Synonyms: MGX, 4-O-methyl-D-glucurono-D-xylan
|Superclasses:||all carbohydrates → a carbohydrate → a glycan → a polysaccharide → hemicellulose → xylan → a (1->4)-beta-D-xylan|
Glucuronoxylans are a component of hemicellulose. They are linear polymers of β-D-xylopyranosyl units linked by (1→4) glycosidic bonds, with many of the xylose units substituted with 2,2 or 2,3-linked glucuronate residue, which are often methylated at position 4. Most of the glucuronoxylans have single 4-O-methyl-α-D-glucopyranosyl uronate residues (MeGlcA) attached at position 2. This structural type is usually named as 4-O-methyl-D-glucurono-D-xylan (MGX).
Angiosperm (hardwood) glucuronoxylans also have a high rate of substitution (70-80%) by acetyl groups, at position 2 and/or 3 of the β-D-xylopyranosyl, conferring on the xylan its partial solubility in water.
The ratio of xylosyl residues to D-glucuronate/4-O-methylglucuronate residues in glucuronoxylans varies greatly among species. An average ratio of 10:1 is accepted, although it can be as high as 2:1, for example, in quince ( Cydonia oblonga) seeds [Vignon98].
Reactions known to consume the compound:
Not in pathways:
xylan + n H2O → n α-D-xylopyranose
Reactions known to produce the compound:
Not in pathways:
acetylxylan + n H2O → xylan + n acetate
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
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
Shatalov99: Shatalov AA, Evtuguin DV, Pascoal Neto C (1999). "(2-O-alpha-D-galactopyranosyl-4-O-methyl-alpha-D-glucurono)-D-xylan from Eucalyptus globulus Labill." Carbohydr Res 320(1-2);93-9. PMID: 10515063
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.
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