Radiation-produced electron migration along 5-bromouracil-substituted DNA in cells and in solutions

Thesis/Dissertation · Thu Jan 01 04:00:00 EST 1981

OSTI ID:5478198

Beach, C M

Results of work by other investigators support the theory of charge migration in DNA. Charge transfer between nucleotides and electron and energy migration in solid state DNA have been detected, but no previous experiments have demonstrated charge migration in aqueous solutions of DNA or in DNA inside an E. coli cell. Such experiments were performed by substituting different amounts of 5-bromouracil (BU) for thymine in E. coli DNA and assaying for the amount of bromide given off from the reaction of bromouracil with hydrated electrons produced by ionizing radiation to form uracil-5-yl radicals and free bromide. By varying the amount of BU incorporated in the DNA, the average distance between the BU bases was varied, and because the number of BU/electron reactions was monitored by the amount of bromide released, the maximum average electron migration distance along the BU-DNA was estimated. Hydrated electrons, e/sub aq/, were shown to react with BU in BU-DNA with the resultant release of bromide with G(-BR/sup -/) = 0.519 +- 0.062. OH radicals were half as reactive as e/sub aq/ toward producing bromide from BU-DNA. O/sub 2/, which has been shown to transfer charge to BU in aqueous solution, did not transfer charge to BU-DNA. The CO/sub 2/ radical was shown to cause the release of bromide from BU-DNA at least as effectively as e/sub aq/. Charge migration was demonstrated, and the maximum average electron migration distance in aqueous solutions of BU-DNA was measured to be 8 to 10 base distances (assuming only intrastrand migration). Only 11% to 16% of the electrons produced attacked BU-DNA in aqueous solution, and only 1% resulted in bromide release from BU-DNA inside E. coli. Charge migration was demonstrated in BU-DNA inside E. coli., and the maximum average migration distance was measured to be 5 to 6 base distances (assuming only intrastrand migration).

• Research Organization: Kansas Univ., Lawrence (USA)
• OSTI ID: 5478198
• Country of Publication: United States
• Language: English

Related Subjects

560111* -- Radiation Effects on Biochemicals-- In Vitro-- (-1987)
560112 -- Radiation Effects on Biochemicals-- In Microorganisms-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANTIMETABOLITES
AQUEOUS SOLUTIONS
AZINES
BACTERIA
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BROMOURACILS
CHARGE EXCHANGE
CHEMICAL RADIATION EFFECTS
CHEMISTRY
DISPERSIONS
DNA
DRUGS
ELECTRONS
ELEMENTARY PARTICLES
ESCHERICHIA COLI
FERMIONS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IN VITRO
IN VIVO
LEPTONS
MICROORGANISMS
MIXTURES
NUCLEIC ACIDS
NUCLEOTIDES
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIMIDINES
RADIATION CHEMISTRY
RADIATION EFFECTS
SOLUTIONS
URACILS