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Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/19490
Title: Preferred 3D-structure of peptides rich in a severely conformationally restricted cyclopropane analogue of phenylalanine
Authors: Crisma, Marco; Borggraeve, Wim M. de; Peggion, Cristina; Formaggio, Fernando; Royo, Soledad; Jiménez, Ana I.; Cativiela, Carlos; Toniolo, Claudio
Keywords: Chirality
Conformation analysis
NMR spectroscopy
X-ray diffraction
Issue Date: 10-Nov-2005
Publisher: Wiley-VCH
Citation: Chemistry - A European Journal 12(1): 251-260 (2005)
Abstract: Terminally blocked, homo-peptide amides of (R,R)-1-amino-2,3-diphenylcyclopropane-1-carboxylic acid (c3diPhe), a chiral member of the family of C-tetrasubstituted -amino acids, from the dimer to the tetramer, and diastereomeric co-oligopeptides of (R,R)- or (S,S)-c3diPhe with (S)-alanine residues to the trimer level were prepared in solution and fully characterized. The synthetic effort was extended to terminally protected co-oligopeptide esters to the hexamer, where c3diPhe residues are combined with achiral -aminoisobutyric acid residues. The preferred conformations of the peptides were assessed in solution by FT-IR absorption, NMR, and CD techniques, and for seven oligomers in the crystal state (by X-ray diffraction) as well. This study clearly indicates that c3diPhe, a sterically demanding cyclopropane analogue of phenylalanine, tends to fold peptides into -turn and 310-helix conformations. However, when c3diPhe is in combination with other chiral residues, the conformation preferred by the resulting peptides is also dictated by the chiral sequence of the amino acid building blocks. The (S,S)-enantiomer of this -amino acid, unusually lacking asymmetry in the main chain, strongly favors the left-handedness of the turn/helical peptides formed.
Description: 10 pages, 11 figures, 2 tables.
Publisher version (URL): http://dx.doi.org/10.1002/chem.200500865
URI: http://hdl.handle.net/10261/19490
DOI: 10.1002/chem.200500865
ISSN: 0935-9648
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