Iron-sulfur centers fumarate reductase

Similar difficulties have been encountered in the case of complex enzymes such as fumarate reductase and nitrate reductase from E. coli, in which substituting certain Cys ligands led to the loss of several if not all the iron-sulfur centers (171, 172). However, in the case of nitrate reductase, which possesses one [3Fe-4S] and three [4Fe-4S] centers, it was possible to remove selectively one [4Fe-4S]... 

FIGURE 12. Stereo diagram of the complete fimiarate reductase complex. The FAD-binding subunit is at the top, the iron-sulfur subunit is in the center and die two membrane anchoring subunits that provide die binding sites for two molecules of menaquinone are at the bottom. In this molecule electron h ansfer occiffs from menaquinone at die bottom to FAD at die top during reduction of fumarate by menaquinone. Skeletal models of two molecules of menaquinone, a 3Fe-4S, a 4Fe-4S, a 2Fe-2S, an FAD molecule and one molecule of oxalate are included. 

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