Hyaluronan synthases catalyze polymerization of hyaluronan.
Hyaluronan synthases (HASs) are bi-functional glycosyltransferases that catalyze polymerization of hyaluronan. HASs transfer both GlcUA and GlcNAc in beta-(1,3) and beta-(1,4) linkages, respectively to the hyaluronan chain using UDP-GlcNAc and UDP-GlcUA as substrates. HA is made as a free glycan, not attached to a protein or lipid. HASs do not need a primer for HA synthesis; they initiate HA biosynthesis de novo with only UDP-GlcNAc, UDP-GlcUA, and Mg2+. Hyaluronan (HA) is a linear heteropolysaccharide composed of (1-3)-linked beta-D-GlcUA-beta-D-GlcNAc disaccharide repeats. It can be found in vertebrates and a few microbes and is typically on the cell surface or in the extracellular space, but is also found inside mammalian cells. Hyaluronan has several physiochemical and biological functions such as space filling, lubrication, and providing a hydrated matrix through which cells can migrate.