A laser-plasma source emitting photons with energies in the water window spectral range has been used to reveal the radiation chemical yields of single-strand breaks in plasmid DNA as a function of ·OH radical scavenger concentration. Direct and indirect effects were investigated separately using DNA samples with various levels of hydration. We experimentally determined the value of the efficiency factor for strand cleavage in DNA caused by the reaction with ·OH radicals at 0.11, which was previously found in the theoretical studies. Additionally, the radiation chemical yield of ·OH radicals specific to the water window radiation emission of the source was determined by comparison with the gamma radiation-induced strand break yields. The ·OH radical yield determined using the plasmid DNA samples as a model was similar to the yield found using sensitive fluorescent dosimeters in previous experiments.

• Keywords
• Gamma radiation, OH radical, Plasmid DNA, Radical scavengers, Soft X-rays,
• MeSH
• DNA * chemistry   MeSH
• Hydroxyl Radical * chemistry   MeSH
• DNA Breaks, Single-Stranded MeSH
• Plasmids chemistry   MeSH
• X-Rays MeSH
• Free Radical Scavengers chemistry   MeSH
• Water * chemistry   MeSH
• Gamma Rays MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• DNA * MeSH
• Hydroxyl Radical * MeSH
• Free Radical Scavengers MeSH
• Water * MeSH

The effects of different types of radiation on the formation of peroxide forms of 2-dioleoyl-sn-glycero-3-phosphocholine were studied under various conditions. For the irradiation, an aqueous solution of small unilamellar vesicles was prepared. Variations in parameters such as the dose rate and molecular oxygen saturation levels were evaluated. Our study suggests that the mechanism of the peroxides formation process remains unchanged under irradiation by accelerated electrons, gamma and accelerated protons. The values of radiation chemical yields of the peroxidic form depend on the type of radiation, dose rate, and the saturation of molecular oxygen. The level of oxygen saturation strongly affects the values of radiation chemical yields as well, as the dissolved oxygen is an important agent participating in peroxidation and it is a source of free radicals during the radiolysis. The values of radiation chemical yields strongly suggest that the mechanism of radiation-induced peroxidation of phosphatidylcholines does not proceed via chain reaction.

• Keywords
• DOPC, Electrons, Gamma rays, Lipid peroxidation, Oxygen saturation, Protons,
• MeSH
• Electrons MeSH
• Phospholipids metabolism   MeSH
• Oxygen metabolism   MeSH
• Lipid Peroxides metabolism   MeSH
• Protons MeSH
• Dose-Response Relationship, Radiation MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Phospholipids MeSH
• Oxygen MeSH
• Lipid Peroxides MeSH
• Protons MeSH