title: Carbon-13 as a tool for the study of carbohydrate structures, conformations and interactions.
abstract: The application of 13C-NMR spectroscopy to problems involving the structures and interactions of carbohydrates is described. Both 13C-enriched and natural abundance compounds were used and some advantages of the use of the stable isotope are described. Carbon-carbon and carbon-proton coupling constants obtained from 1-13C enriched carbohydrates were employed in the assignment of their chemical shifts and to establish solution conformation. In all cases studied thus far, C-3 couples to C-1 only in the beta-anomers while C-5 couples to C-1 only in the alpha-anomers. C-6 and C-2 always couple to C-1 in both anomeric species. The alkaline degradation of glucose [1-13C] to saccharinic acids was followed by 13C-NMR. The conversion of glucose [1-13C] to fructose-1, 6-bisphosphate [1, 6-13C] by enzymes of the glycolytic pathway was shown as an example of the use of 13C-enriched carbohydrates to elucidate biochemical pathways. In a large number of glycosyl phosphates the 31P to H-1 and 31P to C-2 coupling constants demonstrate that in the preferred conformation and phosphate group lies between the O-5 and the H-1 of the pyranose ring. The influence of paramagnetic Mn2 + ions on the proton decoupled 13C-NMR spectra of uridine diphosphate N-acetylglucosamine indicates that the Mn2 + interacts strongly with the pyrophosphate moiety and with the carbonyl groups of the uracil and N-acetyl groups.
mesh_terms: D002241:Carbohydrates / Q000032:analysis; D002247:Carbon Isotopes; D055598:Chemical Phenomena; D002621:Chemistry; D006027:Glycosides; D007553:Isotope Labeling / Q000379:methods; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008968:Molecular Conformation; D009005:Monosaccharides
chemical_list: D002241:Carbohydrates; D002247:Carbon Isotopes; D006027:Glycosides; D009005:Monosaccharides