In order to examine factors influencing cyclodepsitripeptide formation and stability, three cyclic peptide models containing the α‐hydroxyacyl‐α‐aminoacylprolyl sequence, corresponding to the peptide lactone cyclo(‐Xha‐Pro‐Xaa‐) (Xha = Hiv, Lac; Xaa = Phe, dPhe, dAla), retroisomeric with respect to the ergot oxa‐cyclolic peptide moiety, have been considered. Starting from 2,5‐dioxomorpholines, aminoacyl incorporation reaction led, through intermediate tetrahedral adducts (aza‐cyclols), to the corresponding nine‐ membered cyclodepsitripeptides cycle(‐Hiv‐Pro‐dPhe‐) 4a, cycle(‐Lac‐Pro‐dPhe‐) 4b, and cyclo (‐Hiv‐Pro‐ dAla‐) 4c. Compounds 4a‐c contain a CONH peptide bond in the nine‐membered ring and are stable on standing. Solution conformations of 4a‐c, as inferred by NMR spectra and NOE experiments, have been studied. A cis‐cis‐trans backbone conformation, analogous to that observed in the case of previously stud‐ ied nine‐membered cyclodepsitripeptides containing two proline residues in the ring, is proposed for 4a‐c.
|Number of pages||9|
|Journal||International journal of peptide and protein research|
|Publication status||Published - Jul 1993|
- NMR studies
- aminoacyl incorporation
- tetrahedral adducts
ASJC Scopus subject areas