Sensitive 1H-31P correlations with 5' methylene protons of DNA via homonuclear double-quantum coherence.

A novel pulse sequence is presented for the correlation of 5' and 5'' protons in DNA with phosphorus. Double-quantum coherence between the methylene protons is used to generate 1H5'-31P and 1H5''-31P cross peaks in an HMQC-type experiment. The resolution for these cross peaks is significantly improved over that of conventional HSQC experiments, as cross peaks between 1H4' and 31P are largely suppressed and a 3D version of the experiment can be performed with little penalty in sensitivity. In addition, sensitivity is favoured by slower relaxation of the double-quantum coherence and a more favourable multiplet fine structure in the acquisition dimension.