Streptavidin-ZAP converts biotinylated materials into targeted toxins. Streptavidin is a tetrameric protein (molecular weight 53 kDa in its recombinant form), with each subunit able to bind a single biotin molecule. The bond between streptavidin and biotin is rapid and essentially non-reversible, unaffected by most extremes of pH, organic solvents, and denaturing reagents. It is the strongest known noncovalent biological interaction (Ka = 1015 M-1) between protein and ligand. The streptavidin used to make Streptavidin-ZAP contains no carbohydrate group and has a neutral isoelectric point, which therefore reduces the nonspecific binding as compared to avidin. A variety of molecules, including lectins, proteins, and antibodies, can be biotinylated and reacted with streptavidin-labeled probes or other detection reagents for use in biological assays.
Streptavidin-ZAP is also available in three kit variations: Z-kits (KIT-27-Z) include everything you need to perform in vitro internalization assays with your biotinylated targeting agent. For in vivo assays, use KIT-27-A for antibodies and KIT-27-B for peptides.