JBC, Vol. 252, Issue 2, 563-573, Jan, 1977
Purification and properties of a heat-stable glucocerebrosidase activating factor from control and Gaucher spleen
S. P. Peters, P. Coyle, C. J. Coffee and R. H. Glew
Gaucher's disease is a lysosomal storage disease caused by a deficiency in
the enzyme glucocerebrosidase. A small, heat-stable glycoprotein first
obtained from Gaucher spleen (Ho, M. W., and O'Brien, J. S. (1971) Proc.
Natl. Acad. Sci. U. S.A. 68, 2810-2813) has been observed to stimulate the
activity of glucocerebrosidase isolated from normal tissue. It has been
suggested that this material might be important in the physiological
catabolism of glucocerebroside in normal individuals (Ho, M. W. (1974) in
Enzyme Therapy in Lysosomal Storage Diseases (Tager, J. M., Hooghwinkel, G.
J. M., and Daems, W. Th., eds) pp.239-246, North-Holland Publishing Co.,
Amsterdam). In order to investigate this suggestion, glucocerebrosidase
activating factors were isolated and purified from control and Gaucher
spleen and characterized. Although approximately the same mass of activator
was isolated from both spleens, the two activators differ from one another
in a number of important respects: (a) the activator from the control
spleen is only 6 per cent as active (on a protein basis) as the activator
from Gaucher spleen; (b) the amino acid compositions of the purified
activators are significantly different; and (c) carbohydrate analysis of
the purified activators indicates that the activator from Gaucher spleen is
a glycoprotein, while that from control spleen is not. Comparative kinetic
studies demonstrate that the anionic detergent, sodium taurocholate, and
the acidic phospholipid, phosphatidylinositol, both stimulate
glucocerebrosidase activity to a larger extent than the activator substance
from Gaucher spleen. The activator from Gaucher spleen and human liver
glucocerebrosidase both appear to contain significant hydrophobic
character. We conclude that the activator is probably not physiologically
important in the catabolism of glucocerebroside in normal tissues. The
significance of the occurrence of this apparently unique glycoprotein
activator in Gaucher spleen remains obscure; however, its presence
represents another interesting aspect of Gaucher's disease that warrants
further investigation.