Characterization of Glycosaminoglycans by Capillary Electrophoresis

Glycosaminoglycans are linear, sulfated polysaccharides that are found in virtually all animal tissues. With the exceptionof hyaluronic acid, glycosaminoglycans are biosynthesized as proteoglycans in which one or more glycosaminoglycan chains areattached to a core protein (
1
). Chondroitin and dermatan sulfates are comprised of alternating 1→3, 1→4 linked
N
-acetyl-
d
-galactosamine and hexuronic acid (either
d
-glucuronic or
l
-iduronic acid) residues. These saccharide residues can be
O
-sulfonated at various positions on both sugar residues. Heparin and heparan sulfate are structurally related and are comprisedof a hexuronic acid residue (either
l
-iduronic or
d
-glucuronic acid) 1→4 linked to a D-glucosamine (either
N
-sulfo or
N
-acetyl-
d
-glucosamine) residue. Both saccharide residues can be
O
-sulfonated at a variety of different positions, making these glycosaminoglycans structurally complex. Hyaluronic acid containsa simple repeating structure of 1→3, 1→4 linked
N
-acetyl-
d
-glucosamine and
d
-glucuronic acid residues. Hyaluronic acid is an unusual glycosaminoglycan as it is not sulfonated and can have a very highmolecular weight, up to 2 � 10
6
Da compared to 1–3 � 10
5
for the other glycosaminoglycans. Keratan sulfate is a glycosaminoglycan that contains no uronic acid and is comprised ofa repeating 1→3, 1→4 linked,
O
-sulfonated
N
-acetyl-
d
-glu-cosamine and
d
-galactose residues.