Hydrogen Abstraction from Deoxyribose by a Neighboring 3 '-Uracil Peroxyl Radical

• Theoretical examination of the reactivity of the uracil-5-peroxyl radical when abstracting a hydrogen atom from a neighboring 5'-deoxyribose in 5'-ApU-5-peroxyl-3' has been performed using density functional theory with the MPWB1K functional. Halogenated uracils are often used as radiosensitizers in DNA since the reactive uracil-5-yl radical is formed upon radiation and is known to create strand break and alkali-labile sites. Under aerobic conditions, such as in the cell, it has been proposed that the uracil-5-peroxyl radical is formed and would be the damaging agent. Our results show low reactivity for the uracil-5-peroxyl radical, determined by calculating the activation and reaction energies for the plausible hydrogen abstraction sites C1', C2' and C3' of the neighboring 5'-deoxyribose. These findings support the hypothesis that hydrogen abstraction primarily occurs by the uracil-5-yl radical, also under aerobic conditions, prior to formation of the peroxyl radical.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Chemistry

Kemi

Chemistry

Kemi

DENSITY-FUNCTIONAL THERMOCHEMISTRY; SEQUENCE-SELECTIVE PHOTOREACTION; UV-IRRADIATION; EXACT-EXCHANGE; DUPLEX DNA; MODELS; OLIGONUCLEOTIDES; 5-HALOURACILS; DAMAGE

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