Structural analyses of sugar chains from Abrus precatorius agglutinin

The structures of asparagine-linked sugar chains of Abrus precatorius agglutinin were determined. The sugar chains were liberated from the lectin by hydrazinolysis. After N-acetylation, the reducing-end residues of the sugar chains were coupled with 2-aminopyridine. The pyridylamino (PA-) derivatives thus obtained were purified by gel filtration and HPLC. The structures of the purified derivatives were identified by component analysis, comparison of their elution positions on HPLC with those of PA-sugar chains of known structures, stepwise exoglycosidase digestion, and partial acetolysis. The major four surgar chains obtained from A. precatorius agglutinin were Manα1 → 2Manα1 → 6(Manα1 → 3)Manβ1 → 6(Manα1 → 2Manα2 → 2Manα1 → 3)Manα1 → GlcNAcβ1 → GlcNAc-PA, Manα1 → 2Manα1 → 6(Manα1 → 3)Manα1 → 6(Manα1 → 2Manα1 →3)Manβ1 → GlcNAcβ1 → GlcNAc-PA, Manα1 → 6(Manα1 → 3)Manα1 → 6(Manα1 → 2Manα1 → 3)Manβ1 → 4GlcNAcβ1 → 4GlcNAc-PA, and Manα1 → 6(Manα1 → 34) (Xylβ1 → 2)Manβ1 → 4GlcNAcβ1 → 4(Fucα1 → 3)GlcNAc-PA.