Cu/Zn-superoxide dismutase

Klapper, I., Hagstrom, R., Fine, R., Sharp, K., Honig, B. Focusing of electric fields in the active site of cu,zn superoxide dismutase. Proteins Struct. Pune. Genet. 1 (1986) 47-79. 

J Shen, CF Wong, S Subramaniam, TA Albright, JA McCammon. Partial electrostatic charges for the active center of Cu,Zn superoxide dismutase. J Comput Chem 11 346-350, 1990. 

Elroy-Stein, D., Bernstein, Y. and Groner, Y. (1986). Overproduction of human Cu/Zn-superoxide dismutase in transfected cells extenuation of paraquat-mediated cytotoxicity and enhancement of lipid peroxidation. EMBO J. 5, 615-622. 

Seto, N.O.L., Hayashi, S. and Tener, G.M. (1990). Overexpression of Cu-Zn superoxide dismutase in Drosophila does not affect life span. Proc. Natl Acad. Sci. USA 87, 4270-4274. 

Durham HD, Roy J, Dong L, Figlewicz DA. Aggregation of mutant Cu/ Zn superoxide dismutase proteins in culture model of ALS. J Neuropathol Exp Neurol 1997 56 523-530. 

Klapper I, Hagstrom R, Fine R, Sharp K, Honig B (1986) Focusing of Electric Fields in the Active Site of Cu-Zn Superoxide Dismutase Effects of Ionic Strength and Amino-Acid Modification. Proteins 1 47-59. 

Imidazoles are of interest as bridging ligands particularly with regard to mimics of the active site of Cu-Zn superoxide dismutase (SOD). Structures with imidazolate bridges have been... 

Carloni et al.91 applied the DFT(PZ) calculations to investigate the electronic structure of various models of oxydized and reduced Cu, Zn superoxide dismutase. The first stage of the enzymatic reaction involves the electron transfer from Cu" ion to superoxide. The theoretical investigations provided a detailed description of the electronic structure of the molecules involved in the electron transfer process. The effect of charged groups, present in the active center, on the electron transfer process were analyzed and the Argl41 residue was shown to play a crucial role. 

Carloni, P., P. E. Blochl, and M. Parrinello. 1995. Electronic Structure of the Cu, Zn Superoxide Dismutase Active Site and Its Interactions with the Substrate. J. Phys. Chem. 99, 1338. 

Figure 12.2 Copper chaperone function, (a) Copper homeostasis in Enterococcus hirae is affected by the proteins encoded by the cop operon. CopA, Cu1+-import ATPase CopB, Cu1+-export ATPase CopY, Cu1+-responsive repressor copZ, chaperone for Cu1+ delivery to CopY. (b) The CTR family of proteins transports copper into yeast cells. Atxlp delivers copper to the CPx-type ATPases located in the post Golgi apparatus for the maturation of Fet3p. (c) Coxl7p delivers copper to the mitochondrial intermembrane space for incorporation into cytochrome c oxidase (CCO). (d) hCTR, a human homologue of CTR, mediates copper-ion uptake into human cells. CCS delivers copper to cytoplasmic Cu/Zn superoxide dismutase (SOD1). Abbreviations IMM, inner mitochondrial membrane OMM, outer mitochondrial membrane PM, plasma membrane PGV, post Golgi vessel. Reprinted from Harrison et al., 2000. Copyright (2000), with permission from Elsevier Science.

Protection from unwanted side products of oxygen reactions uses the cytoplasmic Cu/Zn superoxide dismutase and vesicular haem catalases as in all eukaryotes as... 

D. Cocco, L. Calabrese, A. Rigo, F. Marmocchi, and G. Rotitlio, Preparation of selectively metal-free and metal-substituted derivatives by reaction of Cu-Zn superoxide dismutase with diethyldithiocar-bamate. Biochem. J. 199, 675-680 (1981). 

Stieber, A., Gonatas, J. O., Moore, J. S. et al. Disruption of the structure of the Golgi apparatus and the function of the secretory pathway by mutants G93A and G85R of Cu, Zn superoxide dismutase (SOD1) of familial amyotrophic lateral sclerosis. /. Neurol. Sci. 219 45-53, 2004. 

Rosen, D. R., Siddique, T., Patterson, D. et al. Mutations in Cu/Zn superoxide dismutase gene are associated with familial amyotrophic lateral sclerosis. Nature 362 59-62, 1993. 

Reaume, A. G., Elliott, J. L., Hoffman, E. K. et al. Motor neurons in Cu/Zn superoxide dismutase-deficient mice develop normally but exhibit enhanced cell death after axonal injury. Nat. Genet. 13 43-47,1996. 

