FIGURE 1.

Identification of a pEtN-modified N-linked glycan attached to antigenic protein HisJ (Cj0734c). A, shown is peptide fragmentation (lowercase y and b) by HCD MS/MS supporting the assignment of the peptide sequence ²⁷ESNASVELK³⁵. B, fragmentation of pEtN leads to the loss of ethanolamine (43.04 Da) followed by phosphate (79.97 Da). C, shown is pEtN and N-glycan fragmentation (uppercase Y and B) supporting the terminal location of pEtN attached to GalNAc. Oxonium ions of N-glycan sugars and pEtN are also annotated.