Biotinylated and Tagged Peptides

Affinity tags such as biotin can be used for

  • The detection of suitably tagged peptides or biotinylated peptides (e.g. with labeled antibodies)
  • The separation of biotinylated peptides or tagged peptides from untagged ones (e.g. with tethered antibodies)

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 for peptide sequences used as tags are epitope tags like the Flag tag, the HA tag and the Myc tag. A recently developed tag is the ALFA peptide tag. For all tags, antibodies are commercially available. See below for respective sequences.

JPT routinely synthesizes tagged peptides carrying various tags. The tags are usually attached at the N-terminus or the C-terminus (via lysine or cysteine), but in principle can be positioned anywhere. All tags can be separated from the peptide by a variety of different so called linkers or spacer molecules of varying length and polarity. If desired, linkers can be made cleavable, e.g. by reduction of sensitive disulfide bonds. Have a look at a list of available linker / spacer / PEGylations. Here is a representation of frequently incorporated tags.

Affinity Tag

Structure/Sequence Binding Partner/Comment


Streptavidin, Avidin

(oxidation resistant, reversible)

Streptavidin, Avidin

Flag tag


Anti flag antibody

HA tag


Anti HA antibody

Myc tag


Anti Myc antibody

For intracellular delivery, peptides can be attached to cell-penetrating peptides (CPPs). Examples of frequently used CPPs are the poly-Arg or the Tat-sequence. Many other CPPs are available, please contact us in case of interest! Cell penetrating peptides can be attached to many positions within a peptide drug or to small molecules.


Sequence Comment

Tat (47-57)


Cell-penetrating peptide



Cell-penetrating peptide

JPT is also able to provide you with a wide range of reactive labels attached to peptides. Examples are the introduction of

  • Azides (reaction with alkines – click chemistry)
  • Maleimides (reaction with thiols, e.g. Cys)
  • Thiols (reaction with maleimides)
  • Cys(Pys/Npys) (reaction with thiols to form disulfides)
 Some representative structures are shown here:

Affinity and Reactive Labeling

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