Korean researchers have applied a new technique to further understand the ionisation of nucleic acids, one of the essential steps in DNA and RNA damage.

Gene damage starts when nucleic acids are ionised after being exposed to radiation. This initiates a charge hopping process along the nucleic acid strand, which leads to DNA or RNA mutation.

Sang Kyu Kim and colleagues at the Korea Advanced Institute of Science and Technology have applied a state-of-the-art experimental technique called vacuum-ultraviolet mass-analysed threshold ionisation (VUV-MATI) spectroscopy to determine the ionisation spectrum of the RNA base uracil, as well as its vibrational structure. This has given important information about the structural change that this base undergoes during ionisation.

Until now, experimental studies on the ionisation of nucleic acids have not been reliable or quantitative. Data has been limited because of experimental problems such as extremely low vapour pressures and very short life times of the electronically excited states. Kim's method provides more information on compounds which are difficult to study in the low pressure gas phase.

The work will now be extended to the study of other nucleic acid bases, their clusters with water solvents, and the larger nucleosides. 'Studies on DNA or RNA building blocks in the gas phase will deepen our knowledge of biological processes at the molecular level' said Kim.

Ruth M Needham