Nitrogen-15 NMR spectroscopy of N-metallated nucleic acids: insights into 15N NMR parameters and N-metal bonds.

It was recently demonstrated spectroscopically that RNA/DNA nucleobases can bind to metal cations in aqueous solution through coordination bonds and covalent bonds. Nitrogen-15 (15N) NMR spectroscopy was employed and shown to be a powerful tool for determining the mode of metal ion binding to nitrogen atoms in RNA/DNA molecules. This review describes 15N NMR spectroscopic characteristics in accordance with the mode of metal ion binding to nitrogen atoms. The general rules for 15N chemical shift changes, which are applicable to the determination of the metal ion binding mode of N-metallated compounds, are also described.