I-Cell disease: isoelectric focusing, concanavalin A-Sepharose 4B binding and kinetic properties of human liver acid beta-D-galactosidases

Plasma alpha-D-mannosidase in mucolipidosis II and mucolipidosis III

There is a marked increase in the acidic alpha-D-mannosidase in the plasma of a patient with mucolipidosis II and of a patient with mucolipidosis III. A small proportion (3--4%) of this acidic alpha-D-mannosidase does not bind to concanavalin A-Sepharose, suggesting an alteration in the glycosylation and some of the enzyme in these disorders. A slight elevation in intermediate alpha-D-mannosidase was also demonstrated in these samples by using a differential assay for the acidic and intermediate alpha-D-mannosidase activities. A combination of chromatography on concanavalin A-Sepharose and Sephadex G-200 showed that intermediate alpha-D-mannosidase components I2 and I4, which account for approximately 80% of the intermediate activity in normal plasma, were also present in ML II and ML III plasma. The minor intermediate alpha-D-mannosidase components in normal plasma, I1 and I3 were either present in small amounts or not detected. These results suggest that a defect in intermediate alpha-D-mannosidase is unlikely to be the primary defect in these disorders.

Multiple molecular forms of certain lysosomal enzymes separated by isoelectric focusing on cellulose acetate membranes

Analytical isoelectric focusing on cellulose acetate membranes offers greater resolution of the enzyme pattern than does standard electrophoresis and offers numerous advantages over other support media in isoelectric focusing. A series of lysosomal enzymes, deficiencies of which cause lethal storage diseases in infants and children, can be shown to exist as multiple molecular forms by analytical isoelectrical focusing on cellulose acetate membranes. This analytical technique should be a valuable tool in the investigation of enzyme polymorphism and genetically determined enzyme deficiency diseases.