Glycosaminoglycans (GAGs) are long unbranched polysaccharides, made up of repeating disaccharides that may be sulphated (e.g. Glucuronic acid , Iduronic acid , Galactose, Galactosamine , Glucosamine). GAGs form an important component of connective tissues.

GAG chains may be covalently linked to a protein to form proteoglycans.

GAGs include:

• Chondroitin sulphate.
• Dermatan sulphate .
• Keratan sulphate .
• Heparan sulphate .
• Heparin.
• Hyaluronan.