|Molar mass||309.27 g·mol−1|
|Appearance||White crystalline powder|
|Melting point||186 °C (367 °F; 459 K) (decomposes)|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
N-Acetylneuraminic acid (Neu5Ac or NANA) is the predominant sialic acid found in mammalian cells.
This negatively charged residue is found in complex glycans on mucins and glycoproteins found at the cell membrane. Neu5Ac residues are also found in glycolipids, such as gangliosides, a crucial component of neuronal membranes found in the brain.
Along with involvement in preventing infections (mucus associated with mucous membranes — mouth, nose, GI, respiratory tract), Neu5Ac acts as a receptor for influenza viruses, allowing attachment to mucous cells via hemagglutinin (an early step in acquiring influenzavirus infection).
Neu5Ac in the biology of bacterial pathogens
Neu5Ac is also important in the biology of a member of pathogenic bacteria  as it can used either as a nutrient, providing both carbon and nitrogen to the bacterium, or in some pathogens, can be activated and placed on the cell surface. Bacteria have evolved transporters for Neu5Ac to enable them to capture it from their environment and a number of these have been characterised including the NanT protein from Escherichia coli, the SiaPQM TRAP transporter from Haemophilus influenze  and the SatABCD ABC transporter from Haemophilus ducreyi.
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- Vimr ER, Kalivoda KA, Deszo EL, Steenbergen SM. (2004). "Diversity of microbial sialic acid metabolism.". Microbiol Mol Biol Rev 68 (1): 132–153. doi:10.1128/mmbr.68.1.132-153.2004. PMC 362108. PMID 15007099.
- Vimr ER, Troy FA. (1985). "Identification of an inducible catabolic system for sialic acids (nan) in Escherichia coli". J. Bacteriol. 164 (2): 845–853. PMC 214328. PMID 3902799.
- Severi E, Randle G, Kivlin P, Whitfield K, Young R, Moxon R, Kelly D, Hood D, Thomas GH. (2005). "Sialic acid transport in Haemophilus influenzae is essential for lipopolysaccharide sialylation and serum resistance and is dependent on a novel tripartite ATP-independent periplasmic transporter". Mol. Microbiol. 58 (4): 1173–1185. doi:10.1111/j.1365-2958.2005.04901.x. PMID 16262798.
- Post DM, Mungur R, Gibson BW, Munson RS Jr. (2005). "Identification of a novel sialic acid transporter in Haemophilus ducreyi.". Infect Immun 73 (10): 6727–35. doi:10.1128/IAI.73.10.6727-6735.2005. PMC 1230923. PMID 16177350.