In this study we have explored the effect of low-energy electrons (LEEs) when rupturing the C3'-O3' and C5'-O5' bonds in 3' and 5' cytosine monophosphate in an aqueous environment. This has been done using a hybrid quantum mechanics/classical mechanics (QM/MM) setup within the framework of Car-Parrinello molecular dynamics (CPMD). Our results are in agreement with experimental findings and indicate that LEEs do not drastically lower the energy barrier for breaking the 3' or 5' phosphodiester bonds for single cytosine nucleotides in aqueous environment. (C) 2008 Elsevier B.V. All rights reserved.