Theoretical and NMR Conformational Studies of ?-Proline Oligopeptides With Alternating Chirality of Pyrrolidine Units.
Theoretical and NMR Conformational Studies of ?-Proline Oligopeptides With Alternating Chirality of Pyrrolidine Units.
Front Chem. 2018;6:91
Authors: Mantsyzov AB, Savelyev OY, Ivantcova PM, Bräse S, Kudryavtsev KV, Polshakov VI
Abstract
Synthetic ?-peptides are potential functional mimetics of native ?-proteins. A recently developed, novel, synthetic approach provides an effective route to the broad group of ?-proline oligomers with alternating patterns of stereogenic centers. Conformation of the pyrrolidine ring, Z/E isomerism of ?-peptide bonds, and hindered rotation of the neighboring monomers determine the spatial structure of this group of ?-proline oligopeptides. Preferences in their structural organization and corresponding thermodynamic properties are determined by NMR spectroscopy, restrained molecular dynamics and quantum mechanics. The studied ?-proline oligopeptides exist in dimethyl sulfoxide solution in a limited number of conformers, with compatible energy of formation and different spatial organization. In the ?-proline tetrapeptide with alternating chirality of composing pyrrolidine units, one of three peptide bonds may exist in an E configuration. For the alternating ?-proline pentapeptide, the presence of an E configuration for at least of one ?-peptide bond is mandatory. In this case, three peptide bonds synchronously change their configurations. Larger polypeptides may only exist in the presence of several E configurations of ?-peptide bonds forming a wave-like extended structure.
PMID: 29644215 [PubMed]
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