Eliminative degradation of polysaccharides containing 1,4-beta-D-hexosaminyl and 1,3-beta-D-glucuronosyl linkages to disaccharides containing 4-deoxy-beta-D-gluc-4-enuronosyl groups. Binds 1 Ca(2+) ion per subunit. Monomer. Belongs to the polysaccharide lyase 8 family.