| preparation of highly potent naja naja atra (formosan cobra) antivenin. | as the preparation of high titer antiserum against naja naja atra venom is a time-consuming process, attempts were made to develop a immunization procedure for producing highly potent antiserums within a short period. rabbits were immunized for 12 weeks with (1) whole venom as used routinely in our institute, (ii) whole venom adsorbed on carboxymethyl-cellulose (cmc) and mixed with freund's complete adjuvant and (iii) neurotoxin adsorbed on cmc and adjuvant mixture followed by cmc-whole venom-ad ... | 1978 | 115651 |
| production of potent antivenin against cobra venom with conjugated-cobrotoxin. | cobra venom (naja naja atra) and its fractions obtained by ammonium sulfate precipitation were subjected to chromatography on cm-cellulose colum. a highly purified cobrotoxin obtained by the repeated chromatography on preparative cm-cellulose column was 6.7 times more toxic than the original cobra venom. the toxin was detoxified by a bifunctional reagent, glutaraldehyde, to about 99.8% and utilized for immunization in animals. mice received 4 weekly immunization with detoxified cobrotoxin and ch ... | 1979 | 121068 |
| the chemistry and biological effects of cardiotoxin from the chinese cobra (n. naja linn.) on hormonal responses in isolated cell systems. | | 1975 | 170713 |
| location of disulfide bridges in cardiotoxin from the venom of formosan cobra (naja naja atra). | the location of the four disulfide bridges in cardiotoxin from the venom of the formosan cobra, naja naja atra, was determined by isolating cystine-containing peptides from the enzymic and partial acid hydrolyzates of the intact toxin. the results indicate that the disulfide bridges are formed by half cystine residues 3--21, 14--38, 42--53, and 54--59. the amino acid sequence at the position 48--49 was revised to -leu-val- instead of val-leu- as reported previously. | 1978 | 649257 |
| primary structures of cardiotoxin analogues ii and iv from the venom of naja jaja atra. | cardiotoxin analogues ii and iv were isolated from the venom of naja naja atra by gel filtration on sephadex g-50 followed by cm-cellulose chromatography. the venom contains at least four cardiotoxin analogues that account for about 54% of the weight of the lyophilized crude venom. these four cardiotoxin analogues, named cardiotoxin analogues i, ii, iii, and iv, show strong cytotoxicity to yoshida sarcoma cells but the lethal toxicity is one-order less. these toxins contain 60 amino acid residue ... | 1977 | 849468 |
| neuromuscular blocking actions of neurotoxins isolated from laticauda semifasciata, naja naja and naja naja atra--a comparative assay--. | | 1977 | 916390 |
| blockade of acetylcholine receptors: a model of myasthenia gravis. | in order to block acetylcholine receptors of muscle, the alpha toxin of the formosan cobra (naja naja atra) was given intravenously to rats. electrophysiological and pharmacological changes typical of myasthenia gravis were recorded, including decremental responses to repetitive stimuli, curare sensitivity, neostigmine reversal, and posttetanic phenomena. this model supports the concept that a reduction of available acetylcholine receptors may play an important role in myasthenia gravis. | 1975 | 1145181 |
| amino acid sequence of cardiotoxin-analogue i from the venom of naja naja atra. | | 1975 | 1147930 |
| [pharmacokinetics of cytotoxin 14 from naja naja atra venom]. | the pharmacokinetics of cytotoxin 14 (ct 14) from naja naja atra venom was studied with biotin-avidin enzyme-linked immunosorbent assay. the plasma concentration-time curve of ct 14 after bolus i.v. 0.2 mg.kg-1 into rabbits was found to fit a two-compartment open model. t1/2 alpha was 5.8 +/- 0.6 min and t1/2 beta was 3.5 +/- 0.2 h. a rapid absorption was seen after im injection (0.5 mg.kg-1) to rabbits. the peak level was 260 +/- 90 ng.ml-1 and tpeak was 13.6 +/- 2.4 min. the absolute bioavaila ... | 1992 | 1302445 |
| inhibition of sendai virus by various snake venom. | viperid, elapid and crotalid snake venoms were screened in vitro for antiviral activity against sendai virus. the hemolysis of 10(8) human erythrocytes in 1 ml, caused by 70 hau of sendai virus, was abolished when the virions were pretreated with 10 ug of the viperid venom of echis coloratus, and was considerably diminished when pretreated with 10 ug of the venom of echis carinatus sochureki, the cobra venoms of naja atra and naja nigricollis nigricollis. these venoms did not affect the erythroc ... | 1992 | 1328790 |
