Synthesis and characterization of oligonucleotides containing formamidopyrimidine lesions (Fapy.dA, Fapy.dG) at defined sites.

The preparation of oligonucleotides containing Fapy.dA (N4-(2-Deoxy-alpha,beta-D-erythro-pentofuranosyl)-4,6-diamino- 5-formamidopyrimidine) and Fapy.dG (N6-(2-Deoxy-alpha,beta-D-erythro-pento-furanosyl)-2,6- diamino-4-hydroxy-5-formamido-pyrimidine) at defined sites was achieved by introducing the lesions as dinucleotide phosphoramidites. Oligonucleotides as composed of as many as 36-nucleotides were prepared by solid-phase synthesis and/or a combination of chemical synthesis and enzymatic ligation. Oligonucleotides containing non-hydrolyzable analogues were also prepared. Oligonucleotides containing these modified nucleotides were characterized by a variety of chemical and biochemical methods.