Biochemistry of copper

One of the intriguing questions in the biochemistry of copper is how it can function in rapid electron-transfer reactions2 when Cu(I) and Cu(II) have such drastically different preferences in coordination geometry. As we have already pointed above, four-coordinate Cu(II) complexes are square-planar, while the corresponding Cu(I) complexes tend to be... 

Walaas, E., Walaas, O., Lovstad, R. The interaction of ceruloplasmin with catecholamines. In The Biochemistry of Copper (Peisach, J., Aisen, P., Blumberg, W. E., eds.). New York-London, Academic Press, 1966, pp. 537-544... 

Many reviews are available on the general biochemistry of copper,899-905 electronic aspects of active sites906,907 and relevant model chemistry of simple copper complexes.908 909... 

In the discussion of the biochemistry of copper in Section 62.1.8 it was noted that three types of copper exist in copper enzymes. These are type 1 ( blue copper centres) type 2 ( normal copper centres) and type 3 (which occur as coupled pairs). All three classes are present in the blue copper oxidases laccase, ascorbate oxidase and ceruloplasmin. Laccase contains four copper ions per molecule, and the other two contain eight copper ions per molecule. In all cases oxidation of substrate is linked to the four-electron reduction of dioxygen to water. Unlike cytochrome oxidase, these are water-soluble enzymes, and so are convenient systems for studying the problems of multielectron redox reactions. The type 3 pair of copper centres constitutes the 02-reducing sites in these enzymes, and provides a two-electron pathway to peroxide, bypassing the formation of superoxide. Laccase also contains one type 1 and one type 2 centre. While ascorbate oxidase contains eight copper ions per molecule, so far ESR and analysis data have led to the identification of type 1 (two), type 2 (two) and type 3 (four) copper centres. 

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