| [specific killing of human leukemic t-cells by a monoclonal antibody coupled to the cytotoxin from chinese cobra]. | the immunotoxin (it) was prepared by conjugating cytotoxin from chinese cobra (naja naja atra) venom with monoclonal antibody (mcab) wu71 directed to human t-cells. first, calcium ions were used to suppress the cytolytic reaction while cell antigen was allowed to react with mcab. then magnesium ions and the chelating agent egta were used to abolish the calcium inhibition. with this treatment, the it showed high cytotoxicity for the leukemic cell line cem, which was antigen positive (82.4% of the ... | 1992 | 1394735 |
| effects of snake venom phospholipase a2 toxins (beta-bungarotoxin, notexin) and enzymes (naja naja atra, naja nigricollis) on aminophospholipid asymmetry in rat cerebrocortical synaptosomes. | the effects of snake venom phospholipase a2 (pla2) toxins (beta-bungarotoxin, notexin) and pla2 enzymes (naja nigricollis, naja naja atra) on aminophospholipid asymmetry in rat cerebrocortical synaptic plasma membranes (spm) were examined. incubation of intact synaptosomes with 2 mm 2,4,6-trinitrobenzene sulfonic acid (tnbs) for 40 min, under non-penetrating conditions, followed by spm isolation, allowed us to calculate the percentage of phosphatidylethanolamine (pe) and phosphatidylserine (ps) ... | 1992 | 1417932 |
| inhibition of phosphorylation of synapsin i and other synaptosomal proteins by beta-bungarotoxin, a phospholipase a2 neurotoxin. | some snake venom neurotoxins, such as beta-bungarotoxin (beta-butx), which possess relatively low phospholipase a2 (pla2) activity, act presynaptically to alter acetylcholine (ach) release both in the periphery and in the cns. in investigating the mechanism of this action, we found that beta-butx (5 and 15 nm) inhibited phosphorylation, in both resting and depolarized synaptosomes, of a wide range of proteins, including synapsin i. naja naja atra pla2, which has higher pla2 activity, also inhibi ... | 1992 | 1431893 |
| mojave toxin affects fusion of myoblasts and viability of myotubes in cell cultures. | mojave toxin is a neurotoxic, heterodimeric phospholipase isolated from the venom of crotalus scutulatus scutulatus. responses of primary rat muscle cell cultures and clonal muscle cell lines to treatment with mojave toxin and its constituent subunits were examined. continuous exposure of cells to 0.5 microm or 1.0 microm mojave toxin or the basic subunit, added 24 hr after plating, prevented fusion of primary myoblasts and c2 myoblasts to multinucleate myotubes. under the same experimental cond ... | 1992 | 1509491 |
| [biotin-avidin-elisa for cytotoxin purified from cobra venom]. | a technique combining the biotin-avidin amplifying system with sandwich enzyme-linked immunosorbent assay (b-a-elisa) was developed for the microassay of the cytotoxin from naja naja atra venom. the horse-peroxidase was used as the marker and polystyrene microhemagglutination plates as solid carrier. the sensitivity was 0.5 ng.ml-1. the assay range was 1.25-320 ngml-1 with coefficient of variation of 4.9% (intragroup) and 8.1% (intergroups), respectively. | 1992 | 1598840 |
| comparative effects of phospholipase a2 neurotoxins and enzymes on membrane potential and na+/k+ atpase activity in rat brain synaptosomes. | beta-bungarotoxin (beta-butx) and notexin are phospholipase a2 (pla2) neurotoxins which cause an irreversible blockade of neurotransmitter release through specific and potent effects at the presynaptic nerve terminal; however, their mechanism of action is uncertain. we examined the effects of beta-butx and notexin on na+/k+ atpase activity using sprague-dawley rat brain synaptosomes in order to determine if alterations in activity might modulate neurotoxin-induced depolarization. treatment of sy ... | 1991 | 1648801 |
| effects of anti-inflammatory drugs on rat hind-paw swelling caused by phospholipase a2 from naja naja atra venom. | rat hind-paw swelling was induced dose-dependently by subplantar injection of acidic phospholipase a2 (nnavpla2) from naja naja atra venom. diphenhydramine and methysergide pretreatment greatly reduced the swelling effect caused by nnavpla2. several doses of compound 48/80 given to deplete the histamine content of rat hind paw, also greatly suppressed nnavpla2-induced paw swelling. the paw swelling caused by nnavpla2 was reduced following pretreatment with bw 755c, a dual inhibitor of cyclooxyge ... | 1991 | 1683689 |
