Speaker
Description
Proteins play an essential role in the functioning of living organisms. The function the protein performs is determined by its three-dimensional structure assumed upon folding. Hydrogen bonding is a key interaction in stabilizing protein structures.
Spectroscopy of gas-phase peptides provides a bottom-up approach to studying protein secondary structures at the fundamental level. Among the different spectral regions, IR spectroscopy of jet-cooled molecules, when combined with quantum chemical calculations, is a particularly sensitive tool for conformational analysis of gas-phase peptides. A traditional method to measure IR spectra of gas-phase molecules is UV-IR double-resonance spectroscopy. The advantage of this method is that it is conformer-specific, but since only 3 proteinogenic amino acid residues can act as UV-chromophore, its application to peptides is rather limited. To overcome this drawback, we have introduced IRMPD-VUV spectroscopy which can be applied to neutral molecules of arbitrary structures, including chromophore-free peptides.
In my presentation I will show the results from our recent FELIX (Free Electron Lasers for Infrared eXperiments) experimental campaign in which we investigated conformational preferences of jet-cooled Gly-Gly-Gly and Ala-Ala-Ala tripeptides. The IRMPD-VUV spectra have also been measured in the amide-A range, which was possible due to the recent extension of the FELIX range to $\approx$3700 cm$^{-1}$. The obtained spectra have been interpreted with the help of DFT calculations which suggest that, in contrast to the Gly-Gly and Ala-Ala dipeptides, both Gly-Gly-Gly and Ala-Ala-Ala assume only bent structures in the gas phase. I will also present the results of the hydrogen-bond analysis undertaken with the NCI method.
| This abstract is submitted for.... | HBond 2025 conference |
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