Catalase is an antioxidant enzyme. Catalase is a common enzyme found in living organisms that changes hydrogen peroxide to water and oxygen. Hydrogen peroxide is formed as a toxic waste product of metabolism. It must be quickly converted into other, less dangerous, chemicals. To manage this problem, the enzyme catalase is frequently used to rapidly catalyse the decomposition of hydrogen peroxide into harmless oxygen and water. In aerobic cells, free radicals are constantly produced mostly as reactive oxygen species. Once produced, free radicals are removed by antioxidant defenses including the enzymes catalase, glutathione peroxidase, and superoxide dismutase. Reactive oxygen species, including nitric oxide and related species, commonly exert a series of useful physiological effects. However, imbalance between prooxidant and antioxidant defenses in favor of prooxidants results in oxidative stress. This results in damage to lipids, proteins, and nucleic acids. Alone or in combination with primary factors, free radicals are involved in the cause of hundreds of diseases.

Catalase Research Update
Mice genetically engineered to produce a human antioxidant enzyme lived longer than normal mice, which points to the possibility that antioxidants can counteract the effects of aging and disease. Chemicals known as free radicals damage cells by generating a reaction called oxidation - the same process that causes metal to rust. Antioxidants interfere with this chemical reaction. Researchers at the University of Washington School of Medicine used genetically engineered mice that made extra amounts of catalase. The mice were precisely designed to produce extra catalase in certain areas of the body - the cells' cytoplasm; the nucleus where DNA is stored; and the mitochondria, the cell's power plant and also a place where some DNA is found. The mice that made more catalase in the mitochondria lived about 20 percent longer - about five months. The mice with more catalase levels in the nucleus and cytoplasm lived only a little longer than normal mice. The mice with catalase in the mitochondria also had healthier heart muscle tissue, indicating the catalase helped protect from age-related heart problems seen in normal mice.