Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
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| expression and mutagenesis studies of cobrotoxin from taiwan cobra. | the cdna encoding cobrotoxin was constructed from the cellular rna isolated from the venom glands of naja naja atra (taiwan cobra). the cdna was subcloned into the expression vector pet20b(+) and transformed into bl21(de3) escherichia coli strain. expressed cobrotoxin was isolated from inclusion bodies of e. coli and subjected to refolding into its folded structure. the refolded cobrotoxin was purified by high-performance liquid chromatography and exhibited a neurotoxicity in inhibiting acetylch ... | 1999 | 10512733 |
| roles of aromatic residues in high interfacial activity of naja naja atra phospholipase a2. | acidic phospholipase a2 (pla2) from the venom of chinese cobra (naja naja atra) has high activity on zwitterionic membranes and contains six aromatic residues, including tyr-3, trp-18, trp-19, trp-61, phe-64, and tyr-110, on its putative interfacial binding surface. to assess the roles of these aromatic residues in the interfacial catalysis of n. n. atra pla2, we mutated them to ala and measured the effects on its interfacial catalysis. enzymatic activities of the mutants toward various vesicle ... | 1999 | 10587453 |
| bioactivities of nerve growth factor from chinese cobra venom. | the nerve growth factor, ngf, from chinese cobra naja naja atra venom was isolated by gel-filtration and ion-exchange chromatography. cobra ngf was characterized by analytical hplc techniques as well as sds-page, and was proven to be a glycoprotein with a mol. wt. of 23 (+/- 2) kd and a pi of 9.2. the amino acid analysis and n-terminal sequencing were performed using conventional methods. bioassays with cultured chick embryos ganglia and rat pheochromocytoma pc-12 cells revealed a promotion of f ... | 1999 | 10591039 |
| predicted three-dimensional structural models of venom serine protease inhibitors and their interactions with trypsin and chymotrypsin. | three homology models of trypsin and chymotrypsin inhibitor polypeptides from snake venom of naja naja naja and leaf-nosed viper in the unbound state and in complex with trypsin and chymotrypsin were built based on homology to bovine pancreatic trypsin inhibitor (bpti). these venom inhibitors belong to the kunitz-type inhibitor family, which is characterized by a distinct tertiary fold with three-conserved disulfide bonds. the general folding pattern in these trypsin and chymotrypsin inhibitor h ... | 1999 | 10591040 |
| a nerve growth factor from the venom of chinese cobra (naja naja atra) and its effects on male reproductive system in rats. | a nerve growth factor (ngf) was isolated from the venom of chinese cobra (naja naja atra) by ion exchange chromatography, gel filtration and fast protein liquid chromatography (fplc). the n-terminal sequence of 22 amino acid residues was identical with other ngfs previously purified from the venom of the same genus. the ngf monomer molecular weight was estimated to be 13,500 by reducing sds-page and the isoelectric point was determined to be 7.2 by isoelectric focusing electrophoresis. ngf impro ... | 1999 | 10622430 |
| isolation and amino acid sequence of a phospholipase a2 inhibitor from the blood plasma of the sea krait, laticauda semifasciata. | a phospholipase a2 (pla2) inhibitor was purified from the blood plasma of a sea krait, laticauda semifasciata, by sequential chromatography on sephadex g-200, mono q, and phenyl sepharose columns. the purified inhibitor was found to be the same type as the pla2 inhibitors, named pligamma, that had been purified from the blood plasma of the thai cobra naja naja kaouthia [ohkura et al. (1994) biochem. biophys. res. commun. 200, 784-788] and chinese mamushi agkistrodon blomhoffii siniticus [ohkura ... | 1999 | 9990137 |
| molecular cloning and expression of a new a chain of beta-bungarotoxin. | the cdna encoding a new a chain of beta-bungarotoxin was cloned from bungarus multicinctus. it encoded a 27-amino acid signal peptide and a mature protein of 120 amino acids. the mature protein had the same 13 cysteines as the other a chains and shared high homology with them. the cdna encoding the pla(2) from naja naja atra was also cloned by the use of the same degenerate primers. the cdnas encoding the new a chain and the pla(2) were highly expressed in e. coli as soluble fusion proteins and ... | 1999 | 12110937 |
