Proteomic Approaches to Cancer Biomarkers Kenneth E. Hung, Kenneth H. Yu  Gastroenterology  Volume 138, Issue 1, Pages 46-51.e1 (January 2010) DOI: 10.1053/j.gastro.2009.11.020 Copyright © 2010 AGA Institute Terms and Conditions

Figure 1 Tandem MS (MS/MS) is typically performed using ion trap MS. Online reversed-phase chromatography allows for presentation of different peptide ions to the MS over time (x-axis; A). (B) Full mass spectra of peptides presented to the MS at the time point represented by the red arrow in A. The most abundant ions (B, red arrow) are typically chosen for fragmentation by collision induced fragmentation. The subsequent spectra of product ions (C) is unique to the amino acid sequence of the peptide. This sequence can be determined by matching the spectra (D) to in silico–generated spectra found in protein databases. Gastroenterology 2010 138, 46-51.e1DOI: (10.1053/j.gastro.2009.11.020) Copyright © 2010 AGA Institute Terms and Conditions

Figure 2 Multiple reaction monitoring (MRM) is typically performed using triple quadrupole MS. A complex mixture of peptide ions are presented to the MS from the ion source. The ion of interest, fibronectin 1 peptide VVTPLSPPTNLHLEANPDTGVLTVSWER, with a m/z of 1014.53 for the MH3+ ion, is selected in the first mass analyzer (Q1) and fragmented by collision-induced dissociation in Q2. The y252+ product ion (m/z 1372.21) is selectively monitored in the Q3 mass analyzer. The resulting MRM chromatogram is highly specific for the peptide of interest. Gastroenterology 2010 138, 46-51.e1DOI: (10.1053/j.gastro.2009.11.020) Copyright © 2010 AGA Institute Terms and Conditions