HRP, Donkey Anti-Sheep IgG

Reactivity: Sheep

What it means: This secondary antibody is designed to recognize sheep primary antibodies (e.g., sheep IgG). It binds to the primary antibody and enables detection through its conjugate (enzyme or fluorophore).

Why it matters: Choose “Sheep” reactivity when your primary antibody is raised in sheep. Note that in sheep-derived samples, endogenous sheep immunoglobulins may contribute to background in certain applications.

Host: Donkey

What it means: “Host” refers to the animal in which the secondary antibody was produced. Host: Donkey means the antibody was generated by immunizing a donkey, and the resulting donkey antibodies were collected and purified to make this secondary antibody.

Why it matters: The host species can affect background and cross-reactivity. For best results, avoid using a donkey-host secondary in workflows where donkey immunoglobulins are present (e.g., donkey serum-based blocking, donkey primary antibodies, or donkey-derived samples), unless the protocol includes appropriate blocking and controls.

This secondary antibody is tagged with HRP so you can visualize/detect your target using an HRP substrate.

What it does: HRP acts as a reporter enzyme. After the secondary binds to your primary antibody, you add an HRP substrate (commonly TMB for ELISA or ECL chemiluminescent substrates for Western blot), and HRP catalyzes a reaction that produces a detectable signal (color or light).

Why it matters: HRP-conjugated secondaries are widely used because they give strong signal, are cost-effective, and work well for WB, ELISA, and IHC (with appropriate substrates).

Application(s): WB, IHC-P, ELISA

WB (Western Blot): Used as a secondary antibody to bind the primary antibody on membranes after SDS-PAGE transfer, enabling detection via enzyme- or fluorophore-based signal readout (depending on the conjugate).

IHC-P (Immunohistochemistry—Paraffin): Used as a secondary antibody to detect primary antibodies bound to antigens in paraffin-embedded (FFPE) tissue sections, enabling visualization after standard deparaffinization and antigen retrieval with the appropriate detection reagent.

ELISA: Used as a secondary antibody in plate-based assays to bind the primary antibody and generate quantitative or semi-quantitative signal through its conjugate-based detection system.

Isotype: Donkey IgG

What it means: This secondary antibody is a donkey-derived immunoglobulin G (IgG). In other words, it is an IgG antibody produced in donkey and purified for use as a secondary reagent.

Why it matters: “Donkey IgG” is mainly useful for understanding the species origin and antibody class of the secondary antibody:

• Species origin (donkey): This tells you the secondary itself is made in donkey. If your assay uses donkey serum for blocking, or your sample contains donkey immunoglobulins, you may need to optimize blocking or choose a different host secondary to minimize background.
• Antibody class (IgG): IgG is the most common antibody class used for secondary antibodies and is well-suited for routine detection due to strong binding and consistent performance.
• Detection and capture compatibility: Many detection systems and reagents (e.g., anti-donkey IgG reagents, and in some workflows Protein A/G) are designed to work with IgG-class antibodies. Knowing it is donkey IgG helps confirm compatibility when additional binding/capture steps are involved.
• Controls: If you are using anti-donkey detection reagents, “donkey IgG” helps when selecting appropriate negative controls to evaluate non-specific binding from donkey-derived antibodies.