title: [NADH- and NADPH-dependent formation of superoxide radicals in liver nuclei].
abstract: A method for the quantitation of the superoxide radical generation rate (V) in murine liver nuclei by the oxidation of 1-hydroxy-2,2,6,6-tetramethyl-4-oxo-piperidine O2-. radicals with the formation of a stable nitroxyl radical recorded by the EPR method, has been developed. It was shown that NADP- and NADPH-dependent superoxide radical generation is suppressed by superoxide dismutase (approximately by 90%). The Km values for NADH and NADPH are 1.5 x 10(-6) and 4.4 x 10(-7) M, respectively; the maximal rate (0.2 nmol.min-1.mg protein-1) is equal for both substrates. Cyanide (greater than 2 mM) causes a practically complete inhibition of the O2-. generation by both substrates. It is suggested that there exists a single readily autooxidized site of O2-. generation by both substrates for NADH- and NADPH-dependent site of the electron transport chain in nuclear membranes.
authors.forename: L S
authors.initials: LS
authors.lastname: Vartanian
authors.forename: S M
authors.initials: SM
authors.lastname: Gurevich
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D005609:Free Radicals; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D051379:Mice; D009243:NAD / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism*
chemical_list: D005609:Free Radicals; D009243:NAD; D013481:Superoxides; D009249:NADP
vernacular_title: NADH- i NADPH-zavisimoe obrazovanie superoksidnykh radikalov v iadrakh pecheni.