title: One-Electron Oxidation of Methionine-Containing Dipeptides of Reverse Sequence: Sulfur versus Sulfoxide Characterized by IRMPD Spectroscopy and Static and Dynamics DFT Simulations.
abstract: Gas-phase structural modifications induced by the oxidation of methionine of the two peptides of reverse sequence, methionine-valine (Met-Val) and valine-methionine (Val-Met), have been studied by mass-selected IR multiple photon dissociation (IRMPD) spectroscopy in the 800-2000 cm-1fingerprint range at the Centre Laser Infrarouge d'Orsay free-electron laser facility. The oxidation has been achieved by•OH radicals generated by γ radiolysis. IRMPD spectra were interpreted by static and harmonic DFT calculations and Born-Oppenheimer molecular dynamics simulations, which are employed to take into account all anharmonic and finite-temperature effects. The diagnostic signature of the sulfoxide group in the final products of Met-Val and Val-Met oxidations, which is missing in the spectra of native peptides, has been recorded. Evidence has also been gathered that a mixture of R and S isomers of close energies is formed. An interconversion between different isomers has been unveiled in the case of the oxidized Met-Val dipeptide.
authors.forename: Barbara
authors.initials: B
authors.lastname: Gregori
authors.affiliation: Dipartimento di Scienza Fisiche e Chimiche, Università degli Studi dell'Aquila , Via Vetoio 2, Coppito, L'Aquila I-64100, Italy.
authors.forename: Leonardo
authors.identifier: 0000-0002-2497-9482
authors.initials: L
authors.lastname: Guidoni
authors.forename: Maria Elisa
authors.initials: ME
authors.lastname: Crestoni
authors.affiliation: Laboratoire de Chimie Physique, Université Paris Sud, Bat. 349, CNRS UMR8000 , 15 rue Georges Clemenceau, Orsay Cedex 91405, France.
authors.forename: Pedro
authors.initials: P
authors.lastname: de Oliveira
authors.affiliation: Laboratoire de Chimie Physique, Université Paris Sud, Bat. 349, CNRS UMR8000 , 15 rue Georges Clemenceau, Orsay Cedex 91405, France.
authors.forename: Chantal
authors.initials: C
authors.lastname: Houée-Levin
authors.affiliation: Laboratoire de Chimie Physique, Université Paris Sud, Bat. 349, CNRS UMR8000 , 15 rue Georges Clemenceau, Orsay Cedex 91405, France.
authors.forename: Debora
authors.identifier: 0000-0003-3931-8481
authors.initials: D
authors.lastname: Scuderi
mesh_terms: D000595:Amino Acid Sequence; D004151:Dipeptides / Q000737:chemistry*; D004583:Electrons; D008715:Methionine / Q000737:chemistry*; D056004:Molecular Dynamics Simulation; D010084:Oxidation-Reduction; D017785:Photons; D011789:Quantum Theory; D012451:Safrole / Q000031:analogs & derivatives* / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013455:Sulfur / Q000737:chemistry*; D013696:Temperature
chemical_list: D004151:Dipeptides; D013455:Sulfur; D008715:Methionine; D012451:Safrole; C005746:sulfoxide