Fluorescein keratan sulfate

Keratin Sulfate (KS) is the only type of sulfated GAGs that do not contain glucuronic acid. It is composed of repeated disaccharides Galb1-4GlcNAc linked by β -1,3-glycosidic bonds. In the biosynthesis process of KS, glycosyltransferase and sulfate transferase work together to alternately add Gal and GlcNAc to the GlcNAc receptor residue at the reduced end of the KS chain, resulting in chain elongation. Both Gal and GlcNAc can undergo sulfation at C6, but it occurs more frequently on GlcNAc than on Gal. The degree of sulfation of KS is uneven, including areas where sulfation does not occur, areas where monosulfation occurs on GlcNAc, and high sulfation areas where both Gal and GlcNAc undergo sulfation. Like other GAGs, it is these variable sulfation regions in KS that determine their interaction characteristics with ligands such as growth factors, morphogenetic factors, and cytokines, and determine the functional properties of tissues containing KS. Different types of KS can be isolated and prepared from animal corneas, cartilage, and egg whites, but commercialization is extremely rare.