Horseradish peroxidase conjugates are prepared by a modified Nakane and Kawaoi procedure (J. Histochem. Cytochem. 1974. 22, 1084). Peroxidase conjugates are commonly used for immunohistochemistry, Western blotting, and ELISA.

Affinity-purified anti-horseradish peroxidase and conjugates are available for detection of horseradish peroxidase antigen, or for signal amplification of HRP-containing reagents. For immunostaining of mammalian cells, an advantage of using anti-horseradish peroxidase is reduced background, since the antibody does not recognize the endogenous peroxidase-like enzymes found in those cells.

Alkaline phosphatase (from calf intestine) conjugates are prepared by a modified method of Avremeas et al., Scand. J. Immunol. 1978. 8 (Supple.7), 7. Resulting conjugates contain heterogeneous, high molecular weight complexes. They are sensitive reagents for solid-phase immunoassays such as ELISA and Western blotting. Although alkaline phosphatase conjugates are commonly used for immunohistochemistry, penetration into whole mount tissues may be limited by their large sizes.