Depending on whether a second fucose is incorporated or not, Lewisa/x or Lewisb/y are built. Then, sialylation of Lewisa/x can occur to give sialyl-Lewisa/x. 3.2.4. Glycosaminoglycans Hyaluronan (HA) is a non-sulfated glycosaminoglycan made of disaccharide repeat units of GlcNAc and ...