A 60-kDa extracellular protein of Streptomyces avidinii with four high-affinity biotin binding sites. Unlike AVIDIN, streptavidin has a near neutral isoelectric point and is free of carbohydrate side chains.

A bacterial protein that has high affinity for biotin. The non-covalent streptavidin-biotin complex is resistant to organic solvents, denaturants, detergents, proteolytic enzymes, and extremes in temperatures and pH. The stability of the complex is leveraged by many research and clinical procedures including protein purification, chemiluminescent, fluorescent and colorimetric immunostaining, atomic force microscopy, synthesis of carbon nanotubes and DNA-based nanoparticles, and targeted immunotherapy.

A small bacterial protein that binds with high affinity to the vitamin biotin. This streptavidin-biotin combination can be used to link molecules such as radioisotopes and monoclonal antibodies together. These bound products have the property of being attracted to, and attaching to, cancer cells, rather than normal cells. The radiolabeled products are more easily removed from the body, thus decreasing their toxicity.