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United States Department of Agriculture

Agricultural Research Service

Title: Mechanisms of Polysaccharide-Polysaccharide and Polysaccharide-Lignin Cross-Linking in Grasses

Authors
item Ralph, John
item Hatfield, Ronald
item Grabber, John
item Quideau, Stephane - UNIV OF WISCONSIN-MADISON
item Helm, Richard - VIRGINIA TECH

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

Technical Abstract: Grasses utilize ferulic acid as an intermediary in cross-linking polysaccharides to each other and to lignin. Until recently, the mechanisms and extent of this cross-linking had been poorly understood and grossly underestimated. Ferulate polysaccharide esters dimerize, via oxidative coupling, to produce a range of dehydrodiferulates, only one of which had previously been recognized and quantitated. Active incorporation of ferulates and dehydrodiferulates directly into the lignin polymer via oxidative coupling mechanisms has been unequivocally demonstrated and predominates over the traditionally invoked incorporation via lignin quinone methides. Such incorporation produces a range of structures from which ferulate or diferulates cannot be released and therefore cannot be quantitated. Ferulates (and presumably diferulates) have now been shown to function as initiation or nucleation sites for wall lignification. They attach exclusively to lignin monomers and are thus critical entities in directing lignification and wall cross-linking during plant development. The cross-linking of polysaccharides to each other and to lignin also has a marked impact on the degradability of wall polysaccharides.

Last Modified: 10/25/2014
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