CMP-iV-acetylneuraminic acid

In order to try to overcome some of the problems associated with chemical synthesis of oligosaccharides containing N-acetylneuraminic acid, Sabesan and Paulson [277] have used a combination of chemical and enzymatic methods using purified sialyl-transferases in the presence of CMP-iV-acetylneuraminic acid and synthetic acceptor molecules to give sialyl derivatives of oligosaccharides which were characterised by NMR. Thus, methyl P-D-galactopyranoside, methyl P-D-lactoside and iV-acetyl-... 

Thiem and Treder [278] have used immobilised enzymes [216] for the separate syntheses of Af-acetyllactosamine and CMP-iV-acetylneuraminic acid. These were allowed to react in solution in the presence of the sialyltransferase to give the 6 -N-acetylneuraminyl glycoside on the 50 pmol scale. 

E. Schreiner, R. Christian, and E. Zribal, Synthesis of 9-deoxy-, 7,9-dideoxy-, and 4,7,9-trideoxy-iV-acetylneuraminic acid and their behaviour towards CMP-sialate synthase, Liebigs Ann. Chem. p. 93 (1990). 

Dufner G, Schworer R, Muller B, Schmidt RR. Base- and sugar-modified cytidine monophosphate iV-acetylneuraminic acid (CMP-Neu5Ac) analogues - synthesis and smdies with (2-6)-sialyltransferase from rat Uver. Eur. J. Org. Chem. 2000 1467—... 

The carbohydrate portion of glycoproteins is formed from UDP-iV-acetylglucosamine and CMP-A-acetylneuraminic acid, and is attached to the protein by A-glycosidic bonds to asparagine amide groups. 

The continued transformation of IV-acetylmannosamine to CMP-N-acetylneuraminic acid may proceed via either of two routes. As seen from Fig. 8A, IV-acetylneuraminate is an intermediate in the synthesis and may be formed directly from IV-acetylmannosamine and pyruvic acid in a reaction catalyzed by IV-acetylneuraminic acid aldolase or by a series of reactions beginning with the phosphorylation of IV-acetylmannosamine. 

The enzymatic preparation of the activated sugar nucleotide may also involve a cofactor regeneration system. An example of this is an economic one-pot procedure, in which N-acetylneuraminic acid (NeuAc) is generated in situ from IV-acetylmannosamine (ManNac) and pyruvate with sialic acid aldolase and then converted irreversibly to CMP-NeuAc ([14], see also Sec. III). 

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