The structure and composition of cartilage keratan sulphate

Keratan sulphate was isolated from bovine intervertebral disc and bovine nasal septum after hydrolysis with proteinases and treatment with dilute alkali. Each preparation was found to contain, per keratan sulphate chain: 1 residue of mannose; 3 residues of N acetyl neuraminic acid (2 residues after alkali treatment); 1 residue of N acetyl galactosamine (lost after alkali treatment); 1 residue or less of fucose. N acetyl neuraminic acid residues were at non reducing termini and were bonded to keratan sulphate through galactose residues. Evidence is presented for 2 different types of linkage between skeletal keratan sulphate and protein. Consideration of molecular parameters and compositions leads to a proposed structure for keratan sulphate protein as found in skeletal proteoglycans.