Copper- and zinc-containing superoxide dismutase can act as a superoxide reductase and a superoxide oxidase

The copper- and zinc-containing superoxide dismutase can catalyze the oxidation of ferrocyanide by O-2(.-) as well as the reduction of ferricyanide by O-2(.-) Thus, it can act as a superoxide dismutase (SOD), a superoxide reductase (SOR), and a superoxide oxidase (SOO). The human manganese-containing SOD does not exert SOR or SOO activities with ferrocyanide or ferricyanide as the redox partners. It is possible that some biological reductants can take the place of ferrocyanide and can also interact with human manganese-containing superoxide dismutase, thus making the SOR activity a reality for both SODs. The consequences of this possibility vis a vis H2O2 production, the overproduction of SODs, and the role of copper- and zinc-containing superoxide dismutase mutations in causing familial amyotrophic lateral sclerosis are discussed, as well as the likelihood that the biologically effective SOD mimics, as described to date, actually function as SORs.