Copper-zinc superoxide dismutase, structure

Tainer, J.A., et al. Determination and analysis of the 2 A structure of copper, zinc superoxide dismutase. 

Structure and Properties of Copper-Zinc Superoxide Dismutases Ivano Bertini, Stefano Mangani, and Maria Silvia Viezzoli... 

Finally, Zn also plays an important role in Cu,Zn-SOD (copper-zinc superoxide dismutase) for which the structure is shown in Figure 8 ". Although it is well-known that Zn(II) is not involved in electron-transfer chemistry, it is generally believed that the essential role of Zn(II) ion in SODs is to accelerate both the oxidation and reduction of superoxide by controlhng the redox potential of the Cu(II) ion and superoxide ion in the catalytic cycle. ... 

Although zinc itself is not redox-active, some class I enzymes containing zinc in their active sites are known. The most prominent are probably alcohol dehydrogenase and copper-zinc superoxide dismutase (Cu,Zn-SOD). AU have in common that the redox-active agent is another transition-metal ion (copper in Cu,Zn-SOD) or a cofactor such as nicotinamide adenine dinucleotide (NAD+/NADH). The Zn(II) ion affects the redox reaction only in an indirect manner, but is nevCTtheless essential and cannot be regarded simply as a structural factor. 

Bossa, F. et al. Studies on the protein structure of copper-zinc superoxide dismutase. In Chemical and Biochemical Aspects of Superoxide and Superoxide Dismutase (Bannister, J. V., Hill, H. A. O., eds.), New York-Amsterdam-Oxford, Elsevier/North-Holland, 1980, pp. 223-229 Marmocchi, F. et al, FEBS Lett. 94, 109 (1978)... 

Fig. 6.2. Schematic structure of the active site of copper-zinc superoxide dismutase [72]. The zinc ion can be substituted, among others, by copper(II), cobalt(II) and nickel(II) ions.

The imidazole-bridge dimetallic centre in copper-zinc superoxide dismutase (EC 1.15.1.1) was a novel structural feature that had not previously been encountered in coordination chemistry [151], The Cu(II) ion is co-ordinated by four histidine side chains, His44, His46, His 118 and His61, and there is evidence for a fifth axial water ligand. 

From One Type 2 Copper Protein to Another Type 2 Copper Protein. It has been shown that a type 2 copper protein called copper-zinc superoxide dismutase (CuZnSOD) (Figure 15b) shares the same overall scaffold as its copper chaperone protein called copper chaperone for SOD (CCS). All of e zinc site ligands and three of four copper site histidine ligands in CuZnSOD are conserved in human CCS (hCCS). The zinc site in hCCS displayed the same structure as in CuZnSOD. The fourth ligand in the copper site of CuZnSOD is replaced by an aspartate residue in hCCS. Although aspartate could... 

CD spectroscopy has also provided valuable insight into the chemical stability and chemical denaturation of proteins. A recent study by Rumfeldt etal. examines the guanidinium-chloride induced denaturation of mutant copper-zinc superoxide dismutases (SODs). These mutant forms of the Cu, Zn-SOD enzyme are associated with toxic protein aggregation responsible for the pathology of amyotrophic lateral sclerosis. In this study, CD spectroscopy was used in conjunction with tryptophan fluorescence, enzyme activity, and sedimentation experiments to study the mechanism by which the mutated enzyme undergoes chemical denaturation. The authors found that the mutations in the enzyme structure increased the susceptibihty of the enzyme to form partially unfolded destabilized monomers, rather than the stable metaUated monomer intermediate or native metallated dimer. 

Bertini I, Magnani S, Viezzoli M-S. (1998) Structure and properties of copper-zinc superoxide dismutases. In Advances in Inorganic Chemistry, Sykes AG. (ed.), pp. 127-250, Academic Press New York. 

Richardson, J. S., Richardson, D. C., Thomas, K. A., Silverton, E. W., and Davies, D. R. Similarity of three-dimensional structure between the immunoglobulin domain and the copper, zinc superoxide dismutase subunit. J. Molec. Biol. 102, 221-235 (1976). 

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