title: Gas phase photo-formation and vacuum UV photofragmentation spectroscopy of tryptophan and tyrosine radical-containing peptides.
abstract: Tryptophan (Trp(•)) and tyrosyl (Tyr(•)) radical containing peptides were produced by UV laser-induced electron detachment from a suitable precursor. Vacuum ultraviolet (VUV) action spectra of these radical peptides were recorded with synchrotron radiation in the 4.5-16 eV range, from which fragmentation pathways and yields are measured as a function of the VUV photon energy. An enhancement in photofragmentation yields of radical species by 1 order of magnitude with respect to nonradical peptides is demonstrated here for the first time. Photofragmentation spectra are compared with absorption spectra for model chromophores calculated in the frame of the time-dependent density functional theory (TDDFT). A qualitative agreement in the position of bands in the 6-8 eV region is observed between experimental photofragmentation and calculated absorption spectra. Photofragmentation spectra of peptide radicals can be useful to better assess the complex deactivation pathways that occur following the absorption of a VUV photon in biomolecular radical anions.
authors: Université de Lyon , F-69622, Lyon, France, Université Lyon 1, 69622 Villeurbanne Cedex, France.
authors: Claire
authors: C
authors: Brunet
authors: Rodolphe
authors: R
authors: Antoine
authors: Abdul-Rahman
authors: AR
authors: Allouche
authors: Philippe
authors: P
authors: Dugourd
authors: Francis
authors: F
authors: Canon
authors: Alexandre
authors: A
authors: Giuliani
authors: Laurent
authors: L
authors: Nahon
mesh_terms: D000042:Absorption; D005609:Free Radicals / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D056951:Photoelectron Spectroscopy / Q000379:methods*; D010782:Photolysis; D017785:Photons; D017356:Synchrotrons; D014364:Tryptophan / Q000737:chemistry*; D014443:Tyrosine / Q000737:chemistry*; D014466:Ultraviolet Rays; D014618:Vacuum
chemical_list: D005609:Free Radicals; D005740:Gases; D010455:Peptides; C408694:tyrosine radical; D014443:Tyrosine; D014364:Tryptophan