• 1 January 1978
    • journal article
    • research article
    • Vol. 11  (3) , 194-208
Abstract
Empirical conformational energy calculations were carried out for the dipeptides cyclo-(L-Ser-L-His) and cyclo-(L-Thr-L-His). Various DKP [diketopiperazine] structures were investigated to study side chain conformations through the DKP ring deformations, and prevalent conformers of monosubstituted and disubstituted dipeptides are discussed. The most stable conformations occur when both side chains are folded over a planar DKP ring, the imidazole ring being in the .epsilon.-tautomeric form. Theoretical results are consistent with those obtained from NMR and crystallographic studies.