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A fluorimetric enzyme assay for the diagnosis of sanfilippo disease type A (MPS IIIA)
Author(s) -
Karpova E. A.,
Voznyi Ya. V.,
Keulemans J. L. M.,
Hoogeveen A. T.,
Winchester B.,
Tsvetkova I. V.,
Diggelen O. P.
Publication year - 1996
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/bf01799255
Subject(s) - heparin , incubation , enzyme , biochemistry , hydrolysis , chemistry , substrate (aquarium) , enzyme assay , microbiology and biotechnology , yeast , specific activity , biology , ecology
Summary 4‐Methylumbelliferyl‐ α ‐ d ‐ N ‐sulphoglucosaminide (MU‐ α ‐GlcNS) was synthesized and shown to be a substrate for the lysosomal heparin sulphamidase. Sanfilippo A patients' fibroblasts ( n =42) and lymphocytes ( n =1) showed 0–3% of mean normal heparin sulphamidase activity; in total leukocytes from patients ( n =8) sulphamidase activity was clearly deficient. In fibroblasts from obligate heterozygotes for Sanfilippo A, the sulphamidase activity was reduced in 9 out of 10 cases. Heparin sulphamidase desulphates MU‐ α GlcNS to MU‐ α GlcNH 2 and further hydrolysis during a second incubation is required to liberate 4‐methylumbelliferone, which can be measured. Yeast α ‐glucosidase, which has low but sufficient α ‐glucosaminidase activity, was used to hydrolyse the reaction intermediate MU‐ α GlcNH 2 to release 4‐methylumbelliferone and free glucosamine.