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Immunoquantification of the low abundance lysosomal enzyme N ‐acetylgalactosamine 4‐sulphatase
Author(s) -
Brooks D. A.,
McCourt P. A. G.,
Gibson G. J.,
Hopwood J. J.
Publication year - 1990
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/bf01799338
Subject(s) - enzyme , medicine , monoclonal antibody , chemistry , endocrinology , enzyme assay , sulfatase , microbiology and biotechnology , biology , biochemistry , antibody , immunology
Summary The low abundance lysosomal enzyme N ‐acetylgalactosamine 4‐sulphatase (4‐sulphatase) has been quantified using a microimmunopurification step and a monoclonal‐based ELISA detection system. The assay is similar in principle to a two‐site ELISA but uses a single monoclonal antibody against one epitope to bind 4‐sulphatase in two separate assay steps. The sensitivity of this assay is sufficient to allow the quantification of 4‐sulphatase in human cultured skin fibroblasts derived from normal controls and patients deficient in 4‐sulphatase activity (mucopolysaccharidosis type VI or Maroteaux‐Lamy syndrome). The results obtained suggest a range of mucopolysaccharidosis type VI or 4‐sulphatase deficient mutants, from those expressing little or no quantifiable 4‐sulphatase protein to those examples with quantifiable levels of 4‐sulphatase protein which is enzymically inactive. Phenotypic variability in patients with a 4‐sulphatase deficiency may therefore be partially attributed to a range of protein expressions. The method should allow the determination of 4‐sulphatase specific activity in mucopolysaccharidosis type VI patients.