Mechanisms for radiation damage in DNA
Recent work in our laboratory has been instrumental in the reformulation of the current model for radiation damage in DNA. We have found that radical ion distribution is a function of strandedness of the DNA. A new model for ion transport through DNA is proposed. We completed an extensive ab initio molecular orbital study of the ion radicals species envolved in DNA radiation damage. In this effort the ionization energies (IE), electron affinities (EA), relative energies, fully optimized structural parameters and spin densities were determined. Joint work with Steven Swarts and Ken Wheeler of Wake Forest on yields of products on irradiation of DNA has also yielded new insights to radiation damage to DNA - specifically the division between the direct and indirect effect. Perhaps our most important work during this period has been in the area of the interaction of thiyl radicals and oxygen as well as (DNA) peroxyl radicals with thiols. The sulfinyl radical, RSO{center dot}, was not previously known to be a product of thiol-or carbon-based peroxyl reaction with RSH. The structure of the thiyl peroxyl radical, RSOO, was uncertain. The conversion of RSOO to the sulfonyl radical, RSO{sub 2}, and the subsequent reaction with oxygen to form the sulfonyl peroxyl radical, RSO{sub 2}OO, had never been suggested in the literature. We have investigated the reactions of thiols with primary ion radicals in {gamma}-irradiated DNA and observed electron transfer from the thiol to the guanine cation radical. This is believed to be the major protective effect of thiols from the direct effect of radiation. Our work with peroxyl radicals has also established that the ESR measured O-17 hyperfine couplings give a good estimate of the relative reactivity of the peroxyl group and shows that the thiol peroxyl radical cannot be a effective hydrogen abstracting agent. 52 refs., 1 tab.
- Research Organization:
- Oakland Univ., Rochester, MI (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG02-86ER60455
- OSTI ID:
- 5942265
- Report Number(s):
- DOE/ER/60455-6; ON: DE91019080
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
DNA
CHEMICAL RADIATION EFFECTS
CHARGE TRANSPORT
ELECTRON SPIN RESONANCE
GAMMA RADIATION
IONS
OXYGEN
PROGRESS REPORT
RADICALS
RADIOPROTECTIVE SUBSTANCES
REACTION INTERMEDIATES
REACTIVITY
RESPONSE MODIFYING FACTORS
THIOLS
CHARGED PARTICLES
DOCUMENT TYPES
DRUGS
ELECTROMAGNETIC RADIATION
ELEMENTS
IONIZING RADIATIONS
MAGNETIC RESONANCE
NONMETALS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
RADIATION EFFECTS
RADIATIONS
RESONANCE
400600* - Radiation Chemistry