A 2D-HSQC-carbon selective/proton selective-constant time COSY, 2D-HSQC-(sel C, sel H)-CT COSY experiment, which is applicable
to uniformly 13C isotopically enriched samples (U-13C) of oligosaccharides or oligonucleotides is proposed for the measurement of proton–proton RDC in crowded regions of 2D-spectra.
In addition, a heteronuclear constant time-COSY experiment, 13C-13C CT-COSY, is proposed for the measurement of one bond carbon–carbon RDC in these molecules. These two methods provide an
extension, to U-13C molecules, of the original homonuclear constant time-COSY experiment proposed by Tian et al. (1999) for saccharides. The
combination of a number of these RDC with NOE data may provide the method of choice to study oligosaccharide conformation
in the free and receptor-bound state.
carbon–carbon couplings - NMR - oligosaccharide conformation - residual dipolar couplings