| 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 |
| effect of anti-inflammatory drugs on the cardiotoxin-induced hind-paw oedema in rats. | cardiotoxin, isolated from naja naja atra venom, induced rat hind-paw oedema. this effect was suppressed by the pretreatment with dexamethasone or bw 755c, or subplantar co-injection with fpl 55712. pretreatment with aspirin alone did not affect this response, while a significant reduction of cardiotoxin-induced paw oedema was achieved with aspirin in combination with diphenhydramine and methysergide. subplantar co-injection of paf antagonist, bn 52021 or l 652731, with cardiotoxin had no effect ... | 1990 | 1983146 |
| fusion of sphingomyelin vesicles induced by proteins from taiwan cobra (naja naja atra) venom. interactions of zwitterionic phospholipids with cardiotoxin analogues. | egg sphingomyelin vesicles were used to assay aggregation/fusion activities of proteins from taiwan (naja naja atra) venom to avoid the problem of phospholipase a2 contamination during protein purification. it led to the identification of a new cardiotoxin (ctx) analogue protein (ctx v) with major aggregation/fusion, but few hemolysis, activities. on the contrary, cardiotoxin (ctx iii) induced significant hemolysis of human red blood cells but exhibited few aggregation/fusion activities. to stud ... | 1991 | 1993698 |
| snake venom cardiotoxins and bee venom melittin activate phospholipase c activity in primary cultures of skeletal muscle. | the effects of cardiotoxin fractions from naja naja kaouthia and naja naja atra snake venoms and synthetic melittin peptide were examined on lipolytic activity in red blood cells and primary skeletal muscle cultures. both native cardiotoxin fractions caused considerable production of free fatty acids in red blood cells. this production was abolished when the fractions were first treated with p-bromophenacyl bromide to reduce the venom phospholipase a2 activity contamination. in equine and human ... | 1991 | 2054159 |
| 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 |
| 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 |
| [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 |
| 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 |
| 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 |
| monoclonal antibodies against vipera lebetina venom nerve growth factor cross-react with other snake venom nerve growth factors. | nerve growth factor (ngf) was isolated from the venom of vipera lebetina and was purified to homogeneity as judged by sds gel electrophoresis. the biologically active ngf was used to immunize balb/c mouse, and the spleen cells from immunized mouse were fused with mouse pai myeloma cells. forty-seven hybrid cell lines, secreting monoclonal antibodies to v. lebetina ngf, were isolated and nine of them purified from ascitic fluids. the isolated antibodies define two partially overlapping epitopes o ... | 1987 | 2448608 |
| 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 |
| 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 |
| 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 |
| comparison of enzymatic and pharmacological activities of lysine-49 and aspartate-49 phospholipases a2 from agkistrodon piscivorus piscivorus snake venom. | the basic lys-49 phospholipase a2 (pla2) from agkistrodon piscivorus piscivorus venom is homologous to the basic asp-49 pla2 from the same venom as well as other snake venom pla2 enzymes. it differs, however, in several respects, most important being replacement of the previously invariant asp-49 at the calcium binding site by lys, resulting in a reversed order of addition of calcium and phospholipid, phospholipid binding first. although the preferences for phospholipid substrates of the two enz ... | 1987 | 3109429 |
| 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 |
| characterization of the anticoagulants from taiwan cobra (naja naja atra) snake venom. | taiwan cobra (naja naja atra) snake venom was separated into 19 fractions by means of cm-sephadex c-50 column chromatography. anticoagulant fractions v-vii were refractionated by gel filtration on sephadex g-50 and the purified component possessed phospholipase a2 activity and an inhibitory effect on collagen-induced platelet aggregation. the anticoagulant action could be antagonized by phospholipid or platelet factor 3. anticoagulant fraction xvii was also further refractionated by gel filtrati ... | 1987 | 3576637 |
