A (13)C-detection NMR approach for large glycoproteins

NMR spectroscopy has great potential to provide us with information on structure and dynamics at atomic resolution of glycoproteins in solution. In larger glycoproteins, however, the detrimental fast (1)H transverse relaxation renders the conventional (1)H-detected NMR experiments difficult. (13)C direct detection potentially offers a valuable alternative to (1)H detection to overcome the fast T(2) relaxation. Here, we applied (13)C-detected NMR methods to observe the NMR signals of (13)C-labeled glycans attached to the Fc fragment of immunoglobulin G with a molecular mass of 56kDa. Spectral analysis revealed that a (13)C-detected (13)C-(13)C NOESY experiment is highly useful for spectral assignments of the glycans of large glycoproteins. This approach would be, in part, complementary to (13)C-(13)C TOCSY and (1)H-detection experiments.