| 摘要 |
A new family Here we report a new family of four-cystine/three-loop conotoxins (designated framework 14). Three peptides of this family (flfl4a-c) were isolated from the venom of Conus floridanus floridensis and one (vill4a) from the venom of Conus villepinii, two worm-hunting Western Atlantic cone snail species. CD spectra and nanoNMR spectroscopy of these conotoxins directly isolated from the cone snails revealed a highly helical secondary structure for the four conotoxins. Sequence-specific nanoNMR analysis at room temperature revealed a well-defined helix-loop-helix tertiary structure that resembles that of the Cs a/a scorpion toxins ?-hefutoxin, K-KTx1.3 and Om-toxins, which adopt a stable three-dimensional fold where the two a-helices are linked by the two disulfide bridges. One of these conotoxins (vill4a) has a Lys/Tyr (or Phe) diad, separated by approximately 6Å, which is a conserved structural feature in K+ channel blockers. |
