Twin-Strep-tag Capture Kit is intended for site-directed, reversible capture of Twin-Strep-tag fusion proteins for biomolecular interaction analysis using surface plasmon resonance (SPR) devices. The kit provides Strep-TactinXT, SPR Immobilization Buffer, Regeneration Buffer, and GFP-Twin-Strep-tag as control protein. It enables the highly stable immobilization of the ligand based on the unique Strep-TactinXT:Twin-Strep-tag interaction, which operates with pM affinity. The key benefits are:• Indirect immobilization protecting the ligand from chemical modification as well as inactivation or manipulation by the immobilization procedure• High affinity enabling measurements over a long period• Chip can be regenerated easily by an established procedure• Ligands can be captured directly from complex samples due to the high affinity and specificityThe use of unconjugated Strep-TactinXT requires a license that is provided with the purchase of the kit as limited use license.