66 by: Kushal Patel
Student – Kushal Patel
Enzyme – Superoxide Dismutase (SOD)
E.C. number 1.15.1.1
Where is enzyme found? Superoxide dismutase (SOD) is found in various forms across nearly all aerobic organisms, including mammals, plants, and bacteria. It occurs in different cellular compartments, such as the cytoplasm, mitochondria, and even the extracellular matrix. Specifically, it is highly present in mammalian tissues such as the liver, erythrocytes (red blood cells), and brain (McCord & Fridovich, 1969)
What does the enzyme do? Superoxide dismutase (SOD) plays a crucial role in protecting cells from oxidative damage by catalyzing the dismutation of the superoxide radical (O2•−), which is a by-product of cellular respiration. It converts two molecules of superoxide anion into oxygen (O2) and hydrogen peroxide (H2O2), thus preventing the toxic effects of superoxide radicals that can cause damage to DNA, proteins, and cell membranes. This reaction is vital in maintaining the balance of reactive oxygen species (ROS) in biological systems (McCord & Fridovich, 1969)
Any other interesting facts or important information on your enzyme – There are several types of SODs that use different metal cofactors, which makes them unique. Cu,Zn-SOD, for example, uses copper and zinc ions, while other forms of SOD such as Mn-SOD (found in mitochondria) and Fe-SOD (found in some bacteria) use manganese or iron ions, respectively. Despite using different metals, all these enzymes perform the same essential function of neutralizing superoxide radicals (Perry et al., 2010). Moreover,research has shown that the activity of SOD enzymes decreases with age, which may contribute to the accumulation of oxidative damage over time. This has made SOD a focus of research in understanding the molecular mechanisms of aging and age-related diseases (Perry et al., 2010). Additionally, SOD enzymes are among the fastest enzymes known, with catalytic rates near the diffusion limit. This means the enzyme works so rapidly that it neutralizes superoxide radicals almost as soon as they are produced, preventing them from causing any harm to the cell (Perry et al., 2010)
References
Perry, J. J. P., Shin, D. S., Getzoff, E. D., & Tainer, J. A. (2010). The structural biochemistry of superoxide dismutases. Biochimica et Biophysica Acta (BBA) – Proteins and Proteomics, 1804(2), 245–262. https://doi.org/10.1016/j.bbapap.2009.11.004
Bray, R. C., Cockle, S. A., Fielden, E. M., Roberts, P. B., Rotilio, G., & Calabrese, L. (1974). Reduction and inactivation of superoxide dismutase by hydrogen peroxide. Biochemical Journal, 139(1), 43-48. https://doi.org/10.1042/bj1390043
McCord, J. M., & Fridovich, I. (1969). Superoxide dismutase: An enzymic function for erythrocuprein (hemocuprein). Journal of Biological Chemistry, 244(22), 6049-6055. https://doi.org/10.1016/S0021-9258(18)63504-5
Azadmanesh, J., & Borgstahl, G. E. O. (2018). A review of the catalytic mechanism of human manganese superoxide dismutase. Antioxidants, 7(2), 25. https://doi.org/10.3390/antiox7020025
Rosa, A. C., Corsi, D., Cavi, N., Bruni, N., & Dosio, F. (2021). Superoxide dismutase administration: A review of proposed human uses. Molecules, 26(7), 1844. https://doi.org/10.3390/molecules26071844
Hsu, J.-L., Hsieh, Y., Tu, C., O’Connor, D., Nick, H. S., & Silverman, D. N. (1996). Catalytic properties of human manganese superoxide dismutase. The Journal of Biological Chemistry, 271(30), 17687–17691. https://doi.org/10.1074/jbc.271.30.17687
Kinnula, V. L., & Crapo, J. D. (2003). Superoxide dismutases in the lung and human lung diseases. American Journal of Respiratory and Critical Care Medicine, 167(12), 1600–1619. https://doi.org/10.1164/rccm.200210-1252SO
