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Peroxidase from horseradish

Type VI, essentially salt-free, lyophilized powder, ≥250 units/mg solid (using pyrogallol)

Peroxidase, Donor:hydrogen-peroxide oxidoreductase, HRP, Horseradish peroxidase, Detection Enzyme
CAS Number:
Enzyme Commission number:
EC Number:
MDL number:

Quality Level


Type VI


essentially salt-free, lyophilized powder

specific activity

≥250 units/mg solid (using pyrogallol)

mol wt

~44 kDa


0.1 M phosphate buffer: soluble 10 mg/mL, clear, orange to red (pH 6.0)

absorbance ratio

RZ 2.5-4.0


diagnostic assay manufacturing

storage temp.


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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.


Horseradish peroxidase (HRP) is isolated from horseradish roots (Amoracia rusticana) and belongs to the ferroprotoporphyrin group of peroxidases.. 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 P8375, type VI, is an essentially salt free lyophilized powder. It is commonly used to determine amounts of glucose and peroxides in solution. It has been used to study sensory input of cervical spinal cord neurons.
The enzyme has been used to develop a thermostable soybean peroxidase-based biosensor by cross-linking and electrically ′wiring′ the enzyme through a redox-conducting hydrogel to a glassy carbon electrode. It has also been used to assay the oxidation of low density lipoprotein.


5000 units in poly bottle
10000, 25000, 100000, 250000 units in glass bottle
1000, 2000 units in glass bottle

Biochem/physiol Actions

When incubated with a substrate, horseradish peroxidase produces a coloured, fluorimetric, or luminescent derivative of the labeled molecule, allowing quantification. Horseradish peroxidase has been shown to slightly reduce the level of inhibition in a cydAB mutant. Known inhibitors are sodium azide, cyanide, L-cystine, dichromate, ethylenethiourea, hydroxylamine, sulfide, vanadate, p-aminobenzoic acid, and Cd2+, Co2+, Cu2+, Fe3+, Mn2+, Ni2+, and Pb2+ ions.
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 including glutaraldehyde, periodate oxidation, through 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 and hence, it is the most desired label. Also, its glycosylation leads to lower non-specific binding.

Unit Definition

One pyrogallol unit will form 1.0 mg purpurogallin from pyrogallol in 20 sec at pH 6.0 at 20 °C.

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


Health hazard

Signal Word


Hazard Statements

Hazard Classifications

Resp. Sens. 1 - Skin Sens. 1

Storage Class Code

11 - Combustible Solids



Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

Certificate of Analysis

Enter Lot Number to search for Certificate of Analysis (COA).

Certificate of Origin

Enter Lot Number to search for Certificate of Origin (COO).

More Documents

Quotes and Ordering

  1. Which document(s) contains shelf-life or expiration date information for a given product?

    If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.

  2. How do I get lot-specific information or a Certificate of Analysis?

    The lot specific COA document can be found by entering the lot number above under the "Documents" section.

  3. How do I convert units of Peroxidase from horseradish, Product P8375, to solid?

    The activity listed on the Certificate of Analysis for each lot can be used to convert from units to milligrams of solid.

  4. What is the optimal pH range of Peroxidase from horseradish, Product P8375?

    The optimal pH range for product P8375 is 6.0 - 6.5.

  5. What can you tell me about the stability of Peroxidase from horseradish, Product P8375, (as is, in suspension and in solution)?

    This product is stable as a powder, kept refrigerated. See the certificate of analysis for a lot-specific recommended retest date. It is also stable as a crystalline suspension of 3.2 M (NH4)2SO4 solution containing potassium phosphate buffer, pH 6.0 (see Product No. P6140). It is reasonably stable in solution in phosphate buffer. We have found that at 10 mg/mL in 0.1 phosphate buffer, pH 6.0, solutions kept frozen at -20°C lose less than 2% of their activity per week.

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  7. What is the Department of Transportation shipping information for this product?

    Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product. 

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Filip Mollerup et al.
PloS one, 14(5), e0216546-e0216546 (2019-05-16)
Copper radical alcohol oxidases belonging to auxiliary activity family 5, subfamily 2 (AA5_2) catalyze the oxidation of galactose and galactosides, as well as aliphatic alcohols. Despite their broad applied potential, so far very few AA5_2 members have been biochemically characterized.
Marilyn S Lee et al.
Synthetic and systems biotechnology, 5(3), 145-154 (2020-07-09)
Cell-free systems contain many proteins and metabolites required for complex functions such as transcription and translation or multi-step metabolic conversions. Research into expanding the delivery of these systems by drying or by embedding into other materials is enabling new applications
Krishna Mohan Pathi et al.
Frontiers in plant science, 11, 543895-543895 (2020-11-17)
Biotic stresses caused by microbial pathogens impair crop yield and quality if not restricted by expensive and often ecologically problematic pesticides. For a sustainable agriculture of tomorrow, breeding or engineering of pathogen-resistant crop varieties is therefore a major cornerstone. Maize
A Thermostable Hydrogen Peroxide Sensor Based on "Wiring" of Soybean Peroxidase
Analytical Chemistry, 67 (23), 4247-4249 (1995)
E Wieland et al.
Proceedings of the National Academy of Sciences of the United States of America, 90(13), 5929-5933 (1993-07-01)
Oxidative modification of low density lipoprotein is believed to be an important pathway by which the lipoprotein becomes atherogenic. The in vitro systems for oxidative modification of low density lipoprotein thus far described all appear to depend upon the presence


Spectrophotometric Determination of Reinheitszahl (RZ) for Peroxidase (EC

Reinheitszahl (RZ) is the ratio of absorbance due to hemin (A403, Soret region) to absorbance due to protein (A275).

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