Conformational characterization of peptides rich in the cycloaliphatic C alpha,alpha-disubstituted glycine 1-aminocyclononane-1-carboxylic acid.
J Pept Sci
; 3(5): 367-82, 1997.
Article
en En
| MEDLINE
| ID: mdl-9391912
ABSTRACT
A series of N- and C-protected, monodispersed homo-oligopeptides (to the pentamer level) from the cycloaliphatic C alpha,alpha-dialkylated glycine 1-aminocyclononane-1-carboxylic acid (Ac9c) and two Ala/Ac9c tripeptides have been synthesized by solution methods and fully characterized. The conformational preferences of all the model peptides were determined in deuterochloroform solution by FT-IR absorption and 1H-NMR. The molecular structures of the amino acid derivatives mCIAc-Ac9c-OH and Z-Ac9c-OtBu, the dipeptide pBrBz-(Ac9c)2-OtBu, the tetrapeptide Z-(Ac9c)4-OtBu, and the pentapeptide Z-(Ac9c)5-OtBu were determined in the crystal state by X-ray diffraction. Based on this information, the average geometry and the preferred conformation for the cyclononyl moiety of the Ac9c residue have been assessed. The backbone conformational data are strongly in favour of the conclusion that the Ac9c residue is a strong beta-turn and helix former. A comparison with the structural propensity of alpha-aminoisobutyric acid, the prototype of C alpha,alpha-dialkylated glycines, and the other extensively investigated members of the family of 1-aminocycloalkane-1-carboxylic acids (Acnc, with n = 3-8) is made and the implications for the use of the Ac9c residue in conformationally constrained analogues of bioactive peptides are briefly examined.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Oligopéptidos
/
Aminoácidos Cíclicos
Idioma:
En
Revista:
J Pept Sci
Asunto de la revista:
BIOQUIMICA
Año:
1997
Tipo del documento:
Article
País de afiliación:
Italia