Anti-Flag affinity gel is a chromatographic resin that contains immobilized anti-Flag monoclonal antibodies. This gel is used to purify proteins that have been fused to the Flag peptide tag. The Flag peptide is a short amino acid sequence (DYKDDDDK) that can be fused to the N- or C-terminus of a protein of interest during recombinant protein expression. How Anti-Flag Affinity Gel Works: Protein binding: The Flag-tagged protein binds specifically to the anti-Flag antibodies immobilized on the gel. Washing: Unbound proteins are washed away. Elution: The bound Flag-tagged protein is eluted from the gel using a competitive elution buffer that contains free Flag peptide.