Redox proteins definition

At this point, what is the exact definition of a BFC According to some authors, BFCs are devices that use redox proteins and enzymes, microorganisms, or mitochondria, in order to assimilate a fuel and generate electric power [20]. At the same time, there is another broader definition in the literature BFCs are fuel cells that convert organic... 

Fe 2S], a [4Fe-4S] and a [3Fe-4S] center. The enzyme catalyzes the reversible redox conversion of succinate to fumarate. Voltammetry of the enzyme on PGE electrodes in the presence of fumarate shows a catalytic wave for the reduction of fumarate to succinate (much more current than could be accounted for by the stoichiometric reduction of the protein active sites). Typical catalytic waves have a sigmoidal shape at a rotating disk electrode, but in the case of succinate dehydrogenase the catalytic wave shows a definite peak. This window of optimal potential for electrocatalysis seems to be a consequence of having multiple redox sites within the enzyme. Similar results were obtained with DMSO reductase, which contains a Mo-bis(pterin) active site and four [4Fe 4S] centers. 

Arnon and his group have definitively established that ferredoxins (iron-sulfur proteins noted for their strongly electronegative redox potentials) are the primary electron acceptors in photosynthesis, and that they are essential electron carriers for the light-induced generation of reducing power and ATP formed in the processes of cyclic and non-c clic photophosphorylation. Reducing power—either reduced ferredoxin or reduced nicotinamide adenine dinucleotides, NAD(P)H—and ATP constitute the assimilatory power required for the further assimilation in the dark of carbon dioxide, nitrate and sulfate. ... 

The overwhelming evidence for transition elements as excellent catalysts forces us to assume that Fe and Cu proteins are nature s most succesful attempt to solve redox problems. Is there any evidence for catalysts other than metal complexes Proving definitely that metals are nonoperative in the catalytic mechanism is much more difficult than proving the contrary. Lack of influence of complexing agents is not a sufficient argument (see for instance pyrocatechase). Nor has research on lipoxidase for instance yet given clear-cut results about catalytic active metals (see survey by Mason, 1957). 

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