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The amino acid sequences of erabutoxins, neurotoxic proteins of sea-snake (Laticauda semifasciata) venom.

ABSTRACT: 1. Erabutoxin b was reduced, S-carboxymethylated and hydrolysed with trypsin. Seven tryptic fragments were isolated by column chromatography and paper electrophoresis. Some of the fragments were further hydrolysed with alpha-chymotrypsin, pepsin, Nagarse, Proctase A or Proctase B. The amino acid sequences of the fragment peptides were determined by subtractive Edman degradation. 2. From the tryptic digest of reduced, S-carboxymethylated and trifluoroacetylated erabutoxin b two fragments were isolated. From the amino acid composition of the fragments and from the terminal sequence studies on the reduced and S-carboxymethylated erabutoxin b, the sequence of the above seven tryptic fragments was elucidated. 3. The tryptic digestion of reduced and S-carboxymethylated erabutoxin a gave fragments, only one of which was different from the corresponding fragment from erabutoxin b. The amino acid sequence analysis of the fragment peptide showed that the only difference between erabutoxins a and b was that the former had asparagine and the latter had histidine at position 26.

SUBMITTER: Sato S

PROVIDER: S-EPMC1176801 | biostudies-other | 1971 May

REPOSITORIES: biostudies-other

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Correction of the amino acid sequences of erabutoxins from the venom of the sea snake Laticauda semifasciata.

Project description:The amino acid sequences of erabutoxins a and b were reinvestigated. The previously reported sequences of Gln-His at positions 6 and 7, and of Pro-Ser at positions 18 and 19 of erabutoxins a and b were corrected to His-Gln and Ser-Pro respectively.

| S-EPMC1144790 | biostudies-other

Studies on sea-snake venoms. Crystallization of erabutoxins a and b from Laticauda semifasciata venom.

Project description:1. The toxic principles in the venom of the sea-snake Laticauda semifasciata were separated into two components by CM-cellulose chromatography and obtained in crystalline forms. They were named ;erabutoxins a and b'. 2. The homogeneity of each toxin was shown by rechromatography, by disk electrophoresis, by ultracentrifuging, by toxicity measurements before and after repeated crystallizations and by N-terminal analysis. 3. They had molecular weights of about 7000. Both of them contained 61 (or 62) amino acid residues/molecule. The only difference between erabutoxins a and b was that one of the aspartic acid (or asparagine) residues in erabutoxin a was replaced by a histidine residue in erabutoxin b. 4. Both of the toxins had LD(50) values of 0.15mug./g. body wt. for mice and 0.07mug./g. for rats. It was shown with frog-muscle preparations that they acted on postsynaptic membrane to block neuromuscular transmission.

| S-EPMC1265051 | biostudies-other

The disulphide bonds of erabutoxin a, a neurotoxic protein of a sea-snake (Laticauda semifasciata) venom.

Project description:Erabutoxin a was partially hydrolysed with enzymes and sulphuric acid and the resulting peptides were separated from each other by column chromatography and paper electrophoresis. From the results of amino acid analyses of the sulphur-containing peptides and their oxidized components, all four disulphide bridges in the toxin molecule were located. The disulphide bonds were found between half-cystine residues at positions 3 and 24, 17 and 41, 43 and 54, and 55 and 60 from the N-terminus.

| S-EPMC1176802 | biostudies-other

Amino acid sequences of three phospholipases A I, III and IV from the venom of the sea snake Laticauda semifasciata.

Project description:Amino acid sequences of three phospholipases A, I, III and IV, from the venom of the sea snake Laticauda semifasciata were elucidated. Each protein consisted of a single chain of 118 amino acid residues, including 14 half-cystine residues. They showed high homology among themselves, and with the other snake-venom phospholipases A and with the enzymes from mammalian pancreas. Phospholipases A III and IV were especially similar to each other, with only four differences out of their 118 amino acid residues. Phospholipase A I contained one tryptophan residue at position 64, which was important for enzymic activity, whereas III and IV did not contain tryptophan residues and their corresponding positions were occupied by leucine residues. The substitution by leucine resulted in a decreased, but definite, phospholipase A activity. The substituted enzymes have a more potent neuromuscular blocking activity. Full experimental details and evidence for the amino acid sequences of the proteins have been deposited as Supplementary Publication SUP 50118 (39 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem.J. (1981) 193, 5.

| S-EPMC1153902 | biostudies-other

The primary structure of the toxin Laticauda semifasciata III, a weak and reversibly acting neurotoxin from the venom of a sea snake, Laticauda semifasciata.

Project description:A weak and reversibly acting neurotoxic protein of Laticauda semifasciata venom, Laticauda semifasciata III (component LsIII), was sequenced. Component LsIII consists of 66 amino acid residues and has five disulphide bridges, one of which was located between residues 26 and 30. The weak and reversible neurotoxicity of component LsIII is discussed in relation to its structure, which falls between those of the neuro- and cardiotoxins of sea snakes and Elapidae snakes isolated and sequenced so far.

| S-EPMC1168091 | biostudies-other

Amino acid sequences of two novel long-chain neurotoxins from the venom of the sea snake Laticauda colubrina.

