Structure of typical disaccharide units found in CS/DS. CS/DS disaccharide units are composed of an N-acetylated glucosamine (GalNAc) associated to an uronic acid (UA) through a β1-3 linkage, with variations in sulfation pattern as indicated. UA is a glucuronic acid for 0-E units (CS disaccharides) and an iduronic acid for i0-iE units (DS disaccharides).