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Conformational Analysis of a 20-Membered Cyclic Peptide Disulfide from Conus virgo with a WPW Segment: Evidence for an Aromatic-Proline Sandwich

Sonti, Rajesh and Rao, Shashanka K N and Chidanand, Sudarshan and Gowd, Konkallu Hanumae and Raghothama, Srinivasarao and Balaram, Padmanabhan (2014) Conformational Analysis of a 20-Membered Cyclic Peptide Disulfide from Conus virgo with a WPW Segment: Evidence for an Aromatic-Proline Sandwich. In: CHEMISTRY-A EUROPEAN JOURNAL, 20 (17). pp. 5075-5086.

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Official URL: http://dx.doi.org/10.1002/chem.201303687

Abstract

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.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the WILEY-V C H VERLAG GMBH, BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY
Keywords: amino acids; aromatic-proline interactions; beta turns; disulfides; peptides
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Division of Chemical Sciences > NMR Research Centre (Formerly Sophisticated Instruments Facility)
UG Programme
Depositing User: Id for Latest eprints
Date Deposited: 24 Jun 2014 07:25
Last Modified: 24 Jun 2014 07:25
URI: http://eprints.iisc.ac.in/id/eprint/49320

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