The Hurler Corrective Factor

The factor which corrects the abnormal mucopolysaccharide metabolism of Hurler fibroblasts (Hurler factor) has been purified 1000-fold from normal human urine. The Hurler factor behaves at high salt concentration as a protein of molecular weight of 87,000, as determined by chromatography on Sephadex G-200; at low salt concentration, it tends to aggregate and become inactive. Two major peaks of corrective activity can be separated by hydroxylapatite chromatography. Experiments with whole cells indicate that Hurler factor accelerates degradation of stored sulfated mucopolysaccharide and that the effect of exogenously supplied Hurler factor persists in Hurler fibroblasts with a half-life of at least 9 days. Hurler factor is distinct from the common lysosomal hydrolases, including β-galactosidase.