availability, three mono-tnp derivatives modified at lys-5, 12, or 44, and three mono-cdnp derivatives at lys-12, 23, or 44 were isolated, respectively. the biological activities of ctx iii were more or less affected after each of these reactive amino ... | 1993 | 8260941 |
| differential effects of mandevilla velutina compounds on paw oedema induced by phospholipase a2 and phospholipase c. | this study compares the effect of mandevilla velutina compounds with some anti-inflammatory drugs against phospholipase a2- and phospholipase c-induced rat hindpaw oedema. injection of phospholipase a2 (naja naja, 2.5-20 u/paw) and phospholipase c (clostridium perfringens, 0.03-0.05 u/paw) caused a dose-and-time-related increase in paw oedema. compounds mv 8608 (55 mumol/kg) and mv 8612 (32 mumol/kg, i.p.) inhibited phospholipase a2-induced paw oedema without interfering with phospholipase c-ind ... | 1993 | 8276072 |
| vasoactive intestinal peptide and helodermin inhibit phospholipase a2 activity in vitro. | we recently reported that the widely distributed neuropeptide vasoactive intestinal peptide (vip) reduces inflammatory lung injury due to a variety of agents and inhibits the associated generation of cyclo-oxygenase and lipoxygenase products. we therefore investigated whether vip may inhibit phospholipase a2 activity, thus reducing the release of arachidonic acid, the common precursor of all eicosanoids. vip dose-dependently inhibited pla2 of porcine pancreas and of naja naja venom, as assessed ... | 1993 | 8278623 |
| effects of different antagonists on depolarization of cultured chick myotubes by cobra venom cardiotoxins and pyrularia thionin from the plant pyrularia pubera. | cardiotoxins (3.12 and 3.12.1) purified from cobra venom (naja naja siamensis) are basic single-chain polypeptides of about 60 residues. although they depolarize nerve and muscle cells and have cytolytic effects, their mechanism of action is still unknown. pyrularia thionin (p-thionin) isolated from nuts of the parasitic plant pyrularia pubera is a strongly basic, single-chain polypeptide containing 47 residues. it is known to be haemolytic and cytotoxic, and to depolarize muscle cells, but its ... | 1993 | 8303717 |
| characteristics of the peptidase activity contained in taiwan cobra (naja naja atra) venom. | cobra venoms (naja species) contain a little-understood peptidase activity which shows specificity towards small peptides containing glycine and non-polar aromatic/aliphatic residues. we have examined the ability of whole cobra venom to degrade several types of peptide with emphasis on the action of taiwan cobra (naja naja atra) venom on l-alanylglycylglycine and glycylglycyl-l-phenylalanine. these are competing substrates, and it proved possible to generate inhibitors of the degradation of glyc ... | 1993 | 8303723 |
| interaction of protein ligands with receptor fragments. on the residues of curaremimetic toxins that recognize fragments 128-142 and 185-199 of the alpha-subunit of the nicotinic acetylcholine receptor. | using a solid-phase assay, we found that 3h-labeled alpha cobtx from naja naja siamensis, a long-chain curaremimetic toxin, and 3h-labelled toxin alpha from naja nigricollis, a short-chain toxin both bind specifically but with substantially different affinities (kd = 4 x 10(-7) m and 50 x 10(-6) m) to fragment 185-199 (t alpha 185-199) of the alpha-subunit of the acetylcholine receptor (acchor) from torpedo marmorata. then we show that monoderivatizations of residues common to both long-chain an ... | 1994 | 8307203 |
| cardiotoxin iii from the taiwan cobra (naja naja atra). determination of structure in solution and comparison with short neurotoxins. | the structure in solution of cardiotoxin iii, a membrane toxin purified from the venom of the taiwan cobra, naja naja atra, is reported. sequence-specific assignment of 1h-nmr lines was completed and the nmr data show the presence of a triple and a double-stranded antiparallel beta-sheet. many noe cross peaks identified in noesy spectra were applied as distance constraints based on a hybrid distance geometry/dynamical simulated annealing technique; 20 structures were found within a single family ... | 1994 | 8308891 |
| probing the functional sites in naja naja atra (taiwan cobra) cardiotoxin iii with monoclonal antibody. | one monoclonal antibody (mab) against naja naja atra cardiotoxin iii was prepared by using the hybridoma technique. the cytotoxic activity of cardiotoxin iii which inhibited human lymphocyte proliferation was effectively neutralized by the mab at a molar ratio of antibody to toxin of 1:2. on the contrary, the mab did not exert a significant inhibition on the hemolytic activity of cardiotoxin iii. these results suggest that the functional site responsible for the cytotoxicity might be different f ... | 1993 | 8330009 |
| cardiotoxin 1 from cobra (naja naja atra) venom causes necrosis of skeletal muscle in vivo. | cardiotoxin 1 from cobra (naja naja atra) venom was tested for its ability to cause necrosis of skeletal muscle cells after i.m. injection into mice. light and electron microscopic examination of tissue indicated that the toxin caused necrosis of skeletal muscle as early as 30 min after injection. the plasma membranes of affected cells were ruptured in the area of delta lesions, and the myofibrils were condensed into dense clumps alternating with clear areas containing elements of the sarcotubul ... | 1993 | 8342169 |
| purification, characterization and binding interactions of the chinese-cobra (naja naja atra) serum antitoxic protein csap. | the characterization of the single-chain protein in chinese-cobra (naja naja atra) blood serum, which yields strong specific protection against the venom of the same snake, is reported. the protein, csap (cobra serum antitoxic protein), was purified to electrophoretic homogeneity. over the ph range 5-9 it formed stable complexes with the neuro- and the cardio-toxin of the snake. the molecular size of the csap was estimated to be 70.3 +/- 0.3 kda. tryptic hydrolysis of csap yielded several peptid ... | 1993 | 8343135 |
