Residual activity of alpha-galactosidase A in Fabry's disease

The alpha-galactosidase A activity from fibroblasts of five Fabry patients and five controls has been separated from alpha-galactosidase B through small DEAE-cellulose columns and in some experiments by treatment of the fibroblast extracts with Sepharose coupled to anti-alpha-galactosidase B antibodies. By these independent methods, it has been shown that there is a residual alpha-galactosidase A in Fabry's disease, which is immunologically similar to the alpha-galactosidase A from the controls. The alpha-galactosidase A from all of the patients and controls has the same apparent Km value for the synthetic substrate 4-methylumbelliferyl-alpha-galactosidase A, while the fifth has a thermolabile enzyme like that from the controls. The amount of immunologically active alpha-galactosidase A seems to be decreased in the patients tested.