Radiation-induced free radicals in solid 5-halouracil derivatives: single crystals of 1-methyl-5-bromouracil

Solid-state radiation chemistry of DNA and its constituents

The molecular structure as well as the mechanisms of formation and decay of free radicals produced in DNA and its constituents by ionizing radiation is reviewed. Starting with the description of the spectral parameters for cations and anions in natural nucleic acid bases, emphasis is given to the comparable species formed in the group of the 5-halogen substituted uracil derivatives. The consequences of the attachment of a ribose or ribosephosphate group to the bases is discussed in terms of the distribution of primary radicals which, again, is shown to be different from those of the subunits in DNA itself. The quantitative aspects of radical formation are discussed in terms of G values and their dependence on the temperature of irradiation. Finally, a schematic presentation of the major modes of radical reactions is given occurring upon warming of the primary species in the DNA subunits and in DNA itself.