Figure 2.

MALDI-TOF MS/MS analysis of isomeric forms of Hex₄HexNAc₂Fuc₁ and Hex₄HexNAc₂Fuc₂Me₁ from the fut-1;fut-6, fut-1;fut-8, and fut-6;fut-8 deletion strains. Five selected isomeric forms each of m/z 1297 and m/z 1457 glycans [M + H]⁺ from PNGase F or A digests of the three double fucosyltransferase mutants (F1F6, F1F8, and F6F8) occurring in RP-HPLC fractions of different glucose units (g.u.) were subject to MALDI-TOF MS/MS in the positive ion mode. Key fragments and the full structures are shown according to the nomenclature of the Consortium for Functional Glycomics (Me, methyl; PA, pyridylamino); the fragments surrounded by dashed squares in panels C, G, and H are putative rearrangement products correlating with the presence of distal (but not antennal) fucose modifications. The 4.2 g.u. form of Hex₄HexNAc₂Fuc₁ (panel B), previously analyzed from the fut-1;fut-6;fut-8 triple mutant, is found in all three double mutants. Loss of fucose or hexose from the parent ions is indicated by −F or −H.