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Preferred conformation of peptides based on cycloaliphatic C α,α ‐disubstituted glycines: 1‐amino‐cycloundecane‐1‐carboxylic acid (Ac 11 c)
Author(s) -
Saviano Michele,
Iacovino Rosa,
Benedetti Ettore,
Moretto Vittorio,
Banzato Alessandro,
Formaggio Fernando,
Crisma Marco,
Toniolo Claudio
Publication year - 2000
Publication title -
journal of peptide science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 66
eISSN - 1099-1387
pISSN - 1075-2617
DOI - 10.1002/1099-1387(200011)6:11<571::aid-psc290>3.0.co;2-r
Subject(s) - pentamer , chemistry , tripeptide , stereochemistry , peptide conformation , dimer , monomer , peptide , pentapeptide repeat , carboxylic acid , trimer , residue (chemistry) , amino acid , oligopeptide , organic chemistry , polymer , biochemistry
Two complete series of N‐protected oligopeptide esters to the pentamer level from 1‐amino‐cycloundecane‐1‐carboxylic acid (Ac 11 c), an α‐amino acid conformationally constrained through a medium‐ring C α i ↔C α i cyclization, and either the L ‐Ala or Aib residue, along with the N‐protected Ac 11 c monomer and homo‐dimer alkylamides, have been synthesized by solution methods and fully characterized. The preferred conformation of these model peptides has been assessed in deuterochloroform solution by FT‐IR absorption and 1 H‐NMR techniques. Furthermore, the molecular structures of one derivative (Z‐Ac 11 c‐OH) and two peptides (the tripeptide ester Z‐Aib‐Ac 11 c‐Aib‐O t Bu and the pentapeptide ester Z‐Ac 11 c‐(Aib) 2 ‐Ac 11 c‐Aib‐O t Bu) have been determined in the crystal state by X‐ray diffraction. The experimental results support the view that β‐bends and 3 10 ‐helices are preferentially adopted by peptides rich in Ac 11 c, the second largest cycloaliphatic C α,α ‐disubstituted glycine known. This investigation has allowed the authors to approach the completion of a detailed conformational analysis of the whole 1‐amino‐cycloalkane‐1‐carboxylic acid (Ac n c, with n=3–12) series, which represents the prerequisite for their recent proposal of the ‘Ac n c scan’ concept. Copyright © 2000 European Peptide Society and John Wiley & Sons, Ltd.