|Superclasses:||all carbohydrates → a carbohydrate → a glycan → a polysaccharide → a galacturonan → a modified galacturonan|
Pectin is a structural heteropolysaccharide consisting of a complex set of polysaccharides that is present in most primary cell walls and is particularly abundant in the non-woody parts of terrestrial plants. It s involved in crosslinking cellulose and hemicellulose fibers, which provides rigidity to the cell wall. The characteristic structure of pectin is a linear chain of α-(1-4)-linked D-galacturonate that forms the pectin-backbone, a homogalacturonan.
Diferent types of pectin have different substitutions and additions. A common type is rhamnogalacturonan I, where some D-galacturonate units are replaced by (1-2)-linked L-rhamnose, to which side chains of various neutral sugars branch off, mostly D-galactose, L-arabinose and α-D-xylopyranose.
In nature, around 80% of the carboxyl groups of the galacturonate units are esterified with methanol. Some plants, including sugar beet, potatoes and pears, contain pectins with acetylated galacturonate in addition to methyl esters.
The salt of partially esterified pectins is called a pectinate, and if the degree of esterification is below 5%, a pectate.
Pectin is used in the animal feed industry and in the food industry as a gelling agent. Phytopathogenic and saprophytic bacteria and fungi can produce variety of extracellular and intracellular enzymes that degrade pectin and its derivatives. Pectinolytic enzymes such as esterases, hydrolases and lyases, are used in the food, fiber and animal feed industries. There is commercial interest in pectinolytic enzymes to convert the pectin-rich by-products from citrus peel and sugar beet processing to higher value material. In [MartensUzunova09] [Abbott08] and reviewed in [Richard09, Reginault08, HugouvieuxCotte96]. Pectin structure is reviewed in [Caffall09].
Child Classes: methylesterified 1,4-α-D-galactosyluronate (0)
Reactions known to consume the compound:
Reactions known to produce the compound:
In Reactions of unknown directionality:
MartensUzunova09: Martens-Uzunova ES, Schaap PJ (2009). "Assessment of the pectin degrading enzyme network of Aspergillus niger by functional genomics." Fungal Genet Biol 46 Suppl 1;S170-S179. PMID: 19618506
©2016 SRI International, 333 Ravenswood Avenue, Menlo Park, CA 94025-3493