title: Characterization and detection in cells of a novel adduct derived from the conjugation of glutathione and dehydroascorbate.
abstract: Glutathione (GSH) and ascorbate (ascorbic acid, vitamin C, ASC) are two critical water-soluble antioxidants in aerobic organisms. The reaction of ascorbate with reactive oxygen species leads to dehydroascorbate. It is generally accepted that GSH reduces dehydroascorbate (DHA) to give oxidized glutathione (GSSG) and ASC (2GSH+DHA-->GSSG+ASC) as a chemical pathway of ascorbate regeneration. Here, we report the formation of a novel conjugation product between GSH and the decomposition of DHA denoted as GS-DHA*. On the basis of MS and NMR analyses, the structure of GS-DHA* consists of an intact GSH moiety attached via the thiol group to a five-carbon fragment of DHA. The conjugation product appears as a mixture of four diastereomers with very similar proton and carbon chemical shifts. The formation of GS-DHA* adducts is demonstrated in Jurkat cells upon incubation with DHA in culture followed by analysis of the whole-cell extracts by HPLC coupled to tandem mass spectrometry. This novel conjugation product may be a useful biomarker of DHA stress and model system of protein modification.
authors.affiliation: Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, QC, Canada.
authors.forename: Peggy
authors.initials: P
authors.lastname: Regulus
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Desilets
authors.forename: Klaus
authors.initials: K
authors.lastname: Klarskov
authors.forename: J Richard
authors.initials: JR
authors.lastname: Wagner
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D002457:Cell Extracts; D002851:Chromatography, High Pressure Liquid; D003683:Dehydroascorbic Acid / Q000031:analogs & derivatives / Q000737:chemistry* / Q000494:pharmacology; D005978:Glutathione / Q000737:chemistry* / Q000302:isolation & purification; D006801:Humans; D019169:Jurkat Cells; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D013438:Sulfhydryl Compounds / Q000737:chemistry
chemical_list: D000975:Antioxidants; D002457:Cell Extracts; D013438:Sulfhydryl Compounds; D005978:Glutathione; D003683:Dehydroascorbic Acid