Xylan from pears

CiiHigOii 326.257 Isol. from partial acid hydrolysates of sunflower (Helianthus annuus) head hemicellulose, from pear cell-wall xylan, from various wheat-straw preparations and from corn hulls. 

A xylan from esparto grass 63, 64) is a singly branched chain of about 76 D-xylopyranose units linked jS-D-1— 4 in the main chain but with a 1—>3 link at the point of branching. From the cell wall of pear wood, another similarly single-branched xylan is obtained which has about 115 D-xylo-pyranose units, but it contains, in addition, a terminal D-glucopyranosyl-uronic acid unit at one point 65), The xylan from the red seaweed 57,58) Rhodymenia palmata seems to be composed only of D-xylopyranose units... 

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