Biochemical Journal

Research article

Age-related changes in the structure of the keratan sulphate chains attached to fibromodulin isolated from articular cartilage

M. Robert LAUDER, N. Thomas HUCKERBY, A. Ian NIEDUSZYNSKI, H. K. Anna PLAAS

Abstract

Bovine articular cartilage fibromodulin has been isolated from animals aged 3 months to 8 years, and the attached keratan sulphate (KS) chains digested with keratanase II. The oligosaccharides generated have been reduced, examined by high-pH anion-exchange chromatography and their structures identified by comparison with standards. It has been shown that in fibromodulin from young articular cartilage, the KS chains do not possess either non-reducing terminal (α2-6)-linked N-acetylneuraminic acid or fucose (α1-3)-linked to sulphated N-acetylglucosamine residues. However, an age-related increase has been observed in the abundance of both (α2-6)-linked N-acetylneuraminic acid and (α1-3)-linked fucose, neither of which is found in KS isolated from non-articular cartilage, irrespective of the age of the source. Interestingly, the KS chain length remains constant as a function of age, which possibly relates to a role in collagen fibril assembly. In addition, no significant age-related changes were identified in levels of galactose sulphation.