[摘要]：A general method for prepg. optically pure guanidine-based g-peptide nucleic acid (gGPNA) monomers for all four natural nucleobases (A, C, G, T) is described. These second-generation gGPNAs differ from the first-generation GPNAs in that the guanidinium group is installed at the g- instead of the a-position of the N-(2-aminoethyl)glycine backbone unit. This positional switch enables GPNAs to be synthesized from relatively cheap L- as opposed to D-amino acids. Unlike their a-predecessors, which are randomly folded, gGPNAs prepd. from L-amino acids are preorganized into a right-handed helix and bind to DNA and RNA with exceptionally high affinity and sequence selectivity and are readily taken up by mammalian cells.
