Design and synthesis of purine nucleoside analogues for the formation of stable anti-parallel-type triplex DNA with duplex DNA bearing the 5m CG base pair.

We herein demonstrated for the first time the direct recognition of duplex DNA bearing the 5-methyl-2'-deoxycytosine and 2'-deoxyguanosine base pair by triplex DNA formation. Triplex-forming oligonucleotides contained the novel artificial nucleoside analogues 2-amino-2'-deoxy-nebularine derivatives, and their molecular design, synthesis, and functional evaluation are described.