Development of a Metal-Ion-Mediated Base Pair for Electron Transfer in DNA

A new C-nucleoside structurally based on the hydroxyquinoline ligand was synthesized that is able to form stable pairs in DNA in both the absence and the presence of metal ions. The interactions between the metal centers in adjacent CuII-mediated base pairs in DNA were probed by electron paramagnetic resonance (EPR) spectroscopy. The metal-metal distance falls into the range of previously reported values. Fluorescence studies with a donor-DNA-acceptor system indicate that photoinduced charge-transfer processes across these metal-ion-mediated base pairs in DNA occur more efficiently than over natural base pairs. Ace of base: DNA duplex stability can be significantly increased by coordinating CuII ions to hydroxyquinoline base pairs (metal-mediated base pairing; see scheme). Fluorescence studies with a donor-DNA-acceptor system indicate that photoinduced charge-transfer processes across these metal-ion-mediated base pairs in DNA occur more efficiently than over natural base pairs.