Occurrence of reducing terminal N-acetylglucosamine 3-sulfate and fucosylated outer chains in acidic N-glycans of porcine zona pellucida glycoproteins

Structures of acidic N-glycans released from porcine zona pellucida glycoproteins by hydrazinolysis were studied. The results indicated that the acidic glycans are of mono- to tetraantennary complex-type with and without N-acetyllactosamine repeating units. Sulfated residues are not only located at the C-6 position of GlcNAc included in the N-acetyllactosamine repeating units, but also at the C-6 position of GlcNAc in the non-repeated antennae and at the C-3 position of reducing terminal GlcNAc residue. Analysis of the oligosaccharide fragments released by endo-P-galactosidase digestion and by hydrazine/nitrous acid treatment also revealed that various sulfated and non-sulfated forms of fucosylated structures such as Fuc alpha 1 --> 2Gal beta 1 --> 4(+/- SO3- --> 6)GlcNAc (type 2H), Gal beta 1 --> 4(Fuc alpha 1 --> 3)(+/- SO3- --> 6)GlcNAc(Le(x)) and Fuc alpha 1 --> 3 or 4(+/- SO3- --> 6)GlcNAc, are expressed in the repeated outer chain moieties.