Sugars biological synthesis

Currently, the mechanism of biological nanoparticle synthesis is not fully understood. For gold nanoparticles synthesized extracellularly by the fungus F. oxyspo-rum, it was reported that the reduction occurs due to NADH-dependent reductase released into the solution [16]. With neem leaf broth, it was reported that terpenoids are believed to be the surface-active molecules stabilizing the nanoparticles, and reaction of the metal ions is possibly facilitated by reducing sugars or terpenoids... 

Vasella has used deoxy-nitro sugars for the synthesis of various biologically important carbohydrates, and the radical nitromethyladon of deoxy-nitro sugars has been used for synthesis of fnictose 6-phosphate" and 6-C-methyl and 6-C-rhydroxymethyl analogiies of iV-acetylnenraitinic acid fsee Scheme7.2. ... 

An attractive feature in this reaction is the possibility of direct substitution and formation of unblocked sugar derivatives containing one or more chlorodeoxy function in essentially two steps. Another facet is the formation of methyl 4,6-dichloro-4,6-dideoxy-hexosides from certain methyl glycosides in one step. Such compounds could be valuable intermediates in the synthesis of dideoxy and diamino sugars of biological importance. 

A more general access to biologically important and structurally more diverse aldose isomers makes use of ketol isomerases for the enzymatic interconversion of ketoses to aldoses. For a full realization of the concept of enzymatic stereodivergent carbohydrate synthesis, the stereochemically complementary i-rhamnose (Rhal EC 5.3.1.14) and i-fucose isomerases (Fuel EC 5.3.1.3) from E. coli have been shown to display a relaxed substrate tolerance [16,99,113,131]. Both enzymes convert sugars and their derivatives that have a common (3 J )-OH configuration, but may deviate in... 

Fong, S., Machajewski, T.D., Mak, C.C. and Wong, C.-H. (2000) Directed evolution of D-2-keto-3-deoxy-6-phosphogluconate aldolase to new variants for the efficient synthesis of d- and L-sugars. Chemistry Biology, 7, 873-883. 

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