Laccase-Catalyzed Oxidation of Lignin Induces Productionof H2O2

Valentina Perna, Anne S. Meyer, Jesper Holck, Lindsay D. Eltis, Vincent G.H. Eijsink, Jane Wittrup Agger*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Laccases are abundantin microorganisms specialized in lignocellulose degradation, but the exact role of the enzymes in this process remains poorly understood. Laccases catalyze oxidation of lignin, initially producing a phenoxy radical. The heterogeneous lignin structure canstabilize these reactive radicals, but eventually, they dissipate by uncharacterized mechanisms. We show that the laccase-catalyzed oxidation of lignin leads to formation of H2O2, likely via a reaction between lignin radicals and O2. Up to 25 μM of H2O2 was generated byeach of four fungal and bacterial laccases catalyzing oxidation of both organosolv lignin and birch wood. The generated H2O2 activated lytic polysaccharide monooxygenases (LPMOs) both in separate reactions, where the LPMOs were fed with laccase-generated H2O2, and in one-pot reactions, where laccases and LPMOs acted simultaneously. These observations are new, and our results reveal a potentially critical connection between conversion of lignin and polysaccharides, suggesting that laccases generate H2O2 for other lignocellulose-depolymerizing enzymes such as lignin peroxidases and LPMOs. This new role for laccases maybe exploited in application settings. 
Original languageEnglish
JournalACS Sustainable Chemistry and Engineering
Volume8
Issue number2
Pages (from-to)831-841
Number of pages11
ISSN2168-0485
DOIs
Publication statusPublished - 2020

Keywords

  • Laccase
  • Lignin
  • H2O2
  • LPMOs

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