MagStrep type3 Strep-Tactin® beads

MagStrep “type3” Strep-Tactin® beads are magnetic beads with an agarose surface coated with the streptavidin variant Strep-Tactin® and intended for purification of biotinylated proteins. Originally, Strep-Tactin® was developed for binding and purification of Strep-tag®II and Twin-Strep-tag® proteins. The binding of the Strep-tag® occurs via the engineered biotin-binding pockets of Strep-Tactin®. This Strep-tag®/Strep-Tactin® system is now widely used in the field of protein purification.

Nevertheless, Strep-Tactin® still has the capability to bind biotin, which is used as specific competitor for elution of Strep-tagged proteins. The binding affinity of biotin to Strep-Tactin® is not as high as for streptavidin and, therefore, biotinylated molecules can bind to Strep-Tactin® in a reversible manner. The release from binding is carried out under mild and physiological conditions by adding an excess of free biotin. This reversible binding to Strep-Tactin® make them to a perfect tool for isolation of biotinylated proteins or complexes via pull-downs, immunoprecipitation (IP), or co-immunoprecipitation (Co-IP) in batch format and/or high-throughput screenings.

Due to the magnetic core no centrifugation step is required since the beads can be easily and swiftly separated with a magnetic separator, reducing the risk of disturbing the pellet or loss of beads within the wash step to zero. The elution of target proteins or complexes can be triggered under mild conditions with the biotin-containing Buffer BXT or under denaturing conditions by boiling in SDS gel loading buffer. 20 μl suspension correspond to 1 μl magnetic beads.