| different susceptibilities of platelet phospholipids to various phospholipases and modifications induced by thrombin. possible evidence of rearrangement of lipid domains. | on the membrane surface of the human platelet, phosphatidylcholine (pc) and phosphatidylethanolamine (pe) were hydrolyzed to different extents by the snake venom phospholipases a2 of varying pi values. the susceptibility of platelet phospholipids to basic phospholipase a2 of naja nigricollis (pi 10.6) has been reported (wang et al. (1986) biochim. biophys. acta 856, 244-258). the susceptibilities of platelet phospholipids to acidic phospholipase a2 of naja naja atra (pi 5.2) and to neutral phosp ... | 1987 | 3580366 |
| electrophysiologic observation of the effects of matrine co against arrhythmia induced by chinese cobra venom on isolated rat sinus node and papillary muscles. | | 1987 | 3613639 |
| multiple effects of alpha-toxins on the nicotinic acetylcholine receptor. | very low concentrations (5 nm) of alpha-toxin from the venom of naja naja atra produced a characteristic fade in muscle compound action potential and tetanus induced by repetitive nerve stimulation which was identical to the effects of curare. high concentrations of alpha-toxin and all concentrations of alpha-bungarotoxin reduced the response but produced very little fade in comparison to curare. these results suggest that alpha-toxins have more than one effect at the neuromuscular junction. | 1987 | 3691793 |
| actions of cardiotoxins from the southern chinese cobra (naja naja atra) on rat cardiac tissue. | the cardiotoxic actions of southern chinese cobra (naja naja atra) venom have been investigated. cardiotoxicity accounted for lethality of crude venom in anaesthetized rats and cardiotoxic polypeptides constituted the bulk of the venom when it was fractionated by cm-sephadex chromatography. the cardiotoxic actions of these polypeptides were investigated in isolated cardiac tissue. actions of cardiotoxins on rate, force and intracellular potentials occurred more readily in ventricular tissue and ... | 1986 | 3715895 |
| effects of modification of tyrosines 3 and 62 (63) on enzymatic and toxicological properties of phospholipases a2 from naja nigricollis and naja naja atra snake venoms. | previously we selectively modified his (48), arg, lys, asp, glu and trp residues in the basic phospholipase a2 from naja nigricollis and the acidic phospholipase a2 from n. n. atra snake venoms. evidence was obtained for the existence of separate but perhaps overlapping sites responsible, respectively, for their enzymatic and pharmacological properties. we have now modified one or two (tyr 3, tyr 62 [63], tyr 3 + 62 [63]) out of the nine tyrosine residues in these enzymes using p-nitrobenzenesul ... | 1986 | 3775785 |
| effect of alkylation of tryptophan residues on the enzymatic and pharmacological properties of snake venom phospholipase a2. | snake venom phospholipases a2 show a remarkable degree of amino acid sequence homology yet differ markedly in enzymatic and pharmacological activities. the basic phospholipase a2 from naja nigricollis venom has much greater lethal potency, cardiotoxicity, hemolytic and anticoagulant activity than the acidic or neutral enzymes from naja naja atra or hemachatus haemachatus venoms, respectively, even though it has lower enzymatic activity than the latter two enzymes. previous studies in which we se ... | 1985 | 3924381 |
| [the detoxification of naja naja atra venom and preparation of potent antivenin]. | the 99.2% toxicity of naja naja atra venom can be detoxified by treatment with 0.25% ga (glutaraldehyde) solution at ph 6.8 and still remains its antigenicity. using the ga treated venom incorporated with freund's complete adjuvant as immunogen, the titer of immune horse sera can be enhanced rapidly. the modified immunization method not only shortened the period of immunization (from 180 to 60 days), but also increased the potency of immune sera (from 75 to 170 units). the method also diminished ... | 1985 | 3933920 |
| effects of beta-bungarotoxin and naja naja atra snake venom phospholipase a2 on acetylcholine release and choline uptake in synaptosomes. | beta-bungarotoxin is a potent presynaptically acting snake venom toxin that exhibits phospholipase a2 activity. we compared the effects of beta-bungarotoxin and a less toxic snake venom phospholipase a2 on synaptosomal 3h-acetylcholine release and 3h-choline uptake. the purpose of these experiments was to study the mode by which beta-bungarotoxin inhibits 3h-acetylcholine release in this preparation. under non-depolarizing conditions, both beta-bungarotoxin and naja naja atra phospholipase a2 st ... | 1986 | 3952766 |
