Streptavidin is a homotetrameric protein found in the culture broth of Streptomyces avidinii. Similar to avidin, one mole of streptavidin can bind 4 moles of biotin with high affinity virtually unmatched in nature. Streptavidin lacks the carbohydrate side chains present in avidin and has an isoelectric point close to neutral.
Therefore, it has a lowering non-specific binding level compared to avidin. Streptavidin has been widely applied in various biological fields, such as ELISA, IHC, TRFIA, PCR quantification, isolation of single-stranded nucleotides, purification of biomolecules, and production of monoclonal antibodies.
Streptavidin is a 60 kDa tetrameric protein purified from the bacterium Streptomyces avidinii and has a high binding affinity for biotin. Capable of binding a biotin molecule with each subunit.
Streptavidin (PI = 6.0-7.5) has a lower level of non-specific binding to various biological components at physiological pH than avidin (PI = 7.4), as a result of its isoelectric point (PI). Streptavidin is useful in affinity chromatography, ELISA, immunohistochemistry, and Western Blot.