streptavidinfluorochrome

Streptavidin is a protein found in the bacterium Streptomyces avidinii. It is renowned for its exceptionally strong and specific binding affinity for biotin, a vitamin also known as vitamin B7 or H. This interaction is one of the strongest known non-covalent bonds between a protein and a small molecule, with an affinity constant in the order of 10^15 M^-1. This remarkable binding strength and specificity make streptavidin an invaluable tool in various biological and biochemical applications.

The streptavidin molecule is a homotetramer, meaning it consists of four identical subunits. Each subunit is capable of binding one molecule of biotin. This multivalent nature of streptavidin allows it to bridge two or more biotinylated molecules, which is a principle exploited in many assay formats. The protein is relatively small, with a molecular weight of approximately 53 kDa. It is also highly stable, retaining its biotin-binding activity under a wide range of pH and temperature conditions, as well as in the presence of many denaturing agents.

Due to its strong affinity for biotin and its inherent stability, streptavidin is frequently used in molecular biology and biotechnology. It is commonly employed in enzyme-linked immunosorbent assays (ELISAs), Western blotting, immunohistochemistry, and purification techniques. In these applications, either streptavidin or biotin is conjugated to antibodies, enzymes, or other detection molecules, allowing for highly sensitive and specific detection or capture of target molecules. Recombinant forms of streptavidin and engineered variants with altered properties are also available for specialized uses.