title: 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.
abstract: 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.
authors.affiliation: Department of Organic Chemistry, University of Padova, Italy.
authors.forename: N
authors.initials: N
authors.lastname: Fabiano
authors.forename: G
authors.initials: G
authors.lastname: Valle
authors.forename: M
authors.initials: M
authors.lastname: Crisma
authors.forename: C
authors.initials: C
authors.lastname: Toniolo
authors.forename: M
authors.initials: M
authors.lastname: Saviano
authors.forename: A
authors.initials: A
authors.lastname: Lombardi
authors.forename: C
authors.initials: C
authors.lastname: Isernia
authors.forename: V
authors.initials: V
authors.lastname: Pavone
authors.forename: B
authors.initials: B
authors.lastname: Di Blasio
authors.forename: C
authors.initials: C
authors.lastname: Pedone
mesh_terms: 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
chemical_list: D000577:Amides; D009842:Oligopeptides