Fig. 4.

LC-MS profiles and the isotopomers of ¹³C-labeled glycan alditols. Hepa1–6 was cultured in a medium containing ¹³C₂-glucosamine for 24 h. N- and O-glycan alditols were analyzed by LC-MS as described in the experimental procedures. (A and B): Base peak chromatograms of N- and O-glycan alditols. C–F Mass spectra of isotopomers of (C) peak 4 (Man₈GlcNAc₂), (D) peak 13 (nonfucosylated disialo-biantennary glycans), (E) peak 15 (core-fucosylated disialo-biantennary glycans) and (F) peak 17 (sialyl core 1). Labeling with ¹³C₂-glucosamine led to increases in the mass signals because of the labeling with the motifs highlighted with bold asterisks. G, Time course of the ratios of unlabeled ions in each glycan. Symbols are defined in the figure.