C(Npys)-Antennapedia Peptide

The Antennapedia homeodomain protein of Drosophila has the ability to penetrate biological membranes and the third helix of this protein, residues 43-58, known as penetratin (RQIKIWFQNRRMKWKK-amide) has the same translocating properties as the entire protein.
This is the 16 amino acid region of Antennapedia peptide (Penetratin) synthesized with an activated cysteine residue C(Npys), wherein Npys is 3-Nitro-2-pyridinesulfenyl group is used for activating S of cysteine and for rapid reaction when a thiol group is introduced. This kind of modification has been used to render this peptide as a carrier peptide applicable in conjugation studies, especially when studying attachment of peptide-like molecules to carriers.