title: Quantitative urinary proteome analysis for biomarker evaluation in chronic kidney disease.
abstract: A limitation of proteomic methods with respect to their clinical applicability is the lack of possibilities to directly deduce the amount of a protein or peptide from a particular mass spectrometry (MS) spectrum. For quantification of chronic kidney disease (CKD)-specific urinary polypeptides in capillary electrophoresis coupled with mass spectrometry (CE-MS), we compared signal intensity calibration methods based on either urinary creatinine or stable isotope labeled synthetic marker analogues (absolute quantification) with those based on ion counting using highly abundant collagen fragments as nonmarker references (relative quantification). Our results indicate that relative quantification of biomarker excretion based on ion counts in reference to endogenous "housekeeping" peptides is sufficient for the determination of urinary polypeptide levels. The calculation of absolute concentrations via exogenous stable isotope-labeled peptide standards is of no additional benefit.
authors.affiliation: Mosaiques Diagnostics & Therapeutics, Hannover, Germany.
authors.forename: Justyna
authors.initials: J
authors.lastname: Jantos-Siwy
authors.forename: Eric
authors.initials: E
authors.lastname: Schiffer
authors.forename: Korbinian
authors.initials: K
authors.lastname: Brand
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schumann
authors.forename: Kasper
authors.initials: K
authors.lastname: Rossing
authors.forename: Christian
authors.initials: C
authors.lastname: Delles
authors.forename: Harald
authors.initials: H
authors.lastname: Mischak
authors.forename: Jochen
authors.initials: J
authors.lastname: Metzger
mesh_terms: D015415:Biomarkers / Q000652:urine*; D002138:Calibration; D019075:Electrophoresis, Capillary / Q000379:methods*; D005260:Female; D006801:Humans; D007477:Ions; D007676:Kidney Failure, Chronic / Q000175:diagnosis* / Q000652:urine*; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D008875:Middle Aged; D010455:Peptides / Q000737:chemistry; D020543:Proteome / Q000032:analysis*; D040901:Proteomics / Q000379:methods*; D012372:ROC Curve; D014556:Urine
chemical_list: D015415:Biomarkers; D007477:Ions; D010455:Peptides; D020543:Proteome