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. Author manuscript; available in PMC: 2011 Jun 9.
Published in final edited form as: Nature. 2010 Nov 17;468(7325):790–795. doi: 10.1038/nature09472

Figure 1. A quantitative approach to globally profile cysteine reactivity in proteomes.

Figure 1

a, isoTOP-ABPP involves proteome labeling, click chemistry-based incorporation of isotopically-labeled cleavable tags, and sequential on-bead protease digestions to afford probe-labeled peptides for MS analysis. The IA-probe is shown in the inset. b, Measured isoTOP-ABPP ratios for peptides from MCF7 cells labeled with four pairwise IA-probe concentrations (10:10 μM, 20:10 μM, 50:10 μM, 100:10 μM). The blue box highlights peptides with low isoTOP-ABPP ratios (R < 2.0). Chromatographs for CKB (low ratio) and LCP1 (high ratio) are shown, with elution profiles for heavy- and light-labeled peptides in blue and red, respectively, and green lines depicting peak-boundaries used for quantitation. Isotopic envelopes are shown for light- and heavy-labeled peptides with green lines representing predicted values. Additional chromatographs from isoTOP-ABPP experiments are in Supplementary Table 7.