Superoxide dismutase structural biology

Hart, R. J. (2006). Rathogenic superoxide dismutase structure, folding, aggregation and turnover. Current Opinion in Chemical Biology, 10, 131-138. 

W.C. Stallings, C. Bull, J.A. Fee, M.S. Lah, and M.L. Ludwig, Iron and manganese superoxide dismutases catalytic inferences from the structures. Current Communications in Cell Molecular Biology. 5, 193-211 (1992). 

Metals in biological systems function in a number of different ways. Group 1 and 2 metals operate as structural elements or in the maintenance of charge and osmotic balance (Table 1.2). Transition metal ions that exist in single oxidation states, such as zinc(II), function as structural elements in superoxide dismutase and zinc fingers, or, as an example from main group +2 ions, as triggers for protein activity—that is, calcium ions in calmodulin or troponin C... 

The most common metal encountered in electron transfer systems is iron, although copper and manganese play vital functions. Merely to emphasise the complexity of the catalysts that are used in biology, the structures of the active sites of ascorbate oxidase (Fig. 10-11) and superoxide dismutase (Fig. 10-12) are presented. It is clear that we have only just begun to understand the exact ways in which metal ions are used to control the reactivity of small molecules in biological systems. 

McRee D E, S M Redford, E D Getzoff, J R Lepock, R A HalleweD and J A Tainer 1990. Changes in Crystallographic Structure and Thermostability of a Cu, Zn Superoxide Dismutase Mutant Resulting from the Removal of Buried Cysteine. Journal of Biological Chemistry 265 14234-14241... 

Copper is markedly different in its reactivity compared to iron. In porphyrins copper is totally buried. Due to the rigid structure of the porphyrins, where no twisting of the ligands is possible no reactivity with oxygen is seen. Hence, copper porphyrin-complexes display no superoxide dismutase activity In biological systems copper is essentially coordinated to nitrogen or sulphur. In octahedral Jahn-Teller distorted Cu(II) complexes a tetragonal distortion of the octahedron, usually an extension... 

The properties of superoxide dismutases (SOD s) have been extensively reviewed . Currently, it seems attractive to work on the biological activity of superoxide dismutases, whereas the chemical aspects are sometimes disregarded. However, devoid of a founded knowledge of the biophysical parameters of these enzymes, the catalytic action of the superoxide dismutases could never have been understood. Thus, a solid structure function correlation is essential. 

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