''N''-Acetylglucosamine (GlcNAc) is an

amide In organic chemistry, an amide, also known as an organic amide or a carboxamide, is a compound with the general formula , where R, R', and R″ represent organic groups or hydrogen atoms. The amide group is called a peptide bond when it i ...

derivative of the monosaccharide

glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...

. It is a secondary amide between glucosamine and acetic acid. It is significant in several biological systems. It is part of a biopolymer in the bacterial

cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mec ...

, which is built from alternating units of GlcNAc and ''N''-acetylmuramic acid (MurNAc), cross-linked with oligopeptides at the

lactic acid Lactic acid is an organic acid. It has a molecular formula . It is white in the solid state and it is miscible with water. When in the dissolved state, it forms a colorless solution. Production includes both artificial synthesis as well as nat ...

residue of MurNAc. This layered structure is called peptidoglycan (formerly called murein). GlcNAc is the monomeric unit of the

polymer A polymer (; Greek '' poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

chitin Chitin ( C8 H13 O5 N)n ( ) is a long-chain polymer of ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is probably the second most abundant polysaccharide in nature (behind only cellulose); an estimated 1 billion tons of chit ...

, which forms the

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton ( endoskeleton) in for example, a human. In usage, some of the ...

s of

arthropod Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and cuticle made of chiti ...

s like

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pa ...

s and

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapoda, decapods, ostracoda, seed shrimp, branchiopoda, branchiopods, argulidae, fish lice, krill, remipedes, isopoda, isopods, barnacles, copepods, ...

s. It is the main component of the

radula The radula (, ; plural radulae or radulas) is an anatomical structure used by molluscs for feeding, sometimes compared to a tongue. It is a minutely toothed, chitinous ribbon, which is typically used for scraping or cutting food before the food ...

s of mollusks, the beaks of

cephalopod A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

s, and a major component of the

s of most

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately fr ...

. Polymerized with glucuronic acid, it forms

hyaluronan Hyaluronic acid (; abbreviated HA; conjugate base hyaluronate), also called hyaluronan, is an anionic, nonsulfated glycosaminoglycan distributed widely throughout connective, epithelial, and neural tissues. It is unique among glycosaminoglyca ...

. GlcNAc has been reported to be an inhibitor of elastase release from human polymorphonuclear leukocytes (range 8–17% inhibition), however this is much weaker than the inhibition seen with ''N''-acetylgalactosamine (range 92–100%).

Medical uses

It has been proposed as a treatment for autoimmune diseases and recent tests have claimed some success.

O-GlcNAcylation

O-GlcNAcylation is the process of adding a single ''N''-acetylglucosamine sugar to the serine or threonine of a protein. Comparable to

phosphorylation In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, wh ...

, addition or removal of ''N''-acetylglucosamine is a means of activating or deactivating enzymes or

transcription factor In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The f ...

s. In fact, O-GlcNAcylation and phosphorylation often compete for the same serine/threonine sites. O-GlcNAcylation most often occurs on

chromatin Chromatin is a complex of DNA and protein found in eukaryote, eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. This prevents the strands from becoming tangled and also plays important ...

proteins, and is often seen as a response to stress. Hyperglycemia increases O-GlcNAcylation, leading to insulin resistance. Increased O-GlcNAcylation due to hyperglycemia is evidently a dysfunctional form of O-GlcNAcylation. O-GlcNAcylation decline in the brain with age is associated with cognitive decline. When O-GlcNAcylation was increased in the

hippocampus The hippocampus (via Latin from Greek , 'seahorse') is a major component of the brain of humans and other vertebrates. Humans and other mammals have two hippocampi, one in each side of the brain. The hippocampus is part of the limbic syste ...

of aged mice, spatial learning and memory improved.

References

External links

Re Multiple Sclerosis
{{DEFAULTSORT:Acetylglucosamine, N- Hexosamines Acetamides Membrane biology

Medical uses

O-GlcNAcylation

See also

References

External links