| comparison of three classes of snake neurotoxins by homology modeling and computer simulation graphics. | we present a systematic structure comparison of three major classes of postsynaptic snake toxins, which include short and long chain alpha-type neurotoxins plus one angusticeps-type toxin of black mamba snake family. two novel alpha-type neurotoxins isolated from taiwan cobra (naja naja atra) possessing distinct primary sequences and different postsynaptic neurotoxicities were taken as exemplars for short and long chain neurotoxins and compared with the major lethal short-chain neurotoxin in the ... | 1999 | 10198241 |
| lys49 phospholipase a2 myotoxins lyse cell cultures by two distinct mechanisms. | three lys49 phospholipase a2 (pla2) myotoxins from agkistrodon contortrix laticinctus (aclmt), bothrops jararacussu (bothropstoxin-i) and bothrops asper (myotoxin ii) snake venoms are enzymatically inactive on artificial substrates, yet addition of these toxins to cell cultures causes the release of fatty acids derived from the hydrolysis of membrane phospholipids. bothropstoxin-i treated with p-bromophenacyl bromide is no longer enzymatically active on cell cultures, suggesting the toxin, not t ... | 1998 | 9792171 |
| polybitoxins: a group of phospholipases a2 from the venom of the neotropical social wasp paulistinha (polybia paulista). | the neotropical wasp polybia paulistinha is very aggressive and endemic in south-east brazil, where it frequently causes stinging accidents. by using gel filtration on sephadex g-200, followed by ion-exchange chromatography on deae-cellulose under a ph gradient, a group of four toxins (designated as polybitoxins-i, ii, iii and iv) presenting phospholipase a2 (pla2) activities was purified. these toxins are dimeric with mol. wts ranging from 115,000 to 132,000 and formed by different subunits. th ... | 1998 | 9604292 |
| snake envenomation and protective natural endogenous proteins: a mini review of the recent developments (1991-1997). | the properties of several factors--antihaemorrhagic, antineurotoxic, antimyotoxic--isolated from the blood serum or plasma of different animals are described with more emphasis placed on the structural differences and similarities among the factors of the snake (trimeresurus flavoviridis) and mammals (didelphis marsupials and herpestes edwardsii). classification of antihaemorrhagic factors of snake and mammals according to structural homologies, and their effectiveness in neutralizing venom haem ... | 1998 | 9792161 |
| cardiolipin hydrolysis by human phospholipases a2. the multiple enzymatic activities of human cytosolic phospholipase a2. | the ability of mammalian phospholipases a2 (pla2) to hydrolyse cardiolipin (diphosphatidylglycerol) was monitored with a fluorescent displacement assay which allows the use of natural phospholipid substrates. the mammalian enzymes used were porcine pancreatic (group i) secretory pla2 (spla2), human non-pancreatic (group ii) spla2 and human cytosolic pla2 (cpla2). high activity was observed with porcine pancreas spla2 whereas the human spla2 demonstrated only minimal activity with this substrate. ... | 1998 | 9487141 |
| identification of diphtheria toxin via screening as a potent cell cycle and p53-independent cytotoxin for human prostate cancer therapeutics. | metastatic human prostate cancer requires novel therapeutic strategies in order to overcome its low proliferative rate and its resistance to conventional chemotherapeutic agents. to identify potential cytotoxin gene products for use in experimental therapeutics such as in vivo gene therapy, an in vitro screen was designed. | 1998 | 9496900 |
| purification and characterization of a new cystatin inhibitor from taiwan cobra (naja naja atra) venom. | cobra cystatin, a new cysteine-proteinase inhibitor of the cystatin superfamily, was isolated from the venom of the taiwan cobra (naja naja atra) by affinity chromatography on s-carboxymethylpapain-sepharose and reverse-phase chromatography. the venom contained two forms of the inhibitor, one of 11870 da and the other of 12095 da, as determined by ms, and pi values of 6.2 and 6.1. cobra cystatin strongly inhibits cysteine proteinases of the papain family, but not calpain. papain, cathepsin l, ca ... | 1998 | 9512485 |
| inhibition of secreted phospholipases a2 by annexin v. competition for anionic phospholipid interfaces allows an assessment of the relative interfacial affinities of secreted phospholipases a2. | the ability of annexins, particularly annexin 1 (lipocortin 1), to inhibit phospholipase a2 (pla2) is well known and a substrate depletion mechanism is now widely accepted as the explanation for most inhibitory studies. in this investigation we have examined the substrate depletion mechanism of annexin v using a variety of phospholipid substrates and secreted pla2's (spla2). the results suggest that the term interfacial competition best describes the inhibitory effect of annexin v although the o ... | 1998 | 9555096 |
