Peroxidase (Peroxidase, abbreviated as POX or MPO) is a class of microorganisms or plants that can catalyze a lot of reactions with hydrogen peroxide as the electron acceptor catalytic substrate oxidation of the enzyme oxidoreductase, mainly in the cellular peroxisomes, with iron porphyrin as a cofactor, which can catalyze the oxidation of phenolic and amine compounds by hydrogen peroxide, and have the elimination of hydrogen peroxide and phenolics and amines. toxicity of hydrogen peroxide and phenols and amines.

Peroxidase (POX) Staining Solution (Benzidine Staining Method) is a POX staining solution recommended by ICSH, based on the principle that intracellular peroxidase can deliver the hydrogen atom of colorless 3,3-diaminobenzidine (DAB) to hydrogen peroxide, which catalyzes the former into a colored dye to be deposited in the cytoplasm of the cell at the site where POX is located. The stain can be used for peroxidase staining of blood, bone marrow or cell smears, and the active site of POX is brownish-yellow in color.