Publications [#260695] of Volker Blum

Journal Articles

1. Rossi, M; Blum, V; Kupser, P; von Helden, G; Bierau, F; Pagel, K; Meijer, G; Scheffler, M, Secondary structure of Ac-Ala $ _n $-LysH $\^+ $ polyalanine peptides ($ n $= 5, 10, 15) in vacuo: Helical or not?, Arxiv Preprint Arxiv:1005.1228, vol. 1 no. 24 (2010), pp. 3465-3470, American Chemical Society (ACS) [doi]
   (last updated on 2023/06/01)

   Abstract:
   The polyalanine-based peptide series Ac-Alan-LysH+ (n = 5-20) is a prime example that a secondary structure motif that is well-known from the solution phase (here: helices) can be formed in vacuo. Here we revisit the series members n = 5,10,15, using density functional theory (van der Waals corrected generalized gradient approximation) for structure predictions, which are then corroborated by room temperature gas-phase infrared vibrational spectroscopy. We employ a quantitative comparison based on Pendry's reliability factor (popular in surface crystallography). In particular, including anharmonic effects into calculated spectra by way of ab initio molecular dynamics produces remarkably good experiment-theory agreement. We find the longer molecules (n = 10,15) to be firmly α-helical in character. For n = 5, calculated free-energy differences show different H-bond networks to still compete closely. Vibrational spectroscopy indicates a predominance of α-helical motifs at 300 K, but the lowest-energy conformer is not a simple helix. © 2010 American Chemical Society.