Radiation-induced free radicals in oriented bromouracil-substituted DNA

Journal Article · Thu Oct 01 04:00:00 EDT 1981 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3575745· OSTI ID:6027226

Graslund, A; Rupprecht, A; Kohnlein, W; Huttermann, J

Electron paramagnetic resonance has been used to study the free radicals reduced by ..gamma.. irradiation in 5-bromouracil-substituted DNA from Bacillus subtilis. The DNA samples were oriented by wet spinning and contained 30% humidity. As in normal DNA, irradiation at 77 K produced two major radical components. One is assigned to guanine cation radicals, similar to those in normal DNA but produced in concentrations 20 to 50% higher than in normal DNA. The other component is assigned to 5-bromouracil anion radicals, apparently replacing the thymine anion radicals in normal DNA. The G value for total radical formation is about 2.0, not significantly higher than the G value of 1.5 determined for normal DNA. Warming the sample above 77 K results in a radical transformation, which may be the 5-bromouracil anion radical transforming into a hydrated uracil-5-yl radical. Above 200 K all radicals decay. As in normal DNA no secondary radicals could be observed from the guanine cation radicals. Replacement of thymine by 5-bromouracil thus results in a modest increase in the quanine cation radical yield. The quantitative results of this study do not directly explain the up to threefold sensitizations enhanced under in vivo conditions. The further reactions of the new 5-bromouracil anion species may also contribute to the sensitization by 5-bromouracil substitution in DNA.

• OSTI ID: 6027226
• Journal Information: Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 88:1; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

560112* -- Radiation Effects on Biochemicals-- In Microorganisms-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINES
ANTIMETABOLITES
AZINES
BACILLUS
BACILLUS SUBTILIS
BACTERIA
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BROMOURACILS
DNA
DRUGS
ELECTROMAGNETIC RADIATION
GAMMA RADIATION
GUANINE
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IONIZING RADIATIONS
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PURINES
PYRIMIDINES
RADIATION EFFECTS
RADIATIONS
RADICALS
RADIOSENSITIVITY
RADIOSENSITIVITY EFFECTS
URACILS