Figure 2.
Validation of the accuracy of quantitative chemoproteomic analysis. RKO proteomes were labeled with the alkyne tagged cysteine alkylating reagent, IPM (Scheme 1), and digested into tryptic peptides. Aliquots of peptide mixtures were conjugated with light or heavy isotopic tagged Az-UV-biotin reagents and mixed in predefined ratios (RL/H = 1:4, 1:2 1:1, 2:1, 4:1). After affinity capture and photorelease, the alkylated peptides were analyzed by LC–MS/MS, and the light/heavy ratios were calculated for IPM-modified cysteine containing peptides. The distributions of these ratios demonstrate the accuracy of this quantitative chemoproteomic workflow. Data are displayed using a log 2 scale on the x axis.