Secondary structure of Ac-Ala$_n$-LysH$^+$ polyalanine peptides ($n$=5,10,15) in vacuo: Helical or not?
| Autor: | Rossi, M., Blum, V., Kupser, P., von Helden, G., Bierau, F., Pagel, K., Meijer, G., Scheffler, M. |
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| Rok vydání: | 2010 |
| Předmět: | |
| Zdroj: | J. Phys. Chem. Lett., 2010, 1, pp 3465-3470 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1021/jz101394u |
| Popis: | The polyalanine-based peptide series Ac-Ala_n-LysH+ (n=5-20) is a prime example that a secondary structure motif which is well-known from the solution phase (here: helices) can be formed in vacuo. We here revisit this conclusion for n=5,10,15, using density-functional theory (van der Waals corrected generalized gradient approximation), and gas-phase infrared vibrational spectroscopy. For the longer molecules (n=10,15) \alpha-helical models provide good qualitative agreement (theory vs. experiment) already in the harmonic approximation. For n=5, the lowest energy conformer is not a simple helix, but competes closely with \alpha-helical motifs at 300K. Close agreement between infrared spectra from experiment and ab initio molecular dynamics (including anharmonic effects) supports our findings. Comment: 4 pages, 4 figures, Submitted to JPC Letters |
| Databáze: | arXiv |
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