Polysaccharides

Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the cell walls of green plants, many forms of algae, and the oomycetes. Some species of bacteria secrete it to form biofilms. Cellulose is the most abundant organic polymer on Earth. The cellulose content of cotton fibre is 90%, that of wood is 40–50%, and that of dried hemp is approximately 57%.

thumb|upright=1.5|3D structure of cellulose, a [[beta-glucan polysaccharide]] thumb|class=skin-invert-image|upright=1.5|Amylose is a linear [[polymer of glucose mainly linked with α(1→4) bonds. It can be made of several thousands of glucose units. It is one of the two components of starch, the other being amylopectin.]]

thumb|upright=1.25|Schematic two-dimensional cross-sectional view of glycogen: A core protein of glycogenin is surrounded by branches of [[glucose units. The entire globular granule may contain around 30,000 glucose units.]] thumb|A view of the atomic structure of a single branched strand of [[glucose units in a glycogen molecule.]]

thumb|Green tea-flavored yōkan, a popular Japanese red bean jelly made from agar thumb|A blood agar plate used to culture bacteria and diagnose infection

thumb|250px|right|Structure of the chitin molecule, showing two of the N-Acetylglucosamine|N-acetylglucosamine units that repeat to form long chains in β-(1→4)-linkage. thumb|250px|right|Haworth projection of the chitin molecule. thumb|A close-up of the wing of a leafhopper; the wing is composed of chitin. thumb|right|A cicada emerges from its nymphal exoskeleton; the shed exoskeleton is mostly modified chitin ([[sclerotin) but the wings and much of the adult body are still unsclerotized chitin at this stage]]

thumb|Commercially produced powder of pectin, extracted from citrus fruits Pectin ( : 'congealed' and 'curdled') is a heteropolysaccharide, a structural polymer contained in the cell walls and middle lamellae of terrestrial plants. The principal chemical component of pectin is galacturonic acid (a sugar acid derived from galactose) which was isolated and described by Henri Braconnot in 1825. Commercially produced pectin is a white-to-light-brown powder, produced from citrus fruits for use as an edible gelling agent, especially in jams and jellies, dessert fillings, medications, and sweets; as

Inulins are a group of naturally occurring polysaccharides produced by many types of plants, industrially most often extracted from chicory. Inulin is used by some plants as a means of storing energy and is typically found in roots or rhizomes. Most plants that synthesize and store inulin do not store other forms of carbohydrate such as starch.

Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch and glycogen. Dextrins are mixtures of polymers of D-glucose units linked by α-(1→4) or α-(1→6) glycosidic bonds.

Amylopectin is a water-insoluble polysaccharide and highly branched polymer of α-glucose units found in plants. It is one of the two components of starch, the other being amylose. thumb|Relation of amylopectin to starch granule|center Plants store starch within specialized organelles called amyloplasts. To generate energy, the plant hydrolyzes the starch, releasing the glucose subunits. Humans and other animals that eat plant foods also use amylase, an enzyme that assists in breaking down amylopectin, to initiate the hydrolysis of starch.

Amylose is a polysaccharide made of α-D-glucose units, bonded to each other through α(1→4) glycosidic bonds. Together with amylopectin, it is one of the two components of starch, making up approximately 20–25% of it. Because of its tightly packed helical structure, amylose is more resistant to digestion than other starch molecules and is therefore an important form of resistant starch.

A hemicellulose (also known as polyose) is one of a number of heteropolymers (matrix polysaccharides), such as arabinoxylans, present along with cellulose in almost all terrestrial plant cell walls. Cellulose is crystalline, strong, and resistant to hydrolysis. Hemicelluloses are branched, shorter in length than cellulose, and also show a propensity to crystallize. They can be hydrolyzed by dilute acid or base as well as a myriad of hemicellulase enzymes.