| solution structure of cardiotoxin v from naja naja atra. | cardiotoxins are small proteins that are found in the venoms of snakes from the elapidae family. these toxins are known to bind to and disrupt the organization, integrity, and function of the cell membrane. most of the well-studied cardiotoxins cause depolarization of membrane potentials and/or lysis of red cells. in contrast, ctx v from naja naja atra displays poor hemolytic activity but is proficient at inducing aggregation and fusion of sphingomyelin vesicles [chien et al. (1991) j. biol. che ... | 1993 | 8347605 |
| influence of chemistry in immobilization of cobra venom phospholipase a2: implications as to mechanism. | phospholipase a2 from naja naja kaouthia venom was covalently coupled onto agarose beads using two different chemistries. the effect of micellar competitive inhibitors in the coupling media was evaluated. enzyme bound to n-hydroxysuccinimide-activated agarose, which is reactive primarily toward epsilon-amino groups, had 20% activity retention against micellar diheptanoylphosphatidylcholine (dic7-pc). enzyme bound through carboxylic groups, using a modification of the carbodiimide method, had 50% ... | 1993 | 8347610 |
| studies on the cobra neurotoxin inhibiting activity in an extract of curcuma sp. (zingiberaceae) rhizome. | a study was carried on the mode of action and some properties of a cobra neurotoxin inhibitor found in the extract of curcuma sp. (zingiberaceae). when the principal postsynaptic neurotoxin (stx) of the thai cobra (naja naja siamensis) was mixed with an aqueous extract of curcuma sp. rhizome, the stx was inactivated as tested in mice or in vitro using a rat hemidiaphragm preparation. the 'neurotoxin inhibitor' ('ntxi') was found only in the water insoluble fraction of the rhizome extract. using ... | 1993 | 8362293 |
| a continuous fluorescence displacement assay for phospholipase a2 using albumin and medium chain phospholipid substrates. | a continuous fluorescence assay for phospholipase a2 is described which involves the displacement of the highly fluorescent fatty-acid probe 11-(dansylamino) undecanoic acid from albumin by decanoic acid released as a result of phospholipase a2-catalyzed hydrolysis of didecanoyl-phosphatidylcholine. using the phospholipase a2 from naja naja, this assay will detect activity from 1 ng of pure enzyme and a linear response in terms of fluorescence change with time is observed up to about 50 ng of en ... | 1993 | 8368517 |
| effect of polar head groups on the interactions of phospholipase a2 with phosphonate transition-state analogues. | several new phosphonate-containing phospholipid analogues were synthesized as inhibitors of cobra venom (naja naja naja) phospholipase a2. these phospholipid analogues contained a novel thioether at the sn-1 position, a tetrahedral phosphonate moiety in place of the scissile ester bond at the sn-2 position, and several different polar head groups, including phosphocholine, phospho(n,n-dimethylethanolamine), phospho(n-methylethanolamine), and phosphoethanolamine. the affinities of these analogues ... | 1993 | 8399145 |
| identification of functional involvement of tryptophan residues in phospholipase a2 from naja naja atra (taiwan cobra) snake venom. | phospholipase a2 (pla2) from naja naja atra snake venom was subjected to trp modification with 2-nitrophenylsulfenyl chloride (nps-cl), and six derivatives were separated by hplc. the results of amino-acid analysis and sequence determination revealed that trp-18, trp-19 and trp-61 were modified by nps-cl. the order of accessibilities of the three trp residues for nps-cl was trp-18 > trp-19 > trp-61. sulfenylation of trp-18 caused a 92% drop in enzymatic activity. modification of trp-19 and trp-6 ... | 1993 | 8399382 |
| the role of phospholipase a2 in interleukin-1 alpha-mediated inhibition of mineralization of the osteoid formed by fetal rat calvaria cells in vitro. | interleukin-1 (il-1) may be an important mediator of bone remodeling, since it is a potent stimulator of bone resorption and has biphasic effects on bone formation. continuous exposure of fetal rat calvaria (rc) cells to il-1 alpha or il-1 beta results in a dose-dependent inhibition of both bone nodule formation and mineralization of the organic matrix. in this study, the effects of recombinant human il-1 alpha on the mineralization process were examined by the addition of il-1 alpha late in the ... | 1993 | 8418103 |
| crystal structure of phospholipase a2 from indian cobra reveals a trimeric association. | phospholipase a2 (pla2) from indian cobra venom (naja naja naja) was crystallized from ethanol in space group p4(3)2(1)2 in the presence of ca2+. the x-ray crystal structure was determined to 2.3-a resolution by molecular replacement techniques using a theoretical model constructed from homologous segments of the bovine pancreatic, porcine pancreatic, and rattlesnake venom crystal structures. the structure was refined to an r value of 0.174 for 17,542 reflections between 6.0- and 2.3-a resolutio ... | 1993 | 8419939 |
| species difference in modulation of calcium release by naja naja kaouthia snake venom cardiotoxin in terminal cisternae from human and equine skeletal muscle. | the modulation of ca2+ release by a cardiotoxin (ctx) from naja naja kaouthia snake venom was examined in terminal cisternae-containing fractions from equine and human skeletal muscle. pretreatment with ctx (10 microm) decreased by 27% (human muscle), or had no effect on (equine muscle), the threshold of ca(2+)-induced ca2+ release. if terminal cisternae fractions were first preloaded with ca2+ to greater than 65% of the threshold of ca(2+)-induced ca2+ release and then ctx added, an immediate a ... | 1993 | 8446962 |
| molecular cloning of a cardiotoxin structural gene from malayan spitting cobra (naja naja sputatrix). | the structural gene and cdna encoding cardiotoxin in naja naja sputatrix have been cloned and characterized with a view to study the gene protein relationships and also to produce pure protein in large amounts. using the polymerase chain reaction on the total rna isolated from the venom glands, the structural gene (180 bp) has been synthesized and expressed in escherichia coli to produce a fusion protein with beta-galactosidase. immunoblotting using polyclonal antibodies raised against the total ... | 1993 | 8446963 |
