Structural analysis on the sugar chains of human alpha 1-antitrypsin: presence of fucosylated biantennary glycan in hepatocellular carcinoma

Abstract

Chemical structures of the sugar chains of alpha 1-antitrypsin (AAT) from patients with hepatocellular carcinoma (HCC) and from healthy individuals with a different affinity for Lens culinaris agglutinin (LCA) were examined by pyridylamination of their oligosaccharides and stepwise exoglycosidase digestion in combination with reversed-phase and size-fractionation high-performance liquid chromatography. We found that the LCA-reactive species of AAT from patients with HCC carried both the biantennary sugar chain with a fucose residue at the innermost N-acetylglucosamine residue, Gal beta 1-4GlcNAc beta 1-2Man alpha 1-6(Gal beta 1-4GlcNAc beta 1-2Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4(Fuc alpha 1-6)GlcNAc-PA, and the biantennary chain without a fucose residue, Gal beta 1-4GlcNAc beta 1-2Man alpha 1-6(Gal beta 1-4GlcNAc beta 1-2Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc-PA, at a ratio of about 1:0.6. The LCA-nonreactive species of AAT contained the biantennary sugar chain Gal beta 1-4GlcNAc beta 1-2Man alpha 1-6(Gal beta 1-4GlcNAc beta 1-2Man alpha 1-3)Man beta 1-4GlcNAc beta 1-4GlcNAc as a major component. These results indicate that a characteristic feature of the carbohydrate chains of AAT from patients with HCC is an increment in fucosylation.