Iduronate sulfatase from human placenta

The major enzyme component of iduronate sulfatase from human placenta was purified 30 000-fold by a five-step procedure. Sucrose gradient centrifugation of the native enzyme gave a molecular weight estimate of 80 000 +/- 10 000. Electrophoresis in sodium dodecyl sulfate of the enzyme reduced with mercaptoethanol showed a protein band of Mr 82 000. We suggest that the enzyme is composed of a single polypeptide chain of Mr 80 000-90 000.