research articles Lin et al. Figure 7. Impact of chemoselective fractionation with IBB on detection of yeast proteins grouped by spectral counts. Proteins are grouped by spectral counts into ﬁve bins on the x-axis. One-way ANOVA analyses indicate signiﬁcant differences in IBB enrichment effect based on protein spectral counts in global (G) fraction. Data points represent log2 (E/G) for detected protein spectral counts in the eluted (E) fraction to the global (G) fraction. Means for each group are indicated by a long black line, and standard error of the mean (SEM) are indicated by short lines. *** Indicates p < 0.001. Figure 8. Impact of chemoselective fractionation with IBB on detection of RKO proteins grouped by spectral counts. Proteins are grouped by spectral counts into ﬁve bins on the x-axis. One-way ANOVA analyses indicate signiﬁcant differences in IBB enrichment effect based on protein spectral counts in global (G) fraction. Data points represent log2 (E/G) for detected protein spectral counts in the eluted (E) fraction to the global (G) fraction. Means for each group are indicated by a long black line, and standard error of the mean (SEM) are indicated by short lines. *** Indicates p < 0.001. into a proteome analysis workﬂow. We recognize that this topic has been studied previously with other reagents and we anticipate that our results broadly reﬂect the impact of thiol- directed capture chemistries. A key element of our study is the 5470 Journal of Proteome Research Vol. 9, No. 10, 2010