Fabry's disease: differentiation between two forms of -galactosidase by myoinositol.

Myoinositol appears to be a competitive inhibitor of alpha-galactosidase activity in fibroblasts of normal human skin but not of the residual alpha-galactosidase activity of fibroblasts obtained from patients with Fabry's disease. It is suggested that normal fibroblasts contain two alpha-galactosidases, only one of which is present in cells from patients with Fabry's disease, and that these enzymes can be distinguished by their different Michaelis constants, rates of heat inactivation, and responses to the inhibitor myoinositol.