| six isoforms of cardiotoxin in malayan spitting cobra (naja naja sputatrix) venom: cloning and characterization of cdnas. | cardiotoxins are the most abundant toxin components of cobra venom. although many cardiotoxins have been purified and characterized by amino acid sequencing and other pharmacological and biochemical studies, to date only five cardiotoxin cdnas from taiwan cobra (naja naja atra), three cdnas from chinese cobra (naja atra) and two more of uncertain origin (either chinese or taiwan cobra) have been reported. in this paper we show the existence of four isoforms of cardiotoxin by protein analysis and ... | 1998 | 9565688 |
| petrosaspongiolides m-r: new potent and selective phospholipase a2 inhibitors from the new caledonian marine sponge petrosaspongia nigra. | five new bioactive sesterterpenes (1-5) have been isolated from the new caledonian marine sponge petrosaspongia nigra bergquist and named petrosaspongiolides m-r. their chemical structures were determined from 1d and 2d nmr studies and ms data. all compounds inhibited different preparations of phospholipase a2 (pla2) by irreversibly blocking these enzymes (particularly human synovial and bee venom, see table 3), with ic50 values in the micromolar range. interestingly, these compounds displayed a ... | 1998 | 9599251 |
| suppression of inflammatory responses by surfactin, a selective inhibitor of platelet cytosolic phospholipase a2. | surfactin inhibits platelet and spleen cytosolic 100 kda phospholipase a2 (pla2). in contrast, this same compound enhances rat platelet group ii pla2 activity by approximately 2-fold and slightly increases group i pla2 activity from porcine pancreas and naja naja venom in vitro. surfactin does not affect a ca2+ -independent pla2 partially purified from bovine brain. thus, this compound inhibits selectively the cytosolic form of pla2. based on in vitro studies utilizing preincubation of surfactin ... | 1998 | 9605421 |
| isolation and characterization of an endogenous inhibitor of phospholipase a2 from indian cobra (naja naja naja) venom. | a pla2-inhibitor has been purified from indian cobra (naja naja naja) venom by the combination of ion-exchange and gel-filtration chromatography. the inhibitor, nn-i3 was a peptide with mol.wt 6500 and has a fluorescence emission maxima ca 340 nm. nn-i3 specifically inhibited the enzyme activity of the three acidic pla2 from the same venom. the inhibition of nn-i2d-pla2 and nn-i2c-pla2 by nn-i3 was of mixed type and nn-i2c-pla2 was of uncompetitive type. neither the inhibitor nor the individual ... | 1998 | 9643477 |
| purification and characterization of three acidic, cytotoxic phospholipases a2 from indian cobra (naja naja naja) venom. | three acidic phospholipases a2 (nn-i2c-pla2, nn-i2d-pla2 and nn-i2c-pla2) were purified by successive chromatography of indian cobra (naja naja naja) venom on cm-sephadex c-25, sephadex g-50 and qae sephadex a-25 columns. they have molecular weights of 13,000-14,500 by sodium dodecyl sulphate polyacrylamide gel electrophoresis. they showed tryptophan specific fluorescence emission spectra (approximately 345 nm). all the three phospholipases a2 were enzymatically highly active with specific activ ... | 1998 | 9663698 |
| conversion of tyrosine to phenolic derivatives by taiwan cobra venom. | we have examined the ability of taiwan cobra (naja naja atra) venom to transform in vitro the amino acid tyrosine to phenolic oxidation products via 4-hydroxyphenylpyruvate. this amino acid can be released from neuropeptide substrates by oligopeptidases present in the venom. using a variety of analytical techniques to probe a complicated series of reactions, we confirm that the l-amino acid oxidase present in the venom initially releases the keto form of 4-hydroxyphenylpyruvic acid and hydrogen ... | 1998 | 9690784 |
| chemically modified non-antimicrobial tetracyclines inhibit activity of phospholipases a2. | tetracyclines have been recognized as useful agents for therapy of inflammatory arthritides. however, prolonged use of tetracyclines is limited by their detrimental antimicrobial properties. recently, a group of chemically modified tetracyclines (cmt) devoid of antimicrobial properties has been synthesized. some cmt were found to inhibit various matrix metalloproteinases (mmp). we reported previously that antimicrobial tetracyclines inhibit the activity of proinflammatory secretory group ii phos ... | 1998 | 9733464 |
