Effect of Low-Energy Electron Irradiation on DNA Damage by Cu2+ Ion

  • Noh, Hyung-Ah (Physics Department, Chungnam National University) ;
  • Park, Yeunsoo (Plasma Technology Research Center, National Fusion Research Institute) ;
  • Cho, Hyuck (Physics Department, Chungnam National University)
  • Received : 2016.10.17
  • Accepted : 2017.01.11
  • Published : 2017.03.31


Background: The combined effect of the low energy electron (LEE) irradiation and $Cu^{2+}$ ion on DNA damage was investigated. Materials and Methods: Lyophilized pBR322 plasmid DNA films with various concentrations (1-15 mM) of $Cu^{2+}$ ion were independently irradiated by monochromatic LEEs with 5 eV. The types of DNA damage, single strand break (SSB) and double strand break (DSB), were separated and quantified by gel electrophoresis. Results and Discussion: Without electron irradiation, DNA damage was slightly increased with increasing Cu ion concentration via Fenton reaction. LEE-induced DNA damage, with no Cu ion, was only 6.6% via dissociative electron attachment (DEA) process. However, DNA damage was significantly increased through the combined effect of LEE-irradiation and Cu ion, except around 9 mM Cu ion. The possible pathways of DNA damage for each of these different cases were suggested. Conclusion: The combined effect of LEE-irradiation and Cu ion is likely to cause increasing dissociation after elevated transient negative ion state, resulting in the enhanced DNA damage. For the decrease of DNA damage at around 9-mM Cu ion, it is assumed to be related to the structural stabilization due to DNA inter- and intra-crosslinks via Cu ion.


Supported by : Chungnam National University


  1. Boudaiffa B, Cloutier P, Hunting D, Huels MA, Sanche L. Resonant formation of DNA strand breaks by low-energy (3 to 20 eV) electrons. Science. 2000;287:1658-1660.
  2. Lu QB, Sanche L. Condensed-phase effects of absolute cross sections for dissociative electron attachment to CFCs and FCFCs adsorbed on Kr. J. Chem. Phys. 2003;119:2658-2662.
  3. Lu QB, Sanche L. Enhancement in dissociative electron attachment to CF4, chlorofluorocarbons and hydrofluorocarbons adsorbed on $H_2O$ ice. J. Chem. Phys. 2004;120:2434-2438.
  4. Christophorou LG, McCorkle DL, Christodoulides AA. Electron-Molecule Interactions and Their Applications. 1st Ed. New York, NY. Academic Press.1984;478-558.
  5. Chutjian A, Garscadden A, Wadehra JM. Electron attachment to molecules at low electron energies. Phys Rep. 1996;264:393-470.
  6. Ying ZC, Ho WJ. Photodissociation of adsorbed MO(CO)6 induced by direct photoexcitation and hot-electro attachment. 2. Physical mechanisms. J. Chem. Phys. 1991;94:5701-5714.
  7. Sanche L. Nanoscopic aspects of electronic aging in dielectrics. IEEE Trans. Dielectr. Electr. Insul. 1997;4:507-543.
  8. Lu QB, Sanche L. Effects of cosmic rays on atmospheric chlorofluorocarbon dissociation and ozone depletion. Phys. Rev. Lett. 2001;87:078501.
  9. Aruoma OI, Halliwell B, Gajewski E, Dizdaroglu M. Copper-iondependent damage to the bases in DNA in the presence of hydrogen-peroxide. Biochem J. 1991;273:601-604.
  10. Keyer K, Imlay JA. Superoxide accelerates DNA damage by elevating free-iron levels. Proc. Natl. Acad. Sci. USA. 1996;93:13635-13640.
  11. Kasprzak KS. Oxidative DNA and protein damage in metal-induced toxicity and carcinogenesis. Free Radic. Biol. Med. 2002; 32:958-967.
  12. Gao YG, Sriram M, Wang AH. Crystallographic studies of metalion DNA interactions-different binding modes of cobalt(III), copper(II) and barium(II) to N-7 of guanines in Z-DNA and a drug-DNA complex. Nucleic. Acid Res. 1993;21:4093-4101.
  13. Lloyd DR, Phillips DH. Oxidative DNA damage mediated by copper(III), iron(II) and nickel(II) Fenton reactions. Mutation Res. 1999;424:23-36.
  14. Walling C. Fenton's reagent revisited. Acc. Chem. Res. 1975;8:125-131.
  15. Walling C, Goosen A. Mechanism of the ferric ion catalyzed decomposition of hydrogen peroxide. Effect of organic substrates. J. Am. Chem. Soc. 1973;95:2987-2991.
  16. Park Y, Noh HA, Cho H. Effect of low-energy electron irradiation on DNA damage by $Fe^{3+}$ ion. Radiation Res. 2012;177:775-780.
  17. Gao YG, Sriram M, Wang AHJ. Crystallographic studies of metal ion - DNA interactions: Different binding modes of cobalt(II), copper(II) and barium(II) to N7 of guanines in Z-DNA and a drug- DNA complex. Nucleic. Acid. Res. 1993;21:4093-4102.
  18. Borkow G, Gabby J. Copper as a biocidal tool. Current Medicinal. Chem. 2005;12:2163-2175.
  19. Theophanides T, Anastassopoulou J. Copper and carcinogenesis. Critical Reviews in Oncology/Hematology. 2002;42:57-64.
  20. Tushar KD, Mas RW, Kaneez FS. Oxidative stress gated by Fenton and Haber Weiss reactions and its association with Alzheimer's disease. Arch. Neurosci. 2015;2:e20078.
  21. Wojciech B, Dazimierz SK. Induction of oxidative DNA damage by carcinogenic metals. Toxicol. Lett. 2002;127:55-62.
  22. Kagawa TF, Geierstanger BH, Wang AHJ, Shing Ho P. Covalent modification of guanine bases in double-stranded DNA. J. Biol. Chem. 1991;266:20175-20184.
  23. Geierstanger GH, Kagawa TF, Chen SL, Guigley GJ, Shing Ho P., Base-specific binding of coffer(II) to Z-DNA. J. Biol. Chem. 1991; 266:20185-20191.
  24. Morris P, Hay RW. In Metal ions in biological sciences Vol.5; Sigel, H. Ed. New York, NY. Marcel Dekker. 2001;173-243.