Hemicellulosic polysaccharides from bamboo shoot cell-walls

Cell-wall polysaccharides of bamboo shoots were extracted with chelating reagent (CDTA, trans-1,2-cyclohexanediamine-N,N,N',N'-acid), Na2CO3 and KOH solutions. Glycosyl composition and glycosyl linkage analyses showed that-the hemicellulose was composed of arabinoxylan; (1 --> 3, 1-->4)-beta-D-glucan, xyloglucan and glucomannan. (1-->3, 1-->4)-beta-D-glucan was purified by anion-exchange chromatography and xylanase-treatment. It consisted of 20-30% of 3-linked and 70-80% of 4-linked glucosyl residues, having a M-r range of 100 000-380 000. Hydrolysis of the glucan with a purified cellulase {endo-beta-(1 --> 4)-glucanase}, released glucose, cellobiose and Glcp-(1 --> 4)-beta-D-Glcp-(1 --> 3)-beta-D-Glcp. Oligosaccharides having contiguous 3-linked glucosyl residues were not detected. The structure of (1 --> 3, 1 --> 4)-beta-D-glucan of bamboo shoot cell-walls was thus determined to be -->3)-beta-D-Glcp-[-(1 --> 4)-beta-D-Glcp-](2-4)-(1--> Xyloglucan was purified by anion-exchange chromatography, precipitation with iodide and gel-permeation chromatography. Arabinoxylan could not be separated completely by the procedure. The remaining arabinoxylan could not be degraded completely by xylanase treatment Any linkage between arabinoxylan and xyloglucan would retard removal of arabinoxylan. (C) 1998 Elsevier Science Ltd, All rights reserved.