title: Lactosylceramidase assays for diagnosis of globoid cell leukodystrophy and GM1-gangliosidosis.
abstract: An assay procedure was developed for accurate estimation of lactosylceramidase II in the presence of relatively high activity of lactosylceramidase I. The procedure involves determination of lactosylceramide-cleaving activities under two different assay conditions, and lactosylceramidase II activity is calculated by the difference. Applicability of the procedure was evaluated with separated soluble fractions of the two beta-galactosidases from normal human brains, and with whole homogenates of gray and white matter, liver and cultured fibroblasts from control individuals and from patients with globoid cell leukodystrophy or GM1-gangliosidosis. The use of the lactosylceramidase I assay procedure developed by Wenger, D.A., Sattler, M., Clark, C. and McKelvey, H. ((1974) Clin. Chim. Acta 56, 199-206) and of the present procedure permits accurate diagnosis of both globoid cell leukodystrophy and GM1-gangliosidosis with one natural substrate, lactosylceramide, irrespective of the relative proportion of the two beta-galactosidases in the tissue.
mesh_terms: D001921:Brain / Q000201:enzymology; D002518:Ceramides; D004796:Clinical Enzyme Tests; D005347:Fibroblasts / Q000201:enzymology; D005677:G(M1) Ganglioside; D005696:Galactosidases / Q000378:metabolism*; D005698:Galactosylceramidase / Q000378:metabolism*; D005733:Gangliosidoses / Q000175:diagnosis*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D007785:Lactose; D007965:Leukodystrophy, Globoid Cell / Q000175:diagnosis*; D008099:Liver / Q000201:enzymology; D001616:beta-Galactosidase
chemical_list: D002518:Ceramides; D007527:Isoenzymes; D005677:G(M1) Ganglioside; D005696:Galactosidases; C021502:acid beta-galactosidase; D001616:beta-Galactosidase; D005698:Galactosylceramidase; D007785:Lactose