Anti-oxidant defenses superoxide dismutase

As for iron, differences in redox potentials are relatively small between the major oxidation states of copper, that is, Cu(I) and Cu(II). This gives copper its main function as a cofactor in enzymatic reactions involving electron-transfer processes. In the human body, most of the copper (about 40%) is present in muscle tissue with significant amounts also present in the liver, brain, and skeleton. About 5% of the copper can be found in serum, of which 80-90% is present as ceruloplasmin. Ceruloplasmin in serum and hephaestin at the basolateral side of the mucosa ensure oxidation of circulating Fe to Fe for iron binding to transferrin. Unbound Fe is a major source of oxidative stress through Fenton/Haber-Weiss chemistry. Copper together with zinc is also a cofactor for superoxide dismutase, a key molecule in the anti-oxidant defense system of the body ]74]. 

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