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The complete amino acid sequence of toxin III of Naja haje (72 residues) has been established mainly by use ora protein sequenator (identification of 70 residues). The two C-terminal residues have been determined by digestion with carboxypeptidases A and B. Addition of succinylated protein or peptide greatly improved the performance of the sequenator for the Edman degradation of peptides: on one peptide (39 residues) degradation went to step 34 with a protein program and on two peptides (10 and 13 residues) degradation reached the last amino acid with a peptide program (use of dimethylbenzylamine). Amino acid analysis of tryptic peptides obtained by digestion of the C-terminal cyanogen bromide peptide are in full agreement with the sequence established by automatic degradation. The sequence of toxin III of Naja haje is unique and is very similar to that of Naja nivea α (although there are 9 differences), of Naja melanoleuca b (11 differences) and also to that of Naja naja A (18 differences). [ABSTRACT FROM AUTHOR]

Six neurotoxins were purified from Dendroaspis viridis venom using gel filtration and equilibrium chromatography. The amino acid sequences of two of these neurotoxins (72 and 73 residues, five disulphide bridges) have been determined using almost exclusively automated Edman degradation. These two sequences are very similar: the only difference lies in the presence of one extra glycine at the C-terminal end of one of them. There is a good homology with the sequences of toxins now isolated from other Elapidae and Hydrophidae venoms. [ABSTRACT FROM AUTHOR]

The apamin sequence has been synthesized by the solid-phase procedure. The synthetic peptide showed the same physicochemical and chemical properties as natural apamin in the following tests: paper electrophoresis, amino acid analyses after acid and enzymatic hydrolyses, sequence analysis, electrophoreses after tryptic and chymotryptic digestions. Synthetic apamin was as active as natural apamin in the neurotoxic assay in mice (LD50, after subcutaneous injection, for the 20-g mouse: 58 μg). [ABSTRACT FROM AUTHOR]

The positions of the disulfide bridges in toxin Il of Androctonus australis Hector were investigated using proteolytic enzymes. The resulting peptides were separated by column and paper chromatography and high-voltage electrophoresis. Determination of the amino acid compositions of the cystinecontaining peptides or their oxidized derivatives and, when necessary, dansyl Edman degradation allowed to locate the disulfide bonds in the toxin. The four disulfide bridges were found to link the half-cystine residues number 12 and 63, 16 and 36, 22 and 46, 26 and 48. These positions are probably the same in all scorpion neurotoxins. [ABSTRACT FROM AUTHOR]

The purification of eleven neurotoxins from the venom of three scorpions (Androctonus australis Hector, Buthus occitanus tunetanus and Leiurus quinquestriatus quinquestreatus) has been performed by Sephadex G-50 filtration (with and without recycling) and equilibrium chromatography on Amberlite CG-50, CM-Sephadex C-50 and DEAE-Sephadex A-50. All the chromatographic steps were carried out in ammonium acetate buffers. Purity of the neurotoxins was assessed by amino acid analysis and zone electrophoresis. All have a molecular weight of about 7000 daltons and do not contain methionine. As shown by amino acid composition and chain length scorpion neurotoxins show a high degree of homology. [ABSTRACT FROM AUTHOR]

The complete amino acid sequence of neurotoxin I of the North African scorpion Androctonus australis Hector collected in Algeria (area of Chellala) is described. S-Methylation of cysteine residues formed by reduction of disulphide bonds was found useful for their identification in sequence determination using the phenylisothiocyanate method. From the N-terminal sequence (38 residues) established in the protein sequenator, and from the sequence of chymotryptic peptides the complete sequence of the protein has been deduced. The molecule consists of a single polypeptide chain cross-linked by four disulphide bridges. An isoneurotoxin (I') has been found in the venom of A. australis collected in Tunisia (area of Tozeur). It differs from neurotoxin I in the replacement, of the valine residue in position 17 by an isoleucine residue. [ABSTRACT FROM AUTHOR]

The complete amino acid sequence of neurotoxin II of the North African scorpion Androctonus auatratis Hector has been determined. From the N-terminal sequence (43 residues) obtained by automatic phenylisothiocyanate degradation in the protein sequenator, and from the sequence of tryptic peptides obtained by digestion of the reduced and methylated toxin of which amino groups had been previously masked by reaction with ethylthioltrifluoroacetate the complete amino acid sequence of the protein has been inferred. It is composed of a single polypeptide chain of 64 amino acid residues, including 8 half-cystines, ended by an histidinamide residue at the C-terminus. [ABSTRACT FROM AUTHOR]