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Integration of Miniaturized Solid Phase Extraction and LC-MS/MS Detection of 3-Nitrotyrosine in Human Urine for Clinical Applications
Published on: July 14, 2017
One-dimensional western blotting coupled to LC-MS/MS analysis to identify chemical-adducted proteins in rat urine
Matthew T Labenski1, Ashley A Fisher, Terrence J Monks
1Department of Pharmacology and Toxicology, Southwest Environmental Health Sciences Center, Center for Toxicology, College of Pharmacy, University of Arizona, Tucson, AZ, USA.
Abstract:
The environmental toxicant hydroquinone (HQ) and its glutathione conjugates (GSHQs) cause renal cell necrosis via a combination of redox cycling and the covalent adduction of proteins within the S₃ segment of the renal proximal tubules in the outer stripe of the outer medulla (OSOM). Following administration of 2-(glutathion-S-yl)HQ (MGHQ) (400 μmol/kg, i.v., 2 h) to Long Evans (wild-type Eker) rats, Western analysis utilizing an antibody specific for quinol-thioether metabolites of HQ revealed the presence of large amounts of chemical-protein adducts in both the OSOM and urine. By aligning the Western blot film with a parallel gel stained for protein, we can isolate the adducted proteins for LC-MS/MS analysis. Subsequent database searching can identify the specific site(s) of chemical adduction within these proteins. Finally, a combination of software programs can validate the identity of the adducted peptides. The site-specific identification of covalently adducted and oxidized proteins is a prerequisite for understanding the biological significance of chemical-induced posttranslational modifications (PTMs) and their toxicological significance.
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