DNA strand breakage induced by CuII and NiII, in the presence of peptide models of histone H2B

In the present study we used the plasmid relaxation assay, a very sensitive method for detection of DNA strand breaks in vitro, in order to evaluate the role of peptide fragments of histone H2B in DNA strand breakage induced by copper and nickel. We have found that in the presence of peptides modeling the histone fold domain (H2B_32-62 and H2B_63-93) as well as the N-terminal tail (H2B_1-31) of histone H2B there is an increased DNA damage by Cu²⁺/H₂O₂ and Ni²⁺/H₂O₂ reaction mixtures. On the contrary, the C-terminal tail (H2B_94-125) seems to have a protective role on the attack of ROS species to DNA. We have rendered our findings to the interactions of the peptides with DNA, as well as with the metal.