|
Nickel Superoxide Dismutase
Nickel superoxide dismutase (Ni-SOD) is a metalloenzyme that, like the other superoxide dismutases, protects cells from oxidative damage by catalyzing the disproportionation of the cytotoxic superoxide , superoxide radical (O) to hydrogen peroxide and molecular oxygen. Superoxide is a reactive oxygen species that is produced in large amounts during photosynthesis and Cellular respiration#Aerobic respiration, aerobic cellular respiration. The equation for the disproportionation of superoxide is shown below: \rm 2O_2^- + 2H^+ \xrightarrow H_2O_2 + O_2 Ni-SOD was first isolated in 1996 from ''Streptomyces'' bacteria and is primarily found in prokaryote, prokaryotic organisms. It has since been observed in cyanobacteria and a number of other aquatic microbes. Ni-SOD is homohexameric, meaning that it has six identical subunits. Each subunit has a single nickel containing active site. The disproportionation mechanism involves a reduction-oxidation cycle where a single electron transfe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metalloenzyme
Metalloprotein is a generic term for a protein that contains a metal ion cofactor. A large proportion of all proteins are part of this category. For instance, at least 1000 human proteins (out of ~20,000) contain zinc-binding protein domains although there may be up to 3000 human zinc metalloproteins. Abundance It is estimated that approximately half of all proteins contain a metal. In another estimate, about one quarter to one third of all proteins are proposed to require metals to carry out their functions. Thus, metalloproteins have many different functions in cells, such as storage and transport of proteins, enzymes and signal transduction proteins, or infectious diseases. The abundance of metal binding proteins may be inherent to the amino acids that proteins use, as even artificial proteins without evolutionary history will readily bind metals. Most metals in the human body are bound to proteins. For instance, the relatively high concentration of iron in the human body i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
