title: Decomposition of protein nitrosothiolsin matrix-assisted laser desorption/ionization and electrospray ionization mass spectrometry.
abstract: The S-nitrosylation of proteins is involved in the trafficking of nitric oxide (NO) in intra- and extracellular milieus. To establish a mass spectrometric method for identifying this post-translational modification of proteins, a synthetic peptide and transthyretin were S-nitrosylated in vitro and analyzed by electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The intact molecular ion species of nitrosylated compounds was identified in the ESI mass spectrum without elimination of the NO group. However, the labile nature of the S-NO bond was evident when the in-source fragmentation efficiently generated [M + H - 30](+) ions. The decomposition was prominent for multiply charged transthyretin ions with high charge states under ordinary ESI conditions, indicating that the application of minimum nozzle potentials was essential for delineating the stoichiometry of nitrosylation in proteins. With MALDI, the S-NO bond cleavage occurred during the ionization process, and the subsequent reduction generated [M + H - 29](+) ions.
authors.affiliation: Department of Molecular Medicine, Osaka Medical Center and Research Institute for Maternal and Child Health, Osaka 594-1101, Japan.
authors.forename: Rina
authors.initials: R
authors.lastname: Kaneko
authors.forename: Yoshinao
authors.initials: Y
authors.lastname: Wada
mesh_terms: D006801:Humans; D017672:Nitrogen Compounds / Q000737:chemistry*; D011228:Prealbumin / Q000737:chemistry; D011506:Proteins / Q000737:chemistry*; D012709:Serum Albumin / Q000138:chemical synthesis / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D017672:Nitrogen Compounds; D011228:Prealbumin; D011506:Proteins; D012709:Serum Albumin; D013438:Sulfhydryl Compounds