Inter-residue coupling

The 3H chemical shifts, coupling constants, temperature coefficients, exchange rates and inter-residual ROEs of the hydroxyl protons of various synthetic type II trisaccharides, analogues of (3-D-Galp-(l - 4)-p-D-GlcpNAc-(l - 2)-a-D-Man-(l - 0)(CH2)7CH3, were reported and interpreted,8 assisted with molecular dynamic simulations, to deduce key information on the conformational behavior of these important molecules in aqueous solution. 

The development of NMR techniques for double-labeled material began in the late 1980s, and there are dozens of different types of experiments that exploit scalar couplings for assignment purposes. These experiments are called triple resonance experiments because they involve three different nuclear spins, H, C, and N (Ikura et al., 1990 Bax and Grzesiek, 1993). To perform experiments of this type, it is usually necessary to isotopically enrich the protein to 99% for the and N atoms. The goal of these experiments is to correlate intra- and inter-residue chemical shifts with the amide proton and nitrogen chemical shifts. 

It is the coupling network that dictates the possibilities to select correlations to be observed. The key idea is to produce a mutually complementary pair of spectra, e.g. HNCA and HN(CO)CA. The former displays both intra- and inter-residue correlations and the latter exclusively the inter-correlations. Alternatively, an exclusive inter-HNCA can be recorded. The pair of spectra displaying for each amide nuclei resonances both intra- and inter-carbon resonances allow one to trace the polypeptide backbone from one residue to another. The sequential walk is interrupted at prolines and at times potentially due to exchange broadening. 

Inter-residue C- H coupling in disaccharides has been used to determine the orientation of the glycosidic linkage. Coupling over three bonds between... 

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