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 oxida tion 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 red uctase (SOR), and a superoxide oxidase (SOO). The human manganese-containin g SOD does not exert SOR or SOO activities with ferrocyanide or ferricyanid e 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 su peroxide dismutase mutations in causing familial amyotrophic lateral sclero sis are discussed, as well as the likelihood that the biologically effectiv e SOD mimics, as described to date, actually function as SORs.