Horseshoe crab

Horseradish Peroxidase (HRP) is an enzyme that is commonly used in biochemistry applications due to its ability to amplify signal in immunoblotting, immunohistochemistry, and ELISA assays. It is derived from the horseradish plant (Armoracia rusticana).

Structure

HRP is a glycoprotein with a molecular weight of approximately 44 kDa. It consists of a single polypeptide chain of 308 amino acids, and contains one heme group, which is responsible for its peroxidase activity.

Function

The primary function of HRP is to catalyze the oxidation of certain organic compounds by hydrogen peroxide. In the presence of hydrogen peroxide, HRP can oxidize a wide variety of organic and inorganic substrates, including phenols, anilines, and diaminobenzidine.

Applications

Due to its ability to amplify signal, HRP is commonly used in various biochemistry applications. These include:

• Immunoblotting: HRP is often used as a reporter molecule in Western blot assays. It is conjugated to a secondary antibody that binds to the primary antibody, which is specific for the protein of interest. The HRP-antibody complex can then be detected using a chemiluminescent substrate.

• Immunohistochemistry: HRP is used in immunohistochemistry to visualize the location of proteins within tissue sections. The HRP-antibody complex is applied to the tissue section, and the location of the protein of interest is revealed by the deposition of a colored product when the HRP enzyme reacts with a suitable substrate.

• ELISA: In enzyme-linked immunosorbent assay (ELISA), HRP is used to detect the presence of specific antigens or antibodies in a sample. The HRP-antibody complex is added to the sample, and the presence of the antigen or antibody of interest is indicated by a color change when the HRP enzyme reacts with a substrate.

See Also

• Peroxidase
• Enzyme
• Biochemistry
• Immunoblotting
• Immunohistochemistry
• ELISA