title: Epitope mapping and targeted quantitation of the cardiac biomarker troponin by SID-MRM mass spectrometry.
abstract: The absolute quantitation of the targeted protein using MS provides a promising method to evaluate/verify biomarkers used in clinical diagnostics. In this study, a cardiac biomarker, troponin I (TnI), was used as a model protein for method development. The epitope peptide of TnI was characterized by epitope excision followed with LC/MS/MS method and acted as the surrogate peptide for the targeted protein quantitation. The MRM-based MS assay using a stable internal standard that improved the selectivity, specificity, and sensitivity of the protein quantitation. Also, plasma albumin depletion and affinity enrichment of TnI by anti-TnI mAb-coated microparticles reduced the sample complexity, enhanced the dynamic range, and further improved the detecting sensitivity of the targeted protein in the biological matrix. Therefore, quantitation of TnI, a low abundant protein in human plasma, has demonstrated the applicability of the targeted protein quantitation strategy through its epitope peptide determined by epitope mapping method.
authors.affiliation: Research Analytical Chemistry, Abbott Diagnostics Division, Abbott Laboratories, Abbott Park, IL, USA.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhao
authors.forename: Beth
authors.initials: B
authors.lastname: Trudeau
authors.forename: Helen
authors.initials: H
authors.lastname: Xie
authors.forename: John
authors.initials: J
authors.lastname: Prostko
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Fishpaugh
authors.forename: Carol
authors.initials: C
authors.lastname: Ramsay
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D015415:Biomarkers / Q000097:blood / Q000737:chemistry; D002138:Calibration; D018604:Epitope Mapping / Q000379:methods*; D006801:Humans; D008969:Molecular Sequence Data; D053719:Tandem Mass Spectrometry / Q000379:methods*; D019210:Troponin I / Q000097:blood* / Q000737:chemistry / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D015415:Biomarkers; D019210:Troponin I
keywords: Epitope mapping; MRM; Targeted quantitation; Technology; Troponin