This peptide corresponds to the protein transduction domain of the TAT protein and is synthesized with an activated cysteine residue C(Npys), wherein Npys is 3-Nitro-2-pyridinesulfenyl group and is used for activating S of cysteine and for rapid reaction when a thiol group is introduced. The N-terminus is rendered free for applications requiring certain conjugation reactions with a free N-terminal end, and a linker GGG is placed at the C-terminal end, and the peptide has been synthesized with the C(Npys) group. This kind of modification has been used to render this peptide as a cell penetrating and carrier peptide applicable in conjugation studies.