Figure 8

Identification of a novel PTCM in Salmonella. Cyano modification on Cys was determined for the sequence CKIEQAPGQHGAR of the Salmonella ribosomal protein S4. Explanation for the determination of modifications is detailed in text. Inset figure demonstrates how sequencing precision in high resolution MS/MS spectra easily resolves residues with close mass like Gln (Q) and Lys (K) which cannot be resolved in low resolution spectra. The map in the lower right corner of contains all predicted fragments observed from the resolved isotopic clusters with shade of spots corresponding to parts per million (ppm) distance from expected value. This map is used to determine the correct identification between all plausible sequences and PTCMs matching observed mass shifts.