Intramolecular Amide Stacking and Its Competition with Hydrogen Bonding in a Small Foldamer

Attractive interactions between two carboxamide groups in a “stacked” geometry are explored under isolated molecule conditions. Infrared spectra of single conformations of a small γ-peptide, Ac-γ2-hPhe-NHMe, reveal the presence of a conformation in which the two amide planes are approximately parall...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2009-10, Vol.131 (40), p.14243-14245
Main Authors: James III, William H, Müller, Christian W, Buchanan, Evan G, Nix, Michael G. D, Guo, Li, Roskop, Luke, Gordon, Mark S, Slipchenko, Lyudmila V, Gellman, Samuel H, Zwier, Timothy S
Format: Article
Language:English
Subjects:
Amides - chemistry
Hydrogen Bonding
Models, Molecular
Peptides - chemistry
Protein Folding
Static Electricity
Thermodynamics
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Summary:Attractive interactions between two carboxamide groups in a “stacked” geometry are explored under isolated molecule conditions. Infrared spectra of single conformations of a small γ-peptide, Ac-γ2-hPhe-NHMe, reveal the presence of a conformation in which the two amide planes are approximately parallel with the amide dipoles in an antialigned orientation. This stacked conformation is energetically comparable to conformations that contain an intramolecular amide−amide H-bond. Amide stacking interactions can compete with H-bonding in circumstances where the amide groups can be brought into a stacking configuration with minimal strain, opening the way for its use in the design of future foldamer structures.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja9054965