title: Immunoquantification of the low abundance lysosomal enzyme N-acetylgalactosamine 4-sulphatase.
abstract: 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.
authors.affiliation: Department of Chemical Pathology, Adelaide Childrens Hospital, Australia.
authors.forename: D A
authors.initials: DA
authors.lastname: Brooks
authors.forename: P A
authors.initials: PA
authors.lastname: McCourt
authors.forename: G J
authors.initials: GJ
authors.lastname: Gibson
authors.forename: J J
authors.initials: JJ
authors.lastname: Hopwood
mesh_terms: D000911:Antibodies, Monoclonal; D002478:Cells, Cultured; D002803:Chondro-4-Sulfatase / Q000032:analysis* / Q000276:immunology; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D008247:Lysosomes / Q000201:enzymology*; D009087:Mucopolysaccharidosis VI / Q000201:enzymology; D012867:Skin / Q000201:enzymology; D013429:Sulfatases / Q000032:analysis*
chemical_list: D000911:Antibodies, Monoclonal; D013429:Sulfatases; D002803:Chondro-4-Sulfatase