Urinary keratan sulfate of Morquio's disease

To elucidate precise chemical nature of urinary keratan sulfate (KS) of Morquio's disease, crude glycosaminoglycans (GAG) were separated from 24-hr urines of 3 patients with Morquio's disease and from pooled urine of a healthy boy, using cetylpyridinium chloride. KS fractions were then separated from the crude GAG after removal of other GAG and acidic glycopeptide by successive digestion with testicular hyaluronidase and chondroitinase ABC, and by nitrous acid treatment, followed by Dowex 1 column chromatography. The distribution of KS in several fractions (1.5 M Fr-5.0 M Fr) obtained by Dowex 1 column chromatography suggested polydispersity of urinary KS. The relative amounts (micrograms/24-hr urine/kg body weight) of the KS fractions excreted into Morquio's urine were 52-63 times as much as that excreted into normal urine. The KS fractions contained galactose, glucosamine and sulfate as the major constituents, together with fairly amounts of galactosamine and sialic acid, and small amounts of mannose, L-fucose and glucose. The KS fractions resembled sulfated glycopeptide with respect to the sugar composition. The contents of sulfate and sialic acid in each KS fraction from Morquio's urine were higher than those in the corresponding one from normal urine, whereas opposite was the case for the ratio of glucosamine to galactosamine. The sulfate contents in the KS fractions from Morquio's urine indicated that the patient excreted over-sulfated KS into urine. The chemical compositions of the KS fractions from Morquio's urine suggest that the sulfatase specific for 6-sulfate linked to sugars with the galactose configuration may act in a early step of the catabolism of oversulfated KS in the normal tissues.