| characterization of phospholipase a2 (pla2) from taiwan cobra: isoenzymes and their site-directed mutants. | extracellular and secretory phospholipase a2 (pla2), a class of phospholipid digesting enzyme, is widely distributed in animal venoms of reptiles and insects. two cdnas encoding pla2 isoenzymes from taiwan cobra (naja naja atra) were cloned into pqe-30 plasmid vector and expressed in escherichia coli. the recombinant products were subjected to refolding using sulfonation under reduction/oxidation conditions with glutathione and enterokinase removal of his-tag, resulting in the active recombinant ... | 1998 | 9735349 |
| cdna sequence analysis and expression of four long neurotoxin homologues from naja naja atra. | the novel cdnas encoding four long neurotoxin homologues were firstly cloned from the venom gland of naja naja atra by reverse transcriptase-polymerase chain reaction. amino acid sequence comparison showed that they may come from two different evolutionary origins. the mature proteins were expressed as soluble fusion proteins in escherichia coli and purified for immunoblotting. the results revealed that they displayed different immunochemical properties. | 1998 | 9838137 |
| four new postsynaptic neurotoxins from naja naja sputatrix venom: cdna cloning, protein expression, and phylogenetic analysis. | cdnas encoding 4 short chain alpha-neurotoxins from malayan spitting cobra (naja naja sputatrix) venom were cloned and expressed in escherichia coli. the recombinant toxins possessed identical amino acid sequences to alpha-neurotoxins. this is the first report on cloning and expression of isoforms of neurotoxins from a species of spitting cobra. two of these isoforms were also identified in the crude venom by reverse phase-high performance liquid chromatography (rp-hplc), capillary electrophores ... | 1998 | 9839671 |
| the composition of naja naja venom samples from three districts of west bengal, india. | the variation in the composition of naja naja venoms from three neighbouring districts of west bengal, eastern india and the corresponding differences in the severity of pathogenesis due to venom composition variation are reported. these venom samples differ with respect to chromatographic elution profile and enzyme activity associated with each fraction. presence of higher quantities of basic phospholipase and plasma protein hydrolase in the venom samples of burdwan and purulia make them more t ... | 1998 | 11249011 |
| structure and organization of the cardiotoxin genes in naja naja sputatrix. | we report the genomic structure, organization and the presence of multiple isoforms of the gene encoding cardiotoxins (ctx) of naja naja sputatrix. the cardiotoxin gene consists of six ctx isoforms, each (2.2 kb) having three exons and two introns. two possible transcription initiation sites as well as consensus tata boxes and transcription factor binding motifs, ap-2, nfil-6/c/ebp, nf-kappab and puf have been identified in the 5'-region of the gene. the ctx gene isoforms show nucleotide variati ... | 1998 | 9738945 |
| structures of two novel crystal forms of naja naja naja phospholipase a2 lacking ca2+ reveal trimeric packing. | three crystal forms of naja naja naja phospholipase a2 were discovered through random crystallization screening, including two heretofore uncharacterized forms. the crystallization conditions for both of these novel crystal forms are ca(2+)-free whereas previously reported conditions include ca2+. one of the new crystal forms has a cubic lattice in the space group p2(1)3 (a = b = c = 69.24 a), the other has an orthorhombic lattice in the space group p2(1)2(1)2(1) (a = 67.22 a, b = 73.48 a, c = 8 ... | 1998 | 9636712 |
| labeling of torpedo californica nicotinic acetylcholine receptor subunits by cobratoxin derivatives with photoactivatable groups of different chemical nature at lys23. | different photoactivatable derivatives of toxin 3 (ctx) naja naja siamensis were obtained after ctx reaction with n-hydroxysuccinimide esters of p-azidobenzoic, p-azidotetraflourobenzoic, p-benzoylbenzoic and p-[3-(trifluoromethyl)-3h-diazirin-3-yl]benzoic acids. the ion-exchange hplc profiles for the reaction products were very similar in four cases, with one predominant peak corresponding to the derivative containing the label at lys23. after [125i]iodination, ctx photoactivatable derivatives ... | 1998 | 9578481 |
