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Abstract Detail


Cell Walls

Rizk, Sandra [1], Baydoun, Elias [2].

Identification of EDTA-soluble polysaccharides form pea epicotyls cell walls and their interaction with xyloglucan.

Nascent pectin and glucuronoxylan were prepared from membrane-bound enzymes obtained from pea epicotyls; they were previously shown to exhibit a protein- and pH-dependant pattern of binding to xyloglucan extracted from cell walls. The same pattern of binding seems to occur between these polymers and cell wall ghosts prepared form pea epicotyls; maximum binding requires a pH of 3-4, and protease treatment of the cell walls prior to binding assays completely abolishes the pH-dependant binding pattern. This confirms the requirement of cell wall proteins, namely assemblins, for the pH-dependant binding of nascent polysaccharides to cell walls. In an attempt to prove that wall polysaccharides deposited in cell walls behave in the same manner, radioactively labeled EDTA-soluble polymers were prepared from formed pea epicotyls cell walls; different enzyme treatments followed by column chromatography analysis, in addition to complete acid hydrolysis followed by paper and thin layer chromatography proves the greater abundance of pectin, with the minor presence of glucuronoxylan, in this EDTA-soluble extract. These radioactively labeled polysaccharides bind to xyloglucan extracted from the second and third internodes of pea epicotyls cell walls in a pH dependant-binding manner, similar to the binding pattern obtained with nascent polymers. Maximum binding, which occurs at pH 3-4 also requires the presence of a protein; however due to insufficient material, it was hard to determine the molecular weight of the protein to confirm that it is the same as the assemblin that was previously shown to have a molecular weight ranging between 21.5 and 31 kDa.


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1 - Lebanese American University, Natural Sciences Division, Sage Hall-303- Lebanese American University of Beirut-Chouran, Beirut, 1102-2801, Lebanon
2 - American University of Beirut, Biology

Keywords:
Pectin
assemblins
cell wall.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P17019
Abstract ID:909


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