Alpha-beta-dehydro-amino acid residues in the design of peptide structures. Molecular and crystal structures of two folded dehydro peptides.
The molecular and crystal structures of two N alpha-protected tripeptide amides, containing in the central position the alpha-beta-dehydro-amino acid residue delta Phe (Z-configurational isomer), were determined by X-ray diffraction. While Z-Gly-delta Phez-L-Pro-NH2 is characterized in the crystal state by the presence of a type I beta-bend conformation (at the delta Phez-L-Pro sequence), Z-D-Ala-delta Phez-Gly-NH2 is folded into two consecutive beta-bends (type II' followed by type I), at the D-Ala-delta Phez and delta Phez-Gly sequences, respectively. In both cases the achiral delta Phez residue adopts a set of phi, psi angles typical of the right-handed helical conformation. The delta Phe residue may be exploited to design aromatic peptides with preferred secondary structures.
Busetti
V
V
Department of Organic Chemistry, University of Padova, Italy.
Crisma
M
M
Toniolo
C
C
Salvadori
S
S
Balboni
G
G
D000595:Amino Acid Sequence; D007202:Indicators and Reagents; D007536:Isomerism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D010649:Phenylalanine / Q000031:analogs & derivatives*; D011487:Protein Conformation; D012984:Software; D014961:X-Ray Diffraction / Q000379:methods
D007202:Indicators and Reagents; D009842:Oligopeptides; D010649:Phenylalanine; C018632:phenyldehydroalanine