Which compound serves as the substrate for horseradish peroxidase (HRP) in standard assays?

Which compound serves as the substrate for horseradish peroxidase (HRP) in standard assays?

• A. Naphthol-AS-phosphate
• B. Hydrogen peroxide
• C. DAB
• D. p-nitrophenyl phosphate

Answer: (B)

Horseradish peroxidase relies on hydrogen peroxide to oxidize a chromogenic substrate, turning it into a colored product. The compound HRP actually acts on is the chromogen, with DAB being the classic substrate that, in the presence of hydrogen peroxide, yields a brown precipitate at the site of the antigen. Hydrogen peroxide is the oxidant required to drive the reaction, not the substrate being oxidized. The other compounds listed are not the standard HRP substrates in typical immunohistochemistry assays. Therefore, the substrate HRP uses in standard reactions is DAB.

Horseradish peroxidase relies on hydrogen peroxide to oxidize a chromogenic substrate, turning it into a colored product. The compound HRP actually acts on is the chromogen, with DAB being the classic substrate that, in the presence of hydrogen peroxide, yields a brown precipitate at the site of the antigen. Hydrogen peroxide is the oxidant required to drive the reaction, not the substrate being oxidized. The other compounds listed are not the standard HRP substrates in typical immunohistochemistry assays. Therefore, the substrate HRP uses in standard reactions is DAB.