• 1 January 1980
    • journal article
    • research article
    • Vol. 15  (1) , 5-19
Abstract
Empirical conformational energy calculations were carried out for the dipeptides cyclo-(L-Asp-L-His) and cyclo-(L-Glu-L-His). The side chain conformations were studied for various DKP (diketopiperazine) ring structures, demonstrating that distortions can modify the stability of some conformations by favoring peptide backbone-side chain or side chain-side chain interactions. The carboxylic side chain of Asp and Glu residues can induce specific interactions with the imidazole ring or the peptide bond of the DKP ring which are not found for Ser or Thr. The necessity of including solute-solvent interactions to account for a more realistic conformational behavior is discussed.