Skip to main content
. Author manuscript; available in PMC: 2019 Jun 27.
Published in final edited form as: J Am Soc Mass Spectrom. 2015 Aug 25;26(12):1981–1991. doi: 10.1007/s13361-015-1231-x

Figure 2.

Figure 2.

Comparison of theoretical and observed tryptic peptides. Five proteins were digested with trypsin and the observed peptides compared with the theoretical digest, assuming complete cleavage at Lys or Arg residues except for Lys-Pro and Arg-Pro, which are poorly cleaved by trypsin. The theoretical products containing Cys were excluded from this analysis. Also, any peptide that would have an m/z of <300 was excluded because this was the lower cut-off for the qTOF analysis. The remaining theoretical products were divided into four groups: less than 500 Da, 500–999 Da, 1000–2000 Da, and >2000 Da. These mass ranges represent the uncharged form of the peptide without TMAB tag, not the observed mass of the labeled peptide; all peptides were labeled with at least one tag—those with Lys were labeled with 2 TMAB tags. The peptides detected by mass spectrometry are indicated in red. Cross-hatching indicated the subset of the detected peptides that were confirmed by MS/MS analysis, either by Mascot or by manual sequencing. Blue indicates predicted peptides that were not detected by mass spectrometry.