P-D-Fructose

The same synthetic scheme was applied to synthesize nucleoside analogues with natural or modified base, starting from a- and p-D-xylo-17 and p-D-ura/uHO-derivatives.105 Grouiller also used the procedure with p-D-fructose to prepare nucleoside derivatives.18 However, the fragility of the oxazoline intermediate and low yields obtained limited the methodology. 

Problem 27.17 What glycosides are formed when each monosaccharide is treated with CH3CH2OH, HCI (a) p-D-mannose (b) a-D-gulose (c) p-D-fructose ... 

Stereospecificity. Sucrose, a major product of photosynthesis in green leaves, is synthesized by a battery of enzymes. The substrates for sucrose synthesis, d-glucose and d-fructose, are a mixture of a and P anomers as well as acyclic compounds in solution. Nonetheless, sucrose consists of a-d-glucose linked by its carbon-1 atom to the carbon-2 atom of P-d-fructose. How can the specificity of sucrose be explained in light of the potential substrates ... 

H.A. Tajmir-Riahi, Carbohydrate adducts with zinc group metal ions. Interaction of p-D-fructose with Zn(ll), Cd(ll) and Hg(II) cations and the effects of metal-ion coordination on the sugar isomer binding. Carbohydr. Res., 172(198) 1. 

Sucrose a-D-glucose + p-D-fructose a,p(1 2) Sugar beet, sugar cane, sorghum and carrot roots. Fermentable. Hydrolysed by dilute acids or enzyme invertase (sucrase) to one molecule of glucose and one molecule of fructose. Relatively stable to reaction with alkali... 

The new compounds formed from these reactions still contain reactive carbonyl groups that can continue the condensation and generate browning polymers. Pyrolysis studies were done on several Amadori compounds from this class [11-13], such as 1-deoxy-1-[(S)-2-(3-pyridyl)-1-pyrrolidinyl]-p-D-fructose [11). However, the nondializable melanoidin from this type of reaction received less interest. 

As a typical acetal bond, a glycosidic bond readily hydrolyzes in an acid-catalyzed reaction. In this manner, di- and oligosaccharides can be split into monosaccharides. It is a common method for manufacturing of invert sugar, a mixture of a-D-glucose and P-D-fructose, from sucrose. 

Important disaccharides include lactose and sucrose. Lactose is a disaccharide of p-D-galactose bonded p(l 4) with D-glucose. In galactosemia, defective metabolism of galactose leads to accumulation of a toxic by-product. The ill effects of galactosemia are avoided by exclusion of milk and milk products from the diet of affected infants. Sucrose is a dimer composed of a-D-glucose bonded (al —> p2) with p-D-fructose. 

P D-fructose 1-phosphate + D-fructose 6-phosphate + acetate <1> (<1> d-fructose 1-phosphate is the predominant product [1]) [1]... 

A similar distance has been calculated for the crystal structure of P-D-fructose for the H-transfer in the propagating step (see below) [12], The G value drops with increasing dose indicating that termination reactions are favoured by imperfections. There is also a characteristic change of the irradiated 2-deoxyribose crystal it turns highly hygroscopic at moderate doses. 

Formulae and atomic numbering of (a) p-D-fructose, (b) o-glucarate, (c) 2-keto-D-gluconate, and (d) a-o-galactumnate... 

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