Conformational versatility of the N alpha-acylated tripeptide amide tail of oxytocin. Synthesis and crystallographic characterization of three C2 alpha-backbone modified, conformationally restricted analogues.
The synthesis, physical and analytical characterization, and crystal-state structural analysis by X-ray diffraction of three analogues of the N alpha-acylated tripeptide amide tail of oxytocin, each containing a cyclic C alpha, alpha-disubstituted glycine at position 2, have been performed. The peptides are Boc-L-Pro-Ac3c-Gly-NH2, Z-L-Pro-Ac5c-Gly-NH2 and Z-L-Pro-Ac6c-Gly-NH2. While the former is folded in a type-II beta-turn conformation at the -L-Pro-Ac3c- sequence, the two latter tripeptides form two consecutive (type-II, type-I') beta-turns. The Ac5c- and Ac6c-tripeptides are the first examples of such a highly folded structural combination in a position-2 analogue of the N alpha-acylated -L-Pro-L-Leu-Gly-NH2 sequence.
Fabiano
N
N
Department of Organic Chemistry, University of Padova, Italy.
Valle
G
G
Crisma
M
M
Toniolo
C
C
Saviano
M
M
Lombardi
A
A
Isernia
C
C
Pavone
V
V
Di Blasio
B
B
Pedone
C
C
D000215:Acylation; D000577:Amides / Q000737:chemistry*; D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry*; D011487:Protein Conformation
D000577:Amides; D009842:Oligopeptides