Figure 12.

NSI-MSn analysis of sulfated O-glycan structure 4. The glycan composition detected at m/z = 1000 in positive mode, corresponding to 955.4 in negative mode (Table 1 and Fig. 7), was fragmented to detect the site and position of sulfation and the presence of Lewis-type structural features. The glycan composition and fragmentation pattern are consistent with an O-Man–initiated structure with a Lewis-type nonreducing terminus bearing a sulfated Hex residue. The sulfate group was detected at the 3-position of the terminal hexose through informative cross-ring fragments generated in negative mode.