| Research Abstract |
(1)Synthesis and disulfide pairing determination of novel conotoxins from cone snail.
We synthesized three novel conotoxins CMrII, CMrIII, and CMrV isolated from Cones marmoreus. All of them have three intramolecular disulfide bonds. In order to determine the disulfide pairings, we synthesized CMrII by selective two-step disulfide bond formation method. HPLC co-elution with native peptide suggested that CMrII has C1-C4, C2-C5, and C3-C6 combinations. Whereas, it was suggested that CMrV has different disulfide patterns. Re-examination is in progress for CMrV.
Four novel conotoxins, AmIV, AmVIIA, AmVIIB, and AmIX were isolated from C. amadis by foreign collaborators. Both C-terminal amidated and free peptides were synthesized for AmIV and AmIX. HPLC co-elution indicated that AmIV and AmIX had free and amidated C-terminals, respectively. AmVIIA and AmVIIB were synthesized and shown to have free C-terminals.
(2)Relationships of disulfide pattern, three-dimensional structure and activity of sc
… More
orpion toxins.
Hefutoxin-1 isolated from scorpion Heterometrus fuIvipes adopts a unique three-dimensional fold of two parallel helices linked by two disulfide bridges without any βsheets. We synthesized two analogs of hefutoxin-1 with deletion of one or two amino acid residues at the central loop region. Enzymatic digestion of deletion analogs showed that both of them have the same disulfide pairings as native peptides. Several analogs with amino acid substitution were synthesized for structure-activity relationship study.
Five novel peptide toxins HS2388, HS2404, HS2620, HS3019, and HS3700 were isolated from scorpion H, spinifer venom. We synthesized all of them and confirmed that HS2388 and HS2404 have amidated C-terminals, whereas others have free C-terminals. Comparison of CD spectra and enzymatic digestion suggested that HS2388, HS2404, HS2620, and HS3019 have the same disulfide pattern as that of hefutoxin-1. Synthetic analogs of HS2620 suggested that the basic residue at the 20th position interfere the interaction of this toxin to K channels. Less
|
