FIGURE 7.

Fragmentation of an abundant neutrophil glycan. The [M + Na]⁺ molecular ion at m/z 3490 from Fig. 6A was subjected to MS/MS analysis to demonstrate the presence of multiple fucose residues on outer arms of a tri-antennary oligosaccharide. The horizontal arrows on the spectrum indicate losses from the molecular ion [M + Na]⁺ of the designated sequences in the inset. The signal at m/z 3039 corresponds to loss of HexNAcFuc from the reducing side of the glycans, indicative of core fucosylation, and the ion at m/z 3284 results from elimination of a fucose residue in a Lewis^x epitope. The ions at m/z 486 and 660 establish the presence of a terminal N-acetyllactosamine unit and a terminal Lewis^x terminal epitope, whereas the ions at m/z 1109 and 1283 correspond to single elongated and double Lewis^x epitopes.