Occurrence of sialic acids

Sialic acids are also absent from most bacteria. Known and firmly established exceptions are Escherichia coli, Neisseria meningitidis, and Salmonella strains19,20,25 remarkably, all of them are hosted by mammals, or are even pathogenic. Sialic acids are rare in viruses they 

Abbreviations, and Indication of Nature and Position of the N- and O-Substituents of Natural Sialic Acids  

N-Acetyl-4-O-acetylneuraminic acid Neu4,5Acj acetyl acetyl H H H 

N-Aeetyl-7-O-acetyIneuraminic acid Neu5,7Ac2 H acetyl acetyl H H 

N-AcetyI-8-O-acetylneuraminic acid Neu5,8Ac2 H acetyl H acetyl H 

In Shigella boydii and Pseudomonas aeruginosa, other rare neuraminic acid derivatives ( pseudaminic acids ) were identified with a different stereochemistry at C-5, -7, and -8 and a 3-hydroxybutyramido or formamido substituent at C-7 (Knirel etal., 1985, 1986, 1987a,b). A further unusual derivative was found in the 0-specific chain of Legionella pneumophila serogroup 1 lipopolysac-charide having an a2,4 homopolymer of 5-acetamidino-7-acetamido-8-0-acetyl-3,5,7,9-tetradeoxy-D-g/yc rc -L-g / cf 9-nonulosonic acid (Knirel et al., 1994). 

Recently, the first proof for the occurrence of sialic acids in insects has been published (Roth et al., 1992). Neu5Ac was identified by mass spectrometry only 

FIGURE 3. Structure of y co y-r -glycero-i galacto-noxv x osomc acid (ketodeoxynonulosonic acid, Kdn). 

Strain %Neu5Ac %Neu5Gc %Neu5,9Ac. jLg sialic acid per 10 cells 

A comparative analysis of 13 different adult and fetal bovine tissues (Schauer et al., 1991) revealed a concentration of 0.1-3.1 mg total sialic acids/g wet weight in adult bovine tissues, while in the corresponding fetal tissues the sialic acid concentration was higher and ranged from 1.1 to 12.5 mg/g wet tissue. The percentage of Neu5Gc in the total sialic acid pool was always greater in the adult 

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Echinoderms constitute a peculiar phylum of invertebrates belonging to the most highly organized animals, the Deuterostomia, including, also, all the phyla of chordates. Among the invertebrates, echinoderms are the richest in glycolipids, and differ from all of the other marine invertebrate phyla in that they contain sialoglycolipids.79 This conforms to the data of Warren, who studied the occurrence of sialic acids in Nature, and found that all of the vertebrates have them, but, of the invertebrates, only the echinoderms practically all of the Protostomia contain no sialic acids.274... 

A6. Anderson, A. J., Some studies on the occurrence of sialic acid in human cartilage. Biochem. J. 78, 399-409 (1961). 

In reproductive biology, sialic acid polymers are receiving more and more attention. Polysialic acid with a(2-8)-linkages was found to be expressed on mouse embryos before and after implantation and the neuronal cell adhesion molecule (NCAM), which bears a polysialic acid chain, seems to be involved in cellular interactions in the early mammalian embryo [101,1076]. A similar function is attributed to polysialic acid observed during a short period of the larval stage of Drosophila melanogaster [1077]. It has to be noted that this is the first report on the occurrence of sialic acid in insects. 

Cornfield, A. P. Schauer, R. Occurrence of Sialic Acids. In Sialic Acids Chemistry, Metabolism and Function Schauer, R., Ed. Springer-Verlag Publishing Co. New York, 1982 Vol. 10, pp 5-39. 

The occurrence of sialic acids in nature is presented in section XII in the form of a phylogenetic chart (Fig. 1). This serves as a basis for comparison in the... 

The wide occurrence of sialic acids in nature is an indication of their great biological importance. As is described in other chapters in this book, the identification of the sialic acids was pioneered in several laboratories, while the biosynthetic mechanism of sialic acid formation was elucidated essentially by the work of Roseman s and Warren s groups in the United States (see Roseman 1962, Warren 1972, Schachter and Roden 1973, McGuire 1976, Schachter 1978). 

Roth J, Kempf A, Reuter G, Schauer R. Gehring WJ. Occurrence of sialic acids in Drosophila melanogaster. Science 1992 256 673-675. 

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