Galactose 6-sulfate sulfatase activity in Morquio syndrome

We have prepared a new substrate (o-beta-D-sulfo-galactosyl-(1-4)-beta-D-6-sulfo-2-acetamido-2-deoxyglucosyl- (1-4)-D-[1-3H]galactitol), from shark cartilage keratan sulfate, for the assay of galactose 6-sulfate sulfatase activity. Using this substrate, we found there was a striking deficiency of galactose 6-sulfate sulfatase activity, in addition to the known deficiency of N-acetylgalactosamine 6-sulfate sulfatase, in the cultured skin fibroblasts of patients with Morquio syndrome. Our results could be explained by the hypothesis that accumulation of keratan sulfate and chondroitin 6-sulfate in Morquio syndrome is due to a deficiency of galactose 6-sulfate sulfatase and N-acetylgalactosamine 6-sulfate sulfatase activity, which are necessary for the degradation of these two mucopolysaccharides.