| characterization and cloning of long neurotoxin homolog from naja naja atra. | the cdna encoding a long neurotoxin homolog was constructed from the cellular rna isolated fom the venom glands of naja naja atra (taiwan cobra) by reverse transcription-polymerase chain reaction. blast searches for sequence similarity in the genbank databases reveal that the cdna sequence of the long neurotoxin homolog is not highly homologous with long and short neurotoxins. although the long neurotoxin homolog exhibited an activity to inhibit acetylcholine-induced muscle contractions as naja ... | 1998 | 9891854 |
| carbonothioate phospholipids as substrate for a spectrophotometric assay of phospholipase a2. | a continuous spectrophotometric assay for phospholipase a2 (pla2) was developed using novel carbonothioate phospholipids. these phospholipid analogues contain a carbonothioate bond in the place of the sn-2 ester of the natural substrates of phospholipase a2 and were synthesized in a one-pot two-step reaction. phospholipase a2 from cobra venom (naja naja atra) hydrolyzes carbonothioate phospholipids and liberates a free thiol, alkylmercaptan, which is reacted with 5,5'-dithiobis(2-nitrobenzoic ac ... | 1998 | 9866705 |
| identification of arg-30 as the essential residue for the enzymatic activity of taiwan cobra phospholipase a2. | taiwan cobra (naja naja atra) phospholipase a2 (pla2) was inactivated by arginine-specific reagents, phenylglyoxal and 1, 2-cyclohexanedione. kinetic analyses of the modification reaction revealed that the inactivation of pla2 followed pseudo-first-order kinetics and the loss of activity was correlated with the incorporation of one molecule of modification reagent per pla2 molecule. this was confirmed by the results of amino acid composition determination, that showed that a marked decrease in e ... | 1998 | 9756621 |
| enkephalin-processing oligopeptidases in cobra venom: inhibition by thiorphan and bestatin reveals co-operative actions. | the peptidase inhibitors thiorphan and bestatin were tested for their ability to inhibit the actions of the oligopeptidases contained in the venom of the taiwan cobra (naja naja atra). with methionine enkephalin (tyrglyglyphemet) as substrate, thiorphan was an effective inhibitor of cleavage of the glyphe peptide bond while bestatin inhibited cleavage of the tyrgly peptide bond. thiorphan and bestatin also inhibited subsequent cleavage of the fragments glyglyphemet and tyrglygly respectively. th ... | 1998 | 9655632 |
| unfolding and refolding of cardiotoxin iii elucidated by reversible conversion of the native and scrambled species. | cardiotoxin analogue iii (ctx iii) isolated from the venom of the taiwan cobra (naja naja atra) is a small molecular weight, all beta-sheet protein, cross-linked by four disulfide bridges. the unfolding and refolding mechanisms of ctx iii have been examined by monitoring the reversible conversion of the native and scrambled species. it is found that, in the presence of a denaturant (urea/guanidinium hydrochloride) and a thiol catalyst, ctx iii forms a mixture of scrambled species by shuffling it ... | 1998 | 9578558 |
| events in the kinetic folding pathway of a small, all beta-sheet protein. | the folding of cardiotoxin analogue iii (ctx iii), a small (60 amino acids), all beta-sheet protein from the venom of the taiwan cobra (naja naja atra) is here investigated. the folding kinetics is monitored by using a variety of techniques such as nmr, fluorescence, and circular dichroism spectroscopy. the folding of the protein is complete within a time scale of 200 ms. the earliest detectable event in the folding pathway of ctx iii is the formation of a hydrophobic cluster, which possess stro ... | 1998 | 9553067 |
| two novel alpha-neurotoxins isolated from taiwan cobra: sequence characterization and phylogenetic comparison of homologous neurotoxins. | two novel postsynaptic neurotoxins (alpha-neurotoxins) isolated and purified from the taiwan cobra venom (naja naja atra) possess distinct primary sequences and different neurotoxicities as compared with the most abundant and lethal component in the venom, i.e., cobrotoxin characterized before from the same venom. the complete sequences of two neurotoxin analogues were determined by n-terminal edman degradation and comparison of amino acid compositions of proteolytic toxin fragments with other h ... | 1998 | 9535272 |
