Structure of the keratan sulphate chains attached to fibromodulin isolated from bovine tracheal cartilage. Oligosaccharides generated by keratanase digestion

Abstract

The structure of the repeat region and chain caps of the N-linked keratan sulphate chains attached to bovine tracheal cartilage fibromodulin has been examined. The chains were fragmented by keratanase digestion, the resultant oligosaccharides isolated by strong anion-exchange chromatography, and their structures determined using high-field 1H-n.m.r. spectroscopy. The chains were found to possess the following general structure: [formula: see text] All of the capping oligosaccharides isolated terminate with alpha(2-3)-linked N-acetylneuraminic acid. No alpha(2-6)-linked N-acetylneuraminic acid chain terminators, nor any fucose, alpha (1-3)-linked to N-acetylglucosamine along the repeat region, were detected. This work demonstrates that the structure of the repeat region and chain caps of N-linked keratan sulphate attached to fibromodulin isolated from bovine tracheal cartilage is identical with that of O-linked keratan sulphate chains attached to aggrecan derived from non-articular cartilage.