xylan


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xylan

(zī′lən)
n.
A yellow, water-soluble, gummy polysaccharide found in plant cell walls and yielding xylose upon hydrolysis.
References in periodicals archive ?
Xylanase production with xylan rich lignocellulosic wastes by a local soil isolate of Trichoderma viride.
Media were supplemented by 0.5 gm of Birchwood xylan and 1 gm of corn cobs as substrates.
The conversion of cellulose and hemicellulose can be expressed by the reaction of glucan (for hexoses) and xylan (for pentose) with water:
Beech wood xylan ([M.sub.w] - 130,000 g/mol) and PVA ([M.sub.w] of 146,000-186,000 g/mol) were purchased from Sigma Aldrich (Germany) and used without further purification.
To obtain beechwood soluble xylan, a suspension of xylan in water (2%, w/v) was autoclaved for 1h at 120[degrees]C (2 kg x [cm.sup.-1]) and centrifuged at 5,000 rpm for 1h at 4[degrees]C.
At the same time, the substrate solution was prepared by dissolving 0.16 g of pure mannan, xylan, a-galactose and [beta]-glucan (Sigma, St Louis, MO, USA) in 20 mL of [Na.sub.2]HP[O.sub.4]-citric acid buffer (pH 2.4).
For selective isolation of xylanase producing fungi Czapeck's Dox Agar with Birch wood xylan 5.0g, Pepton 5.0g, Yeast extract 5.0g, MgS[O.sub.4] 0.2g, K[H.sub.2]P[O.sub.4] 1.0g, Agar-Agar 20.0g, Distilled water 1000 ml.
These include the retention of exoacting cellobiohydrolase (CBH) cellulase genes, but, similar to Postia placenta, the absence of carbohydrate esterase family 1 (CE 1), a family containing feruloyl esterases (EC 3.1.1.73) that might be involved in decoupling xylan from lignin, particularly in the decay of grasses [16].
Hemicelluloses account for 22-35% of the bamboo composition, and the dominant species is xylan [1].
They randomly catalyze the endohydrolysis of 1,4-[beta]-D-xylosidic linkages in xylan [1].
Wallwork also provides dry lubricating films with both Molybdenum Disulphate and Xylan.
The presence of readily metabolizable carbon sources like glucose, cellobiose, xylobiose, or xylose represses the synthesis of xylanase enzymes for the utilization of certain carbon sources such as xylan or cellulose and the process is known as catabolite repression.