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. Author manuscript; available in PMC: 2013 Apr 1.
Published in final edited form as: J Mass Spectrom. 2012 Apr;47(4):411–424. doi: 10.1002/jms.2037

Figure 2.

Figure 2

Effect of varying reaction duration, at a fixed HNE:HSA ratio of 100:1, on reaction progress measured using iTRAQ reporter ion intensity for targeted histidine sites. Linear ion trap/PQD and Orbitrap/HCD data are presented. The targeted mass list was used. Depletion plots are scaled to 100% for the control while relative intensities are given in the accumulation bar plots. Relative abundance measurements were not obtained for targeted site His247, although this site shares the same unmodified peptide with His242. MA indicates Michael addition while SB indicates Schiff base formation. When more than one unmodified peptide for a particular modification site was available, the most frequently-detected unmodified peptide was used.