ARS | Publication request: MOLECULAR MODELLING OF DEHYDRODIFERULATES:ARE INTRAMOLECULAR DIMERS FEASIBLE WITHIN GRASS WALLS?

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: March 28, 1996
Publication Date: N/A

Technical Abstract: The structural and functional role of plant walls is determined by complex interactions among wall components. Molecular modeling is a tool useful for understanding the nature of these interactions, providing a means of predicting the feasibility of bond formation between macromolecules. Recent work with grasses indicates that the formation of cell wall dehydrodiferulates is much more pronounced than previously measured, suggesting a greater extent of arabinoxylan crosslinking, thus changing the physical characteristics of the wall matrix. Arabinoxylan crosslinking would not occur if some dehydrodiferulates arose from intramolecular instead of intermolecular coupling. Molecular modeling was used to evaluate the feasibility of intramolecular diferulate formation. Two ferulates were positioned at various locations along the backbone of an arabinoxylan (16 xylose residues) and the optimized structure generated using MM2 parameters. For ferulates separated by several xylose residues, diferulates could only form if the xylan backbone relaxed allowing chain folding to bring the two ferulates within spatial proximity for bonding. For positions that would allow overlap of ferulates, one or both of the ferulates would have to rotate along the xylan backbone to be positioned for radical coupling. In both cases high energy barriers prevented the complete rotation to allow bond formation. It would therefore seem unlikely for intramolecular dehydrodiferulates to readily form within grass cell walls.