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PNAs: from birth to adulthood
Cyclic PNA Backbone Modification
Figure 1-9: Strucures of the main PNAs bearing cyclic modifications in the backbones
Among PNAs containing six-membered rings, piperidine PNAs 61 (Figure 1-9) showed good
improvements in DNA recognition forming more stable triplexes when hybridized to polyA
complementary DNA, the effect being particularly evident when the modified monomer was
placed at the C-terminus. Aminocyclohexylglycyl PNA (Figure 1-9) 57 showed good
performance when the isomer SR or RS were used. In particular, the choice of the
stereocenter configuration allowed to obtain PNAs more performing when the complementary
DNA sequence had to be recognized, or when RNA had to be discriminated over DNA. While
the insertion of one or two 1R-2S monomers increased the discrimination of a point mutation,
the use of 1S-2R monomers increased the selectivity in poly-A RNA binding (compared to
DNA). When using three modified monomers in the same sequence (one in the middle and
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