Radiolysis of DNA in aqueous solution in the presence of a scavenger: a kinetic model based on a nonhomogeneous reaction of OH radicals with DNA molecules of spherical or cylindrical shape.

Two expressions are given for the survival dose of DNA exposed to high-energy radiation in aqueous solution in the presence of a scavenger. They are derived from a model where a diffusion controlled reaction of OH radicals occurs on the surface of the DNA macromolecules in competition with scavenging in the bulk of the solution. The DNA molecules are approximated either by spheres or by cylinders. The model based on molecules of spherical shape corresponds closely to that developed by van Rijn et al. [20]. Expressions obtained from the cylindrical model are used to account for the dependence on the scavenger concentration of some experimentally measured quantities, namely the survival dose and the G value for single-strand breaks upon Co gamma-irradiation of phi X174 DNA and polyadenylic acid, respectively.