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Isabel A. Abreu Diane E. Cabelli 《Biochimica et Biophysica Acta - Proteins and Proteomics》2010,1804(2):263-274
Superoxide dismutases are enzymes that function to catalytically convert superoxide radical to oxygen and hydrogen peroxide. These enzymes carry out catalysis at near diffusion controlled rate constants via a general mechanism that involves the sequential reduction and oxidation of the metal center, with the concomitant oxidation and reduction of superoxide radicals. That the catalytically active metal can be copper, iron, manganese or, recently, nickel is one of the fascinating features of this class of enzymes. In this review, we describe these enzymes in terms of the details of their catalytic properties, with an emphasis on the mechanistic differences between the enzymes. The focus here will be concentrated mainly on two of these enzymes, copper, zinc superoxide dismutase and manganese superoxide dismutase, and some relatively subtle variations in the mechanisms by which they function. 相似文献
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Ligation of nickel(II) by Trofimenko’s hydrotris(3,5-dimethyl-1-pyrazolyl)borate anion (TpMe,Me) and zwitterionic organoxanthate or dithiocarbamate co-ligands affords neutral high-spin pentacoordinate complexes with formally trianionic N3S2 ligand fields, similar to that of the nickel-dependent superoxide dismutase active site. Given this analogy to NiSOD, the structure, dynamics, and redox properties of the product complexes were examined. X-ray structures revealed rotation of the dithioacid chelates against the scorpionate face, giving coordination geometries between square pyramidal and trigonal bipyramidal limits. The complexes accordingly adopt paramagnetic (S = 1) d8 electron configurations, but magnetic susceptibilities suggest partial isomerization to a diamagnetic state in solution. The complexes also exhibit quasi-reversible one-electron redox couples at potentials suitable for SOD activity. 相似文献
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