title: Disulfide bond decay during matrix-assisted laser desorption/ionization time-of-flight mass spectrometry experiments.
abstract: In our laboratory, we have been studying the reductive processes that occur during matrix-assisted laser desorption/ionization (MALDI) experiments. Recently, we have finished an analysis of the DHB matrix effect on the azo group in cyclic peptides. However, deep understanding of disulfide bond behaviour during a mass spectrometry (MS) experiment is much more important in proteomics as its reduction can cause serious errors in protein spectra interpretation. Therefore, we have focused on intra- and intermolecular disulfide bonds as well as disulfide bonds connecting cysteine and 2-thio-5-nitrobenzoic acid (TNB, Ellman's reagent modification) in model peptides during MALDI MS measurements. While the reduction was not observed for intra- and intermolecular cysteine-cysteine disulfide bonds, the disulfide connection between cysteine and TNB was always affected. It was proved that TNB and Ellman's reagent can act as a matrix itself. The results obtained enabled us to propose a reaction mechanism model which is able to describe the phenomena observed during the desorption/ionization process of disulfide-containing molecules.
authors.affiliation: Institute of Chemical Technology, Prague, Czech Republic. krasnyl@vscht.cz
authors.forename: Lukáš
authors.initials: L
authors.lastname: Krásný
authors.forename: Radovan
authors.initials: R
authors.lastname: Hynek
authors.forename: Milan
authors.initials: M
authors.lastname: Kodíček
mesh_terms: D000595:Amino Acid Sequence; D003545:Cysteine / Q000737:chemistry; D004220:Disulfides / Q000737:chemistry*; D004228:Dithionitrobenzoic Acid / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D008969:Molecular Sequence Data; D009579:Nitrobenzoates / Q000737:chemistry; D010455:Peptides / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D004220:Disulfides; D007477:Ions; D009579:Nitrobenzoates; D010455:Peptides; D013438:Sulfhydryl Compounds; C011136:thionitrobenzoic acid; D004228:Dithionitrobenzoic Acid; D003545:Cysteine