Streptavidin (37-159), His
Description
Product Specs
Product Science Overview
Streptavidin is a tetrameric protein originally derived from the bacterium Streptomyces avidinii. It is widely used in molecular biology and biochemistry due to its extraordinarily high affinity for biotin, a vitamin that is essential for various cellular processes. The binding between streptavidin and biotin is one of the strongest non-covalent interactions known, with a dissociation constant (K_d) on the order of ~10^-14 mol/L .
The recombinant form of streptavidin, specifically the 37-159 amino acid (a.a) variant, is engineered to include a His-tag at the N-terminus. This His-tag facilitates purification and detection of the protein. The recombinant streptavidin is produced in Escherichia coli (E. coli) and consists of a single polypeptide chain containing 148 amino acids (37-159) with a molecular mass of approximately 15.6 kDa .
Streptavidin’s high affinity for biotin makes it an invaluable tool in various applications:
- Affinity Purification: Streptavidin is used to purify biotinylated molecules, such as proteins, nucleic acids, and antibodies.
- Immunoassays: It is employed in techniques like ELISA (Enzyme-Linked Immunosorbent Assay) to detect biotinylated antibodies or antigens.
- Histochemistry and FISH: Streptavidin is used in Fluorescence In Situ Hybridization (FISH) and other histochemical techniques to visualize biotinylated probes.
- Flow Cytometry and Microarrays: It is used to detect biotinylated molecules in flow cytometry and microarray assays .
Recombinant streptavidin offers several advantages over its natural counterpart, avidin:
- Lower Non-Specific Binding: Streptavidin lacks carbohydrate modifications, resulting in lower non-specific binding compared to avidin.
- Neutral pI: Streptavidin has a near-neutral isoelectric point (pI), which reduces background noise in assays.
- Stability: The streptavidin-biotin complex is extremely stable over a wide range of temperatures and pH levels .
Recombinant streptavidin is typically stored at -20°C to maintain its stability and activity. It is recommended to avoid multiple freeze-thaw cycles to preserve its integrity. For long-term storage, adding a carrier protein such as HSA (Human Serum Albumin) or BSA (Bovine Serum Albumin) can be beneficial .
