Low-Energy Electron Damage to DNA and its Basic Constituents

Abstract

The DNA molecule is composed of two long strands of repeated sugar-phosphate units to which the bases are chemically linked. The two strands are held together by hydrogen bonding between the bases. It is reported that low energy (3–20 eV) electrons interacting with vacuum-dry samples of DNA can break a single strand or both. The incident electron energy dependencies of the yields of single and double strand breaks are compared with those of H- ions ejected by electron impact on thin films of the elementary constituents of DNA (i.e., H2O, bases and sugar analogues). The decay of transient anions formed on the DNA’s basic components is found to play a crucial role in producing single and double strand breaks. Since a large portion of the energy deposited by ionizing radiation first leads to the production of low energy secondary electrons, these findings provide basic knowledge necessary to understand the effects of high-energy radiation in biological cells and eventually modify these effects at the molecular level.