Oxidation of milled wood lignin with laccase, tyrosinase and horseradish peroxidase

Stina Grönqvist (Corresponding Author), Liisa Viikari, Marja-Leena Niku-Paavola, M. Orlandi, C. Canevali, Johanna Buchert

Research output: Contribution to journalArticleScientificpeer-review

47 Citations (Scopus)


In this paper the oxidation of milled wood lignin (MWL), catalysed by three enzymes, i.e. laccase, tyrosinase and horseradish peroxidase (HRP) was studied. The oxidation was followed by measuring the consumption of O2 during laccase and tyrosinase treatment and of H2O2 during HRP treatment. Both laccase and HRP were found to oxidise lignin effectively, whereas the effect of tyrosinase was negligible. The changes in MWL molecular-weight distributions caused in the reactions were analysed by gel permeation chromatography. Both laccase and HRP treatments were found to polymerise MWL. Peroxidase treatment was found to decrease the amount of phenolic hydroxyls in MWL, whereas no such effect could be detected in the laccase-treated sample. Both laccase and HRP treatments were, however, found to increase the amount of conjugated structures in MWL. The formation of phenoxy radicals during the treatments was studied by electron paramagnetic resonance spectroscopy. Phenoxy radicals were detected in both laccase and HRP-treated samples. The amount of the formed phenoxy radicals was found to be essentially constant during the detected time (i.e. 20–120 min after the addition of enzyme).
Original languageEnglish
Pages (from-to)489 - 494
Number of pages6
JournalApplied Microbiology and Biotechnology
Issue number4
Publication statusPublished - 2005
MoE publication typeA1 Journal article-refereed


  • lignin
  • milled wood lignin
  • enzymes
  • laccase
  • tyrosinase
  • horseradish peroxidase
  • oxidation

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