Chitosan is a linear polysaccharide composed of randomly distributed β-(1→4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit). It is made by treating the chitin shells of shrimp and other crustaceans with an alkaline substance, such as sodium hydroxide.

thumb|Underwater Eucheuma farming in the [[Philippines for carrageenan production]] Carrageenans or carrageenins ( ; ) are a family of natural linear sulfated polysaccharides. They are extracted from red edible seaweeds. Carrageenans are widely used in the food industry for their gelling, thickening, and stabilizing properties. Their main application is in dairy and meat products, due to their strong binding to food proteins. Carrageenans have emerged as a promising candidate in tissue engineering and regenerative medicine applications as they resemble animal glycosaminoglycans (GAGs). They ar

Dextran is a complex branched glucan (polysaccharide derived from the condensation of glucose), originally derived from wine. IUPAC defines dextrans as "Branched poly-α-d-glucosides of microbial origin having glycosidic bonds predominantly C-1 → C-6". Dextran chains are of varying lengths (from 3 to 2000 kilodaltons).

thumb|right|250px|Astragalus gummifer thumb|A dish of Tragacanth Tragacanth is a natural gum obtained from the dried sap of several species of Middle Eastern legumes of the genus Astragalus, including A. adscendens, A. gummifer, A. brachycalyx, and A. tragacantha. Some of these species are known collectively under the common names "goat's thorn" and "locoweed". The gum is sometimes called Shiraz gum, shiraz, gum elect or gum dragon. The name derives from the Greek words tragos (meaning "goat") and akantha ("thorn"). Iran is the biggest producer of this gum.

polysaccharide found in brown algae

food additive and thickener

The glycocalyx (: glycocalyces or glycocalyxes), also known as the pericellular matrix and cell coat, is an external organelle consisting of a layer of glycosylated biomolecules called glycoconjugates, such as glycoproteins and glycolipids. These are embedded in and extend outwards from the cell membranes of virtually all cells. Generally, the carbohydrate portion of the glycolipids found on the surface of plasma membranes helps these molecules contribute to cell–cell recognition, communication, and intercellular adhesion.

class=skin-invert-image|thumb|Callose is an example of a (1→3)-β-D-glucan composed of [[glucose units]] Beta-glucans, β-glucans comprise a group of β-D-glucose polysaccharides (glucans) naturally occurring in the cell walls of plants (including cereals), bacteria, algae and fungi, with significantly differing physicochemical properties dependent on source. Typically, β-glucans form a linear backbone with 1–3 β-glycosidic bonds but differ with respect to molecular mass, solubility, viscosity, branching structure, and gelation properties, with several physiological roles in these organisms and c

thumb|class=skin-invert-image|right|250px|Structural formula of inulins, linear fructans with a terminal α-D-glucose with 1→2 linkage A fructan is a polymer of fructose molecules. Fructans with a short chain length are known as fructooligosaccharides. Fructans can be found in over 12% of the angiosperms including both monocots and dicots such as agave, artichokes, asparagus, leeks, garlic, onions (including spring onions), yacón, jícama, barley and wheat.

thumb|upright=1.2|right|A sundew with a leaf bent around a fly trapped by mucilage

Hypromellose (INN), short for hydroxypropyl methylcellulose (HPMC), is a semisynthetic, inert, viscoelastic polymer used in eye drops, as well as an excipient and controlled-delivery component in oral medicaments, found in a variety of commercial products.

A glucan is a polysaccharide derived from D-glucose, linked by glycosidic bonds. Glucans are noted in two forms: alpha glucans and beta glucans. Many beta-glucans are medically important. They represent a drug target for antifungal medications of the echinocandin class.

right|thumb|An agarose gel in a trayused for gel electrophoresis

thickening agent

polymer of fructose forming a non-structural carbohydrate

pharmaceutical drug

alt=|thumb|481x481px|Structure of xylan in hardwood. thumb|481x481px|Plant cell wall is composed of cellulose, hemicellulose, pectin and glycoproteins. Hemicelluloses (a heterogeneous group of polysaccharides) cross-link glycans interlocking the cellulose fibers and form a mesh like structure to deposit other polysaccharides.

