title: Nicotinamide adenine dinucleotide glycohydrolase from rat liver nuclei. Isolation and characterization of a new enzyme.
abstract: A new type of nicotinamide adenine dinucleotide glycohydrolase (NADase) has been isolated from rat liver nuclei. When partially purified chromatin is passed through a Sephadex G-200 column in the presence of 1 M NaCl, enzyme activities catalyzing the liberation of nicotinamide from NAD elute in two peaks. One, which appears in the void volume fraction, hydrolyzes the nicotinamide-ribose linkage of NAD to produce nicotinamide and ADP-ribose in stoichiometric amounts. This activity is not inhibited by 5 mM nicotinamide. The other, which elutes much later, catalyzes the formation of poly(ADP-ribose) from NAD and is completely inhibited by 5 mM nicotinamide. The former, NADase, is DNase-insensitive and thermostable, has a pH optimum of 6.5 to 7, a Km for NAD of 28 muM, and a Ki for nicotinamide of 80 mM, and hydrolyzes NADP as well as NAD. The latter, poly(ADP-ribose) synthetase, is sensitive to DNase treatment and heat labile, has a pH optimum of 8 to 8.5, a Km for NAD of 250 muM and a Ki for nicotinamide of 0.5 mM and is strictly specific for NAD. Further, the former NADase is shown to lack transglycosidase activity, which has been documented to be a general property of NADases derived from animal tissues. These results indicate that the NAD-hydrolyzing enzyme newly isolated from nuclei is a novel type of mammalian NADase which catalyzes the hydrolytic cleavage of the nicotinamide-ribose linkage of NAD.
mesh_terms: D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology; D002467:Cell Nucleus / Q000201:enzymology*; D002843:Chromatin / Q000187:drug effects / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D009699:N-Glycosyl Hydrolases / Q000378:metabolism*; D009244:NAD+ Nucleosidase / Q000302:isolation & purification / Q000378:metabolism*; D009536:Niacinamide / Q000494:pharmacology; D051381:Rats
chemical_list: D002413:Cations, Divalent; D002843:Chromatin; D009536:Niacinamide; D009699:N-Glycosyl Hydrolases; D009244:NAD+ Nucleosidase