Sialic acid
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| Sialic acid | |
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| Identifiers | |
| CAS number | |
| PubChem | |
| MeSH | |
| Properties | |
| Molecular formula | C11H19NO9 |
| Molar mass | 309.273 |
| Appearance | White crystalline powder |
| Melting point |
186°C (decomposes) |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references | |
Sialic acid is a generic term for the N- or O-substituted derivatives of neuraminic acid, a nine-carbon monosaccharide. It is also the name for the most common member of this group, N-acetylneuraminic acid (Neu5Ac or NANA). Sialic acids are found widely distributed in animal tissues and in bacteria, especially in glycoproteins and gangliosides. The amino group bears either an acetyl or a glycolyl group. The hydroxyl substituents may vary considerably: acetyl, lactyl, methyl, sulfate, and phosphate groups have been found.
Sialic acid-rich glycoproteins bind selectin in humans and other organisms. Cancer cells that can metastasize often have a lot of sialic acid-rich glycoproteins. This helps these late-stage cancer cells enter the blood stream.
Sialic acid-rich oligosaccharides on the glycoconjugates found on surface membranes help keep water at the surface of cells. The sialic acid-rich regions contribute to creating a negative charge on the cells' surface. Since water is a polar molecule with partial positive charges on both hydrogen atoms, it is attracted to cell surfaces and membranes. This also contributes to cellular fluid uptake.
Sialic acid can "hide" mannose antigens on the surface of host cells or bacteria from mannose-binding lectin. This prevents activation of complement.
The term "sialic acid" (from the Greek σιαλοσ (sialos) 'saliva') was first introduced by Swedish biochemist, Gunnar Blix, in 1952.
See also
Additional images
N-Acetyl-neuraminsäure2.svg
N-acetylneuraminic acid, a sialic acid |
Neuraminicacid.jpg
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External links
- Sialic acid in evolution
- Sialic acid in UniProt knowledgebasede:Sialinsäure
fr:Acide sialique it:Acido sialico ja:シアル酸
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Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