| the relationship between high-affinity noncatalytic binding of snake venom phospholipases a2 to brain synaptic plasma membranes and their central lethal potencies. | the basic phospholipase a2 from naja nigricollis (african spitting cobra) snake venom is enzymatically less active but more toxic than the acidic phospholipase a2 from naja naja atra (taiwan cobra) snake venom, following injection into the right lateral ventricle of the brain of rats. when radiolabeled with 125i, these phospholipases a2 retained enzymatic activities and lethal potencies. both enzymes bound with high affinity and specificity to brain synaptic plasma membrane preparations in vitro ... | 1986 | 3964691 |
| local necrosis induced by cobra (naja naja atra) venom. | | 1972 | 4539445 |
| comparison of naja naja siamensis and naja naja atra venoms. | | 1968 | 4966517 |
| role of cardiotoxin and phospholipase a in the blockade of nerve conduction and depolarization of skeletal muscle induced by cobra venom. | 1. the effects of phospholipase a (pha), cardiotoxin (ctx) and neurotoxin (cobrotoxin) isolated from formosan cobra (naja naja atra) venom on conduction of the rat phrenic nerve and membrane potential of the rat diaphragm were studied.2. phospholipase a, lysolecithin and cobrotoxin were without effect on the axonal conduction. cardiotoxin was the only active agent in cobra venom, but it was less potent than the crude venom.3. the blocking action of cardiotoxin was markedly accelerated by the sim ... | 1972 | 5041453 |
| pharmacological properties of cardiotoxin isolated from the venom of naja naja atra. | | 1966 | 6002954 |
| effects of beta-bungarotoxin and phospholipase a2 from naja naja atra snake venom on atpase activities of synaptic membranes from rat cerebral cortex. | non-neurotoxic phospholipase a2 of formosan cobra venom possessed higher hydrolytic activity on phosphatidylcholine vesicles and also had higher inhibitory action on na+-k+-atpase and mg2+-atpase of the rat synaptic membrane than neurotoxic beta-bungarotoxin of formosan krait venom. na+-k+-atpase was more susceptible than mg2+-atpase to the inhibitory action of toxins, especially in the presence of triton x-100. the inhibition of atpases by toxins followed the michaelis-menton equation. it is in ... | 1982 | 6123164 |
| effect of the purified phospholipases a2 from snake and bee venoms on rabbit platelet function. | effects of seven purified phospholipases a2 from the venoms of snakes (naja naja atra, trimeresurus mucrosquamatus and t. gramineus) and honey bee (apis mellifera) on rabbit washed platelet suspension in the absence of bovine serum albumin have been studied. only phospholipases a2 from n. n. atra, t. mucrosquamatus and a. mellifera venoms induced platelet aggregation with small amounts of 14c-serotonin release. they showed tachyphylaxis and also cross-tachyphylaxis in inducing platelet aggregati ... | 1984 | 6441310 |
| cardiotoxin from naja naja atra snake venom: a potentiator of platelet aggregation. | cardiotoxin, isolated from naja naja atra snake venom, potentiates platelet aggregation induced by adp, thrombin, collagen and venom phospholipase a2. the malondialdehyde formation caused by adp, thrombin and venom phospholipase a2 were also increased in the presence of cardiotoxin. both potentiation of aggregation and increase in malondialdehyde were blocked by indomethacin or ca2+ (5 mm or 0.05 mm). cardiotoxin did not potentiate thrombin-induced aggregation of p-bromophenacyl bromide-modified ... | 1984 | 6474495 |
| effect of carboxylate group modification on enzymatic and cardiotoxic properties of snake venom phospholipases a2. | by treating naja nigricollis and naja naja atra phospholipase a2 with carbodiimide and semicarbazide, we obtained derivatives having varied numbers of modified carboxylate groups. when tested on artificial and natural substrates, derivatives of both enzymes with a modified carboxylate group at the active site (asp-49) retained little enzymatic activity (1/41 to 10%). however, the derivatives of n. nigricollis also lost most of their lethal potency (5% of native), while those of n. n. atra retain ... | 1984 | 6523504 |
