title: Evidence for NAD nucleosidase in rabbit-liver lysosomes.
abstract: A method is described for the isolation of secondary lysosomes from homogenates of rabbit liver; The uptake of Triton WR-1339 by rabbit-liver lysosomes when administered by intraperitoneal injection was used to decrease the density of secondary lysosomes. Lysosomal fractions prepared by this method contain an NAD nucleosidase (NAD glycohydrolase, EC 3;2.25), an enzyme which has previously been considered to be associated with other subcellular fractions. The enzyme has maximum activity at pH 6 and cleaves both NAD and NADP. It is inhibited by nicotinamide (Ki equals 4.5 mM) and by HgCl2. Both nucleosidase and 2'-nucleotidase show in-vitro latency typical of lysosomal acid hydrolases. Rabbit-liver plasma-membrane fractions were isolated which contained most 5'-nucleotidase but relatively little nucleosidase, whereas rabbit liver lysosomes contain both 5'-nucleotidase and nucleosidase enzymes but little adenyl cyclase.
mesh_terms: D000818:Animals; D002458:Cell Fractionation / Q000379:methods; D002462:Cell Membrane / Q000201:enzymology; D002499:Centrifugation, Density Gradient; D006596:Hexosaminidases / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008247:Lysosomes / Q000201:enzymology*; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D009243:NAD / Q000494:pharmacology; D009249:NADP / Q000494:pharmacology; D009708:Nucleotidases / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D011092:Polyethylene Glycols; D011817:Rabbits; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D009243:NAD; D011092:Polyethylene Glycols; D009249:NADP; D009708:Nucleotidases; D010744:Phosphoric Monoester Hydrolases; D006596:Hexosaminidases; D009699:N-Glycosyl Hydrolases