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Catalogue number
PRO-283
Introduction
Streptavidin is a tetrameric protein secreted by Streptomyces avidinii which binds firmly to biotin. Streptavidin is wilyde 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.
Description
Streptavidin is a protein produced by Streptomyces avidinii and isolated by purification from fermentation broth. The pure, homogeneous protein shows predominantly one single band in SDS PAGE. Streptavidin consists of 4 identical subunits, each bearing an active binding site for biotin. Streptavidin has a molecular weight of 55kDa.
Source
Bacterium Streptomyces avidinii.
Physical Appearance
Sterile Filtered lyophilized powder.
Formulation
The Streptavidin was lyophilized from a 25mg/ml solution in 10 mM potassium phosphate buffer pH 6.5
Solubility
Gives a clear solution at 10mg/ml in 4.0 mM potassium phosphate pH 6.5
Stability
Streptavidin although stable at 4°C for 3 weeks, should be stored desiccated below -18°C.
For longer storage in dissolved form add 1mM EDTA and/or 0.02 % NaN3 or pass the solution through a sterile filter.
Please prevent freeze-thaw cycles.
Specific Activity
The biological activity is 16.8 U/mg, 1 unit binds 1µg biotin.
Safety Data Sheet
Usage
ProSpec's products are furnished for LABORATORY RESEARCH USE ONLY. The product may not be used as drugs, agricultural or pesticidal products, food additives or household chemicals.