Copper centres

The effects of these ligands on the second-order rate constants for the Cu (ligand) catalysed reaction of Ic with 2 are modest In contrast, the effects on IC2 are more pronounced. The aliphatic Oramino acids induce an approximately two-fold reduction of Iv relative to for the Cu" aquo ion. For the square planar coordinated copper ions this effect is expected on the basis of statistics. The bidentate ligands block half the sites on the copper centre. 

On the relationship between protein-forced ligand fields and the properties of blue copper centres. H. B. Gray and B. G. Malmstrom, Comments Inorg. Chem., 1983, 2, 203-209 (14). 

Copper proteins. Systems containing the blue copper centre. J. A. Fee, Struct. Bonding (Berlin),... 

While nitrite reductases in many bacteria are haem proteins, some are copper containing homotrimers, which bind three Type I and three Type II copper centres. The Type I copper... 

Finally, we examine azurin, a blue protein (FW = 14 000) devoted to bacterial electron transport, the copper centre of which has a penta-coordinate trigonal bipyramidal geometry, at variance with all the other cupredoxins, Figure 39.73... 

Figure 39 X-Ray structure of the copper centre in azurin from Pseudomonas Aeruginosa...

Negative values for redox couple entropy have also been obtained for the Cu(II)/Cu(I) reduction, in aqueous medium, of the blue copper proteins stellacyanin, plastocyanin and azurin.14 The decrease in molecular disorder has been attributed in this case to the fact that the charge neutralization of the redox site (from + 1 to 0) favours the formation of hydrogen bonds between the solvent (water) and the copper centre.17... 

SCHEME 17. Sheldon s mechanism of an aerobic copper-centred oxidation of alcohols by TEMPO... 

Blue or Type 1 copper centres comprise one of the three types of copper found in biological systems. The distinctive properties of this class of protein is an intense... 

Cytochrome c and Cytochrome c Oxidase. - The mitochondrial electron transport chain is the site at which most of the free energy to be obtained from the oxidation of substrates is released and conserved as the energy-rich molecule ATP. In the final stage of this process, CcO, which is supplied with electrons by cyt c, catalyses the four-electron reduction of oxygen to water. Both are haem proteins, with CcO containing two haem and three copper centres, and both exhibit peroxidase-type activity. 

The multicomponent type IV copper proteins are usually coloured (Figure 95) as they generally contain at least one blue type I copper centre, but as there are usually more than one of each type present, the physical properties of the different types I—III environments are difficult to separate and, for ESR-silent type III centres, difficult to detect.1203 No crystallographic data are yet available on a type IV copper protein. 

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