FIGURE 8.

ESI-MSⁿ spectra of permethylated O-glycan alditols from recombinant α-dystroglycan (hDG8). A, MS² spectrum of the permethylated phosphoglycan H₁N₃p + H⁺ (m/z 1050) as a methanol elimination product. The structures of the glycan alditol at m/z 1050.5 and of the fragment at m/z 360.2 are included. The fragment at m/z 360.2 can be interpreted as indicating a 3-phosphoester of the subterminal GlcNAc. B, MS³ spectrum of the B_2α-fragment (N₂P) at m/z 553.5 revealing a terminal HexNAc (no methanol elimination) and the elimination of methaphosphate (79 Da). All fragments are proton adducts.