Lytic Polysaccharide Monooxygenase Activity in Biomass Degradation

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that catalyse the oxidative cleavage of recalcitrant polysaccharides such as cellulose and hemicellulose. By introducing chain breaks via oxidation rather than hydrolysis, LPMOs disrupt the rigid crystalline structure of lignocellulose and render it more accessible to classical hydrolytic enzymes. Their activity is driven by molecular oxygen or hydrogen peroxide, in conjunction with an external electron donor, and is often enhanced by synergy with cellulases and hemicellulases. In natural ecosystems, LPMOs contribute to carbon cycling by decomposing plant litter, while in industrial biorefineries they underpin advanced enzyme cocktails for the production of fermentable sugars. Recent work has revealed abiotic contributors—such as visible-light-activated lignin fragments—that generate hydrogen peroxide and fuel enzymatic turnover, offering new strategies for process intensification. A deeper understanding of LPMO structure–function relationships, reaction intermediates and electron-transfer pathways is vital to optimise their deployment in sustainable biofuel and bioproduct manufacturing.

Research from Nature Portfolio

Visible-light exposure of lignin has been shown to promote in situ formation of hydrogen peroxide, which primes LPMOs for enhanced oxidative cleavage of cellulose. Photochemical oxidation of aromatic lignin units generates redox equivalents, establishing a link between sunlight and enzymatic biomass conversion. Foundational structural studies of a starch-active LPMO (AA13 family) have elucidated its three-dimensional copper-binding site and demonstrated its ability to boost starch saccharification when paired with amylases. Investigations using electron paramagnetic resonance have revealed that high-molecular-weight lignin serves as a long-range electron reservoir, transferring electrons via low-molecular-weight mediators to the copper centre of LPMOs and uniting lignin and cellulose depolymerisation pathways.

Lytic Polysaccharide Monooxygenase Activity in Biomass Degradation publication trend

The graph below shows the total number of articles in lytic polysaccharide monooxygenase activity in biomass degradation across all publications each year (not limited to Nature Index journals).

Technical terms

Lytic polysaccharide monooxygenase (LPMO): A copper-dependent enzyme that oxidatively cleaves glycosidic bonds in crystalline polysaccharides.

Histidine brace: A bidentate copper-binding motif formed by two histidine residues, essential for LPMO catalytic activity.

Regioselectivity: The preference of an enzyme to oxidise a specific carbon position (e.g. C1 or C4) on a sugar ring.

Crystalline cellulose: Highly ordered cellulose fibrils that resist enzymatic hydrolysis without prior disruption.

Lignocellulose: A composite of cellulose, hemicellulose and lignin forming plant cell-wall biomass.

Electron donor: A molecule (e.g. ascorbate, lignin fragments or photoactivated pigments) that provides reducing equivalents to the LPMO copper centre.

References

1. Visible light-exposed lignin facilitates cellulose solubilization by lytic polysaccharide monooxygenases. Nature Communications (2023).
2. A Conserved Second Sphere Residue Tunes Copper Site Reactivity in Lytic Polysaccharide Monooxygenases. Journal of the American Chemical Society (2023).
3. Electrochemical Monitoring of Heterogeneous Peroxygenase Reactions Unravels LPMO Kinetics. ACS Catalysis (2024).
4. A novel approach to analyze the impact of lytic polysaccharide monooxygenases (LPMOs) on cellulosic fibres. Carbohydrate Polymers (2023).
5. Structure and boosting activity of a starch-degrading lytic polysaccharide monooxygenase. Nature Communications (2015).
6. Enzymatic cellulose oxidation is linked to lignin by long-range electron transfer. Scientific Reports (2015).