title: Relative quantitation of protein nitration by liquid chromatography-mass spectrometry using isotope-coded dimethyl labeling and chemoprecipitation.
abstract: Protein nitration has been recognized as an important biomarker for nitroxidative stress associated with various diseases. While identification of protein targets for nitration is important, its quantitative profiling also is necessary to understand the biological impact of this low-abundance posttranslational modification. We have previously reported an efficient and straightforward enrichment method for nitropeptides to reduce sample complexity and permit unambiguous site-specific identifications by LC-MS analyses. This approach relies on two chemical derivatization steps: specifically reductive methylation of aliphatic amines and, then, conversion of nitrotyrosines to the corresponding aminotyrosines before their selective capture by a solid-phase reagent we introduced previously. Hence, the method inherently offers the opportunity for relative quantitation of nitropeptides by using isotopic variants of formaldehyde for reductive methylation. This simple method was tested via LC-MS analyses of differently N-methylated nitropeptides and nitroubiquitin as a model nitroprotein enriched from human serum albumin digest and from human plasma, respectively.
authors.affiliation: Department of Molecular Biology and Immunology, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA.
authors.forename: Jia
authors.initials: J
authors.lastname: Guo
authors.forename: Katalin
authors.initials: K
authors.lastname: Prokai-Tatrai
authors.forename: Laszlo
authors.initials: L
authors.lastname: Prokai
mesh_terms: D000595:Amino Acid Sequence; D002247:Carbon Isotopes; D011232:Chemical Precipitation; D002853:Chromatography, Liquid / Q000379:methods*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D008969:Molecular Sequence Data; D009574:Nitro Compounds / Q000032:analysis* / Q000737:chemistry; D010455:Peptides / Q000032:analysis / Q000737:chemistry*; D012709:Serum Albumin / Q000032:analysis / Q000737:chemistry; D025801:Ubiquitin
chemical_list: D002247:Carbon Isotopes; D009574:Nitro Compounds; D010455:Peptides; D012709:Serum Albumin; D025801:Ubiquitin