Quantitation of human glutathione S-transferases in complex matrices by liquid chromatography/tandem mass spectrometry with signature peptides

• Published in: Rapid communications in mass spectrometry 2004-01, Vol.18 (4), p.491-498
• Main Authors: Zhang, Fagen, Bartels, Michael J., Stott, William T.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Chromatography, Liquid; Cytosol - chemistry; Electrophoresis, Polyacrylamide Gel; Enzyme Stability; Glutathione Transferase - analysis; Glutathione Transferase - chemistry; Humans; Liver - chemistry; Molecular Sequence Data; Peptide Fragments - analysis; Peptide Fragments - chemistry; Peptide Fragments - metabolism; Peptides - analysis; Peptides - chemistry; Spectrometry, Mass, Electrospray Ionization; Trypsin
• ISSN: 0951-4198; 1097-0231
• DOI: 10.1002/rcm.1364

Direct quantitation of glutathione S‐transferase (GST) isoforms [α (GST‐A) and μ (GST‐M)] in human liver cytosol was achieved by liquid chromatography/tandem mass spectrometry (LC/ESI‐MS/MS) analysis of signature peptides of GST‐A and GST‐M and their corresponding stable isotopic peptide internal standards via multiple reaction monitoring (MRM). The selection of signature peptides was performed via trypsin digestion of commercially available cDNA‐expressed GST‐A1 and GST‐M1, followed by LC/ESI‐MS/MS with an ion trap mass spectrometer and sequencing with the TurboSEQUEST® application. Quantitative analysis of the selected signature peptides in the multi‐reaction monitoring (MRM) mode was performed using a triple‐quadruple mass spectrometer. A series of human cytosol samples was quantitatively analyzed for levels of GST‐A and GST‐M. The total level of GST‐A and GST‐M obtained from this LC/ESI‐MS/MS method was well correlated with the total level of GST determined by the 1‐chloro‐2,4‐dinitrobenzene (CDNB) method. Copyright © 2004 John Wiley & Sons, Ltd.