title: Occurrence of sialidase activity in two distinct and highly homogeneous populations of lysosomes prepared from the brain of developing mouse.
abstract: Light and heavy lysosomes of mouse forebrain were separated from each other by centrifugation on a Percoll gradient. Light lysosomes were then freed from mitochondria and membranes by sucrose density gradient centrifugation and further purified by floatation-centrifugation on a sucrose gradient. The final preparations of light and heavy lysosomes, fairly homogenous, carried sialidase activity, assayed on MU-NeuAc. The optimal pH was 4.0 and 4.2, the apparent Km value 2.8 x 10(-5) M and 4.2 x 10(-5) M and the apparent Vmax value 0.11 and 0.47 mU.mg-1 protein, for the light and heavy lysosome sialidase, respectively. From 4 days to adulthood the specific activity of the light and heavy lysosome sialidase increased 3-fold and 1.7-fold, respectively.
authors.affiliation: Department of Medical Chemistry and Biochemistry, Medical School, University of Milan, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Fiorilli
authors.forename: C
authors.initials: C
authors.lastname: Siniscalco
authors.forename: A
authors.initials: A
authors.lastname: Chiarini
authors.forename: L
authors.initials: L
authors.lastname: Di Francesco
authors.forename: B
authors.initials: B
authors.lastname: Venerando
authors.forename: G
authors.initials: G
authors.lastname: Tettamanti
mesh_terms: D000367:Age Factors; D001921:Brain / Q000201:enzymology* / Q000254:growth & development / Q000648:ultrastructure; D002451:Cell Compartmentation; D002458:Cell Fractionation / Q000379:methods; D002498:Centrifugation; D006863:Hydrogen-Ion Concentration; D008247:Lysosomes / Q000201:enzymology*; D009439:Neuraminidase / Q000378:metabolism*
chemical_list: D009439:Neuraminidase