title: Arylazido-beta-alanine ADP-ribose, a novel irreversible competitive inhibitor of mitochondrial NADH-ubiquinone reductase.
abstract: Arylazido-beta-alanine ADP-ribose, a photoreactive analogue of ADP-ribose, was synthesized. In the dark, arylazido-beta-alanine ADP-ribose acts as a competitive reversible inhibitor of mitochondrial NADH-ubiquinone reductase with a K(i) of 37 microM. Upon photolysis, arylazido-beta-alanine ADP-ribose is converted to a potent irreversible active site-directed inhibitor of the enzyme. Photo-induced inhibition of membrane-bound NADH-ubiquinone reductase by arylazido-beta-alanine ADP-ribose is incomplete and results in a 20-fold reduction of the NADH oxidase and 2.5-fold reduction of the energy-dependent NAD(+) reductase activities. The arylazido-beta-alanine ADP-ribose resistant activities (direct and reverse) of the enzyme are characterized by a two orders of magnitude lower affinity to the corresponding substrates compared to those of the uninhibited NADH-ubiquinone reductase. A different kinetic behavior of the inhibited and native enzyme can be explained by invoking the two catalytically competent nucleotide-binding sites model of NADH-ubiquinone reductase.
authors.affiliation: Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel.
authors.forename: M V
authors.initials: MV
authors.lastname: Frenkin
authors.forename: A B
authors.initials: AB
authors.lastname: Kotlyar
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D000818:Animals; D001386:Azides / Q000737:chemistry; D001665:Binding Sites; D002417:Cattle; D042967:Electron Transport Complex I; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007700:Kinetics; D008929:Mitochondria, Heart / Q000201:enzymology*; D009243:NAD / Q000031:analogs & derivatives / Q000737:chemistry; D009244:NAD+ Nucleosidase / Q000737:chemistry; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors*; D010782:Photolysis
chemical_list: D001386:Azides; D004791:Enzyme Inhibitors; C401021:arylazido-alanine ADP-ribose; C020606:arylazido-beta-alanyl-NAD; D009243:NAD; D000246:Adenosine Diphosphate Ribose; D009247:NADH, NADPH Oxidoreductases; D009244:NAD+ Nucleosidase; D042967:Electron Transport Complex I