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

ABSTRACT: 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.

SUBMITTER: Maeda N

PROVIDER: S-EPMC1168091 | biostudies-other | 1974 Aug

REPOSITORIES: biostudies-other

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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

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

Project description: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.

| S-EPMC1176801 | 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.

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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.

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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.

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

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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.

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Unusual amino acid sequence of fasciatoxin, a weak reversibly acting neurotoxin in the venom of the banded krait, Bungarus fasciatus.

Project description:A weak reversibly acting neurotoxin, fasciatoxin, was found in the venom of Bungarus fasciatus. The sequencing was completed by manual and automated Edman analyses of the reduced and carboxymethylated protein and of the peptides obtained from enzyme digestions. It is composed of 63 amino acid residues with four disulphide bonds and a unique sequence at the C-terminal end. According to the criteria set by Ryden, Gabel & Eaker [(1973) Int. J. Pept. Protein Res. 5, 261-273], fasciatoxin lacks all of the five functionally invariant residues of neurotoxins. The hydropathy index indicates that fasciatoxin is devoid of a strong hydrophilicity domain for binding to the receptor site. Structural comparison with some typical neurotoxins also reveals the uniqueness of fasciatoxin in that the extent of similarity is only about 30%.

| S-EPMC1138485 | biostudies-other

Studies on sea snake venom.

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Comparison of sea snake (Hydrophiidae) neurotoxin to cobra (Naja) neurotoxin.

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