ESR detection at 77 K of the hydroxyl radical in the hydration layer of gamma-irradiated DNA

Journal Article · Sat Oct 01 04:00:00 EDT 1994 · Radiation Research

DOI:https://doi.org/10.2307/3578577· OSTI ID:79340

Becker, D; La Vere, T; Sevilla, M D ^[1]

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

Previous ESR reports of {gamma}-irradiated DNA at low temperatures have suggested that hydroxyl radicals are not formed in the first hydration layer of DNA. In this report we show that hydroxyl radicals are produced in low yield. Due to the glassy nature of this hydration layer at low temperature, the hydroxyl radical gives a broad ESR resonance which is not easily detected. Low-field ESR spectra of hydroxyl radicals in an irradiated 6 M CsF aqueous glass are shown to be nearly identical to those found in DNA; however, the yields in the aqueous glass (G = 0.087 to 0.13 {mu}mol/J) are found to be greater than those in DNA`s first hydration layer (G = 0.035 {+-} 0.02 {mu}mol/J). A large k value for destruction of the OH in DNA`s hydration layer limits the yield of OH at high doses. The yield of H{sub 2}O{sub 2} (which likely results from hydroxyl radical recombinations that occur both during irradiation and upon annealing) is found to 0.0035 {mu}mol/J in the dose range 65 kGy to 195 kGy. The amount of H{sub 2}O{sub 2} formed corresponds to most of that expected from recombination of the OH trapped at 77 K at the equivalent dose. The low yield of trapped OH radicals in the first hydration layer has implications for possible hole transfer to DNA. 32 refs., 5 figs., 2 tabs.

• Sponsoring Organization: USDOE
• OSTI ID: 79340
• Journal Information: Radiation Research, Journal Name: Radiation Research Journal Issue: 1 Vol. 140; ISSN RAREAE; ISSN 0033-7587
• Country of Publication: United States
• Language: English

Related Subjects

55 BIOLOGY AND MEDICINE
BASIC STUDIES
56 BIOLOGY AND MEDICINE
APPLIED STUDIES
DETECTION
DNA
ELECTRON SPIN RESONANCE
GAMMA RADIATION
HYDROXYL RADICALS
RADIATION INJURIES
YIELDS