MetaCyc Compound Class: a pectin

Synonyms: pectin

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].

a pectin compound structure

a pectin compound structure

Child Classes: methylesterified 1,4-α-D-galactosyluronate (0)

SMILES: COC(=O)C4(C([R1])C(O)C(O)C(OC3(C(C([O-])=O)OC(OC2(C(O)C(O)C(OC1(C(C(=O)[O-])OC(O[R2])C(O)C(O)1))OC(C(=O)OC)2))C(O)C(O)3))O4)

Unification Links: CAS:9000-69-5 , ChEBI:17309 , HMDB:HMDB03402 , KEGG:C00714 , PubChem:451205 , Wikipedia:Pectin

Reactions known to consume the compound:

pectin degradation I :
a pectin → 4-(4-deoxy-α-D-galact-4-enuronosyl)-D-galacturonate

pectin degradation II , pectin degradation III :
a pectin + n H2O → a pectate + n methanol

Reactions known to produce the compound:

cellulose and hemicellulose degradation (cellulolosome) :
a feruloyl-polysaccharide + H2O → ferulate + a polysaccharide + H+

In Reactions of unknown directionality:

Not in pathways:
a pectin = n an oligosaccharide with 4-deoxy-6-O-methyl-α-D-galact-4-enuronate end

Revised 31-Aug-2009 by Caspi R , SRI International


Abbott08: Abbott DW, Boraston AB (2008). "Structural biology of pectin degradation by Enterobacteriaceae." Microbiol Mol Biol Rev 72(2);301-16, table of contents. PMID: 18535148

Caffall09: Caffall KH, Mohnen D (2009). "The structure, function, and biosynthesis of plant cell wall pectic polysaccharides." Carbohydr Res 344(14);1879-900. PMID: 19616198

HugouvieuxCotte96: Hugouvieux-Cotte-Pattat N, Condemine G, Nasser W, Reverchon S (1996). "Regulation of pectinolysis in Erwinia chrysanthemi." Annu Rev Microbiol 50;213-57. PMID: 8905080

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

Reginault08: Reginault, Ph., Valette-Collet , O., Boccara, M. (2008). "The importance of fungal pectinolytic enzymes in plant invasion, host adaptability and symptom type." Eur. J. Plant Pathol.

Richard09: Richard P, Hilditch S (2009). "D-galacturonic acid catabolism in microorganisms and its biotechnological relevance." Appl Microbiol Biotechnol 82(4);597-604. PMID: 19159926

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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