Oxidative coupling during lignin polymerization is determined by unpaired electron delocalization within parent phenylpropanoid radicals

Wendy Roslyn Russell, M J Burkitt, A R Forrester, Andrew Chesson

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

The high degree of selectivity observed in the incorporation of phenylpropanoids into lignin may be a consequence of the influence exerted by methoxyl substituents on the ambident radicals generated during biosynthesis. Since unpaired electron distribution may be regarded as an important factor in determining positional selectivity during oxidative coupling, electron spin resonance spectroscopy and Austin Model 1 molecular computation were used to study the effects of methoxyl substitution on unpaired electron distribution in lignin precursor radicals. The data obtained were used to predict the effect of substitution on coupling and were compared with the linkage types observed in complementary dehydrogenation polymerization studies employing each of the lignin precursors. We report that methoxyl substitution increases unpaired electron density on the phenolic oxygen of the precursor phenylpropanoid radicals and that this subsequently determines the nature of the bond formation during polymerization. (C) 1996 Academic Press, Inc.
Original languageEnglish
Pages (from-to)357-366
Number of pages10
JournalArchives of Biochemistry and Biophysics
Volume332
Issue number2
Publication statusPublished - Aug 1996

Keywords

  • phenolic-acids
  • wheat
  • internodes
  • phalaris
  • bridges
  • linkage
  • walls
  • straw
  • EPR

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