Nonulosonic acids

TV-Acetyl neuraminic acid (NANA, O-Sialic acid, 5-acetamido-3,5-dideoxy-D-g/ycero-D-g/acto-2-nonulosonic acid, lactaminic acid) [I3I-48-6JM 309.3, m 159°(dec), 181-... 

The inhibitory activity of furanosyl nonulosonic acid derivative 32, and its structure with N9 sialidase, served as a starting point for the structure-based design of... 

Three 3-deoxynonulosonic acids containing amino groups are known. The most abundant of these is 5-amino-3,5-deoxy-D- /yc ro-D-ga/acto-nonulosonic acid (neuraminic acid, 27), which occurs in different extracellular polysaccharides. Some of these, like colominic acid from E. coli K1, are homopolysaccharides. Neuraminic acid is generally A-acetylated and, as in the animal glycoconjugates, has only been found in the a-pyranosyl form (27). It also occurs in some LPS, for example those from some Rhodobacter... 

Acyclic dienes react with glyoxylic acid via an oxo-Diels-Alder reaction to give dihydropyran derivatives (Eq. 12.53). An excellent application of the oxo-Diels-Alder reaction is reported by Lubineau et al. in the synthesis of the sialic acids, 3-deoxy-Z)-manno-2-octulosonic acid (KDO) and 3-deoxy-D-glycero-D-galacto-2-nonulosonic acid (KDN).123... 

Several observations regarding this aspect have been published, and are briefly mentioned here. 5,6-Dideoxy-6-C-phosphono-D-arabino-hexofuranose (135), an isosteric phosphonate analog of D-arabinose 5-phosphate, is apparently converted, in the presence of enolpyruvate phosphate, into 3,8,9-trideoxy-9-C-phosphono-D-mcmno-2-nonulosonic acid (136) under catalysis by KDO 8-phosphate synthetase from Escherichia coli K 235. Compound 136, an isosteric phosphonate analog of KDO 8-phosphate, is a product inhibitor of the synthetase, and, by the nature of the phosphonate group, is not subject to dephosphorylation as catalyzed by KDO 8-phosphate phosphatase156 (see Scheme 40). Compound 119 (see Scheme 33) is a weak inhibitor of KDO 8-phosphate synthetase.81 KDO inhibits KDO 8-phosphate phosphatase,139 and D-ribose 5-phosphate has an inhibitory... 

Two biologically important ketoaldonic acids should be mentioned here. N-Acetylneuraminic acid (5-acetamido-3,5-dideoxy-D-gh/cero-D-gaiocto-nonulosonic acid) is homomorphous with 3-deoxy-g(uco(and monno)-heptulose, and therefore, in solution, would be expected to be overwhelmingly in the / -D -pyranose form (14). Actually, although the... 

D. Nadano, M. Iwasaki, S. Endo, K. Kitajima, S. Inoue, and Y. Inoue, A naturally occurring deaminated neuraminic acid, 3-deoxy-D-gfycero-D-galacIo-nonulosonic acid (KDN), J. Biol. Chem. 267 11550 (1986). 

Mannose reduced at C-4 (24), or truncated to D-lyxose (giving 25), gave41,42,44 nonulosonic acid 26 and octulosonic acid 27. 

Among all the compounds listed in Table IV under the heading Derivatives of 3-deoxy-2-nonulosonic acids, the only one reported so far as a component of living cells is 3-deoxy-D-g/ycm>D-ga/flcfo2-nonulosonic... 

Y. A. Knirel, N. A. Kocharova, A. S. Shashkov, N. K. Kochetkov, V. A. Mamontova, and T. F. Solov eva, Structure of the capsular polysaccharide of Klebsiella ozaenae serotype K4 containing 3-deoxy-D-g(ycero-D-gra/acta-nonulosonic acid, Carbohydr. Res., 188 (1989) 145-155. 

The present article focuses on the occurrence and characterization of derivatives of 5,7-diamino-3,5,7,9-tetradeoxynon-2-ulosonic acids and presents experimental approaches used to identify them and to elucidate the structures of the bacterial polysaccharides that contain the nonulosonic acids. Recent data on the biosynthesis of these sugars and their role in immune recognition and epitope specificity of bacterial glycopolymers are discussed. 

A fourth sugar was found only in LPS of L. pneumophila.12,40 It was initially identified as the L-glycero-o-talo isomer12 but later revised to the D-glycero-D-talo isomer and named 4-epilegionaminic acid (4).11,40 Two more stereoisomers of the nonulosonic acids were found in several other L. pneumophila isolates40 but their configurations have not yet been determined. 

In most structural studies of the polysaccharides, oligosaccharides containing the nonulosonic acids were prepared in order to have better-resolved NMR spectra and for investigation by MS. In some examples, a monosaccharide or a monosaccharide glycoside were also prepared by chemical degradations. 

In most cases, the nonulosonic acids present in heteropolysaccharides could not be released as monosaccharides by direct acid hydrolysis because of their instability under the drastic conditions that were necessary to cleave the aldosidic linkage of the neighboring sugar residue. A combination of solvolysis with hydrogen fluoride and acid hydrolysis of the resulting... 

Fig. 17. Electron impact MS fragmentation of the fully (a, b) and partially (c, d) methylated reduced open-chain derivatives of the nonulosonic acids. [Taken from Refs. 9 (d), 14 (b), and 23 (a, c) configuration is not shown.]...

---