title: Macromolecular enzymatic product of NAD+ in liver mitochondria.
abstract: Rat liver mitochondria contain a Mg2+-requiring system that transfers the ADP-ribose moiety of NAD+ to an acceptor protein. The enzyme system was extracted in a soluble form and the ADP-ribosylated protein product was isolated by hydroxyapatite and Sephadex chromatography. The ADP-ribosylated protein product has a molecular weight of 100,000 and can be dissociated into subunits of 50,000 daltons by sodium dodecyl sulfate gel electrophoresis. Incubation of the isotopically labeled ADP-ribosylated protein with nicotinamide and a mitochondrial extract yields labeled NAD+, indicating apparent reversibility of the reaction. Enzymatic degradation of the ADP-ribosylated protein with snake venom phosphodiesterase liberates AMP and ADP-ribose or its isomer. Identification of these products and reversibility of the reaction show that the ADP-ribose moiety of NAD+ is the molecular species that is transferred to the acceptor protein. A fraction of the protein-bound ADP-ribose appears to be present as an an oligomer. The enzymatic protein-ADP-ribosylating reaction is inhibited by nicotinamide, ADP-ribose, the fluorophosphate of AMP, and picrylsulfonic acid.
mesh_terms: D000247:Adenosine Diphosphate Sugars / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002845:Chromatography; D004355:Drug Stability; D004591:Electrophoresis, Polyacrylamide Gel; D006882:Hydroxyapatites; D007700:Kinetics; D008930:Mitochondria, Liver / Q000378:metabolism*; D009243:NAD / Q000378:metabolism*; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism*; D051381:Rats; D011955:Receptors, Drug; D012266:Ribose / Q000378:metabolism; D013997:Time Factors
chemical_list: D000247:Adenosine Diphosphate Sugars; D006882:Hydroxyapatites; D011506:Proteins; D011955:Receptors, Drug; D009243:NAD; D011064:Poly Adenosine Diphosphate Ribose; D012266:Ribose