It produces a coloured, fluorimetric[6] or luminescent derivative of the labeled molecule when incubated with a proper substrate, allowing it to be detected and quantified.

Here, the antibody provides the specificity to locate the protein of interest, and the HRP enzyme, in the presence of a substrate, produces a detectable signal.

[7] Horseradish peroxidase is also commonly used in techniques such as ELISA and Immunohistochemistry due to its monomeric nature and the ease with which it produces coloured products.

Peroxidase, a heme-containing oxidoreductase, is a commercially important enzyme which catalyses the reductive cleavage of hydrogen peroxide by an electron donor.

Horseradish peroxidase is ideal in many respects for these applications because it is smaller, more stable, and less expensive than other popular alternatives such as alkaline phosphatase.

This enzyme is suitable for the removal of hydroxylated aromatic compounds (HACs) that are considered to be primary pollutants in a wide variety of industrial wastewater.

The sensitivity is 10- to 100-fold greater, and quantifying of light emission is possible over a wide dynamic range, whereas that for coloured precipitates is much more limited, about one order of magnitude less.

[12] However, Horseradish peroxidase can also be used as a catalyst for Atom Transfer Radical Polymerization reactions[13] and create polymers in absence of any hydrogen peroxide.