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Detection of Strep-tag® fusion proteins

Two different detection systems are provided:

  1. detection via Strep-Tactin® conjugates (for Strep-/Twin-Strep-tag® proteins)
  2. detection via monoclonal antibodies against Strep-/Twin-Strep-tag® or His-tag

Read which detection system is suitable for your applications:

Western blot

For direct detection of Strep-tag® fusion proteins in Western blots

  • via chromogenic and/or chemiluminescence reaction (no secondary antibody needed!) use
    - Strep-Tactin® HRP conjugate (HRP, horseradish peroxidase)
    - StrepMAB-Classic HRP conjugate
  • via chromogenic reaction
    - Strep-Tactin® AP conjugate (AP, alkaline phosphatase)

For protein detection in ELISA use

  • StrepMAB-Classic, unconjugated
  • Strep-Tactin® HRP conjugate

Visualize your Strep-tag® protein with the following dyes:

Strep-Tactin®XT, StrepMAB-Classic and StrepMAB-Immo are available with single fluorescent conjugates:

  • Strep-tag® fluorescent Dy488 conjugates of Strep-Tactin®XT, StrepMAB-Classic and StrepMAB-Immo (50 µg each)

For staining (Twin-)-Strep-tagged proteins in FACS we recommend to use our Strep-Tactin® PE 6-5001-005 or Strep-Tactin® APC 6-5011-005 conjugates, because they lead to a more intensive staining compared with our Oyster and Chromeo dyes and are therefore better suited for a light sensitive application as FACS.

50 μl conjugate are good for staining of approximately 5x107to 1x108 cells.
Use Strep-Tactin PE / APC as follows:

- Wash 5x106 pre-cooled cells with 10 ml of a biotin-free physiological wash buffer in a 15 ml reaction tube to remove potentially interfering  ingredients (e.g. biotin).

- Resuspend the cells in 50 μl wash buffer and transfer cells to a reaction vessel suitable for staining, e.g. a 96-well round bottom microtiter plate.

- Add 5 µl Strep-Tactin®PE (or Strep-Tactin®APC) to the cells and mix thoroughly by gentle pipetting.

- Incubate for 20 minutes at 4°C in the dark.

- Wash cells three times (400xg, 2 min) in 200 μl wash buffer.

- Cells are ready for FACS

Note: The staining intensity depends on the concentration of tagged protein and in case of unsatisfying results the concentration of conjugate has to be adjusted.