High Performance Protein Enrichment Using Streptavidin Magnetic Beads

The binding of streptavidin to biotin is one of the strongest known non-covalent biological interactions and hence a powerful tool used in affinity chromatography. Biomolecules can easily be fused with biotins, to which immobilized streptavidin ligands on chromatography matrices can bind. The usage of magnetic beads for affinity based purifications simplifies small-scale purifications and provides high flexibility with scales ranging from μl to ml. In this study, we show that the magnetic bead medium Streptavidin Mag Sepharose™ offers leading performance concerning binding capacity and achieved purity. Binding capacity of Streptavidin Mag Sepharose for biotinylated rabbit monoclonal IgG was 1.7 mg/ml bead slurry. Immunoprecipitation of 7.5 μg/ml transferrin in a background of 5 mg/ml E.coli protein showed a 420-fold enrichment. Scaling up immuno-precipitation experiments 10 times or changing sample concentration 100 times, resulted in equal purity and recovery (%). The characteristics of the Mag Sepharose beads are; simplify handling by reducing the risk of beads sticking on tubes and pipette tips. Moreover, the beads respond quickly to magnetic fields resulting in rapid separation of the beads from the sample, completed within seconds.