CHARACTERIZATION OF ASPARAGINE-LINKED OLIGOSACCHARIDES ON A MOUSE SUBMANDIBULAR MUCIN

The asparagine-linked oligosaccharides from an adult female mouse subm andibular gland mucin were released by treatment with peptide-N-4-(N-a cetyl-beta-glucosaminyl)aspargine amidase F or endo-beta-N-acetylgluco saminidase H, Endo-beta-N-acetylglucosaminidase H appeared to be more effective at releasing the asparagine-linked oligosaccharides from thi s mucin than was peptide-N-4-(N-acetyl-beta-glucosaminyl)asparagine am idase F. After quantitative reductive labelling with the fluorophore, 8-aminonaphthalene-1,3,6-sulphonic acid, the oligosaccharides were sep arated by polyacrylamide gel electrophoresis and isolated. The individ ual oligosaccharides were sequenced by a battery of recombinant exogly cosidases, Approximately 50% of the oligosaccharides were of the high- mannose type. The five-mannose member of this family was the most prev alent. The second group of oligosaccharides were of the non-bisected h ybrid type. No complex asparagine-linked oligosaccharides were detecte d. The hybrids exhibited both biantennary and triantennary branching p atterns. The triantennary hybrid was the most common hybrid at >30% of all oligosaccharides. With similar to 98% of the hybrid oligosacchari des sialylated and all lacking a bisecting N-acetylglucosamine, these oligosaccharides as a group have been only rarely observed in other gl ycoproteins. The fully sialylated triantennary hybrid may be unique.