Hexa His is an amino acid sequence consisting of 6 His residues in a row, it is also known as Hexa histidine-tag, 6 x His-tag, and by the trademarked name His-tag.

Hexa His Responsible for the degradation of GM2 gangliosides, and a variety of other molecules containing terminal N-acetyl hexosamines, in the brain and other tissues. Form B is active against certain oligosaccharides. The form S has no measurable activity. Hexa acts as a metal-binding site for a recombinant protein. The his-Tag sequence can be placed on the N- or -terminal of a target protein by using vectors from various commercial molecular biology companies. And this Tag is often followed by a cleavage site for a specific protease- for example, the Leu-Val-Arg-Gly-Ser peptide sequence is recognized and cleaved by the protease known as thrombin.