Free radical-induced chain breakage in irradiated aqueous solutions of DNA
The extent of chain breakage induced by free radical attack of calf thymus DNA in dilute aqueous solution has been determined by assay of liberated phosphomonoester groups. The relative effectiveness of hydroxyl radicals and hydrated electrons as initiators of this type of damage was investigated in both native and denatured DNA exposed to $sup 60$Co $gamma$ and 40-MeV electron radiation in the absence of oxygen. Approximately 8 percent of available OH and 6 percent of hydrated electrons react to produce chain breaks in double-stranded DNA, whereas these values are reduced to 5 percent and 1-2 percent respectively, for the denatured material. The double helical polynucleotide structure provides protection for reactive sites on the bases which are fully exposed to attacking radicals in single-stranded DNA. (GRA)
- Research Organization:
- Armed Forces Radiobiology Research Inst., Bethesda, Md. (USA)
- NSA Number:
- NSA-33-025451
- OSTI ID:
- 4031310
- Report Number(s):
- AD/A--008148; AFRRI-SR--74-3
- Country of Publication:
- United States
- Language:
- English
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