THE DOUBLE-DANTE SEQUENCE APPLIED TO NMR OF COMPLEX CARBOHYDRATES

The double-DANTE sequence was implemented in 1D TOCSY and NOESY experiments to overcome some typical problems in the NMR of carbohydrates. In the 1D TOCSY experiment the double-DANTE sequence serves to invert simultaneously two resonances belonging to the same scalar-coupled spin system, thereby substantially increasing the sensitivity of the technique for subspectral editing and providing a valuable alternative to relayed TOCSY in overcoming small-J bottlenecks in monosaccharides such as galactose and sialic acid. Spin-diffusion artifacts in 1D NOESY experiments that are mediated by more than one spin can be effectively eliminated by applying a double-DANTE pulse train for saturation of the mediators during the mixing time. In certain cases, the double-DANTE sequence is also capable of eliminating the three-spin effect in 1D C-13{H-1} NOE difference spectroscopy.