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Sci Rep. 2015 Dec 21;5:18561. doi: 10.1038/srep18561.

Enzymatic cellulose oxidation is linked to lignin by long-range electron transfer.

Author information

1
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1432 Ås, Norway.
2
University of Copenhagen, Faculty of Science, Department of Geoscience and Natural Resources Rolighedsvej 23, 1958 Frederiksberg C, Denmark.
3
Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, 2800 Lyngby, Denmark.
4
University of Copenhagen, Faculty of Science, Department of Food Science Rolighedsvej 30, 1958 Frederiksberg C, Denmark.

Abstract

Enzymatic oxidation of cell wall polysaccharides by lytic polysaccharide monooxygenases (LPMOs) plays a pivotal role in the degradation of plant biomass. While experiments have shown that LPMOs are copper dependent enzymes requiring an electron donor, the mechanism and origin of the electron supply in biological systems are only partly understood. We show here that insoluble high molecular weight lignin functions as a reservoir of electrons facilitating LPMO activity. The electrons are donated to the enzyme by long-range electron transfer involving soluble low molecular weight lignins present in plant cell walls. Electron transfer was confirmed by electron paramagnetic resonance spectroscopy showing that LPMO activity on cellulose changes the level of unpaired electrons in the lignin. The discovery of a long-range electron transfer mechanism links the biodegradation of cellulose and lignin and sheds new light on how oxidative enzymes present in plant degraders may act in concert.

PMID:
26686263
PMCID:
PMC4685257
DOI:
10.1038/srep18561
[Indexed for MEDLINE]
Free PMC Article

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