Signal Enhancers - Streptavidin and Polystreptavidin
Streptavidin is a tetrameric protein (4 x 13 kDa), which binds very tightly to the small molecule Biotin. The binding of streptavidin to biotin is one of the strongest known non-covalent biological bonds, and is resistant to breaking by temperature, pH, solvents and other chemical influences. Biotin will displace almost any other molecule bound to streptavidin and can be easily conjugated to other biomolecules which makes this a highly effective binding system for use in a wide range of applications, particularly immunoassay. A single molecule of streptavidin can bind up to 4 biotin/biotinylated proteins. However, the use of Polystreptavidin allows for many more biotin molecules to bind to a single molecule. The use of Polystreptavidin can reduce noise, increase signal and specificity, and significantly reduce the cost of reagents in the development of immunoassays.