A Striking Periodicity of the <i>cis</i>/<i>trans</i> Isomerization of Proline Imide Bonds in Cyclic Disulfide‐Bridged Peptides

Abstract

cis persists: The population of the cis conformation of the Cys–Pro imide bond of the cyclic disulfide form of peptides of the sequence Ac-Cys-Pro-(Xaa)m-Cys-NH2 (Xaa=Phe, Ala) ranges from 9.3 to 76.9 % and shows a striking periodic dependence on the number of residues in the peptide.