Catalase(CAT) is a class of terminal oxidases,which can be widely found in animals,plants and microorganisms.Catalases can remove hydrogen peroxide produced by cell metabolism,thereby protecting the cells from the toxic peroxides.It is one of the key enzymes of biological defense system.Catalases are now divided into three categories according to similarities and differences in the protein structure and amino acid sequence,including monofunctional catalase,bifunctional catalase-peroxidase and manganese-cont...