According to Reference.com, catalase can be found in most living cells, which means this enzyme that causes hydrogen peroxide to decompose into oxygen and water is not contained in all living tissues. The origin of the word "catalase" dates back to the early 20th century.
According to RCSB.org, a single catalase molecule is able to decompose millions of hydrogen peroxide molecules each second. Human and cow catalase molecules utilize an iron ion during this process. Each catalase enzyme has four identical subunits, and each subunit has its own active site deep inside. Catalases are known as unusually stable enzymes, which help them fight against reactive molecules.