Effects of oxygen on the metabolism of nitroxide spin labels in cells

Journal Article · Tue Mar 21 04:00:00 EST 1989 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00432a022· OSTI ID:5764390

Chen, K; Glockner, J F; Morse, II, P D; Swartz, H M

The products of the reduction of nitroxides in cells are the corresponding hydroxylamines, which cells can oxidize back to the nitroxides in the presence of oxygen. Both the reduction of nitroxides and the oxidation of hydroxylamines are enzyme-mediated processes. For lipid-soluble nitroxides, the rates of reduction are strongly dependent on the intracellular concentration of oxygen; severely hypoxic cells reduce nitroxides more rapidly than cells supplied with oxygen. In contrast, the rates of oxidation of hydroxylamines increase smoothly with increasing intracellular oxygen concentration up to 150 microM. In order to separate the effects on the rates of metabolism of nitroxides due directly to oxygen from effects due to the redox state of enzymes, we studied the cells under conditions in which each of these variables could be changed independently. Oxygen affects the metabolism of these nitroxides primarily by interacting with cytochrome c oxidase to change the redox state of the enzymes in the respiratory chain. Our results are consistent with the conclusions that in these cells reduction of lipophilic nitroxides occurs at the level of ubiquinone in the respiratory chain in mitochondria, and oxidation of the corresponding hydroxylamines occurs at the level of cytochrome c oxidase.

• Research Organization: Univ. of Illinois, Urbana (USA)
• OSTI ID: 5764390
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 28:6; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINES
ANIMAL TISSUES
ANIMALS
ANOXIA
BIOLOGICAL EFFECTS
BODY
BONE MARROW
CELL CULTURES
CHALCOGENIDES
CHEMICAL REACTIONS
CLONE CELLS
CYTOCHROME OXIDASE
ELECTRON SPIN RESONANCE
ELEMENTS
ENZYMES
HAEM DEHYDROGENASES
HEMATOPOIETIC SYSTEM
HYDROXYLAMINE
LYMPHATIC SYSTEM
MAGNETIC RESONANCE
MAMMALS
METABOLISM
MICE
NITROGEN COMPOUNDS
NITROGEN OXIDES
NONMETALS
ORGANIC COMPOUNDS
ORGANS
OXIDES
OXIDOREDUCTASES
OXYGEN
OXYGEN COMPOUNDS
REDOX REACTIONS
RESONANCE
RODENTS
THYMUS
TISSUES
VERTEBRATES