Fig. 2.

Experimental strategy to evaluate and correct the 18-plex TMTpro data.A, schematic diagram of 18-plex TMTpro (TMT18) samples used in TMTc-based correction of reporter quantification. Escherichia coli peptides (1×, 3×, and 10×) were labeled and mixed with 100× of human peptides. The assignment of different amounts to the channels was largely random. However, the amounts of “1×” and “10×” were assigned to adjacent channels to minimize TMT channel crosstalk, since the impurity of TMT reagents often affects alternating channels. The 18 samples were then pooled together and analyzed by LC–MS/MS. B, experimental relative intensities quantified by TMT reporter ions in E. coli. C, experimental relative intensities quantified by TMTc ions in E. coli. The 18 TMTpro reagents lead to the quantification of nine TMTc channels because of some isobaric TMTc ions. D, experimental relative intensities of TMT reporter ions after TMTc-based correction. The error bars indicate the SDs of the analysis. TMTc, complement TMT; TMT, tandem mass tag.