His tag Antibodies Research Reagents

A his-tag, or polyhistidine tag, is a string of histidine residues at either the N or C terminus of a recombinant protein. There can be from four to ten residues in a string, although commonly there are six histidine residues — a hexahistidine tag. The 6× His-tag has several merits, including smaller size, absence of electric charge, low levels of toxicity, and immunogenicity. His-tagging provides good yields of fusion protein from inexpensive, high capacity resins with moderate purity from E. coli extracts but relatively poor purification from mammalian cell extracts.

His tag Antibody (2)

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    His tag Background

    The hexahistidine tag (6× His-tag) is the most frequently used affinity tag for protein enrichment. His-tagged proteins can be purified easily by the chelated metal ions as affinity ligands. The basis for affinity purification is known as immobilized metal affinity chromatography (IMAC). His-tag can bind best to IMAC resin in near-neutral buffer conditions (physiologic pH and ionic strength), and thus the fusion proteins can be eluted with binding buffer containing certain concentrations of imidazole. If possible, the elution is also accomplished with low pH (e.g., 0.1 M glycine-HCl, pH 2.5) or an excess of strong chelator (e.g., EDTA).

    His tag References

    • Zhao X, et al. (2013) Several affinity tags commonly used in chromatographic purification. J Anal Methods Chem 2013 581093.
    • Lin Z, et al. (2015) Aggregating tags for column-free protein purification. Biotechnol J 10 (12): 1877-1886.
    • Brothers SP, et al. (2003) Unexpected effects of epitope and chimeric tags on gonadotropin-releasing hormone receptors: Implications for understanding the molecular etiology of hypogonadotropic hypogonadism. J Clin Endocrinol Metab 88 (12): 6107-6112.

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