Reductive elimination of superoxide: Structure and mechanism of superoxide reductases.
Superoxide anion is among the deleterious reactive oxygen species, towards which all organisms have specialized detoxifying enzymes. For quite a long time, superoxide elimination was thought to occur through its dismutation, catalyzed by Fe, Cu, and Mn or, as more recently discovered, by Ni-containing enzymes. However, during the last decade, a novel type of enzyme was established that eliminates superoxide through its reduction: the superoxide reductases, which are spread among anaerobic and facultative microorganisms, from the three life kingdoms. These enzymes share the same unique catalytic site, an iron ion bound to four histidines and a cysteine that, in its reduced form, reacts with superoxide anion with a diffusion-limited second order rate constant of approximately 10(9) M(-1) s(-1). In this review, the properties of these enzymes will be thoroughly discussed.
Pinto
Ana Filipa
AF
Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157 Oeiras, Portugal.
Rodrigues
João V
JV
Teixeira
Miguel
M
D000595:Amino Acid Sequence; D000818:Animals; D006801:Humans; D008969:Molecular Sequence Data; D010088:Oxidoreductases / Q000737:chemistry* / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013481:Superoxides / Q000737:chemistry* / Q000378:metabolism*
D013481:Superoxides; D010088:Oxidoreductases; C121849:superoxide reductase