Deoxy sugars biosynthesis

Sequence analysis of genes in sugar biosynthesis gene clusters has resulted in tentative assignments for putative functions for the encoded proteins in the biosynthesis of the corresponding deoxy sugars. However, a lack of biochemical... 

The glycosyl esters of this series are characteristic metabolites of micro-organisms and take part in the biosynthesis of deoxy sugars and aminodeoxy sugars. 

Horton, D., Tables of Properties of 2-Amino-2-deoxy Sugars and Their Derivatives, 16, 159-200 Horton, D., and Hutson, D. H., Developments in the Chemistry of Thio Sugars, 18, 123-199 Horton, D. See also, Foster, A. B. Hough, L., and Jones, J. K. N., The Biosynthesis of the Monosaccharides,... 

The key intermediates in the biosynthesis of 6-deoxy sugars are the nucleoside 6-deoxyhexosyl-4-ulose diphosphates (7), formed through enzymic reactions catalyzed by NDP-sugar 4,6-dehydratases (EC 4.2.1.45-47) from primary glycosyl nucleotides. These reactions were observed... 

Detailed Reaction Mechanism of Deoxy Sugar Biosynthesis... 

As shown in the biosynthesis of granaticin, a hydride shift occurs intramolecularly. This process is mediated by an enzyme-bond pyridine nucleotide. A concerted abstraction of H-4 as a hydride in la and a C-5 deprotonation in 2a leads to the 4,5-enol ether 3a. The reduced form of the pyridine nucleotide transfers the hydride to C-6, simultaneously releasing a hydroxide to give 4a. Final tautomerization yields the dTDP-4-keto-6-deoxy-sugar in v-xylo configuration 4a. In other enzymes of the oxidoreductase type, the active site may show a different configuration. Thus, the intermediate 3a can be protonated from above at C-5 to yield the l-arabino isomer of 4a [2]. The stereochemistry of this mechanism was demonstrated by double labelling (cf. l-4b series), and as a net result proved a suprafacial 4—>6 hydride shift. 

More than a dozen branched-chain, deoxy sugars have now been discovered as components of antibiotics. One review on their biosynthesis4 and two5,6 on the chemistry and biochemistry of branched-chain sugars have appeared. These sugars can be divided into two groups according to their biosynthesis. 

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