Multiple forms of membrane-bound beta-glucosidase in Gaucher's disease.

Two forms of membrane-bound beta-glucosidase in the spleen of normal individuals were distinguished by their thermostability properties. The heat-labile form A predominates; it catalyzes the hydrolysis of the natural substrate, glucosylceramide, and is activated by the detergent, sodium taurocholate. The minor heat-stable form B is inactive against glucosylceramide and is inhibited by taurocholate. The activity of form A increases from childhood to adult life, as does the activity of the soluble beta-glucosidase and of glucosylceramide beta-glucosidase. In the spleen of nine patients with different types of Gaucher's disease the residual membrane-bound beta-glucosidase was predominantly heat-stable and inhibited by taurocholate. There was no clear correlation between the properties of the residual enzyme in the different types of the disorder and their respective clinical severity. The results are discussed in relation to the biochemical pathogenesis and the enzymatic diagnosis of Gaucher's disease.