Synthesis of C-nucleoside analogues based on the pyrimidine skeleton for the formation of anti-parallel-type triplex DNA with a CG mismatch site

The triplex DNA forming method is an attractive tool as a gene-targeting agent. Using artificial nucleoside analogues based on C-nucleoside, stable and selective triplex DNA can be formed in a specific region of duplex DNA, and its biotechnology applications will greatly expand. In this study, we designed and synthesized novel C-nucleoside analogues based on the pyrimidine skeleton, ^3MeAP-d(Y-Cl) and ^3MeAP-d(Y-H), capable of recognizing a CG mismatch site that is not recognized by natural nucleosides. After incorporating them into the oligonucleotides, their triplex forming abilities were evaluated by gel-shift assay. Although it was only one sequence, the 3′-GZG-5′ sequence, the stability of the CG mismatch site recognition was greatly improved compared with previous nucleoside analogues.