HRP for sensitive hybridization probes

Product spotlight: You can have HRP directly conjugated to hybridization probes to increase signal amplification in CARD-FISH protocols. Also use this oligo modification in nonradioactive immunoassays, northern/Southern blot analysis, and other in situ hybridization applications.

Quick facts:

Availability: DNA and RNA
Location: 5′ and 3′ Scale: 250 nmol to mid-scale
Purification: HPLC required; PAGE is not recommended as it can impair enzyme activity
IDT ordering symbol: This is a Non-Catalog modification. Please contact with your sequence design for review and quoting.

Horseradish Peroxidase, or HRP (Figure 1), is an enzymatically active glycoprotein that can be conjugated to an oligonucleotide via a maleimide attachment to form a thioester. In the presence of H2O2, this enzyme catalyzes an oxidation reaction that converts reduced, non-fluorescent or non-colorimetric substrates into oxidized, fluorescent or colorimetric forms [1].

Figure 1. 5′ HRP modification. Note that the 3′ HRP modification uses a 3 carbon thiol linker arm.

Research shows that HRP directly conjugated to hybridization probes can increase signal amplification in Catalyzed Reporter Deposition-Fluorescent In Situ Hybridization (CARD-FISH) protocols [2]. This modification can also be used in nonradioactive immunoassays, northern/Southern blot analysis, and other in situ hybridization applications.

How to submit a request for HRP-oligos

Synthesis of HRP-modified oligos requires special chemistry; therefore these sequence designs must undergo review and quoting prior to synthesis. IDT scientific experts meet regularly to review the complexity and feasibility of producing nonstandard sequence requests including oligos containing HRP modifications.

Please direct inquiries to with your contact information and requested sequence, including any additional modifications or yield requirements.


  1. Akkara JA, Senecal KJ, Kaplan DL (1991). Synthesis and characterization of polymers produced by horseradish peroxidase in dioxane. J Polymer Sci 29(11):1561–1574. doi:10.1002/pola.1991.080291105.
  2. Dijk JA, Breugelmans P, et al. (2008). Catalyzed reporter deposition-fluorescent in situ hybridization (CARD-FISH) detection of Dehalococcoides. J Microbiol Methods 73(2):142–147. doi: 10.1016/j.mimet.2008.01.012

Published Sep 30, 2015