title: X-ray structures of aza-proline-containing peptides.
abstract: The aza-analogue of proline (AzPro) contains a nitrogen atom in place of the CH alpha of the cognate residue. The resolution of the crystal structures of seven AzPro-containing peptides, presenting a set of ten AzPro motifs, reveals the structural properties of this particular aza-residue. Because of sterical hindrances, both nitrogen atoms are out of planarity, and the reduced electronic conjugation in the two AzPro-adjacent amide groups probably explains the longer amide bond distances and the weak proton-accepting character of the two pyrazolidine nitrogens. The absolute configuration of both AzPro nitrogens depends on the chemical nature of the sequence. In all cases, the AzPro residue assumes the same intrinsic three-dimensional structure and presents folding tendencies opposed to those induced by proline.
authors.affiliation: CNRS-URA-809, University Henri Poincaré, Vandoeuvre les Nancy, France.
authors.forename: C
authors.initials: C
authors.lastname: Didierjean
authors.forename: V
authors.initials: V
authors.lastname: Del Duca
authors.forename: E
authors.initials: E
authors.lastname: Benedetti
authors.forename: A
authors.initials: A
authors.lastname: Aubry
authors.forename: M
authors.initials: M
authors.lastname: Zouikri
authors.forename: M
authors.initials: M
authors.lastname: Marraud
authors.forename: G
authors.initials: G
authors.lastname: Boussard
mesh_terms: D001372:Aza Compounds / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009584:Nitrogen / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D011392:Proline / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding
chemical_list: D001372:Aza Compounds; D010455:Peptides; D011392:Proline; D009584:Nitrogen