Electron migration along 5-bromouracil-substituted DNA irradiation in solution and in cells

Journal Article · Tue Mar 01 04:00:00 EST 1994 · Radiation Research; (United States)

DOI:https://doi.org/10.2307/3578714· OSTI ID:6551475

Beach, C; Fuciarelli, A F; Zimbrick, J D ^[1]

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1. Pacific Northwest Lab., Richland, WA (United States)

Solvated electrons generated in aqueous solution after exposure to ionizing radiation can be scavenged by DNA and then transferred along the DNA molecule. This mechanism of charge transfer provides an opportunity for radiation damage to be targeted to certain regions in the DNA molecule and is a mechanism by which single-strand breaks contribute to locally multiply damaged sites to enhance cell lethality. Experiments were performed in which different amounts of 5-bromouracil (5-BrU) were substituted for thymine in Escherichia coli DNA. The amount of bromide released was assayed after quantitative reaction of radiation-induced solvated electrons with 5-BrU in DNA samples irradiated in solution and irradiated in the cellular environment. By varying the amount of 5-BrU incorporated in the DNA, the average distance between 5-BrU molecules was systematically changed and, because the number of 5-BrU/electron reactions was monitored by the amount of bromine released, the maximum average electron migration distance along the 5-BrU DNA could be estimated. Using this approach, the maximum average electron migration distance in aqueous solutions of 5-BrU DNA was about 6.5 to 10 base distances in nonhybrid 5-BrU DNA (assuming only intrastrand migration). Similar methods revealed charge migration in 5-BrU DNA incorporated into E. coli, and the maximum average migration distance was about 5 to 6 base distances (assuming only intrastrand migration). Only 11-16% of the electrons produced during radiolysis were scavenged by 5-BrU DNA in aqueous solution, and only 1% resulted in the release of bromide from 5-BrU-DNA inside E. coli. 40 refs., 5 figs.

• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6551475
• Journal Information: Radiation Research; (United States), Journal Name: Radiation Research; (United States) Vol. 137:3; ISSN 0033-7587; ISSN RAREAE
• Country of Publication: United States
• Language: English

Related Subjects

550200 -- Biochemistry
560120* -- Radiation Effects on Biochemicals
Cells
& Tissue Culture
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANTIMETABOLITES
AQUEOUS SOLUTIONS
AZINES
BACTERIA
BROMOURACILS
CHARGED-PARTICLE REACTIONS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
DECOMPOSITION
DISPERSIONS
DNA
DNA SEQUENCING
DRUGS
ELECTRON MOBILITY
ELECTRON REACTIONS
ELECTRONS
ELEMENTARY PARTICLES
ESCHERICHIA COLI
FERMIONS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IRRADIATION
LEPTON REACTIONS
LEPTONS
MICROORGANISMS
MIXTURES
MOBILITY
MOLECULAR STRUCTURE
NUCLEAR REACTIONS
NUCLEIC ACIDS
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PARTICLE MOBILITY
PYRIMIDINES
RADIATION EFFECTS
RADIOLYSIS
SOLUTIONS
SOLVATED ELECTRONS
STRAND BREAKS
STRUCTURAL CHEMICAL ANALYSIS
THYMINE
URACILS