Triplex‐mediated cleavage of DNA by 1,10‐phenanthroline‐linked 2′‐O‐methyl RNA

Abstract
We have previously reported that 2′‐O‐methyl RNAs are efficient probes for duplex DNA. Here we describe the design, synthesis, and DNA cleaving activity of 1,10‐phenanthroline (OP)‐linked 2′‐O‐methyl RNA (OP‐m). Although a local triple helix was formed, both with OP‐m and a control OP‐linked DNA at the target sequence of the duplex DNA, the promoter region of the human thrombomodulin gene, the cleavage efficiencies on both strands were not proportional when OP‐m was used as a cleavage agent. These results may reflect the structural differences of the respective triple helices and the duplex‐triplex junction, formed from the two types of triplex‐forming oligonucleotides, 2′‐O‐methyl RNA and DNA. Since the OP‐ms were found to work as preferential purine‐strand cutters for duplex DNA, they would be useful as unique tools for genome analysis.