Sugar labeling

Reduction of aldonolactones and their derivatives with isotopically modified reducing agents leads to sugars labeled at the anomeric center. Glycosides substituted with deuterium or labeled with tritium are widely employed for kinetic isotope-effect measurements, mechanistic studies, isotope-tracing experiments, and so on. 

Other sugars labeled with F that are used in PET imaging ([ F] FDGal, 2-[ F]-2-deoxytalose, l-[ F]-l-deoxy-D-fructose) are also prepared by means of nucleophilic fluorination (Figure 6.19).1-[ F]-1 -Deoxy-D-fructose cannot be used as aprobe since it... 

Figure 6.19 Preparation of sugars labeled with F 2-[ F]-2-deoxytalose, N-[ F]-fluoroacetyl-D-glucosamine, and 6-fluoro-6-deoxy-L-ascorbic acid.

Sugars labeled with tritium have been used for the assay of enzyme activity where no other method exists. For instance, UDP-2-acet-... 

Sugar labeled radioactively in the reducing-sugar residue. 

Further, C NMR is used with sugars labelled at C-1 by a synthetic method which multiplies the signal intensity by 100. Using special accumulation and prolonged procedures, the six tautomers of D-glucose at 37 C can be observed (Fig. 1.4). Because of the disproportion of concentrations a quantitative presentation is not possible and the reader should consult Table 1.2. 

Identify each of the following sugars. Label each as either a hemiacetal or a hemiketal a. CH,OH... 

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