Fig. 3.

Visualization of OxICAT results. Graphical representation of the LC-MS analysis of aerobically growing E. coli cells. Intensity of each mass signal is given as fraction of blackness. Each mass signal corresponds to one OxICAT labeled peptide. Peptide 44–62 of ribosomal protein RpsQ elutes as ICAT pair with a mass difference of 9.0 Da. Mass signal with lower m/z has incorporated light ICAT, representing the reduced form of the peptide whereas mass signal with higher m/z has incorporated heavy ICAT and represents the oxidized form of the peptide. DppA 257–275 contains a cysteine that is part of a structural disulfide bond and elutes as single mass peak labeled with heavy ICAT.