Stable Copper(I)-Mediated Base Pairing in DNA

A GNA (glycol nucleic acid) functionalized nucleoside analogue containing the artificial nucleobase 1H-imidazo[4,5-f][1,10]phenanthroline (P) was used to form a copper(I)-mediated base pair within a DNA duplex. The geometrical constraints imposed by the artificial nucleobase play a pivotal role in this unprecedented stabilization of copper(I) in aqueous medium via metal-mediated base pairing. The formation of the copper(I)-mediated base pair was investigated by temperature-dependent UV spectroscopy and CD spectroscopy. The metal-mediated base pair stabilizes the DNA oligonucleotide duplex by 23 °C. A redox chemistry approach confirmed that this base pair formation was due to the incorporation of copper(I) into the duplex. This first report of a copper(I)-mediated base pair adds metal-based diversity to the field and consequently opens up the range of possible applications of metal-modified nucleic acids.