Copper cysteinate proteins

In a beautifiil recent work, the groups of K. Pierloot and B. O. Roos have proposed a fairly complete understanding of the relation between the electronic spectra and the stmcture of the mononuclear copper-cysteinate proteins. This theoretical work is based on DFT geometry optimizations of several blue copper protein models from [Cu(NH3)2(SH)(SH2)+] to... 

Even if the calculations were performed on a simple model, the results presented in Figure 8 nicely reflect the structure-electronic spectroscopy relationship between the various types of copper-cysteinate proteins. The copper coordination geometry of axial type 1 proteins is close to trigonal, and their spectroscopic characteristics are reflected by the results obtained for (p > 80°. Rhombic type 1 proteins like pseudoazurin and cucumber basic protein, on the other hand, have (p angles between 70° and 80°. As can be seen from Figure 8, even at such a small... 

Lu, Y. Roe, J. A. Gralla, E. B. Valentine, J. S. Metalloprotein ligand redesign characterization of copper-cysteinate proteins derived from yeast copper-zinc superoxide dismutase. In Bioinorganic Chemistry of Copper Karlin, K. D. Tyeklar, Z., Eds. Chapman and Hall New York, 1993 pp 64-77. 

Type 1.5 and type 2 copper-cysteinate proteins do not exist in nature they have all been constructed by site directed mutagenesis on different proteins, mainly azurin or Cu,Zn-superoxide dismutase. For the type 1.5 proteins, a recent crystal structure is available, the azide derivative of the Met 121-Ala azurin mutant. In addition, preliminary results on the Metl21-His azurin mutant, another type 1.5 protein, have also been presented. ... 

Spectroscopic Properties of Different Types of Copper Cysteinate Protein... 

Table 6 Calculated Spectrum of Cu(NHi)j(SH) " and Cu(NH3)(OH )2(SH) as Models for Type 1.5 and Type 2 Copper Cysteinate Proteins Respectively...

Andrew CR, Yeom H, Valentine JS, Karlsson BG, van Pouderoyen G, Canters GW, Loehr TM, Sanders-Loehr J, Bonander N. Raman spectroscopy as an indicator of Cu-S bond length int5fpe 1 and type 2 copper cysteinate proteins. J Am Chem Soc 1994 116 11489-11498. 

Blue copper proteins. A typical blue copper redox protein contains a single copper atom in a distorted tetrahedral environment. Copper performs the redox function of the protein by cycling between Cu and Cu. Usually the metal binds to two N atoms and two S atoms through a methionine, a cysteine, and two histidines. An example is plastocyanin, shown in Figure 20-29Z>. As their name implies, these molecules have a beautiful deep blue color that is attributed to photon-induced charge transfer from the sulfur atom of cysteine to the copper cation center. 

Cysteine can bind to either one or two metal ions, and is frequently found as a ligand to iron (in Fe-S clusters—see later) and to Cu+ (for example in the copper chaperones, which transfer copper to specific copper-binding proteins). Histidine can bind metal ions in two... 

Considerable progress has been made toward the elucidation of the function of Cox 17 since its identification 5 years ago. It has been shown to be a copper-containing protein that is essential for assembly of the cytochrome c oxidase complex and is present in both the mitochondria and the cytosol. These features are strongly indicative of a copper chaperonelike function. It appears that Cox 17 interacts directly with Scol and Sco2, but the delineation of the remainder of the copper-trafficking pathway from the chaperone to the cytochrome c oxidase complex remains unclear. It is also unclear exactly how Cox 17 binds copper, since the CCXC motif is unique to date. If it binds three copper atoms with only three cysteine residues, the coordination of the metal ions will be extremely interesting, and elucidation of the protein structure will undoubtedly yield new insights into copper transportation in the cell. 

The intensity of the blue band fiirther decreases as the structure is more flattened, and the results obtained for the smallest

yellow colour. We have also performed calculations on more realistic conplexes [34,38] which confirm these predictions. They show that the Cu-Scys c— a excitation is blue-shifted in these models by more than 1 000 cm , in agreement with the experimental shift of this band from 460 to 410 nm when going from type 1 to type 2 copper proteins [81]. 

Copper is a cofactor in several enzymes, including lysyl oxidase and superoxide dismutase. Ceruloplasmin, a deep-blue glycoprotein, is the principal copper-containing protein in blood. It is used to transport Cu2+ and maintain appropriate levels of Cu2+ in the body s tissues. Ceruloplasmin also catalyzes the oxidation of Fe2+ to Fe3+, an important reaction in iron metabolism. Because the metal is widely found in foods, copper deficiency is rare in humans. Deficiency symptoms include anemia, leukopenia (reduction in blood levels of white blood cells), bone defects, and weakened arterial walls. The body is partially protected from exposure to excessive copper (and several other metals) by metal-lothionein, a small, metal-binding protein that possesses a large proportion of cysteine residues. Certain metals (most notably zinc and cadmium) induce the synthesis of metallothionein in the intestine and liver. 

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