| snake venom cardiotoxin can rapidly induce actin polymerization in intact platelets. | the action of taiwan cobra (naja naja atra) venom cardiotoxin on rabbit platelets at 37 degrees c was characterized by observing cytoskeletal alterations and cell lysis. at a concentration of 21.4 microm the toxin produced no cell lysis within 30 s, and less than 5% of the total lactate dehydrogenase activity of intact cells was detected in the suspending medium after the interaction had proceeded for 3 min. the extent of cell lysis was proportional to toxin concentration and interaction time. b ... | 1993 | 8452550 |
| hydrolysis of micellar diheptanoylphosphatidylcholine catalyzed by bovine pancreatic phospholipase a2: kinetic characterization of group i and ii enzymes. | initial velocity data for the hydrolysis of micellar 1,2-diheptanoyl-sn-glycero-3-phosphorylcholine (dic7pc) catalyzed by bovine pancreatic pla2 (group i) were analyzed using the michaelis-menten equation. the km value for the micellar substrate was found to be independent of ca2+ concentration, as was the km value for the monodispersed substrate. the ph dependence curve of km in the presence of saturating amounts of ca2+ showed two transitions reflecting large pk shifts of two ionizable groups ... | 1993 | 8454568 |
| three-dimensional structure of neurotoxin-1 from naja naja oxiana venom at 1.9 a resolution. | neurotoxin-1 from naja naja oxiana venom (ntx-1) has been crystallized by vapor diffusion in sitting drops. the crystals have cell dimensions of a = 25.2 a, b = 75.6 a, c = 35.9 a, and are in space group p2(1)2(1)2(1). three-dimensional data to 1.9 a have been recorded by a syntex p2(1) automatic diffractometer. the atomic structure of the toxin has been determined by molecular replacement using the alpha-cobratoxin (alpha-ctx) as the search model. the position of 534 non-hydrogen protein atoms ... | 1993 | 8458425 |
| pharmacokinetics of cytotoxin from chinese cobra (naja naja atra) venom. | the pharmacokinetics of cytotoxin from chinese cobra (naja naja atra) venom was studied in rabbits after i.v. and i.m. injection of 0.2 and 0.5 mg.kg-1, respectively. the plasma levels of the cytotoxin were analysed by a biotin-avidin enzyme-linked immunosorbent assay. the plasma concentration-time course after i.v. administration fitted a two-compartment open model. the half-life (mean +/- s.d.) of the alpha-phase was 5.8 +/- 0.6 min and that of the beta-phase 3.5 +/- 0.2 hr. apparent volume of ... | 1993 | 8470137 |
| interaction of phospholipase a2 with thioether amide containing phospholipid analogues. | transferred noe experiments have been carried out on cobra venom (naja naja naja) phospholipase a2 (pla2) with substrate analogues which serve as potent inhibitors. 1-(hexylthio)-2-(hexanoylamino)-1,2-dideoxy-sn-glycero-3-pho sphoethanolamine (pe) and the corresponding phosphocholine analogue (pc) are water-soluble, short-chain, nonhydrolyzable substrate analogues which bind tightly to the enzyme. because they are small compounds and monomeric in solution, noes develop inefficiently in the absen ... | 1993 | 8494876 |
| two-dimensional 1h-nmr study of the spatial structure of neurotoxin ii from naja naja oxiana. | the spatial structure of neurotoxin ii from the venom of the central asian cobra naja naja oxiana was determined by two-dimensional 1h-nmr techniques and computational analysis. nearly complete proton resonance assignments for 61 amino acid residues have been made using two-dimensional (2d) homonuclear total correlated spectroscopy, 2d homonuclear double-quantum-filtered correlated spectroscopy and 2d homonuclear noe spectroscopy (noesy) experiments. the cross-peak volumes in noesy spectra spin- ... | 1993 | 8504813 |
| recombinant human type ii phospholipase a2 lacks edema producing activity in rat. | the rat paw edema-inducing, acute inflammatory activity of four snake venom phospholipase a2s (pla2) (naja naja, naja mocambique mocambique, crotalus atrox and recombinant naja naja naja) and of recombinant human type ii pla2 (rh-pla2) found in rheumatoid synovial fluid, were compared after a bolus subplantar injection. the snake venom-derived pla2s, including the recombinant naja naja naja, were potent inducers of paw edema. on the other hand, when given in similar amounts (protein and/or enzym ... | 1993 | 8519280 |
| bovine serum albumin does not completely block synaptosomal cholinergic activities of presynaptically acting snake venom phospholipase a2 enzymes. | bovine serum albumin (bsa), which binds fatty acids, was used to test the contribution of free fatty acid to the presynaptic toxicity of phospholipase a2 (pla2) enzymes. the effects of bsa on inhibition of [14c]choline uptake and stimulation of [14c]acetylcholine (ach) release in synaptosomes by pla2 enzymes that do not have a predominant presynaptic action at the neuromuscular junction (ps-) were compared with those on the cholinergic actions of pla2 enzymes that do have a predominant presynapt ... | 1995 | 8533139 |
| structural importance of the cis-5 ethylenic bond in the endogenous desaturation product of dietary elaidic acid, cis-5,trans-9 18:2 acid, for the acylation of rat mitochondria phosphatidylinositol. | when rats were fed elaidic (trans-9 18:1) acid at a high load in diets that were otherwise marginally or almost completely deficient in linoleic (cis-9,cis-12 18:2) acid, elaidic acid was desaturated to cis-5,trans-9 18:2 acid. this polymethylene-interrupted acid was then incorporated into most phospholipids from rat mitochondria, cardiolipin being an exception. its level of esterification in phospholipids followed the increasing order: phosphatidylethanolamine < phosphatidylcholine < phosphatid ... | 1995 | 8538375 |
| [refinement of the spatial structure of neurotoxin ii from naja naja oxiana venom]. | a set of 19 conformations of the neurotoxin ii from naja naja oxiana was determined by conformational energy minimization using constraints derived from experimental 1h nmr data. the pairwise average root-mean-square deviations were 0.86 a for the backbone heavy atoms and 1.48 a for all heavy atoms of these conformations. a model of the neurotoxin ii dimer is proposed to account for the relatively slow deuterium exchange rates of the val45 and leu51 amide protons, which are exposed to the solven ... | 1995 | 8540898 |
