Catalase（CAT) is a key antioxidant enzyme in the body’s defense against oxidative stress. Furthermore， Catalase is a heme enzyme which is present in the peroxisome of virtually all aerobic cells. Catalase converts the reactive oxygen species hydrogen peroxide to water and oxygen and thus diminishes the toxic effects of hydrogen peroxide. Catalase stimulates growth of cells including T-cells， B-cells， myeloid leukemia cells， melanoma cells， mastocytoma cells and normal and transformed fibroblast cells. Catalase gene polymorphisms are linked with decreases in catalase activity nevertheless， to date， acatalasemia is the only disease known to be caused by the CAT gene.
