STREPTAVIDIN

Background

Streptavidin is a biotin-binding protein found in the culture broth of the bacterium Streptomyces avidinii. Streptavidin can bind to four moles of biotin per mole of protein,and it shows extremely high affinity, approximately 10,000-15,000 Da. Streptavidin lacks the carbohydrate side chains present on avidin and has an isoelectric point of 6.5 to avidin's 10 far closer to that at which most useful biological interactions occur. As a result, Streptavidin frequently exhibits much lower non-specific binding than avidin does.

Uses

Streptavidin from Streptomyces avidinii has been used-

• for blocking of the AFM (atomic force microscopy) tip, during the measurement of unbinding forces in the avidin-biotin system
• for coupling of anti-HA (hemagglutinin) antibodies during cell free synthesis and assembly of proteins on a biochip
• for the coating of the gelatin flow phantoms to eventually determine the feasibility of IVUS (intravascular ultrasound) transducer for (biotinylated) microbubble-based drug delivery
• to immobilize proteins and oligonucleotides

Uses

Applications for enzyme-labeled (HRP, AP) streptavidin: Enzyme immunoassays (EIA), including enzyme-linked immunsorbent assays (ELISA) with biotinylated antibodies Cell and tissue staining (for light microscopy) Western blotting (WB) and other membrane-based biotin detection Applications for fluorescent (FITC, TRITC or Texas Red* Fluor-labeled) streptavidin: Immunofluorescent assays (IFA) Tissue staining (for fluorescence microscopy) Blot immunostaining Cell staining (incl. fluorescent activated cell sorting)

Uses

Streptavidin is used as a tetrameric protein used to visualize biotin conjugated molecules in ELISA. Due to the strong affinity of biotin and biotinylated molecules has made streptavidin one of the most important components in diagnostics and laboratory kits. Streptavidin is widely used in molecular biology through its unique high affinity for the biotin.

General Description

Streptavidin is a crystalline protein isolated from the bacterium Streptomyces avidinii and possesses biotin-binding ability. It has four binding sites for biotin like avidin and binds four molecules of biotin. Streptavidin is now considered as a new type of biotin-binding protein.

Biochem/physiol Actions

Streptavidin is a biotin binding protein and has the ability to bind four molecules of biotin. The biotin binding pocket of streptavidin helps to interact with biotin. It can be used to enhance protein binding and multimerization.

in vivo

Description

Streptavidin Streptomyces Avidinii Recombinant produced in E.Coli.
The molecular weight per tetramer is approximately 52kDa.

Source

Escherichia Coli

Background

Streptavidin is a tetrameric protein secreted by Streptomyces avidinii which binds firmly to biotin. Streptavidin is widely used in molecular biology through its unique high affinity for the vitamin biotin. The dissociation constant (Kd) of the biotin-streptavidin complex is about ~10-15 mol/L. The strong affinity recognition of biotin and biotinylated molecules has made streptavidin one of the most important components in diagnostics and laboratory kits. The streptavidin/biotin system has one of the biggest free energies of association of yet observed for noncovalent binding of a protein and small ligand in aqueous solution (K_assoc = 10**14). The complexes are also extremely stable over a wide range of temperature and pH.

References

[1] Updyke, T.V. and Nicolson, G.L. (1984) J Immunol Methods 73, 83-95.
[2] Buckie, J.W. and Cook, G.M. (1986) Anal Biochem 156, 463-72.
[3] CHAIET, L. and WOLF, F.J. (1964) Arch Biochem Biophys 106, 1-5.
[4] Reznik, G.O. et al. (1998) Proc Natl Acad Sci USA 95, 13525-30.