Electron and biomolecular interactions
Working Group One
First meeting of the working group: 14th/15th February 2004, Aarhus, Denmark - Website
List of group participants: (Last Updated 11/04-06)
The impetus for these studies is as follows. When high energy ionizing radiation, including photons and all types of particles, penetrates biological material, ionization tracks form, creating excited atoms, molecules, ions and secondary electrons within the bulk of the material.
Secondary electrons are generated in large quantities and are a major cause of radiation damage in biological systems. Electrons initiate a complex series of events in both water and in biomolecules. These include ionization, electronic and vibrational excitation, which may be followed by chemical decomposition, ion pair formation and negative ion formation, leading to dissociation into negative ions and neutral radicals. In order to pinpoint the most potent effects of electrons, it is necessary to study the mechanism of these individual processes with water, ribose, aminoacids, peptides, nucleotides, nucleosides, oligonucleotides, DNA and proteins as prime targets. The destructive effects of electrons are strongly electron impact energy dependent. Experiments will therefore be carried out as a function of electron energy in the range from meV to 100 keV, covering the full range of energy of electrons prevalent in radiation damage.
Experiments will be performed in the gas, liquid and condensed phases Gas phase data are important in identifying how destructive pathways in biological systems, involving direct electron-biomolecule collisions, may be initiated on the femtosecond timescale of isolated, or nearly isolated, dissociative events. Gas phase data also serve as reference data for comparison with theory and therefore as a test of the predictive power of theory.
The brief of WG1 is to pursue the studies outlined above to build up a body of knowledge on which to base realistic models of electron-induced damage in biological cells. The aims of WG1 are complementary to those of the other working groups, which are concerned with the effects of ions on biomolecules and the extension into true physiological environments, including track structure in cells.