Speeding Up 13C Direct Detection Biomolecular NMR Spectroscopy

After the exploitation of H-1 polarization as a starting source for C-13 direct detection experiments, pulse sequences are designed which exploit the accelerated H-1 longitudinal relaxation to expedite C-13 direct detection experiments. We show here that 2D experiments based on C-13 direct detection on a 0.5 mM water sample of ubiquitin can be recorded in a few minutes and 3D experiments in a few hours. We also show that fast methods like nonuniform sampling can be easily implemented. As overall experimental time has always been a counter indication for the use of C-13 direct detection experiments, this research opens new avenues for the application of C-13 NMR to biological molecules.