Isomerization of monosaccharides

Isomerization. Both the carbonyl group and the adjacent hydroxyl group are involved in isomerization of monosaccharides. This reaction can be catalyzed by either a base or an enzyme. By this reaction, an aldose is converted into another aldose and a ketose, and a ketose is converted into two... 

Treatment of monosaccharides with alkali usually results in a preponderance of products that are not isomeric with the original sugar. Their molecular-weight distribution indicates that they must... 

Mutation, where repositioning of a phosphate group in the monosaccharide phosphate molecule, e.g. the isomerization of glucose 6-phosphate and glucose 1-phosphate (Figure 8.2), is achieved via an intermediate diphosphate. 

The well-known rotational isomerism of thioamides has been studied in detail for monosaccharide derivatives bearing a thioacetamido substituent at a secondary or primary position.176177 188 189 As common features,... 

Franks F, Lillford PJ, Robinson G (1989) Isomeric equilibration of monosaccharides in solution influence of solvent and temperature. J Chem Soc Faraday Trans 1 85 2417-2426... 

The analysis of carbohydrates continues to be of considerable importance in the biological sciences. The diversity of structure and function of carbohydrates in organisms contributes to the difficulty of analysis of these materials. There exist a number of techniques for the analysis of carbohydrates, but no single technique has universal applicability. For the identification of carbohydrates, trimethylsilyl ethers are widely used in GC/MS. Veness and Evans " showed that GC/FTIR can also be used, with some advantages, for this purpose. A selection of 42 monosaccharides and related compounds were examined and, in each case, unique spectra were obtained for the differing compounds and their isomeric forms, allowing unambiguous identification. These results indicate that GC/FTIR of trimethylsilyl ethers of monosaccharides is a useful analytical technique for their identification. The resultant spectra are unique, easy to interpret, and stereo-isomeric forms are readily differentiated. 

Interconverions. The mutual transformations of monosaccharides involve the following 3 types of reactions a) epimerization, in which the steric arrangement on a C-atom is reversed by epimerases (e.g. in galactose metabolism) b) isomerization, in which aldoses and ketoses are reversibly interconverted by... 

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