Alteration of site-directed sugar chains of α_1-acid glycoprotein in serum of patients and its clinical significance

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N-Glycans of α_1-acid glycoprotein (AGP) in sera of healthy individuals and patients with inflammation were comparatively studied (Clin Chim Acta, 2003). N-Glycans released from purified AGP with N-glycanase were treated with sialidase and subjected to MALDI-TOFMS analysis. N-Glycans of both groups were composed with bi-, tri-and tetra-antennary complex-types and the contents of α1-3 fucosylated N-glycans were bi-□tri-<tetra-antennary. In inflammation patients, increases in bi-antennary, decreases in tri-and tetra-antennary and increases in α1-3 fucosylation were significant.N-Glycans of 5 glycosylation sites in AGP were separately compared (in preparation). Purified AGP was treated with endopeptidase Glu-C and N-glycans of each glycopeptides isolated by a reversed phase HPLC were determined by MALDI-TOFMS. Each glycosylation site was composed with different and characteristic antennary glycans, bi-and tri-in sites 1 and 2 and tri-and tetra-antennary in sites 3 to 5. In inflammatory, i … More ncreases in bi-antennary, decreases in tri-and tetra-antennary and increases in α_1-3 fucosylation were commonly observed in all glycosylation sites, in larger degrees in acute than chronic inflammation.To determine cancerous alteration of N-glycans, N-glycans of glycoproteins secreted from human hepatoma cell lines HuH7 and HepG2 were studied (Anal Sci, 2003). Increases in tri-and tetra-antennary and α1-3 fucosylation were prominently detected in several glycoproteins secreted by HepG2 cells. Moreover, α1-3 fucosylation activities toward NeuAcα2-3Galβ1-4GlcNAc-R were detected 20-fold highly in HepG2, comparing to HuH7.To clarify the biological roles of high-fucosylated N-glycans, NK cells were stimulated on plates coated with high-fucosylated glycoproteins purified from HepG2 culture, medium (unpublished result). High-fucosylated glycoproteins will modulate the NK cell functions, since protein with 17kDa was stimulated to phosphorylate on its tyrosine residues. Further study is in progress. Less