FIG. 8.

Mass spectra of SIVmac239, SIV04, and Jacalin4 gp120 permethylated O-glycans released by reductive elimination. The spectra were acquired in positive-ion mode using the reflectron. Molecular ions of m/z 534, 895, and 1,256 correspond to non-, mono-, and disialylated core 1 structures, respectively, whereas molecular ions of m/z 779, 983, 1,344, and 1,705 were defined as core 2 O-linked glycans. Signals from hexose oligomers are indicated by X's. All molecular ions are [M + Na]⁺, and each panel is normalized to the most abundant signal (100% intensity) in the raw data. The abundance reported in the text for each O-glycan corresponds to its percentage of the total observed O-glycome (based on peak heights). The O-glycome value was obtained by summing the peak heights of the molecular ions attributable to O-glycans. These are noted in each of the panels. Structural assignments are based on monosaccharide composition, fragmentation analyses, and knowledge of the glycan biosynthetic pathways. The sugar symbols used are those employed by the Consortium for Functional Glycomics (www.functionalglycomics.org). (A) SIVmac239; (B) SIV04; (C) Jacalin4; (D) mock transfection.