Streptavidin (Cy3)

Streptavidin is a 52,8 dalton tetrameric protein purified from the bacterium Streptomyces avidinii. It has an extraordinarily high affinity for biotin and is one of the strongest non-covalent interactions known in nature. It is used extensively in biotechnology as, in addition to the high affinity, biotin-binding is resistant to extremes of pH, temperature, organic solvents, denaturants (e.g. guanidinium chloride), detergents (e.g. SDS, Triton) and proteolytic enzymes.Streptavidin conjugated to enzymes or fluorescent molecules is useful for the detection of biotinylated antibodies or proteins in immunological assays. For the detection of biotinylated molecules, streptavidin is superior to egg white avidin (avidin has a lower binding affinity for biotin conjugates, despite avidin having the higher affinity for free, unconjugated biotin).