title: Capillary electrophoresis tandem mass spectrometry of bromine-containing charged derivatives of peptides.
abstract: Novel bromine-containing positively charged labels 5-bromo-1-ethyl-thiazolium (BET+) and 5-bromo-1-ethyl-pyridinium (BEP+) ions were studied for improving the interpretation of MS/MS spectra of peptides. 2,5-Dibromo-1-ethyl-thiazolium tetrafluoroborate (DBET) reacts in the order: epsilon->>alpha-amino group>>hydroxyl group of Tyr while 2,5-dibromo-1-ethyl-pyridinium tetrafluoroborate (DBEP) reacts preferably with thiol group of Cys>>hydroxyl group of Tyr. In this study a simple and fast CE/MS/MS method is presented for investigating the labeling reaction with these new reagents, where the difference in migration times of labeled and unlabeled peptides also gives us information about the position of labeling. These bromine-containing reagents simplify the MS/MS spectra of peptides: the charge of the derivatives increases the intensity of the corresponding ions, thus enhancing the sensitivity of the detection and the characteristic distribution of the bromine isotope (the 79Br and 81Br ratio is nearly one) facilitating the recognition. By eliminating the non-doubled peaks, clear and easily interpretable MS/MS spectra can be produced that contain only the labeled fragments.
authors.affiliation: Department of Medicinal Chemistry, University of Szeged, Dóm tér 8, H-6720 Szeged, Hungary. gyorgyi@ovrisc.mdche.u-szeged.hu
authors.forename: Györgyi
authors.initials: G
authors.lastname: Ferenc
authors.forename: Petra
authors.initials: P
authors.lastname: Pádár
authors.forename: Tamás
authors.initials: T
authors.lastname: Janáky
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Szabó
authors.forename: Gábor K
authors.initials: GK
authors.lastname: Tóth
authors.forename: Lajos
authors.initials: L
authors.lastname: Kovács
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Kele
mesh_terms: D001966:Bromine / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry; D019075:Electrophoresis, Capillary; D007202:Indicators and Reagents; D007553:Isotope Labeling / Q000379:methods; D007554:Isotopes; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis / Q000737:chemistry*; D010455:Peptides / Q000032:analysis* / Q000138:chemical synthesis / Q000737:chemistry*; D017421:Sequence Analysis; D021241:Spectrometry, Mass, Electrospray Ionization; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D053719:Tandem Mass Spectrometry; D014443:Tyrosine / Q000737:chemistry
chemical_list: D007202:Indicators and Reagents; D007554:Isotopes; D010446:Peptide Fragments; D010455:Peptides; D014443:Tyrosine; D003545:Cysteine; D001966:Bromine