https://doi.org/10.1140/epjd/e2005-00206-6
Low energy electron-driven damage in biomolecules
Groupe en Sciences des Radiations,
Département de médecine nucléaire et de radiobiologie
Faculté de médecine, Université de Sherbrooke, Québec,
Canada J1H 5N4
Corresponding author: a Leon.Sanche@USherbrooke.ca
Received:
4
April
2005
Published online:
2
August
2005
The damage induced by the impact of low energy electrons (LEE) on
biomolecules is reviewed from a radiobiological perspective with emphasis on
transient anion formation. The major type of experiments, which measure the
yields of fragments produced as a function of incident electron energy
(
eV), are briefly described. Theoretical advances are also
summarized. Several examples are presented from the results of recent
experiments performed in the gas-phase and on biomolecular films bombarded
with LEE under ultra-high vacuum conditions. These include the results
obtained from DNA films and those obtained from the fragmentation of
elementary components of the DNA molecule (i.e., the bases, sugar and
phosphate group analogs and oligonucleotides) and of proteins (e.g. amino
acids). By comparing the results from different experiments and theory, it
is possible to determine fundamental mechanisms that are involved in the
dissociation of the biomolecules and the production of single- and
double-strand breaks in DNA. Below 15 eV, electron resonances (i.e., the
formation of transient anions) play a dominant role in the fragmentation of
all biomolecules investigated. These transient anions fragment molecules by
decaying into dissociative electronically excited states or by dissociating
into a stable anion and a neutral radical. These fragments can initiate
further reactions within large biomolecules or with nearby molecules and
thus cause more complex chemical damage. Dissociation of a transient anion
within DNA may occur by direct electron attachment at the location of
dissociation or by electron transfer from another subunit. Damage to DNA is
dependent on the molecular environment, topology, type of counter ion,
sequence context and chemical modifications.
PACS: 87.50.Gi – Ionizing radiations (ultraviolet, X-rays, gamma-rays, ions, electrons, positrons, neutrons, and mesons, etc.) / 34.50.Gb – Electronic excitation and ionization of molecules; intermediate molecular states (including lifetimes, state mixing, etc.) / 34.80.Ht – Dissociation and dissociative attachment by electron impact
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005
