Single- and double-strand break formation in DNA irradiated in aqueous solution: dependence on dose and OH radical scavenger concentration
The yields of single- and double-strand breaks (SSB and DSB) in calf thymus DNA, after /sup 60/Co gamma irradiation in dilute aqueous solution, have been determined via molecular weight measurements using a low-angle laser light scattering technique. The irradiations were administered to N/sub 2/O-containing solutions of DNA in the absence and presence of oxygen and with different concentrations of the OH radical scavengers phenol, tertiary butanol, and methanol. OH radicals were found to produce SSB linearly with dose with a G value of 55 nmol J-1 and 54 nmol J-1 in deoxygenated and oxygenated solutions, respectively. DSB were formed according to a linear-quadratic dose relationship and the G value of linearly formed DSB were GDSB alpha(r.t.) = 3.5 nmol J-1 in deoxygenated and 3.2 nmol J-1 in oxygenated solution. The ratio of GSSB/GDSB alpha(r.t.) = gamma of 19 +/- 6 was independent of the scavenger concentration in the case of tertiary butanol and methanol-containing solutions. GDSB alpha(r.t.) is interpreted to result from a radical site transferred from a sugar moiety of the cleaved strand to the complementary intact strand. This process of radical transfer and subsequent cleavage of the second strand occurs with a probability of about 6 +/- 2% in the presence of oxygen at all scavenger concentrations studied. These data on scavenging capacity on GDSB alpha(r.t.) suggest that the double-strand breakage produced via radical transfer remains higher than that resulting from direct effect, up to scavenging capacities of about 10(9) s-1.
- Research Organization:
- Max-Planck-Institute fuer Strahlenchemie, Muelheim a.d. Ruhr, West Germany
- OSTI ID:
- 5359013
- Journal Information:
- Radiat. Res.; (United States), Vol. 112:3
- Country of Publication:
- United States
- Language:
- English
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DNA
GENETIC RADIATION EFFECTS
STRAND BREAKS
RADIOINDUCTION
AQUEOUS SOLUTIONS
CALVES
COBALT 60
DOSE-RESPONSE RELATIONSHIPS
GAMMA RADIATION
HYDROXIDES
HYDROXYL RADICALS
PHENOLS
RADIATION DOSES
SCATTERING
THYMUS
WATER
ANIMALS
AROMATICS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BODY
CATTLE
COBALT ISOTOPES
DISPERSIONS
DOMESTIC ANIMALS
DOSES
ELECTROMAGNETIC RADIATION
GENETIC EFFECTS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LYMPHATIC SYSTEM
MAMMALS
MINUTES LIVING RADIOISOTOPES
MIXTURES
NUCLEI
NUCLEIC ACIDS
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
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RADIATIONS
RADICALS
RADIOISOTOPES
RUMINANTS
SOLUTIONS
VERTEBRATES
YEARS LIVING RADIOISOTOPES
560120* - Radiation Effects on Biochemicals
Cells
& Tissue Culture