Xylan crystalline, properties

The properties of the enzymes used in this study have been described in former publications (10,11,15). Important for the following interpretation are their hydrolytic specificities. The xylanase did not hydrolyze either isolated mannans or celluloses—or only to a very small extent (10). The same is true for the mannanase with respect to xylans and celluloses (11,15). The avicelases, which were not purified to the same extent as the xylanase and mannanase, did not hydrolyze mannans, but they degraded xylans besides crystalline cellulose (10). Also, the highly purified cellobiohydrolase C (12) degraded xylan to some extent (Dr. E. K. Gum, Jr., personal communication). 

Although it was not realized at first, the hydrating properties of xylan extend to its crystalline state. The unit-cell is hexagonal (4) with ... 

The isolated glucuronoxylan was evaluated with respect to material properties. The solubility in water was limited, but it was fully soluble in 0.5 N NaOH solution. Heat treatment of xylan in water at 95 °C for 15 minutes gave an improvement in solubility. This solution was cast ontopetri dishes and the film formation was visually evaluted. The crystallinity of films was... 

In the past SO years wood chemists have learned much about the composition and physical properties of hardwood xylans. Partially acetylated glucuronoxylans are model native hardwood xylans. They exhibit thermoplasticity, film forming properties, crystallization potential and are oriented in the secondary cell wall. Their crystal structure has been determined and the hydration of this crystalline polysaccharide has been defined. The structural regularity of these abundant polysaccharides can be interpreted using the principle of optical superposition. 

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