An activator stimulating the enzymic hydrolysis of sphingoglycolipids.

An activator stimulating the enzymic hydrolysis of sphingoglycolipids has been purified from human liver. The purity of the activator, as examined by disc gel electrophoresis, showed one major band stained with both amido black and periodate-Schiff reagent. Chemical analyses identify the activator as a glycoprotein. The physical properties of the activator are: heat-stable, nondialyzable; molecular weight, about 21,000; isoelectric point (pI), 4.1. The purified activator stimulates the hydrolysis of GM1 by beta-galactosidase, GM2 by beta-hexosaminidase, as well as ceramide trihexoside by alpha-galactosidase A or B. The hydrolysis by glycosidases depends upon the amount of activator added. An antibody against the activator was developed from rabbits. The specificity of the antibody to the activator has been established. The antibody was used to make the affinity column for isolation of the activator. It was also used to develop a sensitive immunodiffusion method to detect the activator.