Taking advantage of the sequence databases that have now accumulated, proteomic or peptidomic analyses of human body fluids such as blood, urine, bile, etc. have become one of the most important issues relating to the identification of biomarkers or disease markers. We have established the workflows using an18O-labeling method for comparative analysis of two paired protein pools or quantitation of a marker candidate peptide in urine or bile. The mass spectra containing18O-incorporated ion species could be precisely interpreted by ISOTOPICA (1), a software application that allows the relative abundances of narrow-split paired peaks to be resolved.
1) Fernandez-de-Cossio J., Gonzalez L.J., Satomi Y., Betancourt L., Ramos Y., Huerta V., Besada V., Padron G., Minamino N., Takao T. Rapid Commun. Mass Spectrom. 18, 2465-2472 (2004); Nucleic Acids Res. 32, 674-678 (2004).
