Chondroitin sulfate (CS) is a class of glycosaminoglycans covalently attached to proteins to form proteoglycans. Chondroitin sulfate is widely distributed in the extracellular matrix and cell surface of animal tissues. The sugar chain consists of the aggregation of alternating glucuronic acids and n-acetylgalactosamine, which is linked to the serine residue of the core protein through a sugar-like link region.

Although the main chain structure of polysaccharides is not complex, there is a high degree of heterogeneity in terms of the degree of sulfidation, the distribution of sulfate groups and the distribution of the two differences into the rechain of isomeric uronic acids. The fine structure of chondroitin sulfate determines the specificity of function and interaction with a variety of protein molecules.