Peroxidase, Horseradish is an archetypal haem-containing enzyme that uses hydrogen peroxide or alkyl peroxides to catalyze oxidative reactions, including the hydroxylation and polymerization of aromatic compounds. It is commonly used as a detection enzyme in biochemical assays like ELISA, Western blotting, and immunohistochemistry, due to its ability to produce strong colorimetric or chemiluminescent signals for sensitive and specific detection.