Gurney, M. E., Pu, H., Chiu, A. Y. etal. Motor neuron degeneration in mice that express a human Cu,Zn superoxide dismutase mutation. Science 264 1772-1775,1994. 

As described in the previous section, four hyperfine lines will be found in the EPR spectrum of Cu,Zn-superoxide dismutase (CuZnSOD) because of the 1 = 312... 

Cu,Zn superoxide dismutase. Essentially, these observations support a stepwise one-electron model again. Interestingly, the oxidation state of copper does not change during the catalytic reaction, i.e. the sole kinetic role of the histidine coordinated metal center is to alter the electronic structures of the substrate and 02 in order to facilitate the electron transfer process between them. 

Carloni, P., Blochl, P. E. and Parrinello, M. Electronic structure of the Cu,Zn superoxide dismutase active site and its interactions with the substrate, J.Phys.Chem., 99 (1995), 1338-1348... 

Parge, H. E., Hallewell, R. A., and Tainer, J. A. (1992). Atomic structures of wild-type and thermostable mutant recombinant human Cu,Zn superoxide dismutase. Proc. Natl. Acad. Sci. USA 89, 6109-6113. 

Warshawsky, A., Rogachev, I., Patil, Y., Baszkin, A., Weiner, L. and Gressel, J. (2001). Copper-specific chelators as synergists to herbicides 1. Amphiphilic dithiocarbamates, synthesis, transport through lipid bilayers, and inhibition of Cu/Zn superoxide dismutase activity, Langmuir, 17, 5621-5635. 

The chelate effect in proteins is also important, since the three-dimensional (3-D) structure of the protein can impose particular coordination geometry on the metal ion. This determines the ligands available for coordination, their stereochemistry and the local environment, through local hydrophobicity/hydrophilicity, hydrogen bonding by nearby residues with bound and non-bound residues in the metal ion s coordination sphere, etc. A good example is illustrated by the Zn2+-binding site of Cu/Zn superoxide dismutase, which has an affinity for Zn2+, such that the non-metallated protein can extract Zn2+ from solution into the site and can displace Cu2+ from the Zn2+ site when the di-Cu2+ protein is treated with excess Zn2+. 

As we will discuss later, in Chapter 8, free copper levels are extremely low within cells because the copper is bound to a family of metallochaperones, which are subsequently involved in the incorporation of copper into copper-containing proteins. The mechanism proposed for copper insertion into the Cu/Zn superoxide dismutase, SOD1, is presented in Figure 3.9. The copper chaperone, CCS, acquires copper as Cu+ from a copper transporter and then docks with the reduced dithiol form of SOD1 (Steps I and II) to give a docked... 

Figure 4.10 (a) The Cu-Zn superoxide dismutase is made up of eight anti-parallel P-strands both the constant (b) and variable (c) domains of immunoglobulins are made up of seven anti-parallel P-strands with the same topology the variable domain contains two additional P-strands. (From Branden and Tooze, 1991. Reproduced by permission of Garland Publishing, Inc.)... 

Fig. 20. An example of antiparallel /3 sheet, from Cu,Zn superoxide dismutase (residues 93-98,28-33, and 16-21). Arrows show the direction of the chain on each strand. Main chain bonds are shown solid and hydrogen bonds are dotted. In the pattern characteristic of antiparallel /8 sheet, pairs of closely spaced hydrogen bonds alternate with widely spaced ones. The direction of view is from the solvent, so drat side chains pointing up are predominantly hydrophilic and those pointing down are predominantly hydrophobic.

Fig. 29. An assortment of/3 barrels, viewed down the barrel axis (a) staphylococcal nuclease, 5-stranded (b) soybean trypsin inhibitor, 6-stranded (c) chymotrypsin, 6-stranded (d) immunoglobulin (McPC603 CH1) constant domain, 7-stranded (e) Cu,Zn superoxide dismutase, 8-stranded (f) triosephosphate isomerase, 8-stranded (g) im-... 

Immunoglobulin, variable and constant domains Cu,Zn superoxide dismutase Staphylococcal nuclease... 

The commonest subgroup of antiparallel /3 barrel structures has a Greek key topology, with -3,+1,+1,-3 connections or a close variant. The first Greek key barrel structures were compared in Richardson et al. (1976), and they and the up-and-down barrels were described as categories in Richardson (1977). Figure 96 illustrates Cu,Zn superoxide dismutase as an example of a Greek key j8 barrel. 

FlC. 96. Cu,Zn superoxide dismutase as an example of a Greek key antiparallel /9 barrel, (a) a-Carbon stereo, viewed from one side of the barrel (b) backbone schematic, viewed as in a. 

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