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Chiroptical Properties and Conformation of Dehydrophenylalanine Peptides
Author(s) -
Pieroni Osvaldo,
Fissi Adriano,
Merlino Stefano,
Ciardelli Francesco
Publication year - 1976
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.197600006
Subject(s) - chemistry , tetrapeptide , stereochemistry , residue (chemistry) , ring (chemistry) , hydrogen bond , crystallography , peptide , molecule , organic chemistry , biochemistry
Some N‐acylated α, β‐unsaturated peptides (dehydropeptides) containing one, two or three dehydrophenylalanine (dehydro‐Phe) residues and a C‐terminal L‐amino acidic residue have been prepared and characterized by NMR, IR and UV absorption. For N‐actyl‐(dehydro‐Phe) 2 ‐L‐Ala the crystal and molecular structure have been determined by X‐ray diffraction analysis. CD spectra of N‐acetyl‐(dehydro‐Phe)‐ϵ‐Cbzo‐L‐Lys and N‐acetyl‐(dehydro‐Phe) 2 ‐ϵ‐Cbzo‐L‐Lys have been measured in different solvents and, of N‐acetyl‐(dehydro‐Phe) 2 ‐L‐Val, in the presence of different amounts of urea. The results have been compared with those for N‐acetyl‐(dehydro‐Phe)‐(dehydro‐Tyr)‐L‐Glu, for the tetrapeptide N‐acetyl‐(dehydro‐Phe) 3 ‐L‐Val, and for analogous compounds already reported [ J. Am. Chem. Soc ., 97 , 5820 (1975)]. Crystalline molecular structure and chiroptical properties are consistent with the hypothesis that the dehydropeptides assume in solution a chiral conformation based on a 4 → 1 hydrogen‐bonded ten‐membered ring, also referred to as β‐turn. The importance of these systems for the understanding of the conformational properties of polypeptides containing D‐L sequences is discussed.