His Tag Nickel Affinity Chromatography Protocol PDF. The Wallert and Provost Lab. Theory and Introduction: Ni-Affinity Chromatography uses the ability of His to bind nickel. Six histadine amino acids at the end of a protein (either N or C terminus) is known as a 6X His tag. Nickel is bound to an
agarose bead by chelation using nitroloacetic acid (NTA) beads. Several companies produce these beads as His
Tagged proteins are some of the most used affinity tags in todayâ€™s market.