Brain ß-galactosidase and gm₁ gangliosidosis

Several properties of ß-galactosidase obtained from brains of controls and patients with Gmi gangliosidosis types I and II were studied. The pH optimum of ß-galactosidase was 4 in both fetal and control brain. In contrast, the pH optimum of brain ß-galactosidase in patients with either type I or type II Gmi gangliosidosis was 3. The residual ß-galactosidase activity in brains of both type I and type II patients was approximately 27% and 6% of the control values when assayed at pH 3 and 4, respectively. Differences in the thermostability of ß-galactosidase in control, type I, and type II patients were observed. On both cellulose acetate and starch gel electrophoresis, brains from type I patients, but not from type II patients had a ß-galactosidase band which migrated towards the anode with a mobility different from that in control brains.