Raghothama, S and Chaddha, Manjula and Banumathi, S and Ravikumar, Krishnan and Velmurugan, D and Balaram, P (1998) Conformational Interconversions in Peptide beta-Turns: Discrimination Between Enantiomeric Conformations by Chiral Perturbation. In: Biopolymers, 45 (3). pp. 191-202.
|
PDF
enantiomeric.pdf Download (222kB) |
Abstract
The crystal structure of the model tripeptide Boc-Aib-Gly-Leu-OMe (1) reveals two independent molecules in the asymmetric unit that adopt ‘‘enantiomeric’’ type I and type I’ beta-turn conformations with the Aib and Gly residues occupying the corner ( i / 1 and I / 2) positions. 13C cross polarization and magic angle sample spinning spectra in the solid state also support the coexistence of two conformational species. 13C-nmr in CDCl3 establishes the presence of a single species or rapid exchange between conformations. 400 MHz 1H-nmr provides evidence for conformational exchange involving a major and minor species, with beta-turn conformations supported by the low solvent exposure of Leu(3) NH and the observation of NiH - Ni/1H nuclear Overhauser effects. CD bands in the region 190–230 nm are positive, supporting a major population of type I’ beta-turns. The isomeric peptide, Boc-Gly-Leu-Aib-Ome (2) , adopts an ‘‘open’’ type II’ b-turn conformation in crystals. Solid state and solution nmr support population of a single conformational species. Chiral perturbation introduced outside the folded region of peptides may provide a means of modulating screw sense in achiral sequences.
Item Type: | Journal Article |
---|---|
Publication: | Biopolymers |
Publisher: | John Wiley & Sons, Inc |
Additional Information: | Copyright for this article belongs to John Wiley & Sons, Inc. |
Keywords: | Conformational interconversions;Peptide beta-turns;Enantiomeric conformations;Chiral perturbations |
Department/Centre: | Division of Biological Sciences > Molecular Biophysics Unit Division of Chemical Sciences > Sophisticated Instruments Facility (Continued as NMR Research Centre) |
Date Deposited: | 12 Oct 2004 |
Last Modified: | 19 Sep 2010 04:16 |
URI: | http://eprints.iisc.ac.in/id/eprint/2093 |
Actions (login required)
View Item |