期刊
CHEMISTRY-A EUROPEAN JOURNAL
卷 20, 期 17, 页码 5075-5086出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/chem.201303687
关键词
amino acids; aromatic-proline interactions; beta turns; disulfides; peptides
资金
- Council of Scientific and Industrial Research (CSIR), India
- INSPIRE faculty fellowship, DST, Government of India
- DBT, Government of India
A novel peptide containing a single disulfide bond, CIWPWC (Vi804), has been isolated and characterised from the venom of the marine cone snail, Conus virgo. A precursor polypeptide sequence derived from complementary DNA, corresponding to the M-superfamily conotoxins, has been identified. The identity of the synthetic and natural peptide sequence has been established. A detailed analysis of the conformation in solution is reported for Vi804 and a synthetic analogue, (CIWPWC)-W-D ((D)W3-Vi804), in order to establish the structure of the novel WPW motif, which occurs in the context of a 20-membered macrocyclic disulfide. Vi804 exists exclusively in the cis W3P4 conformer in water and methanol, whereas (D)W3-Vi804 occurs exclusively as the trans conformer. NMR spectra revealed a W3P4 typeVI turn in Vi804 and a typeII turn in the analogue peptide, (D)W3-Vi804. The extremely high-field chemical shifts of the proline ring protons, together with specific nuclear Overhauser effects, are used to establish a conformation in which the proline ring is sandwiched between the flanking Trp residues, which emphasises a stabilising role for the aromatic-proline interactions, mediated predominantly by dispersion forces.
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