Study of Charge Transport Mechanisms in 125I-induced DNA Damage at Various Temperatures

摘要

PurposeIodine-125 decay induces localized DNA damage by three major mechanisms: 1) direct damage by the emitted Auger electrons, 2) indirect damage by diffusible free radicals, and 3) charge neutralization of the residual, highly positively charged, tellurium daughter atom by stripping electrons from neighboring residues. The charge neutralization mechanism of ¹²⁵I-induced DNA damage is poorly understood. Charge transport along DNA molecule can occur by either a hopping mechanism initiated by charge injection into DNA and propagated by charge migration through DNA bases along the DNA length, or by a tunneling mechanism in which charge transfers directly from a donor to an acceptor residue. In the first case additional damage in DNA nucleotides can be inflicted by the traveling charge; therefore, it is important to learn if charge hopping plays a role in ¹²⁵I-decay-induced DNA damage. In our previous work, we determined that at 193K the charge hopping mechanism was not an appreciable component of the mechanism of ¹²⁵I-induced DNA damage. However, the question whether this is also the case at higher temperatures remained open.