title: Copper-mediated intra-ligand oxygen transfer in gas-phase complexes with 3-nitrotyrosine.
abstract: Gas-phase ternary complexes with Cu(II) and 2,2'-bipyridine (bpy) of tyrosine, 3-aminotyrosine, 3-nitrotyrosine and 3-nitrotyrosine methyl ether are formed readily upon electrospraying aqueous methanol solutions containing the components. In contrast to Cu(bpy) complexes of tyrosine, 3-aminotyrosine and other aromatic amino acids, the complexes of 3-nitrotyrosine and its methyl ether undergo unusual collisionally activated dissociations (CADs) that involve Cu-mediated transfer of an oxygen atom from the nitro group. With 3-nitrotyrosine this results in an expulsion of carbonic acid, H(2)CO(3), whereas with 3-nitrotyrosine methyl ether an OH migration forms Cu(OH)bpy(+) as the predominant product. To the best of our knowledge, this is the first case of an intra-ligand redox reaction in a gas-phase organometallic complex. The reaction mechanism of this unusual dissociation was elucidated by a combination of isotope labeling, accurate mass measurements, energy-resolved CAD mass spectra and density functional theory calculations of ion structures and relative energies.
authors.affiliation: Department of Medicine, University of Washington, Seattle, 98195-1700, USA.
authors.forename: Tomás
authors.initials: T
authors.lastname: Vaisar
authors.forename: Jay W
authors.initials: JW
authors.lastname: Heinecke
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Seymour
authors.forename: Frantisek
authors.initials: F
authors.lastname: Turecek
mesh_terms: D002255:Carbonic Acid / Q000737:chemistry; D003300:Copper / Q000737:chemistry*; D041961:Deuterium Exchange Measurement; D005740:Gases / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008024:Ligands; D046911:Macromolecular Substances; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000737:chemistry*
chemical_list: D005740:Gases; D007477:Ions; D008024:Ligands; D046911:Macromolecular Substances; C002744:3-nitrotyrosine; D014443:Tyrosine; D002255:Carbonic Acid; D003300:Copper; D010100:Oxygen