Electron shuttle reactions copper complexes

Electron shuttle reactions copper(II) complexes, 717 Elongation factor 1 zinc, 1007... 

Iron, copper, and manganese can shuttle between different cationic forms and participate in electron transfer reactions that form the core of bioenergetics. For instance, because the configuration of Fe is [Ar]3d 4s, the Fe and Fe cations have the configurations [ Ar]3d and [Ar]3d respectively. These are the oxidation states adopted by the iron ions bound to the protein cytochrome c as it transfers electrons between complexes II and IV in the mitochondrial electron transport chain (Section 5.10). 

The many redox reactions that take place within a cell make use of metalloproteins with a wide range of electron transfer potentials. To name just a few of their functions, these proteins play key roles in respiration, photosynthesis, and nitrogen fixation. Some of them simply shuttle electrons to or from enzymes that require electron transfer as part of their catalytic activity. In many other cases, a complex enzyme may incorporate its own electron transfer centers. There are three general categories of transition metal redox centers cytochromes, blue copper proteins, and iron-sulfur proteins. 

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