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.