Chapter 12: Using RDCs and PCSs to Study the Structure, Dynamics, and Interactions of Carbohydrates Check Access

The standard NMR parameters applied to deduce the essential structural and conformational information of carbohydrates are chemical shifts, scalar couplings and nuclear Overhauser effects (NOEs). However, there are intrinsic problems in defining the preferred conformation of complex glycans by NMR. Particularly, the lack of signal dispersion hampers the characterization of complex multi-antennary glycans with repetitions of the same monosaccharide in different positions that cannot be distinguished in conventional experiments. In addition, few interresidue NOEs are usually detected to derive the conformation around the glycosidic linkages. In this chapter, the application of paramagnetic NMR in the glycan field is described. Under paramagnetic conditions, pseudo-contact shifts (PCSs), paramagnetic relaxation enhancement (PRE) and residual dipolar couplings (RDCs) can be measured as additional parameters with structural information. Moreover, PCSs increase signal dispersion allowing the individual detection of signals from repeating units in complex glycans.