Applied Microbiology and Biotechnology

, Volume 48, Issue 4, pp 459–464 | Cite as

Identification and quantification of radical reaction intermediates by electron spin resonance spectrometry of laccase-catalyzed oxidation of wood fibers from beech (Fagus sylvatica)

  • C. Felby
  • B. R. Nielsen
  • P. O. Olesen
  • L. H. Skibsted
ORIGINAL PAPER

Abstract

During laccase-catalyzed oxidation of beech wood fibers in an aqueous suspension, phenoxy radicals were detected in steady-state concentrations by electron-spin resonance (ESR) spectrometry of the suspension liquid, suggesting that colloidal lignin functions as a mediator between laccase and the fiber lignin matrix. Phenoxy radicals were observed directly, whereas ESR spin-trapping techniques gave no evidence for reduced oxygen species, such as the superoxide or hydroxyl radical. A reaction mechanism involving parallel direct oxidation of the lignin on fiber surfaces and a phenol/phenoxy cyclic mediator process in the suspension liquid could accordingly describe laccase-catalyzed oxidation of beech wood fibers. Cytochrome c assays for detection of superoxide in systems involving lignin oxidized by oxidoreductases should be used with caution, as cytochrome c may be reduced by species other than superoxide.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • C. Felby
    • 1
  • B. R. Nielsen
    • 2
  • P. O. Olesen
    • 1
  • L. H. Skibsted
    • 2
  1. 1.Plant Fibre Laboratory, Royal Veterinary and Agricultural University, Agrovej 10, DK-2630 Taastrup, DenmarkDK
  2. 2.Department of Dairy and Food Science, Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg C, DenmarkDK

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