General NMR Spectroscopy of Carbohydrates and Conformational Analysis in Solution

Carbohydrates studied by NMR spectroscopy commonly utilize the spin-½ nuclei, 1H and 13C, and when present 15N and 31P, but other nuclei such as 19F and 77Se have also been employed in carbohydrate related studies. Typical chemical shifts and 2D NMR experiments for the assignments of resonances from the NMR active nuclei in carbohydrate molecules are discussed. In addition, 3-D NMR experiments and the use of isotopically enriched carbohydrates are exemplified. The NMR techniques most often used for sequence determination of oligo- and polysaccharides are described. Experimental NMR techniques for conformational dynamics studies based on 1H,1H cross-relaxation, 13C auto-relaxation, indirect spin-spin coupling constants, residual dipolar couplings, exchangeable protons and translational diffusion are illustrated. Molecular simulation techniques such as Monte Carlo and molecular dynamics simulations are discussed and different conformational states populated as a result of conformational flexibility are described.