Proteins copper

Tolman W.B. (1995) Synthetic Modeling of the Interactions of Nitrogen Oxides with Copper Proteins Copper Nitrosyl Complexes Relevant to Putative Denitrification Intermediates, Adv. Chem. Ser., 246, 195. 

Figure 11.10 Absorption spectrum of the protein-copper complex of the biuret reaction.

Copper ions bind to and inhibit many enzymes. Of more importance, perhaps, is that in free solution or when bound to proteins, copper ions catalyse the Fenton reaction which produces the highly dangerous hydroxyl radical, OH (Appendix 9.6). 

Because Cu2+ is the most tightly bound metal ion in most chelating centers (Table 6-9), almost all of the copper present in living cells is complexed with proteins. Copper is transported in the blood by a 132-kDa, 1046-residue sky-blue glycoprotein called ceruloplasmin.471475-477 This one protein contains 3% of the total body copper. 

This protein contains a coupled binuclear copper site that appears to be very similar to that found in hemocyanin (Section 62.1.12.3.8).1399 Tyrosinase catalyzes the hydroxylation of monophenols, and also behaves as an oxidase in the oxidation of orfho-diphenols. The deoxy protein [copper(I)] binds dioxygen to give oxytyrosinase, which is a Cu11 peroxide species with antiferromagnetic coupling between the two Cu11 centres. The oxybinuclear site is diamagnetic to the most sensitive detectors. 

Sakaguchi, U., and Addison, A. W. (1979). Spectroscopic and redox studies of some copper (II) complexes with biomimetic donor atoms implications for protein copper centres. J. Chem. Soc. Dalton Trans., 600-608. 

The protein copper-oxygen complex is formed by combining one molecule of oxygen with the protein to which two adjacent cuprous atoms are attached. 

Calcium-binding Proteins Copper Enzymes in Denitrification Copper Proteins with Type 1 Sites Copper Proteins with Type 2 Sites Iron Heme Proteins Electron Transport Iron-Sulfin Proteins Metal-mediated Protein Modification Metallochaperones Metal Ion Homeostasis Molybdenum MPT-containing Enzymes Nickel Enzymes Cofactors, Nitrogenase Catalysis Assembly Zinc Enzymes. 

Figure 15 Structures of type 1 copper protein, Azurin (a) and Type 2 copper protein, Copper, zinc superoxidase dismutase (b). (Reprinted with permission from Ref. 23. 2001 the American Chemical Society)...

There are four different types of nitrite reductases the copper-containing protein Copper Enzymes in Denitrification and cytochrome cd perform a one-electron rednetion of nitrite to nitric oxide, and are involved in denitrification " the siroheme-containing protein and the cytochrome c ititrite reductase (cNiR) both perform the complete, six-electron reduction, of nitrite to ammonia. The cNiR is present in the y, 5 or e-subclasses of proteobacteria, and is encoded by the nrf operon (nitrite reduction with /ormate), which has different gene composition in the different classes of bacteria, having in common only the gene for the catalytic subunit, ntfA. 

Figure 13 The active site of 2,3QD-substrate complex. Protein copper ligands are represented by orange sticks, substrate is in gray, and the residues in van der Waals contact with the substrate are in green (Reproduced from R.A. Steiner, K.H. KaUs, and B.W. Dijksfra, Proc. Natl. Acad. Sci. USA, 2002, 99, 16625. 2001 National Academy of Sciences, USA)...

Redox catalysis is the catalysis of redox reactions and constitutes a broad area of chemistry embracing biochemistry (cytochromes, iron-sulfur proteins, copper proteins, flavodoxins and quinones), photochemical processes (energy conversion), electrochemistry (modified electrodes, organic synthesis) and chemical processes (Wacker-type reactions). It has been reviewed altogether relatively recently [2]. We will essentially review here the redox catalysis by electron reservoir complexes and give a few examples of the use of ferrocenium derivatives. 

Multhaup G. Amyloid precursor protein, copper and Alzheimer s disease. Biomed Pharmacother 1997 51(3) 105-11. 

Copper was recognized as nutritionally essential by 1924 and has since been fmmd to fxmction in many cellular proteins. ° Copper is so broadly distributed in foods thaf a deficiency has only rarely been observed in humans. However, animals may sometimes receive inadequate amounts because absorption of Cu + is antagonized by Zn + and because copper may be tied up by molybdate as an inert complex. There are copper-deficient desert areas of Australia where neither plants nor animals survive. Copper-deficient animals have bone defects, hair color is lacking, and hemoglobin synthesis is impaired. Cytochrome oxidase activity is low. The protein elastin of arterial walls is poorly crosslinked and the arteries are weak. Genetic defects in copper metabolism can have similar effects. 

Among the electron transport proteins, there are four known classes that have been isolated and studied by X-ray crystallography. These include cytochromes, iron-sulfur proteins, copper blue proteins, and... 

Protein + copper tartrate — — colored complex Schematic structure of the slide ... 

In response to this, experimental work was carried out in two directions. Some work (5) involved studies with purified diets of known compositions. The other series of studies (, 7) involved the addition of nutrient supplements to cereal diets (similar to those shown in Figure 1 as squares) to see if the observed biochemical effects could be reversed by adding selected nutrient supplements to the diet. It was in this latter supplementation work that it soon became evident that protein, copper and possibly zinc were nutrients of prime importance. 

An ever increasing number of copper metalloproteins is being recognized. Those regularly present in mammals are listed in Table 5 with some of their characteristics. Other important naturally occurring copper proteins, such as hemocyanin, laccase, and ascorbic acid oxidase, are not listed since they do not occur in mammals. The metalloprotein nature of some of the proteins listed in Table 5 has not been established fully as yet. The search for further copper proteins, copper-protein complexes, and other forms in which copper may be stored or transported in the body must continue. 

In an early review, Hyde [272] discussed ENDOR in proteins, including flavo-proteins, copper proteins, hemeproteins, two-iron ferrodoxin and bacteriochloro-phyll. Kevan and Kispert s book [19] is an introductory text on ENDOR (electron nuclear double resonance) and ELDOR (electron electron double resonance) techniques. Poole [11] includes a chapter on double resonance techniques in his text. Schweiger [21] has covered ENDOR of transition metal complexes, including a section on biological applications. Recent reviews of ENDOR spectroscopy of chlorophylls [273], heme and heme proteins [274] and iron sulfur proteins [275] demonstrate how additional detail can be obtained from ENDOR data. 

Keywords Biophysical monitors Chemical synthesis of proteins Copper binding Expressed protein ligation Interaction of PrP with small molecules... 

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