LACTOSYLCERAMIDASES IN CANINE GLOBOID CELL LEUKODYSTROPHY

Lactosylceramide‐cleaving activities were examined in the canine form of globoid cell leuko‐dystrophy. Lactosylceramidase I activities were deficient in the brains and livers of affected dogs, while they were intermediate in heterozygous carriers. In contrast, lactosylceramidase II activities were normal in affected dogs. Examination of the total tissue activities, solubilization characteristics, and the behavior in Sephadex G‐200 gel filtration, of the activities of lactosylceramidase I and II, galactosylceramidase, and 4‐methylumbelliferyl β‐galactosidase, indicated that, as in human tissues, lactosylceramidase 1 is probably identical with galactosylceramidase, and that lactosylceramidase II is closely associated with 4‐methylumbelliferyl β‐galactosidase. The canine form of globoid cell leukodystrophy is analogous with the human disease with respect to lactosylceramidases, and the lactosylceramidase I assay system of Wengeret al. (1974) is directly applicable also for canine tissues.