Sequences around the unnatural base pair in DNA templates for efficient replication.

Unnatural base pairs, compatible with PCR amplification, could potentially increase the versatility of nucleic acids. We recently reported an unnatural base pair, between 7-(2-thienyl)-imidazo[4,5-b]pyridine (denoted by Ds) and 2-nitropyrrole (denoted by Pn), which specifically and efficiently functions in PCR. Toward the efficient incorporation of extra, functional components into DNA fragments, we examined the influence of the sequences around the unnatural base pair and the dependence of the substrate concentrations on the selectivity and efficiency of replication by DNA polymerase.