The biological function of proteins is largely determined by the three-dimensional structure they adopt in vivo. It is a great challenge for theory to predict this structure which is determined by a delicate interplay between various non-covalent forces. To verify that theoretical models describe the underlying physics correctly, comparison with benchmark experiments is essential. The most rigorous test is perhaps to compare theoretical and experimental data on small peptides in the gas phase.

Infrared spectroscopy of gas phase biomolecular ions can be used to obtain information on the ion structure (conformation) as the vibrational frequencies are sensitive to the local environment. This talk will demonstrate how conformation-specific infrared spectra can be measured in the gas phase and the results obtained with a peptide consisting of nine amino acids are presented. Finally, some of the limitations of the approach are discussed.

 

Peter Staanum and Nicolai Nygaard