Antibodies were made against acid α-glucosidase (α-glu) from human liver. This enzyme is missing in patients with Pompe's disease (PD). Fibroblasts from patients with PD and controls were labelled in culture with 3-H-leucine for a 24 hour period. Afterwards the fibroblasts were harvested and immunoprecipitation was carried out employing the mentioned antibody and Protein A - Sepharose Cl-4B gel. The resultant immunoprecipitates were analysed by SDS gel electrophoresis. It could be demonstrated that α-glu deficient fibroblasts form polypeptides which can be precipitated with antibodies against α-glu. These polypeptides show the same electrophoretic mobility as subunits of α-glu in controls. "Chase experiments" (overdose of unlabelled leucine after labelling with 3-H-leucine) showed that these polypeptides disappear rapidly in fibroblasts of patients with PD. By multiplying the percentage of 3-H-leucine incorporated in α-glu with the specific enzyme activity, a value is formed which seems characteristic for the variant forms of PD. It may be speculated that with the help of 1. specific antibodies, 2. Protein A - Sepharose Cl-4B gel and 3. radioactive labelled cells many enzyme defects cannot only be diagnosed more correctly but also characterized and localized within the cell.
展开▼