| evidence of the coevolution of a snake toxin and its endogenous antitoxin cloning, sequence and expression of a serum albumin cdna of the chinese cobra. | a full-length cdna of the serum albumin (csa) of the cobra (naja naja kaouthia) was cloned from a lambda gt 11 library. it encodes a mature protein of 614 amino-acid residues homologous to the precursor of mammalian serum albumins. the 1 degree and 2 degrees structures of the csa resemble those of the human variety. the putative toxin binding sites are mainly located in the subdomains iia and iiia. the relation between structural homology and function of the serum albumins (sa) is discussed. an ... | 1995 | 8561913 |
| effects of marine 2-polyprenyl-1,4-hydroquinones on phospholipase a2 activity and some inflammatory responses. | three 2-polyprenyl-1,4-hydroquinone derivatives (2-heptaprenyl-1,4-hydroquinone: is1, 2-octaprenyl-1,4-hydroquinone: is2 and 2-[24-hydroxy]-octaprenyl-1,4-hydroquinone: is3) isolated from the mediterranean sponge ircinia spinosula, were evaluated for effects on phospholipase a2 activity of different origin (naja naja venom, human recombinant synovial fluid and bee venom), as well as on human neutrophil function and mouse ear oedema induced by 12-o-tetradecanoylphorbol 13-acetate (tpa). is1 inter ... | 1995 | 8575515 |
| purification and characterization of a novel phospholipase a2 from king cobra (ophiophagus hannah) venom. | a novel phospholipase a2, designated as oh-de-2, was isolated from the venom of ophiophagus hannah (king cobra) by successive chromatography on sp-sephadex c-25, de-52, and q-sepharose columns. oh-de-2 with pi 5.1 showed an apparent molecular weight of 14 kd as revealed by sds-page and gel filtration. the amino acid sequence was homologous with those of pla2s from elapidae venoms. oh-de-2 was effectively inactivated by p-bromophenacyl bromide, indicating that the conserved his-48 is essential fo ... | 1995 | 8593185 |
| pefabloc, 4-[2-aminoethyl]benzenesulfonyl fluoride, is a new, potent nontoxic and irreversible inhibitor of paf-degrading acetylhydrolase. | we report here that 4-[2-aminoethyl]benzenesulfonyl fluoride (pefabloc sc, pefabloc), a new irreversible serine proteinase inhibitor, efficiently inhibits both human and rat platelet activating factor (paf)-degrading acetylhydrolase (acetylhydrolase). indeed, low concentrations of pefabloc (0.1 mm) rapidly and totally inactivate both human plasma-, vldl-, idl-, ldl- and hdl-associated acetylhydrolase, and in addition, acetylhydrolase synthesized and released by human adherent monocytes in cultur ... | 1996 | 8597590 |
| nerve growth factor from the venom of the chinese cobra naja naja atra: purification and description of non-neuronal activities. | nerve growth factor (ngf) was separated from crude naja naja atra venom by using weak cation-exchange chromatography, followed by reversed-phase liquid chromatography. the yield of the purification was 0.2-0.5% (w/w). the mol. wt was determined to be 13,600 and the protein still induced the typical fibre outgrowth of cultured pc-12 cells in a concentration range of 5-10 ng/ml. beside this neuronal effect we demonstrated non-neuronal effects of cobra venom ngf, such as induction of plasma extrava ... | 1995 | 8599177 |
| cloning, direct expression, and purification of a snake venom cardiotoxin in escherichia coli. | the cardiotoxin analogue iii (ctx iii), isolated from the taiwan cobra (naja naja atra) venom, is a sixty-amino acid, all beta-sheet protein. we report the direct expression of ctx iii from its synthetic gene as inclusion bodies in escherichia coli. the yield of the expressed protein is about 40 mg/liter of the culture. ctx iii trapped as inclusion bodies is dissolved and refolded by the slow refolding technique. the refolded protein is purified by reverse phase high performance liquid chromatog ... | 1996 | 8605008 |
| liver class-i alcohol dehydrogenase isozyme relationships and constant patterns in a variable basic structure. distinctions from characterization of an ethanol dehydrogenase in cobra, naja naja. | the major ethanol dehydrogenase of cobra liver was characterized in order to clarify isozyme relationships and functional motifs of the vertebrate enzyme. the cobra protein is a class-i form, most related to one of the isozyme subunits (the a form) in uromastix (lizard) liver. this positions the isozyme duplication and defines the main-line alternative. the new structure also allows extensive correlations with structure/function relationships for alcohol dehydrogenases in general, of which 38 an ... | 1996 | 8612631 |
| cdna sequence analysis and expression of cardiotoxins from taiwan cobra. | the cdnas encoding cardiotoxins i, iii and n were constructed from the cellular rna isolated from the venom glands of naja naja atra by reverse transcription-polymerase chain reaction. a high degree of sequence homology was observed with the three cardiotoxins. the cardiotoxins were subcloned in the expression vector pet 20b(+) and transformed in bl 21(de3) e. coli strain. the expressed protein was isolated from the inclusion bodies of e. coli and purified by reversed phase high performance liqu ... | 1996 | 8619792 |
| role of interferon-gamma against invasion by toxoplasma gondii in a human monocytic cell line (thp1): involvement of the parasite's secretory phospholipase a2. | we examined the role of ifn gamma in protection against toxoplasma gondii in the monocytoid cell line thp1. the addition of ifn gamma to cultured infected thp1 cells reduced the number of parasitized cells without altering intracellular multiplication during the first 24 hr. this reduction was potentiated by bacterial lipopolysaccharide (lps). we also examined the role of an enzyme important for t. gondii cellular invasion, secretory phospholipase-a2 (spla2) and its relation with ifn gamma-induc ... | 1996 | 8620549 |
| 2,2,2-trifluoroethanol induces helical conformation in an all beta-sheet protein. | the effect of 2,2,2-trifluoroethanol (tfe) on the structure of an all beta-sheet protein, cardiotoxin analogue ii (ctx ii), from the taiwan cobra (naja naja atra) is studied. using circular dichroism studies, it is found that higher concentrations of tfe induced a structural transition from beta-sheet to alpha-helix, both in the native state (nctx ii) and in denatured but not disulfide reduced ctx ii (dctx ii) samples. the beta-sheet to alpha-helix conversion is shown to be cooperative. however, ... | 1996 | 8630070 |
