Nucleotide sugars, synthesis

We have established a new aspect in nucleotide sugar synthesis by the application of sucrose synthase (UDPG D-fructose 2 glucosyltransferase, EC 2.4.1.13) the use of sucrose as a renewable resource for nucleotide sugar synthesis [273]. 

Bulter, T. and Elling, L. (1999) Enzymatic synthesis of nucleotide sugars. Glycoconjugate Journal, 16, 147-159. 

I 5 Multi-Enzyme Systems for the Synthesis of Clycoconjugates Table 5.2 Enzymes used in modules for combinatorial biocatalysis of nucleotide sugars. 

In summary, the synthesis and in situ regeneration of nucleotide sugars by combinatorial biocatalysis suffers from the main disadvantage that each enzyme has to be produced in sufficient amounts. This affords efficient recombinant protein produchon hosts being a bottleneck for some genes [25]. However, once a multi-enzyme system has been developed, the productivity can be improved by repetitive use of the biocatalysts as demonstrated for repetitive batch syntheses with soluble enzymes [25, 38] or with immobilized enzymes [48]. The advantage... 

M. Nomura, S. Shuto, M. Tanaka, T. Sasaki, S. Mori, S. Shigeta, and A. Matsuda, Nucleosides and Nucleotides. 185. Synthesis and biological activities of 4 -a-C-branched-chain sugar pyrimidine nucleosides, J. Med. Chem., 42 (1999) 2901-2908. 

Further functionalization at OH-2 was also explored [187]. From monosacchari-dic (ot-gluco, 129) and disaccharidic (a-malto, 143) CMGLs, several types of bisfunctionalized systems were synthesized by reaction with allylamine or propar-gylamine. For example, compound 155 was prepared and used in a synthesis of the nucleotide sugar analog 156 (Scheme 38). In the context of studies on the... 

The same procedure was applied212 for the preparation of uridine 5 -(a-D-glucopyranosyl pyrophosphate-4"-t, or -5"-f. A cell-free extract of Phytophthora cinnamoni was used for the synthesis of the 6"-t derivative,213 as well as yeast pyrophosphorylase.2133 An enzyme from Salmonella typhimurium was found quite satisfactory214 for obtaining this and other labeled nucleotide sugars. ... 

The D-mannose nucleotide sugars derived from 2 -deoxyguan-osine234 and inosine50,234 were prepared by using enzymes that catalyze the synthesis of guanosine 5 -(a-D-mannopyranosyl pyrophosphate). 

The rapid and extensive depletion of UTP is thought to be the basic cause of the toxicity. Galactosamine combines with UDP to form UDP-galactosamine (Fig. 7.62), which sequesters UDP, and therefore does not allow cycling of uridine nucleotides. Consequently, synthesis of RNA and hence protein are depressed, and sugar and mucopolysaccharide metabolism are disrupted. The latter effects may possibly explain the membrane damage that occurs. The toxic effects of galactosamine can be alleviated by the administration of UTP or its precursors. 

The mechanism of glucose activation in starch synthesis is similar to that in glycogen synthesis. An activated nucleotide sugar, in this case ADP-glucose, is... 

Several nucleotides have been detected in milk (see Table 1.9). The list includes the common mono-and dinucleotides, 3, 5 cyclic AMP, and adenosine triphosphate (ATP). The ATP is located entirely in the casein micelles (Richardson et al. 1980). Several nucleotide sugars, undoubtedly excess intermediates left over from mammary synthesis of glycoproteins, are present. Both DNA and RNA have been detected in milk (Swope and Brunner 1965 Swope et al. 1965 Langen 1967) they are probably found primarily in milk leukocytes. 

Enzymes for the Synthesis of Primary and Secondary Nucleotide Sugars. 109... 

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