Recombinant streptavidin from streptomyces avidinii, produced in E.coli.
Biotin, a 244Da vitamin (Vitamin H) molecule, exhibits an extraordinary binding affinity for streptavidin (Ka=1015M-1). Biotin and streptavidin interaction is rapid and once the bond is established it can survive up to 3M guanidine-hydrochloride and extremes of pH. Biotin-streptavidin bonds can only be reversed by denaturing the streptavidin protein molecule with 8M guanidine-hydrochloride at pH1.5 or by autoclaving.
Streptavidin is a tetrameric protein that has no carbohydrate modifications. The solubility of streptavidin (isoelectric pH5) in aqueous buffer is lower than avidin, but the binding of streptavidin to biotin is similar to that of avidin. The advantage of streptavidin is that the lack of carbohydrates significantly reduces the amount of non-specific binding.
Streptavidin is also available immobilized on agarose and coated on 96-well plates
- White lyophilizate, lyophilized in 20mM potassium phosphate, pH6.5
- Molecular weight: ~52,000Da
- pH stability: pH 5.0-9.0
- Solubility: 10mg/ml in water
- Isoelectric point: 6.8-7.5
- KD: 10-15M
- Purity: Single band by SDS-PAGE