Iron-sulfur clusters Fe3S4 centers

Figure 5 The most commonly encountered FeS centers (a) the monoiron center of rubredoxin, (b) the FeySy cluster of plant-type ferredoxins, (c) the FeySy cluster of Rieske proteins, (d) the Fe3S4 cluster of ferredoxins, and (e) the Fe4 4 cluster of ferredoxins and high potential iron-sulfur proteins (FliPiPs).

Figure 16-26 (A) Stereoscopic view of the structure of the Desulfovibrio gigas hydrogenase as an a-carbon plot. The electron density map at the high level of 8o is superimposed and consists of dark spheres representing the Fe and Ni atoms. The iron atoms of the two Fe4S4 and one Fe3S4 clusters are seen clearly forming a chain from the surface of the protein to the Ni-Fe center. (B) The structure of the active site Ni-Fe pair. The two metals are bridged by two cysteine sulfur atoms and an unidentified atom, perhaps O, and the nickel is also coordinated by two additional cysteine sulfurs. Unidentified small molecules LI, L2, and L3 are also present. From Volbeda et Courtesy of M. Frey.

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