| phospholipid hydrolysis in serum lipoproteins by a basic phospholipase a2 from naja nigricollis snake venom and an acidic phospholipase a2 from naja naja atra snake venom. | apparent km and vmax values for pc and pe hydrolysis were determined following exposure of hdl, ldl, and vldl to a basic phospholipase a2 from n. nigricollis snake venom and an acidic phospholipase a2 from n. nigricollis snake venom and an acidic phospholipase a2 from n. n. atra snake venom. both enzymes hydrolyzed the lipoprotein phospholipids approximately as fast as they hydrolyzed pure phospholipids in mixed micelles, however, the n. nigricollis enzyme, which has a much stronger anticoagulan ... | 1983 | 6623492 |
| dissociation of pharmacological and enzymatic activities of snake venom phospholipases a2 by modification of carboxylate groups. | the carboxylate groups in an acidic and in a basic phospholipase a2 (pla2) enzyme, purified, respectively, from naja naja atra and naja nigricollis snake venoms, were modified with carbodiimide and semicarbazide. the derivatives modified at ph 3.5 and ph 5.5 had less than 1% (n. nigricollis) or 2% (n. n. atra) residual enzymatic activity, whereas 12-16% enzymatic activity remained following modification at ph 5.5 in the presence of ca2+. in marked contrast, these derivatives retained variable, b ... | 1983 | 6651873 |
| the inhibitory effect of purified cobra venom factor, isolated from the venom of naja naja atra, on the in vivo immune response in galleria mellonella. | | 1981 | 6786928 |
| dissociation of enzymatic activity from lethality and pharmacological properties by carbamylation of lysines in naja nigricollis and naja naja atra snake venom phospholipases a2. | | 1981 | 6795762 |
| effect of methylation of histidine-48 on some enzymatic and pharmacological activities of snake venom phospholipases a2. | the effects on some pharmacological and enzymatic properties were determined following methylation of histidine at the enzymatic active site of the basic relatively toxic naja nigricollis and the acidic relatively non-toxic naja naja atra phospholipases a2. following methylation a very low residual enzymatic activity (0.4-1% of control) was accompanied by a parallel loss in intraventricular lethality, anticoagulant potency, direct hemolytic action and ability to block directly and indirectly evo ... | 1983 | 6834999 |
| effect of modification of one histidine residue on the enzymatic and pharmacological properties of a toxic phospholipase a2 from naja nigricollis snake venom and less toxic phospholipases a2 from hemachatus haemachatus and naja atra snake venoms. | | 1981 | 7222090 |
| effects of arginine modification of naja nigricollis and naja naja atra snake venom phospholipases a2 on enzymatic activity, lethality and anticoagulant action. | | 1981 | 7302958 |
| sequence analysis and expression of phospholipase a2 from taiwan cobra. | polymerase chain reaction (pcr) was employed to amplify cdnas constructed from the poly(a)+rna of venom glands in taiwan cobras to facilitate the cloning and sequencing of phospholipase a2 (pla2) gene. the pcr product was then subcloned into puc18 vector and transformed in e. coli strain jm109. plasmids purified from the positive clones were prepared for nucleotide sequencing by dideoxynucleotide chain-termination method. sequencing several clones containing about 0.5 kb dna inserts constructed ... | 1994 | 7510963 |
| inhibition of protein kinase c by snake venom toxins: comparison of enzyme inhibition, lethality and hemolysis among different cardiotoxin isoforms. | cardiotoxins, neurotoxins and phospholipase a2 (pla2) are three major classes of toxic components present in the taiwan cobra, naja naja atra of the elapidae family. cardiotoxins (or called cytotoxins), a group of major polypeptides of around 60 amino-acid residues present abundantly in the elapid family of snakes, comprise about 45-55% of the crude venom of taiwan cobra. in contrast to another prominent group of structurally similar neurotoxins with well-established acetylcholine receptors and ... | 1995 | 7549929 |
| beta-bungarotoxin blocks phorbol ester-stimulated phosphorylation of marcks, gap-43 and synapsin i in rat brain synaptosomes. | the phospholipase a2 neurotoxin, beta-bungarotoxin, presynaptically blocks acetylcholine release. its mechanism of action is unknown; however, our previous studies suggest that it inhibits phosphorylation of synaptosomal proteins, which might be expected to decrease neurotransmitter release. in our present study, we found that 1 nm beta-butx blocked phorbol ester-stimulated phosphorylation of gap-43, marcks and synapsin i without affecting their basal phosphorylation. in contrast, a 1 nm concent ... | 1995 | 7676466 |
