Toxicity, Mutagenesis and Aging due to Endogenous Oxygen Radicals.
Abstract
We have been examining the oxidation of ammonia to nitrite by oxygen radicals generated by the xanthine oxidase reaction. This oxidation (NH3-yields-NO2(-)), which can easily be demonstrated, is inhibited by superoxide dismutase, or by catalase, or by scavengers of the hydroxyl radical. We conclude that the iron-catalyzed reduction of H2O2 to OH(-) + OH by O2(-) is involved and that OH is the first oxidant of NH3. When NH3 is replaced by NH2OH we see NO2(-) production which is inhibited by superoxide dismutase but not by catalase. In this case we conclude that O2(-), per se, can oxidize NH2OH to NO2(-). We have been reinvestigating the killing of E. coli by paraquat. Our earlier studies showed that the lethality of paraquat was dependent upon O2 and an electron source and was decreased by elevated intracellular levels of superoxide dismutase. All of this, plus measurements of cyanide-resistant respiration, showed that O2 was essential for expression of the lethality of paraquat. This work was done in a nutrient broth medium. We now see that paraquat is much more lethal in the nutrient broth than it is in a simpler Vogel/Bonner medium. Originator-supplied keywords include: Superoxide radical, Hydroxyl radical, Hydrogen peroxide, Superoxide dismutases, Paraquat, Nitrite, Catalase, Sulfur dioxide.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 21, 1984
- Accession Number
- ADA150121
Entities
People
- I. Fridovich
Organizations
- Duke University Hospital