= Keratan sulfate
<Keratan sulfate> is a sulfated <glycosaminoglycan> with a backbone of alternating <galactose> and <N-acetylglucosamine> residues. Unlike <hyaluronic acid> and many other <glycosaminoglycans>, its characteristic two-sugar repeat does not contain a <uronic acid>. Backbone identity and the extent of sulfation are separate structural questions.<Isolation and partial characterization of keratan sulphate from human brain by I. Eronen and others>[Abstract: sulfated galactose–N-acetylglucosamine disaccharide repeat]{ref}
An ideal backbone segment with 30 complete repeats has 30 <galactose> residues and 30 <N-acetylglucosamine> residues, for 60 sugar residues altogether. This count does not fix its number of sulfate groups or the molecular mass of an actual preparation.
A 1985 study isolated a sulfated fraction from human brain and combined chemical analysis with susceptibility to a keratan-sulfate-cleaving <enzyme>. Agreement between the repeat structure and cleavage behavior supported its identification as <keratan sulfate>; size measurements also showed heterogeneity. Several different observations make identification stronger than reliance on a sulfated material's charge alone.<Isolation and partial characterization of keratan sulphate from human brain by I. Eronen and others>[Abstract: isolation, gel filtration, repeat structure and endo-beta-galactosidase susceptibility]{ref}
Back to article page
