ISSN:
0006-3525
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
In an effort to explore the residue preferences in three-residue reverse turns (so-called -γ-turns), two cyclic pentapeptides - cyclo(Gly1-Pro2-D-Phe3-Gly4-Ala5) (I) and cyclo (Gly1-Pro2-D-Phe3-Gly4-Val5) (II) - have been synthesized and analyzed by nmr. It was anticipated that the Gly-Pro-D-Phe-Gly portions of these molecules would favor a β-turn conformation, leaving the remainder of the molecule to adopt a γ turn, as seen in several previously studied model cyclic pentapeptides. The nmr data for both peptides in CDCl3 (5% DMSO-d6) and in neat DMSO-d6 indicate that the most populated conformation contains a distorted β turn around Pro2-D-Phe3, which includes a γ turn around D-Phe3. The distorsion in the β turn does not impede the formation of an inverse γ turn around residue 5, and indeed, this conformation is observed in both peptides. Both the alanine and the bulkier valine residues are therefore found to be compatible with an inverse γ turn. Molecular dynamics simulations on the title peptides are reported in the following paper. These simulations indicate that there is conformational flexibility around the D-Phe3-Gly4 peptide bond, which enables the formation of the γ turn around D-Phe3. The third paper in this series explores the impact of a micellar environment on conformational equilibria in II. © 1992 John Wiley & Sons, Inc.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/bip.360321213
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