The enzyme chondro-4-sulfatase (EC 3.1.6.9) catalyzes the reaction4-deoxy-β-D-gluc-4-enuronosyl-(1→3)-N-acetyl-D-galactosamine 4-sulfate + H2O 4-deoxy-β-D-gluc-4-enuronosyl-(1→3)-N-acetyl-D-galactosamine + sulfate