Abstract
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 language | English |
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Pages (from-to) | 489 - 494 |
Number of pages | 6 |
Journal | Applied Microbiology and Biotechnology |
Volume | 67 |
Issue number | 4 |
DOIs | |
Publication status | Published - 2005 |
MoE publication type | A1 Journal article-refereed |
Keywords
- lignin
- milled wood lignin
- enzymes
- laccase
- tyrosinase
- horseradish peroxidase
- oxidation