Horseradish peroxidase (HRP) is the most widely used enzyme for IHC labeling. Its mechanism is such that an enzyme-substrate complex is formed between HRP and excess hydrogen peroxide (H2O2).In the presence of a chromogen, the oxidized product of this reaction polymerizes to yield a color specific to the chromogen itself.
Commonly used chromogens with HRP include:
- 3-amino-9-ethylcarbazole (AEC)
- 3,3’-diaminobenzidine (DAB)
