Fig 7. Comparison of HPLC profiles of 2-AB-labeled N-linked glycans released from HRP by various conditions.

(A) HPLC chromatograms of glycopeptidase A digestion (i), alkaline de-N-glycosylation with 20% hydroxylamine at 50°C for 1 h (ii), and alkaline de-N-glycosylation with 20% hydroxylamine at 80°C for 1 h (iii). (B) Comparison of glycan recovery. Bar graph indicates sum of all glycan peak areas in the HPLC chromatograms. All chromatograms were obtained by injection of equal volumes of glycan solution prepared from the same quantity of glycoproteins. The numbered peaks were determined by MS and MS/MS and are summarized in Table 3. Glycan structures are depicted by using CFG graphical notation for glycans (http://www.functionalglycomics.org/static/consortium/CFGnomenclature.pdf).