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  • Title: Macromolecular enzymatic product of NAD+ in liver mitochondria.
    Author: Kun E, Zimber PH, Chang AC, Puschendorf B, Grunicke H.
    Journal: Proc Natl Acad Sci U S A; 1975 Apr; 72(4):1436-40. PubMed ID: 165508.
    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.
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