| expression of glutathione s-transferase-cardiotoxin fusion protein in escherichia coli. | we report here the construction of cardiotoxin v gene, from cobra snake venom (naja naja atra), by chemically synthesized oligonucleotides and its expression as a glutathione s-transferase-cardiotoxin fusion protein in the inclusion bodies of escherichia coli. the expression of cardiotoxin fusion protein in protein with a yield of about 35 mg/liter culture was confirmed by highly specific anti-peptide antibodies generated against the unique amino acid residues located at the tip of loop ii of ca ... | 1994 | 7725337 |
| chemical modification and inactivation of phospholipases a2 by a manoalide analogue. | chemical modification and inactivation of bovine pancreatic, porcine pancreatic, naja naja atra and pseudechis australis phospholipases a2 (pla2s), belonging to group i, and of trimeresurus flavoviridis, vipera russelli russelli and agkistrodon halys blomhoffii pla2s, belonging to group ii, were investigated by the use of a manoalide (mld)-analogue, 1-(2,5-dihydro-hydroxy-5-oxo-3-furanyl)-8,12-dimethyl-4-formyl-3,7, 11-tridecatrienol. at appropriate time intervals, residual pla2 activities towar ... | 1995 | 7755577 |
| binding mode of phospholipase a2 with a new type of phospholipid analog having an oxazolidinone ring. | inhibition of phospholipases a2 (pla2s) by a new type of monodispersed phospholipid analog, 3-dodecanoyl-4-phosphatidylcholinohydroxymethyl-2-oxazolidinone (oxazolidinone-pc), was investigated by the ph stat assay method using monodispersed 1,2-dihexanoyl-sn-glycero-3-phosphorylcholine (dic6pc) as the substrate. the pla2s used were those from bovine pancreas and cobra (naja naja atra) venom (group i) and from japanese mamushi (agkistrodon halys blomhoffii) venom (group ii). this new-type substra ... | 1995 | 7775386 |
| chemical modification of lys-6 in taiwan cobra phospholipase a2 with 4-chloro-3,5-dinitrobenzoate. | phospholipase a2 (pla2) from naja naja atra snake venom was modified with 4-chloro-3,5-dinitrobenzoate, and one major carboxydinitrophenylated (cdnp) pla2 was separated by high performance liquid chromato-graphy. cdnp-pla2 contained only one cdnp group on lys-6 and showed a 93% drop in enzymatic activity. however, carboxydinitrophenylation did not significantly affect the secondary structure of the enzyme molecule as revealed by the cd spectra, and ca2+ binding and antigenicity of cdnp-pla2 were ... | 1994 | 7804147 |
| sequence comparison and computer modelling of cardiotoxins and cobrotoxin isolated from taiwan cobra. | six cardiotoxins and one neurotoxin isolated and purified from the taiwan cobra venom (naja naja atra) possess distinct pharmacological and biochemical properties despite the existence of a grossly similar tertiary structure among these toxins, i. e., a core consisting of a series of short loops and four disulfide bridges. a systematic structure comparison of these major toxin isoforms was made by the secondary-structure predictions together with computer model-building based on the primary sequ ... | 1995 | 7818523 |
| protective effect of cobra venom factor on pulmonary injury induced by oleic acid. | the protective effect of cobra venom factor (cvf), separated from the venom of naja naja atra, on pulmonary injury induced by oleic acid was reported. the blood gas tensions, tidal volume, transthoracic pressure and pulmonary arterial pressure in anaesthetized dogs were continually monitored. the experimental results showed that cvf, given 20 h before the dosage depleting complements exceed 95%, significantly attenuated oleic acid-induced pulmonary dysfunction, including hypoxemia, increasing ve ... | 1994 | 7868302 |
| role of ca2+ in the binding of phospholipase a2 with a monomeric substrate and with its amide-type analog. | effects of ca2+ on the kinetic parameters for the hydrolysis of monodispersed 1,2-dihexanoyl-sn-glycero-3-phosphorylcholine (dic6pc), catalyzed by group i phospholipases a2 (pla2s) from pseudechis australis, naja naja atra, and bovine pancreas and by group ii enzymes from vipera russelli russelli, agkistrodon halys blomhoffii, and trimeresurus flavoviridis, were studied by the ph-stat assay method at 25 degrees c, ph 7.5-8.2, and an ionic strength of 0.1 or 0.2 in the absence or presence of an a ... | 1994 | 7883763 |
