''N''-Acetylneuraminic acid (Neu5Ac or NANA) is the predominant

sialic acid Sialic acids are a class of alpha-keto acid sugars with a nine-carbon backbone. The term "sialic acid" () was first introduced by Swedish biochemist Gunnar Blix in 1952. The most common member of this group is ''N''-acetylneuraminic acid ...

found in human cells, and many mammalian cells. Other forms, such as

N-Glycolylneuraminic acid ''N''-Glycolylneuraminic acid (Neu5Gc) is a sialic acid molecule found in most non-human mammals. Humans cannot synthesize Neu5Gc because the human gene ''CMAH'' is irreversibly mutated, though it is found in other apes. The gene ''CMAH'' encodes ...

, may also occur in cells. This residue is negatively charged at physiological pH and is found in complex

glycans The terms glycans and polysaccharides are defined by IUPAC as synonyms meaning "compounds consisting of a large number of monosaccharides linked glycosidically". However, in practice the term glycan may also be used to refer to the carbohydrate ...

mucin Mucins () are a family of high molecular weight, heavily glycosylated proteins ( glycoconjugates) produced by epithelial tissues in most animals. Mucins' key characteristic is their ability to form gels; therefore they are a key component in ...

s and glycoproteins found at the

cell membrane The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extr ...

. Neu5Ac residues are also found in glycolipids, known as

ganglioside A ganglioside is a molecule composed of a glycosphingolipid (ceramide and oligosaccharide) with one or more sialic acids (e.g. N-acetylneuraminic acid, ''N''-acetylneuraminic acid, NANA) linked on the sugar chain. NeuNAc, an acetylated derivative ...

s, a crucial component of neuronal membranes found in the

brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...

. Along with involvement in preventing infections (

mucus Mucus (, ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both Serous fluid, serous and muc ...

associated with

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It ...

s—mouth, nose, GI, respiratory tract), Neu5Ac acts as a receptor for

influenza Influenza, commonly known as the flu, is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These sympto ...

viruses, allowing attachment to mucous cells via

hemagglutinin The term hemagglutinin (alternatively spelt ''haemagglutinin'', from the Greek , 'blood' + Latin , 'glue') refers to any protein that can cause red blood cells (erythrocytes) to clump together (" agglutinate") ''in vitro''. They do this by bindin ...

(an early step in acquiring influenzavirus infection).

In the biology of bacterial pathogens

Neu5Ac is also important in the biology of a number of pathogenic and symbiotic bacteria as it can be used either as a nutrient, providing both carbon and nitrogen to the bacteria, 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 characterized including the NanT protein from ''

Escherichia coli ''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...

'', the SiaPQM TRAP transporter from ''

Haemophilus influenzae ''Haemophilus influenzae'' (formerly called Pfeiffer's bacillus or ''Bacillus influenzae'') is a Gram-negative, Motility, non-motile, Coccobacillus, coccobacillary, facultative anaerobic organism, facultatively anaerobic, Capnophile, capnophili ...

'' and the SatABCD

ABC transporter The ABC transporters, ATP synthase (ATP)-binding cassette transporters are a transport system superfamily that is one of the largest and possibly one of the oldest gene families. It is represented in all extant phyla, from prokaryotes to huma ...

from ''

Haemophilus ducreyi ''Haemophilus ducreyi'' are fastidious gram-negative coccobacilli bacteria. This species causes the sexually transmitted disease chancroid, a major cause of genital ulceration in developing countries characterized by painful sores on the geni ...

''.

Medical use

In Japan, Neu5Ac is approved under the trade name Acenobel for the treatment of

distal myopathy with rimmed vacuoles Hereditary inclusion body myopathies (HIBM) are a group of rare genetic disorders which have different symptoms. Generally, they are neuromuscular disorders characterized by muscle weakness developing in young adults. Hereditary inclusion body my ...

References

{{DEFAULTSORT:Acetylneuraminic Acid, N- Amino sugars Sugar acids Monosaccharides

In the biology of bacterial pathogens

Medical use

See also

References