The interaction of a protein–DNA surface complex with low-energy electrons

Low-energy electrons are abundant throughout the fundamental processes determining radiation chemistry. They can attach to DNA via molecular resonances and induce strand breaks. We investigate for the first time how a protein bound to DNA modifies this interaction. By a fluorescence method we demonstrate much lower damage due to 3 eV electrons to the surface tethered (dT)25 oligonucleotides complexed with a single-strand-binding (SSB) protein, as compared to the oligonucleotides not engaged in the complex formation. Density functional theory calculation suggests that in addition to the physical shielding the protein might also impede the DNA electron damage through the bonding interactions.