Diagnosis of Maroteaux—Lamy syndrome by the use of radiolabelled oligosaccharides as substrates for the determination of arylsulphatase B activity

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Abstract
The kinetic parameters (Km and V) of human arylsulfatase B (4-sulfo-N-acetylgalactosamine sulfatase) activity in cultured skin fibroblasts were determined with a variety of substrates matching structural aspects of the physiological substrates in vivo chondroitin 4-sulfate and dermatan sulfate. More structurally complex substrates, in which several aspects of the aglycone structure of the natural substrate were maintained, were desufhated up to 4400 times faster than the minimum arylsulfatase-B-specific substrate, namely the monosaccharide N-acetylgalactosamine 4-sulfate. Aglycone structures that influence substrate binding and/or enzyme activity were an adjacent-residue C-6 carboxy group and a second but internal N-acetylgalactosamine 4-sulfate residue. Arylsulfatase B activity in fibroblast homogenates assayed with O-(.beta.-N-acetylactosamine 4-sulfate)-(1 .fwdarw. 4)-O-D-(.beta.-glucuronic acid)-(1 .fwdarw. 3)-O-D-N-acetyl[1-3H]galactosaminitol 4-sulfate derived from chondroitin 4-sulfate as substrate clearly distinguished Maroteaux-Lamy-syndrome patients from normal controls and other mucopolysaccharidosis patients. We recommended the use of the above trisaccharide substrate for both postnatal and prenatal diagnosis of Maroteaux-Lamy syndrome.

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