Fig. 4.

Identification of glycopeptides and glycans derived from PilA of the type A strain SCHU S4. (A) MS² CID spectrum generated using the ion trap mass spectrometer of the doubly charged peptide at m/z 717.82+ showing that the peptide ⁷²GLPSGA⁷⁷ derived from PilA is glycosylated. Abundance is shown as a percentage on the y axis. (B) MS² CID spectrum generated using the ion trap mass spectrometer of the doubly charged peptide at m/z 877.52+ showing that the peptide ¹⁰¹VSSGAITW¹⁰⁸ derived from PilA is glycosylated. Both spectra are dominated in the high-m/z region by the sequential losses of HexNAc and Hex carbohydrate moieties, allowing the identification of the glycan as a pentasaccharide consisting of HexNAc-Hex-Hex-HexNAc-HexNAc (gray squares, HexNAc; filled circles, Hex). pep, peptide.