The tris-NTA/His-tag system comprises one of the smallest high-affinity recognition elements known to date. This interaction is based on the capacity of the histidine’s imidazole groups to form coordinative bonds with transition metal ions such as Ni(II). The presence of high concentrations of other transition metals such as Co(II), Cu(II) or Zn(II), however, can interfere with the tris-NTA/His-tag interaction. Zn(II), for example, has been described to mediate the dimerization of His-tagged proteins at low micromolar concentrations.

peptide – ion interaction | dimerization | His₆-tag | competitive assay | MO-P-071