Metal chelation studies on Cu, Zn superoxide dismutase

The redox-active metal ions Fe2+ and Cu2+ are believed to play a central role in the promotion of hydroxyl radical formation from the partially reduced oxygen species, superoxide and hydrogen peroxide, which are themselves generated in all mammalian cells. The Cu, Zn Superoxide dismutase is a cytosolic enzyme containing 2 moles of Cu and Zn per mole of holoenzyme and its activity is dependent on the availability of copper. From the studies conducted so far, it has been shown that agents which capture Cu(II) from the enzyme molecule resulted in complete loss of its biological activity suggesting that the reduction of Cu(II) mediate the inactivation of enzyme. There are certain dietary polypheonlic compound which are widely distributed in various foods and beverages of plant origin. Some flavonoids are well known for their interaction with metal ions generating free radicals and strand scission in DNA. It is very well known whether bound Cu2+ of Cu, Zn SOD may involve in such type of interaction either resulting in loss of enzyme activity or generating certain free radicals. We have carried out studies in this direction by selecting one metal-ion-complexing agent. 1,10 phenanthroline (OP) which can chelate several metal ions, the most relevant being Cu2+, Fe2+ and Zn2+. These studies are aimed to investigate the possible interaction of 1,10 phenanthroline with Cu, Zn SOD involving its Cu(II). The role of bound Cu2+ of Cu, Zn SOD in the modulation of enzyme activity as well as the conditions for inactivation of enzyme in the presence and absence of free copper and other agents have been discussed.