1D and 2D NMR

One-dimensional NMR

  • 1D NMR defines the types of anomeric configuration (a,b) present, provides information about non-carbohydrate substituents (e.g. acetyl or pyruvyl moieties) and quantify degree of substitution.
  • 1D NMR provides information about the purity of the carbohydrate.
  • For polysaccharides with a repeating sequence, both 13C-NMR and 1H-NMR give information regarding the number of monosaccharide residues contained in the repeating glycosyl.
  • 13C-NMR can provide some information regarding glycosyl linkage and can detect the presence of unusual or rarely observed sugars. We can also acquire 31P-NMR spectra.

Two-dimensional NMR

  • If a sufficient amount of pure polysaccharide (>5 mmol) is available, 2-D NMR spectroscopy is probably the single most powerful technique for the elucidation of the precise carbohydrate structure.
  • A routine set of experiments for structural determination of a polysaccharide would include COSY, TOCSY, HSQC, HMBC and NOESY or ROESY.
  • Additional experiments include HSQC-TOCSY to correlate carbon resonances within a given monosaccharide residue, DOSY for the determination of molecular weight and of intermolecular bonding, band-selective homonuclear decoupled experiments for crowded spectra, and 1H-31P-HMQC and HMQC-TOCSY to establish the attachment sites of phosphomono-and diesters, as well as spin-diffusion experiments to determine the binding sites of small ligands to large receptors.
NMR instrumentation Complex Carbohydrate

The CCRC has the following NMR instruments available for use:

  • 300 MHz (2 channel, gradients)
  • 500 MHz (, 3 channel, gradients), can be used in conjunction with dynamic hyperpolarization
  • 600 MHz (3 channel, gradients, cryoprobe)
  • 800 MHz (3 channel, gradients, cryoprobe)
  • 900 MHz (3 channel, gradients, cryoprobe)