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Bactericidal potency of hydroxyl radical in physiological environments
R G Wolcott1, B S Franks, D M Hannum
1Department of Chemistry, Biochemistry, and Molecular Biology, Oregon Graduate Institute of Science and Technology, Portland 97291-1000.
The Journal of Biological Chemistry
|April 1, 1994
Summary
Radiolytic inactivation of bacteria is enhanced by chloride and bicarbonate ions, with toxic effects originating extracellularly. Free radical scavengers protect bacteria, suggesting specific radical species mediate the damage.
Area of Science:
- Radiation chemistry
- Microbiology
- Biophysics
Background:
- Radiolytic inactivation of bacteria is a known phenomenon.
- The role of specific ions and radical species in this process requires further elucidation.
Purpose of the Study:
- To investigate the impact of chloride and bicarbonate ions on bacterial radiolytic inactivation.
- To identify the reactive species responsible for enhanced toxicity and their mechanisms of action.
Main Methods:
- Bacteria were suspended in N2O-saturated solutions containing chloride or bicarbonate ions.
- Free radical scavengers were used to assess the origin of toxicity.
- Hypochlorous acid and carbonate radical adducts were identified using chemical and EPR spectroscopy.
Main Results:
- Chloride and bicarbonate ions significantly increased bacterial radiolytic inactivation rates.
- Toxicity was confirmed to be extracellular, as free radical scavengers provided protection.
- Hypochlorous acid was identified in irradiated chloride solutions, and carbonate radicals in irradiated bicarbonate solutions.
Conclusions:
- Carbonate and chlorine radicals are uniquely toxic to bacteria.
- Chloride ion reactions are unlikely in biological settings.
- The carbonate radical may contribute to peroxide-induced cellular damage in confined biological spaces like phagosomes.