Measurement of activities of human serum sulfotransferases which transfer sulfate to the galactose residues of keratan sulfate and to the nonreducingend N-acetylglucosamine residues of N-acetyllactosamine trisaccharide: Comparison between normal controls and patients with macular corneal dystrophy

Human serum sulfotransferase activities were measured in normal controls an d patients with macular corneal dystrophy (MCD), an inherited disorder char acterized by the decreased sulfation of keratan sulfate in the corneal stro ma and serum, using two kinds of acceptor: partially desulfated keratan sul fate and a trisaccharide with a GlcNAc residue at the nonreducing terminal, GlcNAc beta 1-3Gal beta 1-4GlcNAc. When partially desulfated keratan sulfa te was used as the acceptor, only sulfotransferase activity which transfers sulfate to position 6 of the Gal residues was detected, In contrast, when GlcNAc beta 1-3Gal beta 1-4GlcNAc was used as the acceptor, sulfotransferas e activity which transfers sulfate to position 6 of the nonreducing termina l GlcNAc residue could be detected, Although keratan sulfate levels in the sera of MCD patients determined by ELISA were much lower than those in norm al controls, there were no detectable differences in either the sulfotransf erase activity responsible for the sulfation of position 6 of Gal residues or that responsible for the sulfation of position 6 of nonreducing end GlcN Ac residues between normal controls and MCD patients, These results suggest that the sulfotransferase involved in the sulfation of keratan sulfate, wh ich is assumed to be deficient in MCD patients, may not be secreted into th e serum, and that direct measurement of the sulfotransferase activity prese nt in affected tissues such as the cornea instead of serum may be necessary to confirm the postulated deficiency in the biosynthesis of keratan sulfat e in MCD.