Mechanism of toxicity of hydrogen peroxide
We examined the capacity of hydrogen peroxide to injure E. coli. Externally applied hydrogen peroxide rapidly permeates the bacterial cell and causes at least two classes of potentially lethal damage. These classes were initially distinguished by the kinetics of their production. Additional distinctions have been made regarding the chemistry of cell injury and the details of the cell response. One class of cell damage consists of DNA lesions; if unrepaired, mode one killing results. Hydrogen peroxide does not directly attack the DNA. Instead, ferrous iron reduces the peroxide to generate a hydroxyl-radical-like species, which acts as a DNA oxidant. The peculiar kinetics of mode-one killing may reflect an high reaction rate between this radical and peroxide itself. Interestingly, NADH may chemically reduce ferric iron in order to start and maintain the sequence of redox reactions. The target of the other class of cell damage is unknown. This damage, unlike that associated with mode-one killing, does not rely upon Fenton chemistry. Scavenging enzymes, such as catalase and superoxide dismutase, contribute to resisting oxidative stress. Increases in catalase titer accelerate detoxification of peroxide and are responsible for the protective effects of oxyR induction. When oxidants elude this defense and nick DNA, a variety of enzymes-exonuclease III, endonuclease IV, and DNA polymerase I-repair the damage.
- Research Organization:
- California Univ., Berkeley, CA (USA)
- OSTI ID:
- 5559874
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ESCHERICHIA COLI
SENSITIVITY
HYDROGEN PEROXIDE
TOXICITY
HYDROXYL RADICALS
BIOSYNTHESIS
CATALASE
CELL KILLING
DNA REPAIR
ENDONUCLEASES
NADH2
SUPEROXIDE DISMUTASE
BACTERIA
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
COENZYMES
DNA-ASE
ENZYMES
ESTERASES
HYDROGEN COMPOUNDS
HYDROLASES
MICROORGANISMS
NUCLEOTIDES
ORGANIC COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PEROXIDASES
PEROXIDES
PHOSPHODIESTERASES
RADICALS
RECOVERY
REPAIR
SYNTHESIS
560300* - Chemicals Metabolism & Toxicology