| phospholipase a2 from naja naja sputatrix venom is a muscarinic acetylcholine receptor inhibitor. | a variety of snake venoms was tested for the ability to inhibit the binding of antagonists to specific muscarinic acetylcholine receptors (machrs); the highest activity was found in the venom of naja naja sputatrix. the active principle in this venom was isolated by column chromatography on sephadex g-50, sephadex g-150, and cm-sephadex c-25. the final preparation was homogeneous as determined by polyacrylamide gel electrophoresis and hplc; about sevenfold purification was achieved with a yield ... | 1996 | 8638927 |
| effect of chaotropic denaturant on the binding of 1-anilino-8-naphthalene sulfonic acid to proteins. | 1-anilino-8-naphthalene sulfonic acid (ans), a hydrophobic dye, is widely used to monitor conformational changes occurring in proteins during their folding/unfolding. using cardiotoxin iii (whose conformation remains unperturbed even in 6 m urea) from the taiwan cobra (naja naja atra) venom, it is demonstrated that chaotropic denaturant such as urea directly competes with the interaction between ans and the protein. the results presented in this report, in our opinion, has significant implicatio ... | 1996 | 8645725 |
| cdna sequence analysis and expression of cardiotoxin v and a new cardiotoxin vii from naja naja atra (taiwan cobra). | the cdnas encoding cardiotoxin v and a new cardiotoxin vii were constructed from the cellular rna isolated from the venom glands of naja naja atra by reverse transcription-polymerase chain reaction. although 95% nucleotide sequence homology was observed with the two cardiotoxins, there were nine amino-acid substitutions between cardiotoxin v and cardiotoxin vii. the cardiotoxins were subcloned into the expression vector pet 20b(+) and transformed into bl21(de3) e. coli strain. the expressed prot ... | 1996 | 8679666 |
| heart and t-lymphocyte cell surfaces both exhibit positive cooperativity in binding a membrane-lytic toxin. | cobra venom cytotoxins (ctx) have been shown to disrupt cells as different as immunocytes, skeletal myocytes, erythrocytes and tumor cells. nevertheless, even subpopulations of tumor cells are differentially susceptible to ctx by an order of magnitude. in the present study, our objective was to compare ctx-specific binding with cytolytic potency for two disparate cell types in vitro. we investigated the lytic activity of cytotoxin-iii from naja naja atra (nna, fraction d) using heart cells and h ... | 1996 | 8699476 |
| conformational change and inactivation of membrane phospholipid-related activity of cardiotoxin v from taiwan cobra venom at acidic ph. | the phospholipid binding activity of cardiotoxin v from naja naja atra (ctx a5) was studied by use of langmuir monolayers and found to exhibit ph-dependence in binding to phosphatidylcholine membrane with an apparent pka around 6.0. proton nmr investigation of the ctx a5 molecule in the presence of phosphatidylcholine micelles reveals a decrease in association of ctx a5 with membranes at low ph as a result of the protonation of his-4 near the membrane binding site of loop i region of ctx. the ph ... | 1996 | 8703922 |
| the role of acidic amino acid residues in the structural stability of snake cardiotoxins. | we have recently shown that membrane-related activities of cardiotoxin v from naja naja atra (ctx a5) are diminished at acidic ph although the overall beta-sheet structure of the molecule is maintained. in order to understand more about the mechanism of inactivation of ctx at acidic ph, we studied the effect of ph and denaturing reagents on the structural stability of ctx. we found, first, ph-induced structural transitions occurred in ctx a5 at two ph values as judged by the cd ellipticity aroun ... | 1996 | 8703923 |
| sir joseph fayrer md frs (1824-1907) indian medical service: snakebite and mortality in british india. | whilst professor of surgery at the calcutta medical college, dr fayrer studied all aspects of snake poisoning. his work, the thanatophidia of india being a description of the venomous snakes of the indian peninsula, with an account of the influence of their poison of life; and a series of experiments was published in 1872. collating information from official government records of death due to snakebite, fayrer recorded a mortality of 11,416 persons for the year 1869 in the presidency of bengal a ... | 1996 | 8711752 |
| a case study of cardiotoxin iii from the taiwan cobra (naja naja atra). solution structure and other physical properties. | 1996 | 8726052 | |
| specificity of polyunsaturated fatty acid release from rat brain synaptosomes. | release of specific polyunsaturated fatty acids for cell membranes may have a significant implication in biological function, considering the involvement of various fatty acids in cell signal transduction. in the present study, release of polyunsaturated fatty acids from rat brain synaptosomes by endogenous synaptosomal lipase activity was examined in comparison to that by cobra venom phospholipase a2 (naja naja naja). cobra venom phospholipase a2 (naja naja naja) preferentially hydrolyzed docos ... | 1996 | 8729124 |
| antibody-mediated neutralization and binding-reversal studies on alpha-neurotoxins from micrurus nigrocinctus nigrocinctus (coral snake) venom. | an elisa based, non-radioactive acetylcholine receptor (achr) binding assay was used to detect the alpha-neurotoxins present in micrurus nigrocinctus nigrocinctus venom. sera from horses hyperimmunized against m. nigrocinctus venom contain antibodies which inhibit the binding of m. n. nigrocinctus alpha-neurotoxins to achr and reverse the binding of toxins already complexed with the receptor. this result supports the importance of using antivenom therapeutically in m. n. nigrocinctus envenomatio ... | 1996 | 8730930 |
