Tagging peptides with affinity tags such as biotin is a frequently used strategy in life sciences research. Affinity tags are used for detection of suitably tagged peptides (e.g. with antibodies) or for the separation of tagged peptides from untagged ones.
The tags can be small organic molecules, like biotin (which binds strongly and non-covalently to streptavidin) or a short peptide sequence. The most prominent examples thereof are epitope tags (like the Flag tag, the HA tag, the His tag and the Myc tag), for each of which antibodies are commercially available. The respective sequences are presented in the table below.
Pepscan routinely applies the various tags in the synthesis of tagged peptides. The tags are usually attached at the N-terminus or the C-terminus (via lysine or cysteine), but in principle can be positioned anywhere. If so required, the tags can be separated from the peptide via a spacer. A variety of different so called linkers or spacer molecules of varying length and polarity are available. The linkers can also be made cleavable, e.g. by reduction of sensitive disulfide bonds.
|Flag tag||DYKDDDDK||Anti-flag antibody|
|HA tag||YPYDVPDYA||Anti-HA antibody|
|HA 12Ca5 tag||CYPYDVPDYA||12CA5 antibody|
|Myc tag||EQKLISEEDL||Anti-Myc antibody|
|His tag||HHHHHH||Anti-His antibody|
|V5 tag||GKPIPNPLLGLDST||anti-V5 antibody|