title: α,ε-Hybrid foldamers with 1,2,3-triazole rings: order versus disorder.
abstract: Two epimeric series of foldamers characterized by the presence of a repeating α,ε-dipeptide unit have been prepared and characterized by (1)H NMR and ECD spectroscopies together with X-ray diffraction. The first series contains L-Ala and D-4-carboxy-5-methyl-oxazolidin-2-one (D-Oxd). The other series contains L-Ala and L-Oxd. The L,D series of oligomers forms ordered β-turn foldamers, characterized by a 311 pattern. The L,L series is not ordered. Simulations show that an ordered L,L trimer lies more than 2 kcal/mol higher than the more stable nonfolded extended conformations. Cu(2+) forms complexes with both series but is not able to order the L,L series. Analysis of the EPR spectra shows that the L,D foldamers bear two types of complexation sites that are assigned as a nitrogen donor of the triazole ring and a carboxylate ligand. The L-Ala-D-Oxd-Tri-CO motif may be introduced in any peptide sequence requiring the presence of a stable β-turn conformations, like in the study of protein-protein interactions.
authors.affiliation: Dipartimento di Chimica "G. Ciamician", Alma Mater Studiorum Università di Bologna , Via F. Selmi 2, 40126 Bologna, Italy.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Milli
authors.forename: Michele
authors.initials: M
authors.lastname: Larocca
authors.forename: Mattia
authors.initials: M
authors.lastname: Tedesco
authors.forename: Nicola
authors.initials: N
authors.lastname: Castellucci
authors.forename: Elena
authors.initials: E
authors.lastname: Ghibaudi
authors.forename: Andrea
authors.initials: A
authors.lastname: Cornia
authors.forename: Matteo
authors.initials: M
authors.lastname: Calvaresi
authors.forename: Francesco
authors.initials: F
authors.lastname: Zerbetto
authors.forename: Claudia
authors.initials: C
authors.lastname: Tomasini
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D004151:Dipeptides / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D023303:Oxazolidinones / Q000737:chemistry*; D054730:Protein Interaction Domains and Motifs; D014230:Triazoles / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D056831:Coordination Complexes; D004151:Dipeptides; D008024:Ligands; D023303:Oxazolidinones; D014230:Triazoles; D003300:Copper