| the role of acetic acid in the prevention of salt-induced aggregation of snake venom cardiotoxins. | snake venom cardiotoxins (ctxs) exhibit a strong tendency to aggregate upon desalting and hence it is extremely difficult to prepare salt-free cardiotoxin(s). in the present study, we describe a new method for preparation of salt-free ctx based on dialysis against acetic acid. based on experimental observation and the three dimensional solution structure of cardiotoxin analogue iii from the taiwan cobra (naja naja atra), a molecular mechanism for the prevention of aggregation of cardiotoxins by ... | 1998 | 9503145 |
| main-chain dynamics of cardiotoxin ii from taiwan cobra (naja naja atra) as studied by carbon-13 nmr at natural abundance: delineation of the role of functionally important residues. | cardiotoxin analogue ii (ctx ii) is an all beta-sheet, small molecular mass (6.8 kda), basic protein possessing a wide array of biological properties. nearly complete assignment of the protonated carbon resonances has been achieved by heteronuclear nmr experiments. the study shows that the correlation between the carbon-13 chemical shifts and ctx ii structure is good in general, but interesting deviations are also noticed. to characterize the internal dynamics of ctx ii, longitudinal, transverse ... | 1998 | 9425035 |
| elucidation of a new biological function of an old protein: unique structure of the cobra serum albumin controls its specific toxin binding activity. | although few proteins have been studies as thoroughly as serum albumin, a new biological property of this evolutionary ancient protein was recently discovered: the ability of cobra serum albumin (csa) to specifically sequester lethal endogenous toxins. a study of the structural basis of this property is reported in this contribution. two independent approaches were used to alter the structure of the csa at defined positions: directed mutagenesis and limited proteolysis. the conserved pattern of ... | 1998 | 9608676 |
| genomic structures of cardiotoxin 4 and cobrotoxin from naja naja atra (taiwan cobra). | two genomic dnas with the size of 2.3 kb and 2.4 kb, which were isolated from the liver of naja naja atra (taiwan cobra), encoded the precursors of cardiotoxin 4 and cobrotoxin, respectively. both genes shared virtually identical overall organization with three exons separated by two introns, which were inserted in the similar positions of the gene's coding regions. moreover, their nucleotide sequences shared approximately 84.2% identity. this result reveals the evolutionary relationship between ... | 1997 | 9367842 |
| cardiotoxin-like basic protein (clbp) from naja naja atra is not a cardiotoxin. | 1997 | 9403962 | |
| comparison of the hemolytic activity and solution structures of two snake venom cardiotoxin analogues which only differ in their n-terminal amino acid. | cardiotoxin analogues iv (ctx iv) and ii (ctx ii) isolated from the venom of taiwan cobra (naja naja atra) differ in their amino acid sequence by a single amino acid at the n-terminal end. leucine at the n-terminal end in ctx ii is replaced by arginine in ctx iv. ctx iv is an unique snake venom cardiotoxin as it is the only cardiotoxin isoform known so far which possesses a positively charged residue at the n-terminal amino acid. all other cardiotoxins have a hydrophobic amino acid (leucine or i ... | 1997 | 9398182 |
| specificity of helix-induction by 2,2,2-trifluoroethanol in polypeptides. | the specificity of helix-induction in polypeptides by 2,2,2-trifluoro ethanol (tfe) is studied using an all beta-sheet protein such as cardiotoxin analogue i (ctx i) from the taiwan cobra (naja naja atra) and a homopolymer such as poly-l-lysine. it is found that alcohols including tfe can 'non-specifically' induce helix at high concentrations both in ctx i and polylysine at neutral ph. however, among the alcohols used, only tfe could transform the heat-induced beta-sheet conformation of polylysi ... | 1997 | 9352368 |
| the action of taiwan cobra venom on methionine enkephalin: a useful assay for oligopeptidase content. | the pentapeptide methionine enkephalin is readily hydrolysed by the oligopeptidase activity contained in taiwan cobra (naja naja atra) venom. it is a significantly better substrate than the peptides previously used to identify the presence of this enzyme, but it retains many of the sequence characteristics shared by these other peptides. analysis of the manner of hydrolysis by means of high-performance liquid chromatography and electrospray mass spectrometry revealed the simultaneous actions of ... | 1997 | 9248009 |
| cdna sequence analysis of cardiotoxin variants from taiwan cobra. | five cdnas encoding cardiotoxin variants 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 nucleotide sequence homology was observed between these variants and other determined ones. among them, a novel cardiotoxin 6 had 61 amino acid residues rather than 60 ones that usually observed with naja naja atra cardiotoxins. the other cardiotoxin variants were the homologues of cardiotoxins 1, v o ... | 1997 | 9192088 |
