Figure 1.

Common GAG-linker region and repeating disaccharide region of DS and CS with their potential sulfation sites. The DS backbone is composed of IdoUA and GalNAc, whereas CS is a stereoisomer of DS that includes GlcUA instead of IdoUA. These carbohydrate residues may be sulfated at various positions indicated by “SO₃⁻”. It should be noted that sulfation modification of the hydroxy group occurs with various combinations but not all the hydroxy groups. 4-O-Sulfation on GalNAc residues in both DS and CS predominantly occurs in mammals. The linkage region tetrasaccharide, IdoUA-Gal-Gal-Xyl-, was isolated from DS-PGs of bovine aorta [25].