Project description:From the venom of a population of the sea snake Laticauda colubrina from the Solomon Islands, a neurotoxic component, Laticauda colubrina a (toxin Lc a), was isolated in 16.6% (A280) yield. Similarly, from the venom of a population of L. colubrina from the Philippines, a neurotoxic component, Laticauda colubrina b (toxin Lc b), was obtained in 10.0% (A280) yield. The LD50 values of these toxins were 0.12 microgram/g body wt. on intramuscular injection in mice. Toxins Lc a and Lc b were each composed of molecules containing 69 amino acid residues with eight half-cystine residues. The complete amino acid sequences of these two toxins were elucidated. Toxins Lc a and Lc b are different from each other at five positions of their sequences, namely at positions 31 (Phe/Ser), 32 (Leu/Ile), 33 (Lys/Arg), 50 (Pro/Arg) and 53 (Asp/His) (residues in parentheses give the residues in toxins Lc a and Lc b respectively). Toxins Lc a and Lc b have a novel structure in that they have only four disulphide bridges, although the whole amino acid sequences are homologous to those of other known long-chain neurotoxins. It is remarkable that toxins Lc a and Lc b are not coexistent at the detection error of 6% of the other toxin. Populations of Laticauda colubrina from the Solomon Islands and from the Philippines have either toxin Lc a or toxin Lc b and not both of them.

| S-EPMC1153851 | biostudies-other

The isolation of an easily reversible post-synaptic toxin from the venom of a sea snake, Laticauda semifasciata.

Project description:A weakly neurotoxic component (Ls-III) was isolated by CM-cellulose column chromatography from the venom of a sea snake Laticauda semifasciata. The content of component LsIII was about 10-20% of the venom as determined by u.v. absorption at 280nm. Component LsIII was homogeneous on rechromatography and disc electrophoresis, and its molecular weight was shown to be 7100 by ultracentrifugation and 7300 by sodium dodecyl sulphate-polyacrylamide-gel disc electrophoresis. The isoelectric point of component LsIII was pH7.2. Component LsIII consisted of 66 amino acid residues including 10 half-cystine residues. The LD(50) of component LsIII by intramuscular injection was 1.24mug/g body wt. for mice and 0.45mug/g for baby chicks, which is about eight to ten times less toxic than erabutoxins a, b and c, all of which are contained in the same venom. Experiments with three isolated muscle preparations from different species indicated that component LsIII was a post-synaptically acting toxin, the action of which was easily reversed by washing.

| S-EPMC1168090 | biostudies-other

Northward dispersal of sea kraits (Laticauda semifasciata) beyond their typical range.

Project description:Marine reptiles are declining globally, and recent climate change may be a contributing factor. The study of sea snakes collected beyond their typical distribution range provides valuable insight on how climate change affects marine reptile populations. Recently, we collected 12 Laticauda semifasciata (11 females, 1 male) from the waters around southern South Korea-an area located outside its typical distribution range (Japan, China including Taiwan, Philippines and Indonesia). We investigated the genetic origin of Korean specimens by analyzing mitochondrial cytochrome b gene (Cytb) sequences. Six individuals shared haplotypes with a group found in Taiwan-southern Ryukyu Islands, while the remaining six individuals shared haplotypes with a group encompassing the entire Ryukyu Archipelago. These results suggest L. semifasciata moved into Korean waters from the Taiwan-Ryukyu region via the Taiwan Warm Current and/or the Kuroshio Current, with extended survival facilitated by ocean warming. We highlight several contributing factors that increase the chances that L. semifasciata establishes new northern populations beyond the original distribution range.

| S-EPMC5482473 | biostudies-literature

The isolation, properties and amino acid sequence of erabutoxin c, a minor neurotoxic component of the venom of a sea snake Katicauda semifasciata.

Project description:Erabutoxin c, a minor neurotoxic component of the venom of a sea snake Laticauda semifasciata, was isolated in pure form by repeated column chromatography on CM-cellulose columns. The toxin was crystallizable and monodisperse in rechromatography, disc electrophoresis and isoelectric focusing (isoelectric point, pH9.23-9.25). The molecular weight of the toxin, as estimated by gel filtration, was 7000. The toxin showed the same lethal activity to mice (0.13mug/g body wt., intramuscular injection) and the same effect on isolated frog muscle as erabutoxins a and b, the main toxic components of the venom. The toxin inhibited the acetylcholine contracture but not the potassium chloride contracture of muscle. Erabutoxin c consisted of 62 amino acid residues, containing one fewer lysine and one more histidine than erabutoxin a and one fewer lysine and one more aspartic acid (or asparagine) than erabutoxin b. Erabutoxin c was reduced, S-carboxymethylated and hydrolysed with trypsin. The only fragment different from the corresponding fragments from erabutoxin b was hydrolysed further with pepsin. One of the peptic fragments, which was assumed to have the aspartic acid (or asparagine) residue in question at the C-terminal end, was treated with carboxypeptidase A. The C-terminal residue was found to be an asparagine. It was therefore concluded that erabutoxin c was [51-asparagine]-erabutoxin b.

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Studies on sea snake venom.

Project description:Erabutoxins a and b are neurotoxins isolated from venom of a sea snake Laticauda semifasciata (erabu-umihebi). Amino acid sequences of the toxins indicated that the toxins are members of a superfamily consisting of short and long neurotoxins and cytotoxins found in sea snakes and terrestrial snakes. The short neurotoxins to which erabutoxins belong act by blocking the nicotinic acetylcholine receptor on the post synaptic membrane in a manner similar to that of curare. X-ray crystallography and NMR analyses showed that the toxins have a three-finger structure, in which three fingers made of three loops emerging from a dense core make a gently concave surface of the protein. The sequence comparison and the location of essential residues on the protein suggested the mechanism of binding of the toxin to the acetylcholine receptor. Classification of snakes by means of sequence comparison and that based on different morphological features were inconsistent, which led the authors to propose a hypothesis "Evolution without divergence."

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