Description

• General description: Horseradish peroxidase is isolated from horseradish roots (Amoracia rusticana) and belongs to the ferroprotoporphyrin group of peroxidases. HRP is a single chain polypeptide containing four disulfide bridges. It is a glycoprotein containing 18% carbohydrate. The carbohydrate composition consists of galactose, arabinose, xylose, fucose, mannose, mannosamine, and galactosamine depending upon the specific isozyme. Its molecular weight (~44 kDa) includes the polypeptide chain (33,890 Daltons), hemin plus Ca2+ (~700 Daltons), and carbohydrate (~9,400 Daltons). At least seven isozymes of HRP exist. The isoelectric point for horseradish peroxidase isozymes ranges from 3.0 - 9.0.
• Application: Horseradish peroxidase (HRP) is isolated from horseradish roots (Amoracia rusticana). It is used in biochemistry applications such as western blots, ELISA and Immunohistochemistry. Horseradish peroxidase is used to amplify a weak signal and increase detectability of a target molecule, such as a protein. Product P6782 is type VI-A and it is essentially a salt-free, lyophilized powder. It is used to quantify cholesterol and cholesterol esters[1] and to study in vitro lipid deposition on hydrogel and silicone hydrogel contact lenses[2].
• Biochem/physiol Actions: HRP readily combines with hydrogen peroxide (H2O2) and the resultant [HRP-H2O2] complex can oxidize a wide variety of hydrogen donors. The optimal pH is 6.0-6.5 and the enzyme is most stable in the pH range of 5.0-9.0. HRP can be conjugated to antibodies by several different methods that include the use of glutaraldehyde, periodate oxidation, disulfide bonds, and also via amino and thiol directed cross-linkers. It is smaller and more stable than the enzyme labels, β-galactosidase and alkaline phosphatase. Hence, it is the most desired label. Also, its glycosylation leads to lower non-specific binding.[8] Sodium azide, cyanide, L-cystine, dichromate, ethylenethiourea, hydroxylamine, sulfide, vanadate, p-aminobenzoic acid, as well as Cd2+, Co2+, Cu2+, Fe3+, Mn2+, Ni2+, and Pb2+ ions are found to inhibit the enzyme activity.[9]
• Packaging: Packaged in mg solid
• Linkage: Similar to P8375
• Unit Definition: One ABTS unit will oxidize 1 μmole of ABTS per minute at 25 °C at pH 5.0
• Preparation Note: Solutions of this product at 1 mg/mL in 0.1 M phosphate buffer (pH 6.0) remain active for at least two weeks at room temperature. The solution retains activity after 5 freeze-thaw cycles.
• Analysis Note: The RZ (Reinheitszahl) is the absorbance ratio A403/A275 determined at 0.5-1.0 mg/ml in deionized water. It is a measure of hemin content, not enzymatic activity. Even preparations with high RZ may have low enzymatic activity.
• Other Notes: View more information on peroxidase at www.sigma-aldrich.com/enzymeexplorer.