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. 2012 Feb;93(1):1–10. doi: 10.1111/j.1365-2613.2011.00807.x

Figure 1.

Figure 1

Structural Diversity of Glycosaminoglycan repeating disaccharide units. The repeating disaccharide units of Hyaluronan (HA), Keratan Sulphate (KS), Chondroitin Sulphate (CS), Dermatan Sulphate (DS), Heparin (Hep) and Heparan Sulphate (HS) consist of a hexosamine [either Glucosamine (GlcN) or Galactosamine (GalN) - Squares] and a uronic acid [either Glucuronic (GlcUA) or Iduronic acid (IdUA) - Triangles] or Galactose (Gal) –Circles. These sugar and disaccharide units are joined to one another by different anomeric glycosidic linkages (α1-4, β1-3 or β1-4) between the sugar hydroxyl groups. The hexosamine, uronic acid and galactose sugars in each disaccharide unit can also be substituted with sulphate groups on the sugar hydroxyls in the 2- (2S), 3- (3S), 4- (4S) and 6- (6S) positions. The hexosamine is usually N-acetlyated (NAc), but in Hep/HS, it can also be N-sulphated (NS) or occur as the free amine (N). HA is the only non-sulphated GAG and it is also not found covalently attached to a proteoglycan core protein.