The Strep-tag system for one-step purification and high-affinity detection or capturing of proteins

Nat Protoc. 2007;2(6):1528-35. doi: 10.1038/nprot.2007.209.


The Strep-tag II is an eight-residue minimal peptide sequence (Trp-Ser-His-Pro-Gln-Phe-Glu-Lys) that exhibits intrinsic affinity toward streptavidin and can be fused to recombinant proteins in various fashions. We describe a protocol that enables quick and mild purification of corresponding Strep-tag II fusion proteins--including their complexes with interacting partners--both from bacterial and eukaryotic cell lysates using affinity chromatography on a matrix carrying an engineered streptavidin (Strep-Tactin), which can be accomplished within 1 h. A high-affinity monoclonal antibody (StrepMAB-Immo) permits stable immobilization of Strep-tag II fusion proteins to solid surfaces, for example, for surface plasmon resonance analysis. Selective and sensitive detection on western blots is achieved with Strep-Tactin/enzyme conjugates or another monoclonal antibody (StrepMAB-Classic). Thus, the Strep-tag II, which is short, biologically inert, proteolytically stable and does not interfere with membrane translocation or protein folding, offers a versatile tool both for the rapid isolation of a functional gene product and for its detection or molecular interaction analysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Affinity Labels / analysis
  • Affinity Labels / chemistry*
  • Binding Sites
  • Escherichia coli
  • Escherichia coli Proteins / chemistry
  • Escherichia coli Proteins / metabolism
  • Immunoassay / methods*
  • Oligopeptides / analysis
  • Oligopeptides / chemistry*
  • Protein Binding
  • Proteins / analysis
  • Proteins / chemistry*
  • Proteins / isolation & purification*
  • Recombinant Proteins


  • Affinity Labels
  • Ala-Trp-Arg-His-Pro-Gln-Phe-Gly-Gly
  • Escherichia coli Proteins
  • Oligopeptides
  • Proteins
  • Recombinant Proteins