Horseradish peroxidase is a 44,173. 9-dalton glycoprotein with 4 lysine residues for conjugation to a labeled molecule. It produces a coloured, fluorimetric, or luminescent derivative of the labeled molecule, allowing it to be detected and quantified. HRP is often used in conjugates (molecules that have been joined genetically or chemically) to determine the presence of a molecular target. Synonyms: Monoclonal HRP antibody, Anti-HRP antibody, Horseradish Peroxidase antibody.