| 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 |
| 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 |
| 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 |
| 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 |
| zanhasaponins a and b, antiphospholipase a2 saponins from an antiinflammatory extract of zanha africana root bark. | a meoh extract from z. africana was examined for topical antiinflammatory activity and proved to be active against arachidonic acid (aa) acute edema, 12-o-tetradecanoylphorbol 13-acetate (tpa)-induced chronic inflammation, and oxazolone delayed-type hypersensitivity in mice. the extract also showed significant inhibitory activity of naja naja phospholipase a2 when a polarographic method was used. two oleanane-type triterpene saponins, zanhasaponins a (1) and b (2), and the cyclitol pinitol (4), ... | 1997 | 9392883 |
| naja naja cobra bite. | most venomous snakes in the united states are of the crotalidae family. another family of snakes, the elapidae, are not so common, but their bites may be a threat to zoo keepers and persons who have exotic snakes as pets. because elapidae envenomation is not common, signs and symptoms of such envenomation may not be recognized. elapidae venom, because of a curare-like property, can produce respiratory compromise followed by death within 10 minutes. antivenin, cholinesterase inhibitors, and mecha ... | 1997 | 9288976 |
| 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 |
| 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 |
| 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 |
| 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 |
| the mechanism of 2,2,2-trichloroacetic acid-induced protein precipitation. | the mechanism of 2,2,2-trichloroacetic acid (tca)-induced precipitation of proteins is studied. the tca-induced protein precipitation curves are observed to be u-shaped. it is bound that the protein-precipitate-inducing effects of tca are due to the three chloro groups in the molecule. using cardiotoxin iii (ctx iii) isolated from the taiwan cobra (naja naja atra), as a model protein, we attempt to understand the molecular basis for the tca-induced effects. employing circular dichroism, proton-d ... | 1997 | 9188068 |
| variabilin: a dual inhibitor of human secretory and cytosolic phospholipase a2 with anti-inflammatory activity. | the marine product variabilin was identified as a novel inhibitor of phospholipase a2 (pla2), which exhibited ic50 values of 6.9 microm and 7.9 microm for human synovial secretory pla2 and u937 cells cytosolic pla2 activities, respectively. this compound was less potent on bee venom or zymosan-injected rat air pouch enzymes and failed to affect naja naja venom pla2. the production of leukotriene b4 by human neutrophils stimulated with calcium ionophore a23187 was also inhibited by variabilin, wh ... | 1997 | 9223548 |
| flavonoids as phospholipase a2 inhibitors: importance of their structure for selective inhibition of group ii phospholipase a2. | the inhibitory effect of the plant flavonoid, rutin, on group i phospholipase a2 (pla2-i) from porcine pancreas and naja naja, and on group ii phospholipase a2 (pla2-ii) from vipera russelli and crotalus atrox was investigated. rutin efficiently inhibited pla2-ii from both vipera russelli and crotalus atrox but was only a weak inhibitor of pla2-i from porcine pancreas and naja naja. the lack of strong inhibition of pancreatic pla2-i was not due to contaminating proteins in the enzyme preparation ... | 1997 | 9246576 |
| a study of epidemiology, risk factors and preventive measures against snake bites. | the epidemiology and exposing causes of snake bites were studied in 274 patients between 1 january 1982 and 30 december 1990. they comprised 142 males (51.82%) and 132 females (48.18%). their ages ranged from 1 month to 86 years old. the age group most frequently bitten found in this study was between 15 to 29 years old amounting to 106 cases (38.69%). of those 274 cases, 212 (77.37%) were the victims of poisonous snakes, namely, the green pit viper (trimeresurus spp.) 156 cases (73.58%), the co ... | 1997 | 9347666 |
