W-Acetylneuraminic acid

Figure 24-9. Biosynthesis of gangliosides. (NeuAc, W-acetylneuraminic acid.)...

Y. Itoh and T. Ogawa, Highly stereoselective glycosylation of W-acetylneuraminic acid aided by a phenylthio substituent as a stereocontrolling auxiliary. Tetrahedron Lett. 29 3981 (1988). 

T. Kondo, H. Abe, and T. Goto, Efficient synthesis of 2a-glycoside of W-acetylneuraminic acid via phenylsulfenyl chloride adduct of 2-deoxy-2,3-dehydro-lV-acetylneuraminic acid methyl esier tetra-O-acetate, Chem. Lett., p. 1657 (1988). 

A. Hasegawa, J. Nakamura, and M. Kiso, Synthesis of alkyl ot-glycosides of 2-thio-W-acetylneuraminic acid, J. Carbohydr. Chem. 5 11 (1986). 

O. Kanie, M. Kiso, and A. Hasegawa, Glycosylation using methylthioglycosides of W-acetylneuraminic acid and dimethyl(methylthio)sulfonium triflate, J. Carbohydr. Chem. 7 501 (1988). 

A. Hasegawa, H. Ohki, T. Nagahama, H. Ishida, and M. Kiso, A facile, large-scale preparation of the methyl 2-thioglycoside of W-acetylneuraminic acid, and its usefulness for the re-stereoselective synthesis of sialoglycosides, Carbohydr. Res. 212 211 (1991). 

K. Koppert and R. Brossmer, Synthesis of the C-5 homologue of W-acetylneuraminic acid bj enzymatic chain elongation of 2-C-acetamidomethyl-2-deoxy-D-mannose, Tetrahedron Lett. 33 8031 (1992). 

Outline of biosynthesis of some glycosphingolipids. (Glc = glucose, Gal = galactose, GalNAc = A-acetylgalactosamine, NeuAc = w-acetylneuraminic acid. 

R. L. Halcomb, W. Fitz, and C.-H. Wong, Enzymahc synthesis of 7-deoxy-At-acetylneuraminic acid and 7-O-methyl-W-acetylneuraminic acid. Tetrahedron Asymm. 5 2437 (1994). 

R. Csuk, M. Hugener, and A. Vasella, A new synthesis of W-acetylneuraminic acid, Helv. Chim. Acta 77 609 (1988). 

U. Kragl, D. Gygax, O. Ghrsalba, and C. Wandrey, Enzymatic two-step synthesis of V-acetyl-neuraminic acid in the enzyme membrane reactor, Angew. Chem. Int. Ed. Engl. 30 827 (1991). M.-J. Kim, W. J. Hennen, H. M. Sweers, and C.-H. Wong, Enzymes in carbohydrate synthesis W-Acetylneuraminic acid aldolase catalyzed reactions and preparation of 7V-acetyl-2-deoxy-D-neuraminic acid derivatives, J. Am. Chem. Soc. 770 6481 (1988). 

Figure 6-15. Synthesis of sphingolipids. NANA = W-acetylneuraminic acid G/c = glucose Gal = galactose GalNAc = N-acetylgalactosamine PIP = pyridoxal phosphate FA = fatty acyl groups derived from fatty acids = hydrophobic chains of ceramide. The dashed box contains the portion of ceramide derived from serine.

Prior to this, its methyl ester (although it was not recognized as such) had been isolated from dialyzed, hydrolyzed cow s colostrum, and designated methoxylactaminic acid. Independently, the free acid was also isolated from both the dialyzable and the non-dialyzable carbohydrate fractions of human milk, and described under the name gynaminic acid. With the development of improved procedures of isolation, particularly recrystallization from acetic acid and water to obtain the alkyl-free acids, it was shown that gynaminic, lactaminic, and ovine sialic acids are identical with W-acetylneuraminic acid. The final identification was made by comparison of their infrared absorption spectra and x-ray powder diffraction patterns, which were respectively identical. 

W-Acetylneuraminic acid has an empirical composition of CnHuNOg, and [ ] —32.0° (in water) m. p. 183-185°. On heating with methanolic hydrogen chloride, it is readily converted to monomethoxyneuraminic acid with concomitant loss of its reducing properties. Boiling the compound with alkgli yields 2-pyrrolecarboxylic acid. ... 

Gangliosides, the most complex sphingolipids, have oligosaccharides as their polar head groups and one or more residues of W-acetylneuraminic acid (NeuBAc), a sialic acid (often simply called sialic acid ), at the... 

NeuAc, W-acetylneuraminic acid Cer, ceramide Glc, glucose enzyme reaction. 

Potent inhibitor toward W-acetylneuraminic acid synthetase... 

W-acetylneuraminic acid. This receptor determinant appears to be present on both glycoproteins and gangliosides [139, 140]. HPIVl also recognizes a2-3 linkages, whereas HPIV3 has a2-6 specificity [141]. 

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