Conformational Transitions between Enantiomeric 310‐Helices

Abstract
The 310‐helix enantiotopermerization of the decapeptide Z‐(Aib)10‐OtBu occurs at 1200 interconversions per second at room temperature. This finding, obtained by 13C‐DNMR measurements, was derived from the coalescence temperature of 265 K for this 3−3‐helix interconversion, observed here for the first time. The corresponding free energy of activation is only 46 kJ mol −1. Aib is the achiral α‐aminoisobutyric acid building block, which is important in drug design.