Peroxidase (Horseradish source) Synonym: Hydrogen peroxide oxidoreductase; HRP

Horseradish peroxidase (HRP) is isolated from the roots of horseradish (Amoracia rusticana) and belongs to the ferroprotoporphyrin group of peroxidases. HRP readily combines with hydrogen peroxide (H2O2). The resultant [HRP-H2O2] complex can oxidize a wide variety of hydrogen donors:
Donor + H2O2 → Oxidized Donor + 2 H2O
HRP will oxidize various substrates (see Table 1):
• Chromogenic
• Chemiluminescent (such as luminol or isoluminol)
• Fluorogenic (such as tyramine, homovanillic acid, or 4-hydroxyphenyl acetic acid)
HRP is a single chain polypeptide that contains four disulfide bridges. HRP is a glycoprotein that contains 18% carbohydrate. The carbohydrate composition consists of galactose, arabinose, xylose, fucose, mannose, mannosamine, and galactosamine, depending upon the specific isozyme.

HRP is a widely used label for immunoglobulins in many different immunochemistry applications, including immunoblotting, immunohistochemistry, and ELISA. HRP can be conjugated to antibodies by several different methods, including glutaraldehyde, periodate oxidation, through disulfide bonds, and also via amino and thiol directed cross-linkers. HRP is the most desired label for antibodies, since it is the smallest and most stable of the three most popular enzyme labels (peroxidase, β-galactosidase, alkaline phosphatase) and its glycosylation leads to lower non-specific binding. A review of glutaraldehyde and periodate conjugation methods has been published.

Peroxidase is also utilized for the determination of glucose4 and peroxides in solution. Several publications, 6-24 theses, 25-29 and dissertations 30-46 have cited use of P8375 in their research protocols.