Chirality‐Controlled Formation of β‐Turn Secondary Structures in Short Peptide Chains: Gas‐Phase Experiment versus Quantum Chemistry

Spontaneous formation of secondary structures (i.e., β-turns) by isolated capped dipeptides in the gas phase was investigated by laser spectroscopy following supersonic expansion, and by quantum chemical calculations. The two most stable calculated β-turn structures I and II′ of one of the dipeptides were related to species B and B′, respectively, identified in the near-UV spectrum (see figure).