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. 2013 Feb 26;18(3):2571–2586. doi: 10.3390/molecules18032571

Figure 5.

Figure 5

Analysis of sialic acid residues of glycoproteins isolated from HUVECs after incubation with per-O-acetylated ManNProp, ManNBut, and ManNAc. (A) Sialic acid residues obtained after DMB-labeling were separated by RP-HPLC. For control, HUVECs were not incubated with any sialic acid precursors. Peaks related to DMB reagent are labeled with an asterisk (*) and those related to unknown impurities are marked with a triangle (▼). (B) EIC of sodium adducts ([M+Na]+) of Neu5Prop (m/z 462) and Neu5But (m/z 476) present in glycoproteins from HUVECs incubated with ManNProp and ManNBut, respectively. (C) ESI-MS/MS analyses of Neu5Prop (upper profile) and Neu5But (lower profile) registered as proton adducts ([M+H]+). Annotation of fragment ions was carried out as defined in Figure 4.