Native like helices in a specially designed β peptide in the gas phase.

Journal Article

In the natural peptides, helices are stabilized by hydrogen bonds that point backward along the sequence direction. Until now, there is only little evidence for the existence of analogous structures in oligomers of conformationally unrestricted β amino acids. We specifically designed the β peptide Ac-(β(2)hAla)6-LysH(+) to form native like helical structures in the gas phase. The design follows the known properties of the peptide Ac-Ala6-LysH(+) that forms a α helix in isolation. We perform ion-mobility mass-spectrometry and vibrational spectroscopy in the gas phase, combined with state-of-the-art density-functional theory simulations of these molecular systems in order to characterize their structure. We can show that the straightforward exchange of alanine residues for the homologous β amino acids generates a system that is generally capable of adopting native like helices with backward oriented H-bonds. By pushing the limits of theory and experiments, we show that one cannot assign a single preferred structure type due to the densely populated energy landscape and present an interpretation of the data that suggests an equilibrium of three helical structures.

Full Text

Duke Authors

Cited Authors

  • Schubert, F; Pagel, K; Rossi, M; Warnke, S; Salwiczek, M; Koksch, B; von Helden, G; Blum, V; Baldauf, C; Scheffler, M

Published Date

  • February 2015

Published In

Volume / Issue

  • 17 / 7

Start / End Page

  • 5376 - 5385

PubMed ID

  • 25611682

Electronic International Standard Serial Number (EISSN)

  • 1463-9084

International Standard Serial Number (ISSN)

  • 1463-9076

Digital Object Identifier (DOI)

  • 10.1039/c4cp05216a

Language

  • eng