Peroxidase from horseradish

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.

This product is assayed using ABTS for easy comparison to other suppliers′ unit: approx. 1,000 units per mg solid

Linkage

Similar to P8375

Other Notes

View more information on peroxidase at www.sigma-aldrich.com/enzymeexplorer.

Packaging

Packaged in mg solid

Unit Definition

One ABTS unit will oxidize 1 μmole of ABTS per minute at 25 °C at pH 5.0

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

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 premium quailty. It is essentially a salt-free, lyophilized powder. It is used to quantify cholesterol and cholesterol esters¹ and to study in vitro lipid deposition on hydrogel and silicone hydrogel contact lenses².

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.

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.