The enzyme releases 4-deoxy-4,5-didehydro?D-glucuronic acid or 4-deoxy-4,5-didehydro?L-iduronic acid from chondroitin disaccharides, hyaluronan disaccharides and heparin disaccharides and cleaves both glycosidic (1¡ú3) and (1¡ú4) bonds. It prefers the sulfated disaccharides to the unsulfated disaccharides.