Chris Greene and his former Ph.D. student Stefano Tonzani, with colleagues from the Université de Sherbrooke are working on a long-term project to understand DNA damage caused by low-energy electrons. Low-energy electrons can be knocked out of DNA molecules by high-energy radiation. They get captured by the DNA bases, temporarily forming a negatively charged molecule, or anion. The anion lasts just long enough to transfer its excess energy to the weakest nearby chemical bond, often breaking it. In DNA, the weakest link is the carbon-oxygen bond between the sugar and phosphate groups that form its backbone. These bonds can break one or both strands of the DNA double helix, increasing the likelihood that the genetic code will be misread, causing permanent, and potentially catastrophic, biological changes.

The Greene group performed a theoretical analysis of electron resonances within DNA bases at the moment of electron capture. The researchers discovered that the electrons stay long enough inside the ring structure of the bases to lead to bond breaking. Then the group analyzed low-energy electron capture by chemical models for the sugar-phosphate DNA backbone. The next step is to find out more about the mechanism that allows captured electrons to leave the ring structure and transfer their energy to the DNA backbone.

The content provided by Answer Tips does not come from JILA or NIST, but from other sources. Any content provided by Answer Tips within JILA or NIST web pages is for information only; it does not imply recommendation or endorsement by JILA or NIST.