title: Native like helices in a specially designed β peptide in the gas phase.
abstract: 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.
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin, Germany. schubert@fhi-berlin.mpg.de baldauf@fhi-berlin.mpg.de.
authors.forename: Franziska
authors.initials: F
authors.lastname: Schubert
authors.forename: Kevin
authors.initials: K
authors.lastname: Pagel
authors.forename: Mariana
authors.initials: M
authors.lastname: Rossi
authors.forename: Stephan
authors.initials: S
authors.lastname: Warnke
authors.forename: Mario
authors.initials: M
authors.lastname: Salwiczek
authors.forename: Beate
authors.initials: B
authors.lastname: Koksch
authors.forename: Gert
authors.initials: G
authors.lastname: von Helden
authors.forename: Volker
authors.initials: V
authors.lastname: Blum
authors.forename: Carsten
authors.initials: C
authors.lastname: Baldauf
authors.forename: Matthias
authors.initials: M
authors.lastname: Scheffler
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D005740:Gases / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
chemical_list: D000596:Amino Acids; D005740:Gases; D010455:Peptides