title: Vibrational circular dichroism of a 2,5-diketopiperazine (DKP) peptide: Evidence for dimer formation in cyclo LL or LD diphenylalanine in the solid state.
abstract: The diastereomer diketopiperazine (DKP) peptides built on phenylalanine, namely, cyclo diphenylalanine LPhe-LPhe and LPhe-DPhe, were studied in the solid phase by vibrational circular dichroism (VCD) coupled to quantum chemical calculations. The unit structure of cyclo LPhe-LPhe in KBr pellets is a dimer bridged by two strong NH…O hydrogen bonds. The intense bisignate signature in the CO stretch region is interpreted in terms of two contributions arising from the free COs of the dimer and the antisymmetrical combination of the bound COs. In contrast, cyclo LPhe-DPhe shows no VCD signal in relation to its symmetric nature.
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS and Univ Paris-Sud, Université Paris-Saclay, Orsay, France.
authors.forename: Ariel
authors.initials: A
authors.lastname: Pérez-Mellor
authors.affiliation: Institut des Sciences Moléculaires d'Orsay (ISMO), CNRS and Univ Paris-Sud, Université Paris-Saclay, Orsay, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Zehnacker
mesh_terms: D002942:Circular Dichroism; D054659:Diketopiperazines / Q000737:chemistry*; D004151:Dipeptides; D006860:Hydrogen Bonding; D010455:Peptides / Q000737:chemistry*; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D060327:Solid-Phase Synthesis Techniques; D013237:Stereoisomerism
chemical_list: D054659:Diketopiperazines; D004151:Dipeptides; D010455:Peptides; D011108:Polymers; C010939:2,5-dioxopiperazine; C026650:phenylalanylphenylalanine; D010649:Phenylalanine
keywords: DKP; FTIR spectroscopy; VCD; diketopiperazine; hydrogen bond; peptide; vibrational circular dichroism