| taxonomic changes and toxinology: systematic revisions of the asiatic cobras (naja naja species complex) | until recently, all asiatic cobra populations were regarded as belonging to one single species, naja naja. recent revisions have shown that there are in fact at least 10 full species of asiatic naja. in order to allow the existing literature to be reconciled with these recent discoveries, an interpretation of the older nomenclature is provided. problematic areas, especially concerning the species n. sumatrana and n. siamensis, are highlighted. | 1996 | 8735239 |
| thermal denaturation of an all beta-sheet protein--identification of a stable partially structured intermediate at high temperature. | the thermal unfolding of an all beta-sheet protein, cardiotoxin analogue iii, from the taiwan cobra (naja naja atra) is studied at ph 2.0, 4.0 and 6.0. at ph 4.0, using circular dichroism and 1-anilino naphthalene-8-sulphonic acid (ans) fluorescence binding studies, a stable partially structured intermediate is detected at 90 degrees c. | 1996 | 8739135 |
| no role for enzymatic activity or dantrolene-sensitive ca2+ stores in the muscular effects of bothropstoxin, a lys49 phospholipase a2 myotoxin. | the role of low levels of phospholipase a2 (pla2) activity and intracellular ca2+ stores in the pharmacological action of bothropstoxin (bthtx), a myotoxic lys49 pla2 homologue isolated from the venom of bothrops jararacussu, was investigated. we examined the muscular effects of bthtx in the mouse diaphragm and its pla2 activity in radiolabeled human and rat primary cultures of skeletal muscle. although it is a lys49 pla2 homologue, bthtx had a low, but easily detectable, level of enzymatic acti ... | 1995 | 8744987 |
| inhibition by multivalent cations of contraction induced by chinese cobra venom cardiotoxin in guinea pig papillary muscle. | the effects of cardiotoxin (ctx), purified from the venom of chinese cobra (naja naja atra) by a three-step chromatography, on the contractile responses of isolated guinea pig papillary muscle preparation and its antagonism by lanthanum ion (la3+) and divalent cations were examined. ctx induced tonic contraction following a transient augmentation of electrically evoked rhythmic contractions, which is similar to that seen in perfused heart preparation. multivalent cations, la3+, ca2+, mn2+ and mg ... | 1996 | 8761008 |
| the interaction of 8-anilinonaphthalene-1-sulfonate with his-47 of taiwan cobra phospholipase a2 perturbing by the binding of calcium ion. | the 8-anilinonaphthalene-1-sulfonate (ans) fluorescence intensity of ans-naja naja atra (taiwan cobra) phospholipase a2 (pla2) complex increased with the addition of ca2+, but the observed fluorescence enhancement markedly decreased after methylation of his-47 in pla2 molecule. however, the binding affinities of methylated pla2 for ans and ca2+ were similar to or even greater than those observed with native pla2. these results, together with the finding that ans electrostatically interacted with ... | 1996 | 8799461 |
| the essentiality of his-47 and the n-terminal region for the binding of 8-anilinonaphthalene-1-sulfonate with taiwan cobra phospholipase a2. | the binding of the apolar fluorescent dye 8-anilinonaphthalene-1-sulfonate (ans) to naja naja atra phospholipase a2 (pla2) as well as the enhancement of ans fluorescence of the pla2-ans complex decreased with increasing ph in a ph range from 3 to 9. these ph-dependent curves can be well interpreted as the perturbation of an ionizable group with pk value of 5.8, which was assigned as his-47 in the active site of pla2. the ionizable group with pk 5.8 was no longer observed after methylation of his ... | 1996 | 8804572 |
| chemical modification of methionines in a cobra venom cytotoxin differentiates between lytic and binding domains. | cytotoxin-iii from naja naja atra (ctx) was chemically modified at either or both of its two methionine residues: over 50% oxidation of methionine-26 occurred with a 1:1 molar ratio of chloramine-t:methionine; at a 5:1 molar ratio, methionine-26 was almost completely oxidized, while methionine-24 was modified only 26%; at a 10:1 molar ratio, both methionines were completely oxidized. each oxidized derivative demonstrated a lower toxicity toward t-cells than toward heart cells. conversely, bindin ... | 1996 | 8806839 |
| the structural elements of phospholipase a2 affecting the enhancement of 8-anilinonaphthalene-1-sulfonate fluorescence. | the binding of the apolar fluorescent dye 8-anilinonaphthalene-1-sulfonate (ans) to naja naja atra and bungarus multicinctus phospholipase a2 (pla2) as well as the ans fluorescence enhancement of pla2-ans complexes were ph-dependent. however, the ph-dependent curves and the ionizable groups perturbed by the binding of ans were essentially different for the two pla2 enzymes. methylation of his residue or removal of the n-terminal octapeptide made the ans fluorescence of pla2-ans complexes become ... | 1996 | 8829622 |
| presynaptically acting snake venom phospholipase a2 enzymes attack unique substrates. | synaptosomes were incubated with bovine serum albumin (bsa) to examine whether the presynaptic action of snake venom phospholipase a2 (pla2) toxins is due either to the release of fatty acids resistant to extraction by bsa or to the liberation of a specific fatty acid type. in the presence of bsa (0.5% or 1.0%) two pla2 enzymes from naja naja atra and naja naja kaouthia snake venoms that do not have a predominant presynaptic action at the neuromuscular junction (ps-) did not stimulate acetylchol ... | 1995 | 8866614 |
| modification of tyrosine-3 (63) and lysine-6 of taiwan cobra phospholipase a2 affects its ability to enhance 8-anilinonaphthalene-1-sulfonate fluorescence. | the tyr-3 (63) and lys-6 of naja naja atra phospholipase a2 (pla2) were modified with p-nitrobenzenesulfonyl fluoride and 4-chloro-3,5-dinitrobenzoate, respectively. although the ability of the lys-modified derivative to enhance the ans fluorescence was lower than that observed with native pla2, the ans-binding affinity of the lys-modified derivative was similar to that of the native enzyme. modifications on tyr-3 or/and tyr-63 of pla2 resulted in the complete loss of its ability to enhance the ... | 1996 | 8896745 |
