Identity of ‘acid’ β-glucosidase and glucocerebrosidase in human spleen

Abstract

1. Glucocerebrosidase, in association with a membrane-bound ‘acid’ β-glucosidase, was separated from a soluble ‘neutral’ β-glucosidase that had no activity towards glucocerebroside as substrate. 2. Glucocerebrosidase, as well as ‘acid’ β-glucosidase activity depended upon the association of factor P (a heat-stable, soluble, acidic glycoprotein) with factor C (a heat-labile membrane-bound protein). 3. Factor C was solubilized under certain conditions. 4. Solubilized factor C, as well as membrane-bound factor C, could be alternatively stimulated by sodium taurocholate to give both glucocerebrosidase and ‘acid’ β-glucosidase activities. 5. Membrane-bound factor C reacted optimally with factor P whereas solubilized factor C was preferentially stimulated by taurocholate. 6. Factor P-dependent glucocerebrosidase activity differed in kinetic properties from the taurocholate-stimulated enzyme activity. 7. The results are discussed in the light of (a) identity of glucocerebrosidase and ‘acid’ β-glucosidase, (b) application in clinical diagnosis, (c) physiological significance of the enzyme system, and (d) polygenic inheritance in adult Gaucher's disease.