Abstract
The application of ^13^C‐NMR spectroscopy to problems involving the structures and interactions of carbohydrates is described. Both ^13^C‐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‐^13^ C 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 β‐anomers while C‐5 couples to C‐1 only in the α‐anomers. C‐6 and C‐2 always couple to C‐1 in both anomeric species. The alkaline degradation of glucose [1‐^13^ C] to saccharinic acids was followed by ^13^C‐NMR. The conversion of glucose [1‐^13^ C] to fructose‐1,6‐bisphosphate [1,6‐^13^ C] by enzymes of the glycolytic pathway was shown as an example of the use of ^13^C‐enriched carbohydrates to elucidate biochemical pathways. In a large number of glycosyl phosphates the ^31^P to H‐1 and ^31^P to C‐2 coupling constants demonstrate that in the preferred conformation the phosphate group lies between the O‐5 and the H‐1 of the pyranose ring. The influence of paramagnetic Mn^2+^ ions on the proton decoupled ^13^C‐NMR spectra of uridine diphosphate N‐acetylglucosamine indicates that the Mn^2+^ interacts strongly with the pyrophosphate moiety and with the carbonyl groups of the uracil and N‐acetyl groups.