In these cases, aromatic ring currents shift resonances out of their well-defined regions in the NMR spectrum, or drug proton resonances may overlap with DNA proton resonances. We have shown that the DNA spectrum may be simplified by selectively suppressing the geminal proton resonances using the HAL experiment. We have also devised a new experiment that contains a Hahn spin echo and pulsed field gradients. This experiment suppresses the geminal proton resonances as effectively as the HAL experiment, and is superior at retaining the other deoxyribose resonances and requires no phase cycling. The same pulse sequence can be used to simplify protein spectra.
Work is in progress to assess applications to protein chemistry.