Description Streptavidin Streptomyces avidinii protein recombinantly expressed in E. coli. The molecular weight per tetramer is approximately 52 kDa. Summary 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. CAS Registry No. 9013-20-1 Amino Acid Sequence MAEAGITGTWYNQLGSTFIVTAGADGALTGTYESAVGNAESRYVLTGRYDSAPATDGSGTALGWTVAWKNNYRNAHSATTWSGQYVGGAEARINTQWLLTSGTTEANAWKSTLVGHDTFTKVKPSAAS. Source E. coli Formulation Sterile filtered white lyophilized (freeze-dried) powder. Lyophilized in 10mM potassium phosphate buffer pH 6.5. Purity Greater than 98.0% as determined by SDS-PAGE and HPLC. Biological Activity > 17 U/mg (one unit binds 1 μg D-biotin). Proteolytic Activity < 10-3 U/mg protein (Azocoll, 25 °C, 24 h, pH 8.0). Reconstitution It is recommended to reconstitute the lyophilized Streptavidin in sterile 18MΩ-cm H2O not less than 0.5 mg/ml, which can then be further diluted to other aqueous solutions. Shipping At ambient temperature. Upon receipt, store the product at the temperature recommended below. Storage/Expiration Store at -20°C. Please prevent freeze/thaw cycles. Usage This product is intended for Laboratory Research Use Only. Not for use in diagnostic or therapeutic procedures. This product may not be used as a pharmaceutical or veterinary drug, agricultural product, or food additive. Resources Product Datasheet (PDS)
