Catalysis of the reaction: beta-D-4-deoxy-Delta(4)-GlcpA-(1->3)-beta-D-GalpNAc6S + H2O = 5-dehydro-4-deoxy-D-glucuronate + N-acetyl-beta-D-galactosamine 6-sulfate.
unsaturated chondroitin disaccharide hydrolase activity