Gamma-carboxyglutamate in a neuroactive toxin.

TLDR

Let's collect content. Lines: 1: [Background, Mechanism, Findings] The venom of a fish-hunting cone snail (Conus geographus) contains a novel toxin, the "sleeper" peptide, which induces a sleep-like state in mice when injected intracerebrally.We demonstrate that this peptide contains 5 mol of y-carboxyglutamate (Gla) in 17 amino acids.The amino acid sequence of the sleeper peptide isGly-Glu-Gla-Gla-Leu-Gln-Gla-Asn-Gln-Gla-Leu-Ile-Arg-Gla-Lys-Ser-Asn-NH2.We have described the isolation and properties of a variety of peptide toxins from the venoms of two piscivorous snails, Conus geogruphus Linn.and C. magus Linn.(1-4). 2: [Background, Mechanism] '*'Most recently we reported3 the purification of a peptide from C.

Abstract

The venom of a fish-hunting cone snail (Conus geographus) contains a novel toxin, the "sleeper" peptide, which induces a sleep-like state in mice when injected intracerebrally.We demonstrate that this peptide contains 5 mol of y-carboxyglutamate (Gla) in 17 amino acids.The amino acid sequence of the sleeper peptide isGly-Glu-Gla-Gla-Leu-Gln-Gla-Asn-Gln-Gla-Leu-Ile-Arg-Gla-Lys-Ser-Asn-NH2.We have described the isolation and properties of a variety of peptide toxins from the venoms of two piscivorous snails, Conus geogruphus Linn.and C. magus Linn.(1-4). '*'Most recently we reported3 the purification of a peptide from C. geogruphus that has a most remarkable biological activity, i.e. intracerebral injection of submicrogram amounts into young mice induces a prolonged sleep-like state.Unlike the other toxins we have found, this peptide lacks disulfide bridges and is extremely acidic rather than basic.We report here the complete amino acid sequence of the sleeper peptide, conotoxin GV, which is as remarkable as the biological activity; it contains five residues of y-carboxyglutamate in a total of 17 amino acids and has a net charge of -8 at pH 7. MATERIALS AND METHODSIsolation of Peptide-Purification was carried out by Method I1 of Olivera et al.? using gel filtration on Sephadex G-25, and reversephase HPLC.Bioassays were also performed as described in that paper.Amino Acid Analysis-Authentic DL-y-carboxyglutamate was obtained from Sigma.A quantitative standard was prepared and analyzed on a Beckman 121C amino acid analyzer both before and after hydrolysis to glutamic acid (5.7 N HCl, 18 h, 110 "C).Peptide samples were hydrolyzed in vacuo in 5.7 N HCl (18 h, 110 "C), or in 2 N KOH (22 h, 110 "C).In the latter case, samples were placed in small polypropylene tubes (Eppendorfj which were enclosed in a sealed, evacuated desiccator containing a reservoir of 2 N KOH.The volumes were kept below 0.15 ml so that no desalting