Effect of adenine moiety on DNA binding property of copper(II)-terpyridine complexes

Two novel copper(ii) terpyridine complexes, Cu(atpy)(NO(3))(H(2)O)](NO(3)).3H(2)O () and Cu(ttpy)(NO(3))(2)] () (atpy = 4'-p-N9-adeninylmethylphenyl-2,2':6,2'-terpyridine; ttpy = 4'-p-tolyl-2,2':6,2'-terpyridine) have been prepared and structurally characterized by X-ray crystallography. Both complexes show a CuN(3)O(2) coordination in a square pyramidal (4 + 1) geometry with terpyridine acting as an equatorial ligand. For complex , intermolecular AA base pairing interaction is observed between N(6) and N(1) of adjacent adenines with N(6)N(1) of 3.027(7) A. A molecular dynamics simulation of the DNA binding of two complexes showed that the adenine moiety plays an important role in the intercalation of into DNA. This is verified by UV, fluorescence, circular dichroism and flow linear dichroism studies. The promotional effect from the adenine moiety to the intracellular DNA binding of complex is also confirmed by the inductively coupled plasma mass (ICP-MS) spectrometry data which showed a significant higher copper content in DNA isolated from complex treated MCF-7 and HeLa cells.