Superoxide reductase activities of neelaredoxin and desulfoferrodoxin metalloproteins

Superoxide reductases have now been well characterized from several organisms. Unique biochemical features include the ability of the reduced enzyme to react with O2- but not dioxygen (reduced SORs are stable in an aerobic atmosphere for hours). Future biochemical assays that measure the reaction of SOR with O2- should take into account the difficulties of assaying O2- directly and the myriad of redox reactions that can take place between components in the assay, for example, direct electron transfer between cytochrome c and Dfx. Future prospects include further delineation of the reaction mechanisms, characterization of the putative (hydro)peroxo intermediate, and studies that uncover the components between reduced pyridine nucleotides and SOR in the metabolic pathway responsible for O2- detoxification.