<Table> <Tr> <Td_colspan="2"> View / Edit Human </Td> <Td_colspan="2"> View / Edit Mouse </Td> </Tr> </Table> <Tr> <Td_colspan="2"> View / Edit Human </Td> <Td_colspan="2"> View / Edit Mouse </Td> </Tr> <P> Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals). It catalyzes the decomposition of hydrogen peroxide to water and oxygen . It is a very important enzyme in protecting the cell from oxidative damage by reactive oxygen species (ROS). Likewise, catalase has one of the highest turnover numbers of all enzymes; one catalase molecule can convert millions of hydrogen peroxide molecules to water and oxygen each second . </P> <P> Catalase is a tetramer of four polypeptide chains, each over 500 amino acids long . It contains four iron - containing heme groups that allow the enzyme to react with the hydrogen peroxide . The optimum pH for human catalase is approximately 7, and has a fairly broad maximum: the rate of reaction does not change appreciably between pH 6.8 and 7.5 . The pH optimum for other catalases varies between 4 and 11 depending on the species . The optimum temperature also varies by species . </P>

What is catalase and what does it do
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