| the hydrolysis of phosphatidyl-alcohols by phospholipases a2: effect of head group size and polarity. | the ability of a variety of secretory phospholipases a2 (spla2: ec 3.1.1.4) to bind to and hydrolyse a series of phosphatidyl-alcohol substrates, in the absence of detergent, was explored by both fluorescence-based kinetic and interfacial binding assays. the enzymes used were spla2 from porcine pancreas, naja naja venom and a recombinant human non-pancreatic enzyme. four dioleoyl phosphatidyl-alcohols were used with different headgroups, methanol, ethanol, propanol and butanol. comparative kinet ... | 1997 | 9393676 |
| presynaptic snake beta-neurotoxins produce tetanic fade and endplate potential run-down during neuromuscular blockade in mouse diaphragm. | the present study investigated the ability of a number of presynaptic snake neurotoxins (snake beta-neurotoxins) to produce nerve-evoked train-of-four fade, tetanic fade and endplate potential run-down during the development of neuromuscular blockade in the isolated mouse phrenic-hemidiaphragm nerve-muscle preparation. all the snake beta-neurotoxins tested, with the exception of notexin, produced train-of-four and tetanic fade of nerve-evoked isometric muscle contractions. train-of-four fade was ... | 1997 | 9402043 |
| molecular mechanics calculations of proteins. comparison of different energy minimization strategies. | a general strategy for performing energy minimization of proteins using the sybyl molecular modelling program has been developed. the influence of several variables including energy minimization procedure, solvation, dielectric function and dielectric constant have been investigated in order to develop a general method, which is capable of producing high quality protein structures. avian pancreatic polypeptide (app) and bovine pancreatic phospholipase a2 (bp pla2) were selected for the calculati ... | 1997 | 9439995 |
| cytotoxic activity of acetylcholine receptor ligands. | acetylcholine receptor ligands were studied for cytotoxicity in k562 human erythroid leukemia tumor cells. cytotoxicity of carbachol, an agonist of acetylcholine receptors, atropine, an antagonist of muscarinic acetylcholine receptor, neurotoxin 11 (nt ii) from naja naja oxiana cobra venom and tubocurarine, antagonists of acetylcholine receptor of nicotinic type was exhibited in the 10-7-10-5 m concentration range. several cytolytic processes, two for carbachol and three for other ligands, corre ... | 1997 | 19856291 |
| a novel neurotoxin, cobrotoxin b, from naja naja atra (taiwan cobra) venom: purification, characterization, and gene organization. | a novel neurotoxin, cobrotoxin b, was isolated from naja naja atra (taiwan cobra) venom by successive chromatographies on gel filtration and sp-sephadex c-25 columns. the yield of this novel toxin was 5% of that of cobrotoxin from the same venom. its neurotoxicity determined as the inhibition of acetylcholine-induced muscle contractions was approximately 50% of that of cobrotoxin. cobrotoxin b consists of 61 amino acid residues including 8 cysteine residues. moreover, there are 12 amino acid sub ... | 1997 | 9498573 |
| novel snornas from naja naja atra (taiwan cobra) and bungarus multicinctus (taiwan banded krait), form extended sequence complementarity to 5s rrna. | during the mapping and sequencing of naja naja atra cobrotoxin and cardiotoxin 4 genes, we have found that novel small nucleolar rnas (snornas) are encoded in the first intron of the two genes. the snornas in naja naja atra were amplified from the venom glands cdna mixtures of naja naja atra by reverse transcription-polymerase chain reaction using the primers designed from the first intronic sequences of cobrotoxin and cardiotoxin 4 genes. likewise, the snornas in bungarus multicinctus were also ... | 1997 | 9245733 |
| 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 |
| 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 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 |
| enzymatic activities of some snake venoms from families elapidae and viperidae. | alkaline phosphomonoesterase, phosphodiesterase, l-amino acid oxidase, hyaluronidase, 5'-nucleotidase, arginine ester hydrolase, phospholipase a2 and proteinase activities were determined in eight snake venoms, including three from sea snake, of families elapidae and viperidae from pakistan. the species includes three sea snakes hydrophis cyanocinctus, enhydrina schsitosa, microcephalophis gracilis gracilis and two land snakes naja naja naja, bungarus caeruleus of family elapidae while three lan ... | 1996 | 16414774 |
| 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 |
| [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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| [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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |