American Chemical Society
jo900222g_si_007.cif (156.19 kB)

Stable Right- and Left-Handed Peptide Helices containing Cα-Tetrasubstituted α-Amino Acids

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posted on 2009-05-15, 00:00 authored by Andreas A. Grauer, Chiara Cabrele, Manfred Zabel, Burkhard König
Short peptidomimetics with stable secondary structures in solution are of interest for applications in chemistry, biology, and medicine. One way to rigidify the backbone of a peptide is the use of cyclic Cα-tetrasubstituted α-amino acids (TAAs) like compound 14. The structures resulting from the incorporation of this unnatural amino acid into peptides were investigated. In total, 13 different peptides with a length of up to eight residues and alternating sequences of TAA 14 and (S)- or (R)-valine were synthesized. Their structures were characterized by X-ray diffraction analysis and NMR and CD measurements showing that the all-S-backbone-configured peptides 5 and 6 (SS)2−3 form right-handed 310-helices, while the all-R-configured peptides 1113 (RR)2−4 form left-handed 310-helices in the solid state and solution.