Neuraminic acid

Neuraminic acid
Names
IUPAC name
5-Amino-3,5-dideoxy-d-glycero-d-galacto-non-2-ulosonic acid
Systematic IUPAC name
(4S,5R,6R,7S,8R)-5-Amino-4,6,7,8,9-pentahydroxy-2-oxononanoic acid
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
MeSH Neuraminic+Acids
UNII
  • InChI=1S/C9H17NO8/c10-5-3(12)1-9(17,8(15)16)18-7(5)6(14)4(13)2-11/h3-7,11-14,17H,1-2,10H2,(H,15,16)/t3-,4+,5+,6+,7+,9-/m0/s1 checkY
    Key: CERZMXAJYMMUDR-YOQZMRDMSA-N checkY
  • InChI=1/C9H17NO8/c10-5-3(12)1-9(17,8(15)16)18-7(5)6(14)4(13)2-11/h3-7,11-14,17H,1-2,10H2,(H,15,16)/t3-,4+,5+,6+,7+,9-/m0/s1
    Key: CERZMXAJYMMUDR-YOQZMRDMBH
  • O=C(O)[C@@]1(O)O[C@@H]([C@H](O)[C@H](O)CO)[C@H](N)[C@@H](O)C1
Properties
C9H17NO8
Molar mass 267.233 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
Two-dimensional representation of neuraminic acid in its straight chain form.

Neuraminic acid (5-amino-3,5-dideoxy-D-glycero-D-galacto-non-2-ulosonic acid) is an acidic (in particular ulosonic) amino sugar with a backbone formed by nine carbon atoms.[1] Although nine-carbon sugars do not occur naturally, neuraminic acid may be regarded as a theoretical nine-carbon ketose in which the first link of the chain (the –CH2OH at position 1) is oxidised into a carboxyl group (–C(=O)OH), the hydroxyl group at position 3 is deoxidised (oxygen is removed from it), and the hydroxyl group at position 5 is substituted with an amino group (–NH2). Neuraminic acid may also be visualized as the product of an aldol-condensation of pyruvic acid and D-mannosamine (2-amino-2-deoxy-mannose).[1]

Neuraminic acid does not occur naturally, but many of its derivatives are found widely distributed in animal tissues and in bacteria, especially in glycoproteins and gangliosides. The N- or O-substituted derivatives of neuraminic acid are collectively known as sialic acids, the predominant form in mammalian cells being the acetylated N-acetylneuraminic acid. The amino group bears either an acetyl or a glycolyl group, the latter being N-glycolylneuraminic acid. The hydroxyl substituents may vary considerably: acetyl, lactyl, methyl, sulfate and phosphate groups have been found.

History

The name "neuraminic acid" was introduced by German scientist Ernst Klenk in 1941, in reference to the brain lipids from which it was derived as a cleavage product from treatment with methanolic hydrochloric acid.[2] The compound which Klenk actually produced is now known to have been de-acetylated sialic acid from treatment with methanolic hydrochloric acid, and had been sialic acid in vivo. Sialic acid had previously been isolated intact by Gunnar Blix in 1936 from bovine submaxillary glands. Blix continued improving his purification protocol and named the compound "sialic acid" in 1952, publishing his conclusion that Klenk's compound was the de-actylated version, which Klenk later confirmed.[3] In 1957 Blix, Klenk, and another biochemist working on sialic acids named Alfred Gottschalk jointly published a brief note in Nature agreeing to the nomenclature of "neuraminic acid" as being the encompassing group, with "sialic acid" among other substituted derivatives.[4] Regarding the enzymes which cleave the monosaccharide residues in general, they stated that either "neuraminidase" or "sialidase" could be used, which has led to confusion in the field as viral neuraminidases in fact bind only sialic acid.

Nomenclature

The IUPAC symbol used for neuraminic acid is Neu, and the residue is typically found with additional chemical modifications in biological systems. As a family, these residues are known as sialic acids. For example, N-acetylneuraminic acid, Neu5Ac, is typical in human glycoproteins. The Symbol Nomenclature for Glycans is a brown diamond.

Biological functions

Among their many biological functions, these structures are substrates for neuraminidase enzymes which cleave neuraminic acid residues. Human flu viruses have a neuraminidase enzyme, signified in the name "H#N#", where the H refers to an isoform of hemagglutinin and N refers to an isoform of viral neuraminidase.

See also

References

  1. 1 2 Blanco, Antonio; Blanco, Gustavo (2017-01-01), "Chapter 4 - Carbohydrates", in Blanco, Antonio; Blanco, Gustavo (eds.), Medical Biochemistry, Academic Press, pp. 73–97, doi:10.1016/b978-0-12-803550-4.00004-5, ISBN 978-0-12-803550-4, retrieved 2020-12-16
  2. ↑ Klenk, E. 1941. Neuraminsäure, das Spaltprodukt eines neuen Gehirnlipoids. Zeitschr. f. Physiol. Chem. 1941; 268:50-58.
  3. ↑ Lundblad, Arne (May 2015). "Gunnar Blix and his discovery of sialic acids. Fascinating molecules in glycobiology". Upsala Journal of Medical Sciences. 120 (2): 104–112. doi:10.3109/03009734.2015.1027429. ISSN 2000-1967. PMC 4463483. PMID 25921326.
  4. ↑ Blix, F. G.; Gottschalk, A.; Klenk, E. (May 1957). "Proposed Nomenclature in the Field of Neuraminic and Sialic Acids". Nature. 179 (4569): 1088. Bibcode:1957Natur.179.1088B. doi:10.1038/1791088b0. ISSN 1476-4687. PMID 13430805.
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