Biotin, a 244Da vitamin (Vitamin H) molecule, exhibits an extraordinary binding affinity for avidin (Ka=10 ¹5M- ¹) and streptavidin (Ka=10 ¹5M- ¹). Biotin and (strept)avidin interaction is rapid. Once the bond is established, it can survive up to 3M guanidine-hydrochloride and extreme levels of pH. Biotin-avidin bonds can only be reversed by denaturing the avidin protein molecule with 8M guanidine-hydrochloride at a pH of 1.5, or by boiling in SDS Page Sample Loading Buffer. Streptavidin is a tetrameric protein containing 4 biotin binding sites. In many respects, streptavidin is similar to avidin, but it does not contain a carbohydrate, and its molecular weight (about 60kDa) is slightly lower. The solubility of streptavidin (isoelectric pH5) in aqueous buffer is much lower than avidin; however, the binding of streptavidin to biotin is very similar to that of avidin. The advantage of streptavidin is that the lack of carbohydrates significantly reduces the amount of non-specific binding. The streptavidin used for immobilization on porous 6% cross-linked agarose is a recombinant form, with a mass of 53kDa and a near neutral pH. The streptavidin is covalently coupled to the agarose, resulting in minimal leaching, and is stable over a pH range of 2 to 11. The Streptavidin Resin is designed for the single-step, small and large scale affinity purification of proteins, antibodies and other molecules with a biotin tag. The resin can also be used for assay development and immunopreciptations of proteins using biotin labeled antibodies. Our streptavidin is supplied as resin slurry or in a 1ml spin-column format. Specific Binding and Elution Buffers are also available. Click here to request bulk or custom sizes.

Immunopreciptation of proteins using biotin labeled antibodies Assay development (pull down assays) using biotinylated proteins Purification of biotinylated molecules, including: proteins, antibodies, DNA, carbohydrates & other molecules with a biotin tag