Catalase is a common enzyme found in nearly all living organisms exposed to oxygen (such as bacteria, plants, and animals) which catalyzes the decomposition of hydrogen peroxide to water and oxygen.[5] It is a very important enzyme in protecting the cell from oxidative damage by reactive oxygen species (ROS). 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.[6]
Catalase is a tetramer of four polypeptide chains, each over 500 amino acids long.[7] It contains four iron-containing heme groups that allow the enzyme to react with hydrogen peroxide. The optimum pH for human catalase is approximately 7,[8] and has a fairly broad maximum: the rate of reaction does not change appreciably between pH 6.8 and 7.5.[9] The pH optimum for other catalases varies between 4 and 11 depending on the species.[10] The optimum temperature also varies by species.[11]
^"EC 1.11.1.6 - catalase". BRENDA: The Comprehensive Enzyme Information System. Department of Bioinformatics and Biochemistry, Technische Universität Braunschweig. Retrieved 2009-05-26.
