Background: Studies on the interactions of metal ions and DNA suggests the significant effect of metals on DNA and its damage. This study was carried out to examine the effects of some trace metals including Cadmium, Chromium and Copper on E.coli (ptcc1399) DNA.

Materials and Methods: Purified DNA from bacteria was incubated with different concentrations of metals (1-100µM) and H2O2 for 1 hour in 37cº. Then the damage on treated DNA was examined using the electrophoresis and spectrophotometric methods. To control the activity of metal ions, EDTA and catalase were used.

Results: Increasing the concentrations of the mentioned metals and H2O2, did not alone cause damage to DNA, but treatment of DNA with a mixture of the metals and H2O2 in concentrations > 10 µM could lead to breaks in DNA. Furthermore, the addition of EDTA and catalase to the mixture prevented DNA damage.

Conclusion: Since DNA damage has occurred only in the presence of metals and H2O2, there is a generation of free radicals by this mixture. Therefore, the main reason for this evidence probably shows the participation of the metals in fenton reaction.