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-Tactin®XT, 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-Tactin®XT: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 (high affinity in low pM range; T1/2 = 13 h) • Chip can be regenerated easily by an established procedure – cost effective • Ligands can be captured directly from complex samples due to the high affinity and specificity of the Twin-Strep-tag®:Strep-Tactin®XT interaction The use of unconjugated Strep-Tactin®XT requires a license that is provided with the purchase of the kit as limited use license.