| exposure of phosphatidylcholine and phosphatidylinositol in plasma membranes from rat brain synaptosomes treated with phospholipase a2 toxins (beta-bungarotoxin, notexin) and enzymes (naja nigricollis, naja naja atra). | phospholipase a2 (pla2) toxins act presynaptically to block acetylcholine release and are much more potent and specific in their actions than pla2 enzymes even though they have lower enzymatic activity. since their mechanism of action is not completely understood, it was of interest to examine the toxins' effects on phospholipid asymmetry as changes in asymmetry are associated with changes in membrane functioning. rat brain synaptosomes were treated with the pla2 toxins beta-bungarotoxin (beta-b ... | 1994 | 7940575 |
| characterization of monoclonal antibodies against naja naja oxiana neurotoxin i. | seven monoclonal antibodies (mabs) were developed against neurotoxin i (nt-1), a protein from central asian cobra (naja naja oxiana) venom which binds specifically to nicotinic acetylcholine receptor (achr). all of the mabs cross-reacted with another long-chain post-synaptic neurotoxin, bungarus multicinctus alpha-bungarotoxin (alpha-bt), but not naja naja kaouthia alpha-cobratoxin, in an enzyme-linked immunosorbent assay (e.l.i.s.a.). short-chain post-synaptic neurotoxins like naja naja atra co ... | 1994 | 7945236 |
| effects of direct lytic factors from southern chinese cobra venom on ca2+ movement in rabbit aorta strip. | the purified direct lytic factors (dlf) from southern chinese cobra (naja naja atra) venom induced a contractile response in ca(2+)-free krebs' solution and a further increase in the tension following a subsequent addition of ca2+ into bath. after depletion of intracellular ca2+ pool by phenylephrine, dlf failed to induce any contractile response. in 45ca2+ experiments, dlf increased both 45ca2+ release and 45ca2+ influx. procaine 2 mmol.l-1 decreased the dlf induced 45ca2+ release and 45ca2+ in ... | 1993 | 8010046 |
| [distribution of 131i-cytotoxin 14 from naja naja atra venom in rats]. | cytotoxin 14 (ct14) from naja naja atra venom was labelled with 131i by chloramine-t method and its tissue distribution was studied in rats. the highest concentration of the cytotoxin was found in kidney, 5979 dpm per mg weight, 14 times more than that of the control animals, at 0.5 h after i.v. injection and high concentrations were found in liver, spleen, pancreas, and adrenal. ct14 was also found in brain at 2 h after injection, 50 dpm per mg weight, 3 times more than that of the control. | 1994 | 8010097 |
| 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 |
| [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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| characterization of epitopes in native and unfolded cobrotoxin: evidence of an immunodominant c-terminal region related to the production of precipitating and non-precipitating antibodies against cobrotoxin. | rabbits hyperimmunized with cobrotoxin from taiwan cobra venom produced non-precipitating as well as precipitating antibodies. both antibody preparations exhibited higher affinity for native cobrotoxin than for reduced and s-carboxymethylated (rcm) cobrotoxin. this indicated that the epitope structures in cobrotoxin are mostly conformation-dependent. in order to identify the conformational epitopes, native cobrotoxin was hydrolyzed with acid protease a, and 12 peptides were obtained on hplc. thr ... | 1995 | 8576079 |
| 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 |
| 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 |
| 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 |
| 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 |
| respiratory toxicity of direct lytic factor in the venom of the southern chinese cobra (n. naja atra) in dogs. | the effects of direct lytic factor (dlf) on respiratory ventilation, gas exchange as well as hemodynamics were studied in anesthetized dogs. after an intravenous dlf dose of 1 mg/kg, the initial manifestation of intoxication was observed as follows: (1) increase in airway impedance characterized by slowed air flow rate and increased negative transpulmonary pressure. (2) decrease in dynamic compliance. (3) progressive increase in venoarterial shunt (qs/qt) and decrease in pao2, (4) elevation of p ... | 1996 | 8863057 |
| 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 |
| 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 |
| 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 |