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Strep-Tactin®XT coated microplates

Efficient immobilization of (Twin-)Strep-tag®II fusion proteins


Using the MTP assay the binding capacity of Strep-Tactin® XT was examined and compared to Strep-Tactin®. For this purpose BAP was fused with Strep-tag®II and applied in different amounts onto the Strep-Tactin®/Strep-Tactin®XT coated microplates. After washing the remaining amounts of BAP were measured. Resulting in almost 100% recovery* of BAP-Strep-tag®II on Strep-Tactin® XT compared to 8% recovery on Strep-Tactin® (red area).

Note, the binding affinity of Strep-Tactin® XT to Twin-Strep-tag® is in the pM range and therefore much higher as for Strep-tag®II (nM).

Strep-Tactin® coated microplates

Capture of functional target proteins on Strep-Tactin® coated microplates

Determination of an alkaline phosphatase (AP) Strep-tag® II fusion protein

Capture of Strep-tag® II fusion protein onto Strep-Tactin® coated microplates

General conditions:

  1. Strep-Tactin® coated microplate was incubated with different amounts of recombinant E. coli alkaline phosphatase/Strep-tag® II fusion protein
  2. Washing cycles
  3. Colorimetric determination of bound AP-activity

H. pylori urease as antigen in a solid phase immunoassay

General conditions:
  1. Strep-Tactin® coated microplate was incubated with recombinant H. pylori urease/Strep-tag® II fusion protein, followed by 3 washing cycles.
  2. Second incubation with human sera followed by 3 washing cycles.
  3. Third incubation with rabbit anti-human lgG conjugated to peroxidase, followed by 3 washing cycles.
  4. Colorimetric determination of bound peroxidase activity.

Comparison of Strep-Tactin®XT and Strep-Tactin® coated microplates