Lentinan is a polysaccharide isolated from the fruit body of shiitake mushroom (Lentinula edodes).

Fucoidan is a long-chain sulfated polysaccharide found in various species of brown algae, such as seaweed, and in marine invertebrates. Fucoidan occurs in the cell walls of seaweed serving structural roles.

thumb|right|A segment of galactomannan showing mannose backbone (below) with a branching galactose unit (top) Galactomannans are polysaccharides consisting of a mannose backbone with galactose side groups, more specifically, a (1-4)-linked beta-D-mannopyranose backbone with branchpoints from their 6-positions linked to alpha-D-galactose, (i.e. 1-6-linked alpha-D-galactopyranose).

Pullulan is a polysaccharide consisting of maltotriose units, also known as α-1,4- ;α-1,6-glucan'. Three glucose units in maltotriose are connected by an α-1,4 glycosidic bond, whereas consecutive maltotriose units are connected to each other by an α-1,6 glycosidic bond. Pullulan is produced from starch by the fungus Aureobasidium pullulans. Pullulan is mainly used by the cell to resist desiccation and predation. The presence of this polysaccharide also facilitates diffusion of molecules both into and out of the cell.

The molecule laminarin (also known as laminaran) is a storage glucan (a polysaccharide of glucose) found in brown algae. It is used as a carbohydrate food reserve in the same way that chrysolaminarin is used by phytoplankton, especially in diatoms. It is created by photosynthesis and is made up of β(1→3)-glucan with β(1→6)-branches. It is a linear polysaccharide, with a β(1→3):β(1→6) ratio of 3:1. Its hydrolysis is catalyzed by enzymes such as laminarinase (EC 3.2.1.6) that breaks the β(1→3) bonds. It has been suggested that the annual production of algae laminarin amounts to 12 ± 8 gigatons,

Glucomannan is a water-soluble polysaccharide that is considered a dietary fiber. It is a hemicellulose component in the cell walls of some plant species. Glucomannan is a food additive used as an emulsifier and thickener. It is a major source of mannan oligosaccharide (MOS) found in nature, the other being galactomannan, which is insoluble.

thumb|500px|Subunit of a typical mannan showing four 1,4-linked beta-D-mannose units, one with a galactose side chain. Mannans are polymers containing the sugar mannose as a principal component. They are a type of polysaccharide found in hemicellulose, a major source of biomass found in higher plants such as softwoods. These polymers also typically contain two other sugars, galactose and glucose. They are often branched (unlike cellulose).

Callose is a plant polysaccharide. Its production is due to the glucan synthase-like gene (GLS) in various places within a plant. It is produced to act as a temporary cell wall in response to stimuli such as stress or damage. Callose is composed of glucose residues linked together through β-1,3-linkages, and is termed a β-glucan. It is thought to be manufactured at the cell wall by callose synthases and is degraded by β-1,3-glucanases. Callose is very important for the permeability of plasmodesmata (Pd) in plants; the plant's permeability is regulated by plasmodesmata callose (PDC). PDC is mad

Zymosan is a beta-glucan with repeating glucose units connected by β-1,3-glycosidic linkages. It binds to TLR 2 and Dectin-1 (CLEC7A). Zymosan is a ligand found on the surface of fungi, like yeast.

anionic polysaccharide produced by bacteria

chemical compound

Curdlan is a water-insoluble linear beta-1,3-glucan, a high-molecular-weight polymer of glucose. Curdlan consists of β-(1,3)-linked glucose residues and forms elastic gels upon heating in aqueous suspension.

