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PNAs embedding NLS peptide
the modified PNA 3 (Figure 6-5). RH30 cells were then incubated with the modified PNA 4
(10 µmol/L) and analyzed after 3 hours, in order to confirm the specificity of the uptake
mechanism for PNA 3. The results obtained showed a very scarce and punctuated
internalization (Figure 6-5). Although the number of positively charged side chains was the
same for the PNA 3 and 4, a different uptake is clear from the images in figure 6-5. This
suggests that, while PNA 4 probably undergoes an unspecific uptake process and for this
reason only a small amount is internalized, PNA 3 is selectively recognized by the cargo
protein complex and carried in the nucleus through a specific uptake with the same
mechanism of the NLS peptide 1, indicating that such PNA can behave as peptide mimic.
6.3 Conclusions
We have demonstrated the chemical feasibility of synthesizing Peptide Nucleic Acids
embedding in the structure amino acid side chains mimicking a complex peptide sequence.
The preliminary data here reported on an NLS-mimicking PNA demonstrate that the
pseudopeptide sequence encripted in the backbone of such modified PNA can behave as a
fully functional peptide mimic, shedding light on a new dimension concerning the PNA
properties, which may find numerous applications in bioorganic chemistry and molecular
biology. For example, a PNA embedding the NLS sequence could be used for efficiently
traslocate the PNA in the cell nuclei after injection in the blood stream avoiding the
degradation from serum proteases, as it may happen when the NLS sequence is simply linked
as normal peptide at the C-terminus. In general terms, a peptide nucleic acid embedding the
functionalities of the proteins might be potentially used in order to develop PNAs endowed of
catalytic functions, fully exploiting their intrinsic double nature of nucleic acid and peptide.
6.4 Experimental section
6.4.1 Materials and reagents
PNA N-Boc protected standard monomers, N-[1H-1,2,3-(benzotriazol-1-yl)-
(dimethylamino)methylene]-N-methylmethanaminium hexafluorophosphate N-oxide
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