Electronic and Steric Control of n→π* Interactions: Stabilization of the α-Helix Conformation without a Hydrogen Bond.

ABSTRACT: The preferred conformations of peptides and proteins are dependent on local interactions that bias the conformational ensemble. The n→π* interaction between consecutive carbonyls promotes compact conformations, including the α-helix and polyproline II helix. In order to further understand the n→π* interaction and to develop methods to promote defined conformational preferences through acyl N-capping motifs, a series of peptides was synthesized in which the electronic and steric properties of the acyl group were modified. Using NMR spectroscopy, van't Hoff analysis of enthalpies, X-ray crystallography, and computational investigations, we observed that more electron-rich donor carbonyls (pivaloyl, iso-butyryl, propionyl) promote stronger n→π* interactions and more compact conformations than

SUBMITTER: Wenzell NA 

PROVIDER: S-EPMC6458595 | biostudies-literature | 2019 Apr

REPOSITORIES: biostudies-literature