Relative abundances of primary ion radicals in. gamma. -irradiated DNA: Cytosine vs thymine anions and guanine vs adenine cations

Journal Article · Thu Apr 18 00:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100161a080· OSTI ID:5756490

Sevilla, M D; Becker, D; Yan, Mengyao; Summerfield, S R ^[1]

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1. Oakland Univ., Rochester, MI (United States)

An ESR study of the relative distribution of ion radicals formed in DNA equilibrated with D{sub 2}O and {gamma}-irradiated at 77 K is presented. The ESR spectra of irradiated DNA and polynucleotides (poly(dG){center dot}poly(dC) and poly(dAdT){center dot}poly(dAdT)) were obtained and employed in a computer-assisted analysis for the individual ion-radical distribution. Analysis of spectra as a function of power allowed the separation of the spectra of the pyrimidine anions (T{sup {sm bullet}{minus}}, C{sup {sm bullet}{minus}}) from the spectra of the purine cations (G{sup {sm bullet}+}, A{sup {sm bullet}+}). The spectra of the mononucleotide ion radicals, dCMP{sup {sm bullet}{minus}}, dTMP{sup {sm bullet}{minus}}, dGMP{sup {sm bullet}+}, and dAMP{sup {sm bullet}+}, were produced in 8 M LiCl glasses. In addition, the spectra of the ion radicals of all of the mononucleotide ion radicals except dAMP{sup +} were simulated by using hyperfine and g tensors from the literature. Basis spectra derived from (1) power saturation experiments, (2) polynucleotide and mononucleotide spectra, (3) spectra of mononucleotides alone, and (4) anisotropic simulations were used to fit the spectra of DNA by use of a linear least-squares analysis. Each of the four separate analyses confirms that the cytosine anion dominates the spectra of DNA at 100 K. Three analyses included the cationic composition, and they strongly favor the guanine cation over the adenine cation. An average of the authors results gives the DNA ion radicals' relative to abundances as ca. 77% C{sup {sm bullet}{minus}}, 23% T{sup {sm bullet}{minus}} for the anions and >90% G{sup {sm bullet}+} for the cations about equal amounts of anions and cations are present. No difference in results is found for DNA irradiated in frozen D{sub 2}O solutions or simply exchanged at 100% D{sub 2}O humidity.

• OSTI ID: 5756490
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:8; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
560120 -- Radiation Effects on Biochemicals
Cells
& Tissue Culture
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ADENINES
AMINES
ANIONS
ANTIMETABOLITES
AROMATICS
AZAARENES
AZINES
CATIONS
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CYTOSINE
DATA
DNA
DRUGS
ELECTROMAGNETIC RADIATION
ELECTRON SPIN RESONANCE
EXPERIMENTAL DATA
GAMMA RADIATION
GUANINE
HEAVY WATER
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
IONIZING RADIATIONS
IONS
IRRADIATION
ISOTOPIC EXCHANGE
LEAST SQUARE FIT
MAGNETIC RESONANCE
MATHEMATICAL MODELS
MAXIMUM-LIKELIHOOD FIT
NUCLEIC ACIDS
NUMERICAL DATA
NUMERICAL SOLUTION
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXYGEN COMPOUNDS
PURINES
PYRIMIDINES
RADIATION EFFECTS
RADIATIONS
RADICALS
RESONANCE
SAMPLE PREPARATION
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
THEORETICAL DATA
THYMINE
URACILS
WATER