Synthesis of a Pseudocytidine Nucleoside to Form a Stable and Selective Base Pair with Iso-guanosine in RNA

Non-natural base pair formation provides insight into new functions of nucleic acids. Therefore, various artificial base pairs have been developed in both DNA and RNA. In this work, we successfully synthesized pseudocytidine from commercially available pseudouridine to form base pairs with isoguanine, also known as 2-OH-adenine, in RNA. Measurement of the melting temperature with the base pair incorporated at the center of a 13-mer RNA showed the highest value for the ψ-rC and iso-rG (2-OH-rA) base pair. This base pair formation exhibited a high melting temperature regardless of whether it was incorporated into the pyrimidine or purine strand, indicating that it can form a stable and selective duplex RNA.