|Superclasses:||all carbohydrates → a carbohydrate → a glycan → a polysaccharide|
Please note that hemicellulose is a not a precise biological term.
The plant cell wall is composed of cellulose and many additional complex polymers. Unlike cellulose, which is crystalline and resistant to hydrolysis, the other polymers are amorphous and are easily hydrolyzed by dilute acid or base.
Hemicellulose is a heterogeneous term that is used for all the plant cell wall components that are soluble in dilute alkali solutions, or that go into solution quite readily in hot dilute mineral acids with the formation of simple sugars. The term is often used to describe all the polysaccharide components of the cell wall other than cellulose.
Hemicelluloses constitute about one-fourth of perennial plants and about one-third of annual plants. Since the term does not refer to a particular chemical entity, hemicelluloses extracted from different plant sources are rarely identical. However, D-xylose is the dominant building unit of the hemicelluloses of most woods and annual plants. D-xylose occurs as the polymer xylan, as derivatives of xylan, such as glucuronoxylan and arabinoxylan, and as side chains on other types of backbones, such as xyloglucan and xylogalacturonan. D-Mannose is also very abundant, and occurs as the polymer mannan or in combination with D-glucose or D-galactose as glucomannans, galactomannan, or galactoglucomannan. Arabinose is common as well, either in the form of L-arabinan or in the form of side chains on other polysaccharides.
Hemicellulose consists of shorter chains than cellulose, typically 500 - 3,000 sugar units, and is usually branched.
Unification Links: Wikipedia:Hemicellulose
Reactions known to produce the compound:
Capek00: Capek P, Kubackova M, Alfoldi J, Bilisics L, Liskova D, Kakoniova D (2000). "Galactoglucomannan from the secondary cell wall of Picea abies L. Karst." Carbohydr Res 329(3);635-45. PMID: 11128591
Gordillo06: Gordillo F, Caputo V, Peirano A, Chavez R, Van Beeumen J, Vandenberghe I, Claeyssens M, Bull P, Ravanal MC, Eyzaguirre J (2006). "Penicillium purpurogenum produces a family 1 acetyl xylan esterase containing a carbohydrate-binding module: characterization of the protein and its gene." Mycol Res 110(Pt 10);1129-39. PMID: 17008082
Katsuraya03: Katsuraya, K., Okuyama, K., Hatanaka, K., Oshima, K., Sato, T., Matsuzaki, K. (2003). "Constitution of konjac glucomannan: chemical analysis and 13C NMR spectroscopy." Carbohydr Polym. 53: 183-189.
Madson03: Madson M, Dunand C, Li X, Verma R, Vanzin GF, Caplan J, Shoue DA, Carpita NC, Reiter WD (2003). "The MUR3 gene of Arabidopsis encodes a xyloglucan galactosyltransferase that is evolutionarily related to animal exostosins." Plant Cell 15(7);1662-70. PMID: 12837954
Reid95: Reid, J.S.G., Edwards, M.E. (1995). "Galactomannans and other cell wall storage polysaccharides in seeds." In: Stephen AM (ed), Food polysaccharides and their applications. Marcel Dekker, New York, p. 155-186.
Schadel10: Schadel C, Richter A, Blochl A, Hoch G (2010). "Hemicellulose concentration and composition in plant cell walls under extreme carbon source-sink imbalances." Physiol Plant 139(3);241-55. PMID: 20113432
Teleman03: Teleman A, Nordstrom M, Tenkanen M, Jacobs A, Dahlman O (2003). "Isolation and characterization of O-acetylated glucomannans from aspen and birch wood." Carbohydr Res 338(6);525-34. PMID: 12668108
Vignon98: Vignon, M. R., Gey, C. (1998). "Isolation, 1H and 13C NMR studies of (4-O-methyl-D-glucurono)-D-xylans from luffa fruit fibres, jute bast fibres and mucilage of quince tree seeds." Carbohydrate Research 307(1-2):107-111.
Whitney95: Whitney, S. E. C., Brigham, J. E., Darke, A. H., Reid, J. S. G., Gidley, M. J. (1995). "In vitro assembly of cellulose/xyloglucan networks: ultrastructure and molecular aspects." Plant J 8, 491-504.
York93: York WS, Harvey LK, Guillen R, Albersheim P, Darvill AG (1993). "Structural analysis of tamarind seed xyloglucan oligosaccharides using beta-galactosidase digestion and spectroscopic methods." Carbohydr Res 248;285-301. PMID: 8252539
Zandleven07: Zandleven J, Sorensen SO, Harholt J, Beldman G, Schols HA, Scheller HV, Voragen AJ (2007). "Xylogalacturonan exists in cell walls from various tissues of Arabidopsis thaliana." Phytochemistry 68(8);1219-26. PMID: 17336350
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