Steptavidin, a bacterial protein isolated from Streptomyces avidinii, is similar to egg-white avidin in its ability to bind biotin, and has been used as a replacement for egg-white avidin because of its more favorable chemical properties.
Conjugates of streptavidin are recommended for use with Biotin-SP-conjugated antibodies and Biotin-SP-conjugated ChromPure proteins.
Conjugate: Alkaline Phosphatase
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 sometimes used for immunohistochemistry, penetration into whole mount tissues may be limited by their large sizes.