| [secondary structure and conformational heterogeneity of naja naja oxiana cytotoxin ii]. | the proton resonances of cytotoxin ii from naja naja oxiana were sequentially assigned in 2d 1h nmr spectra for all of its 60 amino acid residues of both major and minor components of the spectra. the presence of the minor component was shown to be due to a conformational heterogeneity of the cytotoxin. the proton-deuterium exchange rates of amide groups were measured in 2h2o at a ph of 5.0 and at 10 degrees c. experimental data obtained (d-connectivities, h-nc alpha-h coupling constants and lon ... | 1996 | 8929219 |
| differential effects of snake venom phospholipase a2 neurotoxin (beta-bungarotoxin) and enzyme (naja naja atra) on protein kinases. | the phospholipase a2 (pla2) neurotoxin, beta-bungarotoxin (beta-butx), presynaptically alters acetylcholine release. we previously found that beta-butx inhibits protein phosphorylation in rat brain synaptosomes. this inhibition was not due to the inhibition of atp synthesis, the action of arachidonic acid (aa) metabolites, or the stimulation of phosphatase activities. a typical pla2 enzyme from naja naja atra (n. n. atra) venom also inhibited phosphorylation but with lesser potency than that of ... | 1996 | 8937437 |
| inhibition of phospholipase a2 activities and some inflammatory responses by the marine product ircinin. | the marine product ircinin has been tested for its effects on secretory and cytosolic phospholipase a2 (pla2) activities in vitro as well as for inhibition of cellular functions in human neutrophils and inflammatory responses in mice. ircinin inhibited naja naja venom, human synovial recombinant, bee venom and zymosan-injected rat air pouch pla2 with ic50 values in the microm range, similar to those of the known inhibitor scalaradial. on the other hand, ircinin was less active on cytosolic pla2 ... | 1996 | 8938669 |
| cobra venom cardiotoxin induces aggregation of washed rat platelets: dual effects of ca2+. | the effects of cardiotoxin isolated and purified from the venom of naja naja atra on the platelet aggregation were investigated using washed rat platelets prepared chromatographically. in the presence of 1 mm ca2+, cardiotoxin concentration-dependently induced aggregation of platelets. while extracellular ca2+ was necessary for the induction of aggregation by cardiotoxin, high concentration of ca2+ (e.g., 5 mm) prevented cardiotoxin-induced aggregation. cardiotoxin-induced platelet aggregation w ... | 1996 | 8948018 |
| evidence that porcine pancreatic phospholipase a2 via its high affinity receptor stimulates extracellular matrix invasion by normal and cancer cells. | cellular migration and extracellular matrix (ecm) invasion are some of the critical steps in embryonic implantation, inflammation, wound healing, and cancer metastasis. extracellular phospholipases a2 (pla2s), belonging to either group i (pla2-i) or group ii (pla2-ii), play an essential role in the generation of proinflammatory lipid mediators (e.g. prostaglandins, leukotrienes, etc.). recent reports indicate that pla2-i, in addition to its digestive function, has receptor-mediated effects. for ... | 1997 | 8999944 |
| the essentiality of calcium ion in the enzymatic activity of taiwan cobra phospholipase a2. | in order to address the mechanism whereby ca2+ wad crucial for the manifestation of the enzymatic activity of phospholipase a2 (pla2), four divalent cations were used to assess their influences on the catalytic activity and the fine structures of naja naja atra pla2. it was found that substitution of mg2+ or sr2+ for ca2+ in the substrate solution caused a decrease in the pla2 activity to 77.5% or 54.5%, respectively, of that in the presence of ca2+. however, no pla2 activity was observed with t ... | 1996 | 9008293 |
| [effect of phospholipase a2 from naja naja oxiana venom on activity of na+,k+-atpase isoenzymes in rat brain]. | the specific sensitivity of the isoforms of the rat brain na+,k(+)-atpase catalytic subunit to phospholipase a2 (pl a2) from naja naja oxiana venom has been estimated on the basis of changes in the two-component dose response curve of ouabain inhibition of na+,k(+)-atpase activity. moderate na+,k(+)-atpase inactivation of pl a2 is accompanied by a decrease of the apparent affinity for ouabain in comparison with the untreated enzyme without any significant changes in the isoform activity ratio in ... | 1996 | 9011252 |
| induction of helical conformation in all beta-sheet proteins by trifluoroethanol. | the effect of 2,2,2-trifluoroethanol (tfe) on the structure of five all beta-sheet proteins, isolated from the venom of the taiwan cobra (naja naja atra), is studied. in all the toxins used, it is observed that significant amount of alpha-helix is induced at higher concentrations of tfe. in all these proteins, the induction of helical conformation and disruption of the tertiary structure seem to occur simultaneously. the structural transitions induced by tfe in reduced and denatured protein appe ... | 1996 | 9016415 |
| characterization of a partially structured state in an all-beta-sheet protein. | cardiotoxin analogue iii (ctx iii) is a low-molecular-mass all-beta-sheet protein isolated from the taiwan cobra (naja naja atra) venom. a stable partially structured state similar to the "molten globule' state has been identified for ctx iii in a 3% (w/v) solution of 2,2,2-trichloroacetic acid at 298 k. this stable state has been structurally characterized using a variety of techniques such as cd, 1-anilinonaphthalene-8-sulphonate fluorescence binding, fourier transform ir and two-dimensional n ... | 1997 | 9020881 |
| destabilisation of native tertiary structural interactions is linked to helix-induction by 2,2,2-trifluoroethanol in proteins. | the effect of 2,2,2-trifluoroethanol (tfe) on the structure of an all beta-sheet protein, cardiotoxin analogue 111 (ctx iii) from the taiwan cobra (naja naja atra) is studied. it is found that high concentrations (> 80% v/v) of tfe induced a beta-sheet to alpha-helix structural transition. it is found that in denatured and reduced ctx iii (rctx iii) helical conformation is induced even upon addition of low concentrations (> 10% v/v) of tfe. using three other proteins, namely, ribonuclease a (rna ... | 1996 | 9024898 |
