Sites copper

The zinc oxide component of the catalyst serves to maintain the activity and surface area of the copper sites, and additionally helps to reduce light ends by-product formation. Selectivity is better than 99%, with typical impurities being ethers, esters, aldehydes, ketones, higher alcohols, and waxes. The alumina portion of the catalyst primarily serves as a support. 

Electron Transfer in Complex IV Involves Two Hemes and Two Copper Sites... 

Cytochrome c oxidase contains two heme centers (cytochromes a and %) as well as two copper atoms (Figure 21.17). The copper sites, Cu and Cug, are associated with cytochromes a and respectively. The copper sites participate in electron transfer by cycling between the reduced (cuprous) Cu state and the oxidized (cupric) Cu state. (Remember, the cytochromes and copper sites are one-electron transfer agents.) Reduction of one oxygen molecule requires passage of four electrons through these carriers—one at a time (Figure... 

Hakulinen N, Kiiskinen LL, Kruus K, Saloheimo M, Paananen A, Koivula A, Rouvinen J. 2002. Crystal structure of a laccase from Melanocarpus albomyces with an intact trinuclear copper site. Nature Struct Biol 9 601-605. 

Ndi g5Ceo.i5Cu04 Substitution of Ce" for Nd " ions involves the formation of charge compensating electrons distributed among the copper sites... 

RBa2Cu40g (R = Sm, Y, Er) Nuclear-quadrupole coupling parameters at the rare-earth metal and copper sites from Cu ( Zn) and Ga( Zn) Mossbauer emission spectroscopy, EEG tensor in comparison with point charge model, shows that holes in lattices are localized primarily at chain-oxygen sites... 

Y2Ba4Cu7025 Nuclear quadrupole interaction at copper sites, EFG tensor at all sites is calculated using the point charge model, conclusion that holes in the Y2Ba4Cu70i5 lattice are localized predominantly at positions of chain oxygen... 

On the other hand a direct hydrogen transfer through a Meerwein-Ponndorf mechanism, involving coordination of both the donor alcohol and the ketone to the copper site may also be considered. In this case, by using alcohols other than 2-propanol, we could expect some difference in stereochemistry. This would also imply the possibility of carrying out the enantioselective reduction of a prochiral ketone with a chiral alcohol as donor. 

Figure 12.1 Structure of the four copper sites in ascorbate oxidase showing their spatial relationship. From Lippard and Berg, 1994. Reproduced by permission of University Science Books.

Antholine, W.E., Hanna, P.M., and McMillan, D.R. 1993. Low frequency EPR of Pseudomonas aeruginosa azurin analysis of ligand superhyperfine structure from a type 1 copper site. Biophysical Journal 64 267-272. 

J.A. Fee and R.G. Briggs, Reconstitution of bovine erythrocyte superoxide dismutase. V. Preparation and properties of derivatives in which both zinc and copper sites contain copper. Biochim. Biophy. Acta. 400, 439 150 (1975). 

Co-immobilization of this redox polymer with a fungal laccase from Trametes versicolor, possessing a Tl copper site reduction potential of +0.57 V vs Ag/AgCl ( +0.77 vs NHE), was achieved using a diepoxide cross-linker, in an approach... 

Laccase contains four copper atoms that have been classified as type 1 or blue (Tl), type 2 or normal (T2), and type 3 (T3) or coupled binuclear copper sites, where the coppers are antiferromagnetically coupled through a bridging ligand (Fig. 4.4). 

Table 1. Summary of Nature of Copper Sites in hCP from Spectroscopic Dataa,b Linder [13], Modified from Frieden [15]...

P-Strands 7-8 Domains which contain mononuclear copper sites ... 

Figure 4. Electron transfer pathways between the mononuclear copper sites.

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