Fig. 1.

MALDI-TOF/TOF-MS and MS/MS spectra of the molecular ion m/z 1331 [M + Na]⁺ detected in the mass fingerprinting of the stomach from wild-type and C2GnT2 knockout mice. Selected sections from O-glycomic mass fingerprinting of the stomach from wild-type (A) and C2GnT2 knockout (B) mice showing several [M + Na]⁺ peaks with the same m/z. High-sensitivity MS/MS data differentiate glycans of the same composition (HexNAc₂Hex₂Fuc₂) and mass (m/z 1331) but with different O-glycan core types. In the wild-type stomach (C), the core 2 O-glycan was the only isoform detected, whereas in the C2GnT2 knockout mice (D), there was a mixture of core 2 and core 1 O-glycans with the latter as the major component. Na, sodium.