Role of the Sugar

Isbell and Hudson identified lactones as the oxidation products of aldoses in buffered solution. The conditions were such that any free aldonic acid formed would be converted into the salt. Hence, lactones are the initial oxidation products and it was concluded that cyclic sugars give 5-lactones by oxidation with bromine water. The reactions were carried out in a solution buffered with barium carbonate and carbon dioxide. In the slightly acidic medium employed, the oxidation was rapid and interconversion between the anomeric forms of the sugars was relatively slow. In some cases the oxidation was 95% complete in five minutes. The extent of the reactions can be seen in Table X. 

The products were 5-lactones and their concentration was determined by titration of the filtered solutions with alkali. Any free aldonic acid formed in the oxidation would be present in the solution as the barium salt and thus would not enter into this titration. The type of lactone was determined by the rate of change in the pH and in the optical rotation of the reaction solution, after the oxidation had been stopped by removal 

This method was of value in that it gave an insight into the actual reaction of an aldose during bromine oxidation, and was also indicative of its ring structure. The method should be used with caution, however, especially in respect to the relative velocity of the anomeric forms of the various sugars. Formation of 5-lactones can be considered excellent 

Oxidation of Sugar Solutions at 0°C. with Bromine Water in the Presence of Barium 

Sugar oxidation measurements equilibrium solutions at O.S°C. crystalline sugars  

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Grosse S, Aron Y, Honore I, Thevenot G, Danel C, Roche A-C, Monsigny M, Fajac I (2004) Lactosylated polyethylenimine for gene transfer into airway epithelial cells role of the sugar moiety in cell delivery and intracellular trafficking of the complexes. J Gene Med 2004 (6) 345-356... 

Olano C, Abdelfattah MS, Gullon S et al (2008) Glycosylated derivatives of steffimycin insights into the role of the sugar moieties for the biological activity. ChemBioChem 9 624-633... 

It hardly seems proper to close this symposium, however, without some consideration of the place held by sugars among the general food resources of the human race, and the role of the sugars in human nutrition. 

Zunino F, Pratesi G, Perego P. Role of the sugar moiety in the pharmacological activity of anthracyclines development of a novel series of disaccharide analogues. Biochem Pharmacol 2001 61 933-938. 

Molecular dynamics simulations of duplex DNA or RNA in solution now yield stable structures for a duration of well over 1 ns. Different force fields, however, lead to different equilibrium stmctures. Presented are details of the equilibrium between the A and B forms of DNA by the CHARMM all-hydrogen force field for several sequences, including previously unpublished results on the d[GCGCGCG]2 and d[ATATATA]2 duplexes in solution. Comments are also included on the performance of other force fields. Based on a combination of observations a dominate role of the sugar and phosphodiester backbone moieties in the equilibrium between the A and B forms of DNA is suggested. 

Glycosylated e/ tA/ o-P-hydroxy-L-histidine compounds have been prepared (from d-G1c, d-Man, D-Gal) in the study of the role of the sugar in bleomycin they show excellent dioxygen activating capability. ... 

M. Takeuchi and A. Kobata, Structures and functional roles of the sugar chains of human erythropoietins. Glycobiology, 1 (1991) 337-346. 

Gerhard U, Mackay IP, Maplestone RA, Williams DH. The role of the sugar and chlorine suhstituents in the dimerization of vancomycin antibiotics. J. Am. Chem. Soc. 1993 115 ni-Tii. 

We are now studying to clarify the carbohydrate structure and the biological role of the sugar moiety of Vipera and Crotalus adamanteus NGFs. 

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