Structural studies of the carbohydrate component of a human, parotid-saliva, proline-rich glycoprotein

The carbohydrate chains of the human, parotid-saliva, proline-rich glycoprotein were released as oligosaccharides by hydrazinolysis and were fractionated by high-pressure-liquid chromatography. Four oligosaccharides were characterized. On the basis of compositional analysis, sequential enzymic degradation, and methylation data, the carbohydrate moiety of the glycoprotein was found to be a complex-type oligosaccharide containing a tri-D-mannosyl-di-N-acetylchitobiose core with two and three lactosamine branches, and an L-fucosyl group linked to O-6 of the asparagine-linked 2-acetamido-2-deoxy-D-glucose residue. In addition, several L-fucosyl groups, linked at O-6 of the penultimate D-galactose residues, are present in variable proportions. The biological significance of these results is discussed.