Copper complexes sites

The interaction of NO, N20, and N02 reactants with the secondary copper-oxo sites leads to terminal 02, restoring the initial active sites (Figure 2.26). The central N02 semi-product is produced through oxidation of NO on the 3CuO Z centers, similarly to the nickel complexes described in Section 6.2.1. 

Rao, S. B. K., A. M. Tyryshkin et al. (2000). Inhibitory copper binding site on the spinach cytochrome bf complex Implications for Q0 site catalysis. Biochemistry 39 3285-3296. 

X-ray crystallographic data has become available on the commercially important 1 1 copper complex azo dyes. The symmetrical dihydroxyazo ligand (16) forms the 1 1 square planar complex (17).13 A pyridine molecule occupies the fourth coordination site since this complex facilitated the formation of crystals suitable for X-ray diffraction. The complex (17) actually exists as an unusual trimer which is held together by long bridging interactions between the copper atom in one molecule and one of the hydroxy oxygen atoms from the adjacent molecules. 

Calixarenes, when in their cone-conformation (54), represent versatile host systems for metalated container molecules and many examples have been reported in the literature (55-61). Reinaud and coworkers have carried out extensive work concerned with calix[6]arenes that are functionalized at the small rim by nitrogen arms (62), aiming to reproduce the hydro-phobic binding site of mononuclear zinc and copper metalloen-zymes. A recent example is the calix[6]arene ligand L1 (Fig. 3), in which a tris(2-methylpyridyl)amine unit covalently caps the calixarene small rim (63). The ligand forms copper complexes of... 

These are reddish blue 1 1 copper-complex monoazo dyes derived from a 2-naphthylamine-or 2-aminonaphtholsulphonate as diazo component and another aminonaphtholsulphonate as coupler. Often such dyes are more easily prepared using a 2-naphthylaminesulphonate and oxidatively coppering the resulting monoazo dye (section 5.5.3). In orthodox structures the imino link of H acid carries the reactive system (7.99), but in other instances the naphthylamine diazo component provides the site of attachment of a haloheterocyclic (7.100) or sulphatoethylsulphone (7.101) grouping. 

Nair, U.B. et al.. Elucidation of vancomycin s enantioselective binding site using its copper complex. Chirality, 8, 590, 1996. 

Interaction of dioxygen species with Fe aq and with Fe " aq has been very briefly reviewed. In relation to 0x0-, peroxo-, and superoxo-complexes as models for intermediates in oxygenase activity, a brief report on a 2000 symposium on activation of oxygen summarizes the then-current situation in the search for a mechanism common to mono- and dinuclear iron sites, mono- and dinuclear copper sites, and copper-iron sites. The outline proposals comprise ... 

Uniquely, the Cu +-neomycin B system has been shown to form two-centered copper complexes at pH values below 6.5 if the metal ion is present in excess (Table 8.3) with less than 15% (relative to total Cu + present) of mononuclear species detected at pH values in the range of 4 to 6. At a 2 1 Cu + neomycin B stoichiometric ratio it was shown that only the dinuclear species exists in solution at pH 7.5. The second binding site in the dinuclear complex was proposed to be in ring D, however, this unique feature is only observed in the case of the copper complex of neomycin B. 

The other copper-only binuclear centre to be considered is the CuA or purple copper complex. It is part of the terminal oxidase in mitochondrial respiration, cytochrome c oxidase (COX). Its EPR signature, a seven-line spectrum, has since long been known to be different from the classes type 1 to 3 and arises from two copper ions in a 1.5 valence (or mixed valence) state, first proposed from EPR-analysis of a similar center in nitrous oxide (N20) reductase. There is a close correspondence between the blue and purple states of copper since each of the two copper ions in CuA can be considered as being structurally related to the mononuclear blue site coordination. 

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