Figure 6.

Extracted fragment ATDs of Hex₈-containing ions (m/z 1558). (a) Fragments of composition Hex₈GlcNAc₁-O-CH=CH-O^- (m/z 1558). The red trace is the ^2,4A_R ion (au) from the d1d1d3-isomer of Man₈GlcNAc₂ (6). The blue trace is the corresponding ion (as) from the d1d1d2-isomer of Man₈GlcNAc₂ (6) and the green trace (at) the ion from the d1d2d3 isomer. Glycans with extended 3-antennae (e.g., Glc₃Man₉GlcNAc₂) also gave this ion (pink trace). The orange trace is a fragment of Glc₃Man₇GlcNAc₂ but its structure is uncertain. (b) The blue trace (as) is the ^2,5A_R ion from the d1d1d2-isomer of Man₈GlcNAc₂ (6) and the red trace is the corresponding profile of Man₈GlcNAc₂ from porcine thyroglobulin showing both isomers 6 and 7. The green trace (av) is from Man₉GlcNAc₂ showing fragmentation by losses of each of the α-mannose residues