Xyloglucan is a hemicellulose that occurs in the primary cell wall of all vascular plants; however, all enzymes responsible for xyloglucan metabolism are found in Charophyceae algae. In many dicotyledonous plants, it is the most abundant hemicellulose in the primary cell wall. Xyloglucan binds to the surface of cellulose microfibrils and may link them together. It is the substrate of xyloglucan endotransglycosylase, which cuts and ligates xyloglucans, as a means of integrating new xyloglucans into the cell wall. It is also thought to be the substrate of alpha-expansin, which promotes cell wall

Chrysolaminarin is a linear polymer of β(1→3) and β(1→6) linked glucose units in a ratio of 11:1. It used to be known as leucosin.

thumb|Gummy bears made with polydextrose Polydextrose is a synthetic polymer of glucose. It is a food ingredient classified as soluble fiber by the US FDA as well as Health Canada, . It is frequently used to increase the dietary fiber content of food, to replace sugar, and to reduce calories and fat content. It is a multi-purpose food ingredient synthesized from dextrose (glucose), plus about 10 percent sorbitol and 1 percent citric acid. Its E number is E1200. The FDA approved it in 1981.

Lichenin, also known as lichenan or moss starch, is a complex glucan occurring in certain species of lichens and grains. It can be extracted from Cetraria islandica (Iceland moss). It has been studied since about 1957.

Arabinogalactan, also known as galactoarabinan, larch arabinogalactan, and larch gum, is a biopolymer consisting of arabinose and galactose monosaccharides. Two classes of arabinogalactans are found in nature: plant arabinogalactan and microbial arabinogalactan. In plants, it is a major component of many gums, including gum arabic and gum ghatti. It is often found attached to proteins, and the resulting arabinogalactan protein (AGP) functions as both an intercellular signaling molecule and a glue to seal plant wounds.

Arabinoxylan is a form of the hemicellulose xylan found in both the primary and secondary cell walls of plants which in addition to xylose contains substantial amounts of another pentose sugar, arabinose. The term arabinoxylan usually refers to feruloyl-arabinoxylan from grasses and other commelinids containing moieties of the phenolic ferulic acid that can undergo oxidative coupling (in the same way as lignin units) forming crosslinks between arabinoxylan chains and with lignin. Whilst arabinose has been found linked to xylan in non-commelinid plants, ferulic acid has not been reported on the

Paramylon is a carbohydrate similar to starch. The chloroplasts found in Euglena contain chlorophyll which aids in the synthesis of carbohydrates to be stored as starch granules and paramylon.

Acemannan is a D-isomer mucopolysaccharide in aloe vera leaves. This compound has potential immunostimulant, antiviral, antineoplastic, and gastrointestinal properties.

Schizophyllan (Sonifilan, SPG) is a neutral extracellular polysaccharide produced by the fungus Schizophyllum commune. Schizophyllan is a β-1,3 beta-glucan with β-1,6 branching. Schizophyllan is also known as sizofiran.

chemical compound

Homopolysaccharides are polysaccharides composed of a single type of sugar monomer. For example, cellulose is an unbranched homopolysaccharide made up of glucose monomers connected via beta-glycosidic linkages; glycogen is a branched form, where the glucose monomers are joined by alpha-glycosidic linkages. Depending upon the molecules attached that are of the following types:

thumb|upright=2|Components of Ficoll Ficoll is a neutral, highly branched, high-mass, hydrophilic polysaccharide synthesized from repeating sucrose units, which dissolves readily in aqueous solutions. Ficoll radii range from 2 to 7 nm. It is prepared by reaction of the polysaccharide with epichlorohydrin. Ficoll is a registered trademark owned by GE Healthcare companies.

Agaropectin is one of the two main components of agar.

Icodextrin (INN, USAN) is a colloid osmotic agent, derived from maltodextrin, used in form of an aqueous solution for peritoneal dialysis under the trade name Extraneal, and after gynecological laparoscopic surgery for the reduction of post-surgical adhesions (fibrous bands that form between tissues and organs) under the trade name Adept.

Pleuran is an insoluble polysaccharide (β-(1,3/1,6)-D-glucan), isolated from Pleurotus ostreatus.