Identification of N-glycan structures using MALDI-MS
MALDI spectra from permethylated N-glycans were consistent with most glycans being core-fucosylated biantennary types (FA2G2; H5N4F1) with zero, one, or two sialic acids (Figure 4). Masses corresponding to core-fucosylated triantennary glycans (FA3G3; H6N5F1) with one, two, or three sialic acids were also detected. We also acquired positive control data from the N-glycan of fetuin, and no peaks were detected in the negative controls (data not shown). Annotation of R27T N-glycan structures revealed complex glycans with variable degrees of core fucosylation, galactosylation, and sialylation. The major di-sialylated, core-fucosylated biantennary structure was consistent with the 2-AB labeling HPLC results.