Mass spectrometric‐based revision of the structure of a cysteine‐rich peptide toxin with γ‐carboxyglutamic acid, TxVIIA, from the sea snail, Conus textile

A mollusk‐specific toxin, TxVIIA, having potent paralytic activity was isolated from the venom of sea snail Conus textile (Fainzilber M et al., 1991, Eur J Biochem 202:589–595). The structure reported above was based upon amino acid analysis and the Edman degradation. We have recently reinvestigated this toxin employing some of the most novel techniques in mass spectrometry. We now report a revised structure based primarily on high‐energy collision‐induced dissociation analysis of the two Asp17‐N peptides of the reduced, pyridinylethyl derivative representing the entire sequence using matrix‐assisted laser desorption ionization (MALDI) as CGGYSTYCγVDSγ CCSDNCVRSYCTLF‐NH2 (γ, γ‐carboxyglutamic acid or Gla).

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