MagStrep "type3" Strep-Tactin® beads

MagStrep “type3” Strep-Tactin® beads consist of a magnetic core coated in 6% agarose that is conjugated with the streptavidin variant Strep-Tactin® and are intended for purification of biotinylated proteins. Strep-Tactin® was originally developed for binding and purification of Strep-tag®II and Twin-Strep-tag® proteins via the engineered biotin-binding pockets. This Strep-tag®/Strep-Tactin® system is now widely used in the field of protein purification.

Strep-Tactin® still has the capability to bind biotin, which is used as specific competitor for elution of Strep-tagged proteins. Biotin has a lower binding affinity to Strep-Tactin® than it has to streptavidin. Therefore, biotinylated molecules can bind to Strep-Tactin® in a reversible manner. By the addition of free biotin in excess, the binding can be released under mild and physiological conditions. This reversible binding to Strep-Tactin® makes MagStrep “type3” Strep-Tactin® beads 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.

The beads can be easily and swiftly separated with a magnetic separator, eliminating the need for centrifugation and 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.