histidinetagged

Histidinetagged refers to a common technique in molecular biology and biochemistry where a short sequence of histidine amino acids, typically six (His-tag), is attached to a recombinant protein. This histidine tag serves as an affinity handle for purification. The His-tag binds specifically to immobilized metal ions, such as nickel or cobalt, which are immobilized on a chromatography resin. This interaction allows for the selective capture and purification of the tagged protein from a complex mixture, such as a cell lysate, while leaving other cellular components unbound.

The purification process typically involves lysing the cells expressing the His-tagged protein, then passing the lysate over a column containing the metal-charged resin. The His-tagged protein adheres to the resin, while impurities are washed away. The purified protein is then eluted from the column by using a competitive ligand, such as imidazole, which competes with the histidine tag for binding to the metal ions, or by changing the pH of the buffer. Histidinetagged purification is widely used due to its efficiency, cost-effectiveness, and the ability to achieve high purity levels of the target protein. The tag is generally small and often does not significantly interfere with the protein's function, although in some cases, it may be cleaved off using specific proteases.