Hexa-His

Hexa-His (6X His Tag) is a commonly used affinity tag made up of six histidine residues. HEXA-HIS can bind to affinity chromatography media containing transition metal ions like nickel (Ni2+) or cobalt (Co2+), making it useful for protein purification[1][2].

[1] Watly J, et al. Insight into the coordination and the binding sites of Cu(2+) by the histidyl-6-tag using experimental and computational tools. Inorg Chem. 2014 Jul 7;53(13):6675-83. DOI:10.1021/ic500387u
[2] Ana Paula de Mattos Arêas, et al. Synthesis of cholera toxin B subunit gene: cloning and expression of a functional 6XHis-tagged protein in Escherichia coli.Protein Expr Purif.2002 Aug;25(3):481-7. DOI:10.1016/s1046-5928(02)00026-8