Purification, Properties, and Partial Structure Elucidation of a High-Molecular-Weight Glycoprotein from Cervical Mucus of the Bonnet Monkey (Macaca radiata)

A high-molecular-weight glycoprotein has been purified from the cervical mucus of the bonnet monkey (Macaca radiata). The glycoprotein was shown to be homogeneous by electrophoresis, sedimentation equilibrium, and N-terminal group determination, and to contain 19% protein, 19% d-galactose, 18% A′-acetyl-d-galactosamine, 15% N-acetyl-Dglucosamine, 11% l-fucose, 10% sialic acid, and 1% sulfate groups, corresponding to about 1800 amino acid residues and 400 carbohydrate side chains of about 9 monosaccharides. The carbohydrate chains are linked to the peptide backbone through N-acetyl-d-galactosamine and serine (or threonine) residues. Reduction with dithiothreitol and alkylation with iodoacetic acid reduced the molecular mass from 1 to 0.5 × 106 daltons and produced subunits having the same size, charge, and N-terminal amino acid. Electrophoretic studies suggested the presence of disulfide bonds between two chains of the glycoprotein. Degradation with alkaline borohydride gave, after fractionation on Bio-Gel P-2, fractions containing Lfucose, d-galactose, N-acetyl-d-galactosaminitol, N-acetyl-d-galactosamine, N-acetyl-d-glucosamine, and sialic acid in the ratio of 1.0:3.0:1.0:1.0:1.3:1.0. Further fractionation by electrophoresis and paper chromatography gave a charged fraction representing 13% of the original glycoprotein. Enzymic degradation and methylation studies indicated the presence of the structure α-Gal-(1→ 3)-[Fuc(1 → 2)]-Gal-(1 → 4)-GlcNAc, linked to a core component containing Nacetyl-D-galactosaminitol.