Biophysical, spectroscopic and biochemical investigation of DNA–Cu(II)-GSH interactions

Synthesis, DNA interaction and anticancer activity of copper(II) complexes with 4'-phenyl-2,2':6',2″-terpyridine derivatives

Three novel copper(II) complexes CuL(1)Cl2 (1) (L(1)=4'-(3-methoxyphenyl)-2,2':6'- 2″-terpyridine), CuL(2)Cl2 (2) (L(2)=4'-(4-methoxyphenyl)-2,2':6'-2″-terpyridine) and CuL(3)Cl2 (3) (L(3)=4'-(3,5-dimethoxyphenyl)-2,2':6'-2″-terpyridine) have been synthesized and characterized. Absorption spectral titration experiments, ethidium bromide displacement assays, and cyclic voltammetric experiments were carried out and the results suggested that these complexes bound to DNA through an intercalative mode. Moreover, these complexes were found to cleave pBR322 DNA efficiently in the presence of glutathione (GSH), and exhibited good anticancer activity against HeLa, Hep-G2 and BEL-7402 cell lines. Nuclear chromatin cleavage was also observed by acridine orange/ethidium bromide (AO/EB) staining assays and comet assays. These results demonstrated that these three Cu(II) complexes caused DNA damage and induced the apoptosis of HeLa cells. Mechanistic investigations revealed the participation of reactive oxygen species which can be trapped by reactive oxygen species (ROS) radical scavengers and ROS sensors.

Probing the coordination properties of glutathione with transition metal ions (Cr2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+) by density functional theory

Complexes formed by reduced glutathione (GSH) with metal cations (Cr(2+), Mn(2+),Fe(2+),Co(2+),Ni(2+),Cu(2+),Zn(2+),Cd(2+),Hg(2+)) were systematically investigated by the density functional theory (DFT). The results showed that the interactions of the metal cations with GSH resulted in nine different stable complexes and many factors had an effect on the binding energy. Generally, for the same period of metal ions, the binding energies ranked in the order of Cu(2+)>Ni(2+)>Co(2+)>Fe(2+)>Cr(2+)>Zn(2+)>Mn(2+); and for the same group of metal ions, the general trend of binding energies was Zn(2+)>Hg(2+)>Cd(2+). Moreover, the amounts of charge transferred from S or N to transition metal cations are greater than that of O atoms. For Fe(2+),Co(2+),Ni(2+),Cu(2+),Zn(2+),Cd(2+) and Hg(2+) complexes, the values of the Wiberg bond indices (WBIs) of M-S (M denotes metal cations) were larger than that of M-N and M-O; for Cr(2+) complexes, most of the WBIs of M-O in complexes were higher than that of M-S and M-N. Furthermore, the changes in the electron configuration of the metal cations before and after chelate reaction revealed that Cu(2+), Ni(2+),Co(2+) and Hg(2+) had obvious tendencies to be reduced to Cu(+),Ni(+),Co(+) and Hg(+) during the coordination process.

Metal ion-promoted conformational changes of oligonucleotides

The review will discuss the influence of metal ions on conformational changes of oligonucleotides. First, a short definition of the torsion angles is given, followed by a concise yet critical overview of the commonly applied experimental techniques. Finally, the possible role of metals upon the following conformational changes of oligonucleotides is discussed: (i) the denaturation of double-strands, (ii) the transition from B- to A-DNA, (iii) the transition from right- to left-handed DNA and RNA, (iv) the condensation, (v) and other conformational changes. We conclude with a summary and outlook.