Stuttgart 2012 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 11: Biomolecules
MO 11.5: Vortrag
Dienstag, 13. März 2012, 15:00–15:15, V38.02
IR/UV investigations of isolated β-turn and β-sheet peptides — •Kirsten Schwing1, Thomas Schrader2, and Markus Gerhards1 — 1TU Kaiserslautern, Physikal. und Theoret. Chemie, 67663 Kaiserslautern — 2Universität Duisburg-Essen, Organische Chemie, 45117 Essen
Due to the direct correlation between structure and functionality of biomolecules the structural investigation of peptides is of great scientific interest. Beyond the influence from the peptide environment intrinsic properties as amino acid sequence and secondary structure are of high importance for conformational preferences. The latter can be studied in molecular beam experiments with combined IR/UV spectroscopy as well as DFT calculations. This strategy is applied to two tripeptide models containing the aromatic amino acids phenylalanine and tyrosine (Ac-Phe-Tyr(Me)-NHMe and Boc-Phe-Tyr(Me)-NHMe). Both species prefer β-turn-structures energetically favoured by aromatic π...π interactions, whose impact on the stability of secondary structures has been revealed for biological systems. Further important secondary structure motifs are β-sheets, whose formation in the brain tissue is involved in the pathogenesis of different neurodegenerative diseases. Here we describe the first IR/UV analysis of an isolated hetero dimer in a molecular beam. The chosen systems Ac-Val-Tyr-NHMe and Ac-Ala-Ala-Ala-OMe can form different binding motifs as isolated monomer species but the hetero dimer gives a clear evidence of a β-sheet arrangement indicating driving forces for specific structural preferences in isolated peptides.