| mechanism of action of beta-bungarotoxin, a presynaptically acting phospholipase a2 neurotoxin: its effect on protein phosphorylation in rat brain synaptosomes. | the snake venom phospholipase a2 neurotoxin, beta-bungarotoxin, acts presynaptically to alter acetylcholine release in both the peripheral and central nervous systems. in investigating the mechanism of this action, we found that beta-bungarotoxin inhibited phosphorylation of synapsin i, gap-43 and marcks in rat brain synaptosomes. this inhibition was not due to the inhibition of atp synthesis, action of arachidonic acid metabolites, or stimulation of phosphatase activities. furthermore, the acti ... | 1996 | 9027977 |
| cloning and characterization of cdnas encoding three isoforms of phospholipase a2 in malayan spitting cobra (naja naja sputatrix) venom. | cdnas encoding three phospholipase a2 (pla2) isoforms in naja naja sputatrix were cloned and characterized. one of them encoded an acidic pla2 (apla) while the others encoded neutral pla2 (npla-1 and npla-2). the specific characteristics of apla and npla were attributed to mutations at nt139 and nt328 from g to c and g to a, respectively, resulting in amino acid substitutions from asp20 and 83 in apla to his20 and asn83 in npla. amino acid sequencing of purified protein also showed the presence ... | 1997 | 9028006 |
| modulation of the inflammatory response by corticotropin-releasing factor. | peptides of the corticotropin-releasing factor (crf) family have been shown to have either pro- or anti-inflammatory activities. crf (10-30 micrograms/kg) administered subcutaneously or intravenously could inhibit edema and dye leakage in the rat paw produced by several injuries. these findings are opposed to some results suggesting a predominantly pro-inflammatory effect of crf mainly in arthritic processes. the purpose of this work was to identify in vivo and in vitro the conditions for the pr ... | 1997 | 9030902 |
| effect of lipid composition on lipoprotein lipase activity measured by a continuous fluorescence assay: effect of cholesterol supports an interfacial surface penetration model. | the breakdown of normal substrates by lipases requires an interfacial binding step prior to hydrolysis. interfacial binding and subsequent hydrolysis will be affected by the lipid components and hence physical properties of the substrate surface. in order to investigate in detail the effect of lipid structure on the activity of lipoprotein lipase (lpl), triolein-containing emulsion particles of defined composition have been used as substrates. in addition, lipase activity has been measured using ... | 1997 | 9032472 |
| cobra venom cytotoxin free of phospholipase a2 and its effect on model membranes and t leukemia cells. | membrane-active toxins from snake venom have been used previously to study protein-lipid interactions and to probe the physical and biochemical states of biomembranes. to extend these studies, we have isolated from naja naja kaowthia (cobra) venom a cytotoxin free of detectable phospholipase a2 (pla2). the amino acid composition, pi (10.2), and net charge of the cytotoxin compares well with membrane-active toxins isolated from venoms of other cobras. the cytotoxin, shown by a spin label method, ... | 1997 | 9049107 |
| probing calcium ion-induced conformational changes of taiwan cobra phospholipase a2 by trinitrophenylation of lysine residues. | phospholipase a2 (pla2) from naja naja atra (taiwan cobra) snake venom was subjected to lysine modification with trinitrobenzene sulfonate (tnbs). three major derivatives, tnp-1, tnp-2, and tnp-3, were separated by high-performance liquid chromatography (hplc) from the reaction mixtures in the absence of ca2+. however, only tnp-2 and tnp-3 were isolated when trinitrophenylated reaction was carried out in the presence of ca2+. tnp-1 and tnp-2 contained only one tnp group, on lys-65 and lys-6, res ... | 1997 | 9055207 |
| purification of the nicotinic acetylcholine receptor protein by affinity chromatography using a regioselectively modified and reversibly immobilized alpha-toxin from naja nigricollis. | a new method of affinity chromatography purification of the detergent-solubilized nicotinic acetylcholine receptor protein (nachr) is presented, based on the reversible coupling of a chemically monomodified alpha-toxin from naja nigricollis to a resin. the alpha-toxin was monothiolated on the epsilon-amino group of its lysine-15 by reaction with n-succinimidly-3-(2-pyridyldithio)propionate and was covalently linked in a reversible manner to a thiopropyl-activated agarose resin by thiol-disulfide ... | 1997 | 9059496 |
| non-specific helix-induction in charged homopolypeptides by alcohols. | the specificity/non-specificity of helix-induction in charged homopolymers such as polylysine and polyglutamic acid, at neutral ph, by various alcohols namely 2,2,2-trifluoroethanol (tfe), methanol, ethanol and 1-propanol is studied. it is found that all the alcohols used, non-specifically induced helical conformation at high concentrations. in addition, the effect(s) of tfe on an all beta-sheet protein, such cardiotoxin analogue i (ctx i) from the taiwan cobra (naja naja atra) is also studied. ... | 1997 | 9074617 |
| the structural variations of epsilon-amino groups in phospholipase a2 enzymes from naja naja atra and bungarus multicinctus venoms. | comparative studies on naja naja atra phospholipase a2 (nna-pla2), bungarus multicinctus phospholipase a2 (bm-pla2), and their lys-modified derivatives were made to assess the differences in the fine structures around the conserved lys residues of pla2 enzymes. it has found that the accessibility of lys residues of pla2 enzymes toward modified reagent, trinitrobenzene sulfonate, were not the same. moreover, the extent of decrease in pi values of pla2 enzymes that resulted from trinitrophenylatio ... | 1997 | 9112606 |
| the role of the n-terminal leucine residue in snake venom cardiotoxin ii (naja naja atra). | the n-terminal leucine residue of snake venom cardiotoxin ii (ctx ii) (naja naja atra) was systematically replaced with d-leucine (ctxii-l1-d-l), glycine (ctxii-l1g) or deleted [ctxii-(2-60)] to study the role of leucine residue in ctx ii molecule. ctx ii, ctxl1-d-l, ctxl1g and ctx(2-60) were produced by chemical synthesis method and purified by high performance liquid chromatography. owing to folding problem in ctxii-(2-60), only ctx ii, ctxii-l1-d-l and ctxii-l1g were produced in a pure form a ... | 1997 | 9168920 |