His tag ELISA kits are assays designed to detect a polyhistidine tag, which consists of six or more consecutive histidine residues at either terminus of a recombinant protein of interest. Also called the 6x-His tag or hexahistidine tag, it is one of the most common affinity purification tags in use. While histidine tags generally rely on metal-based affinity for purification, immunoassays targeting the His tag epitope can serve as an additional means of detecting His tagged proteins. Visit the supplier page for more information about detection range and reactivity.