Electrochemical Insight into the Copper Redox Chemistry and H 2 O 2 and O 2 Reducing Capability of Two AA10 Lytic Polysaccharide Monooxygenases

Journal article

Lytic polysaccharide monooxygenases ([L]­PMOs) are copper-containing enzymes that catalyse cleavage of the glycosidic bond, a process central to microbial biomass degradation. Here, we describe electrochemical methods used to investigate the Cu2+/1+ redox chemistry and the polysaccharide-free catalytic activity of two AA10 LPMOs: CjAA10B from Cellvibrio japonicus and CfAA10 from Cellulomonas fimi. Immobilisation of these enzymes on the surface of a graphite electrode allows for direct electrochemical measurements of Cu2+/1+ redox cycling as well as the ability of both LPMOs to reduce H2O2 vs O2. These measurements can be advantageous when compared to biological dye assays as they provide direct kinetic measurements and allow for investigation over a wider range of environmental conditions. Values of k cat and K M- are reported for H2O2 and O2 reduction by CjAA10B and CfAA10 from pH 5–7, with CfAA10 consistently outperforming CjAA10B. Both enzymes perform faster catalysis with H2O2 but when comparing the affinity-coupled specificity constant (k cat/K M), the LPMOs perform similarly with both H2O2 and O2, suggesting both substrates are viable. We also note an increase in redox signals as pH is decreased that correlates with EPR data suggesting a second species is formed

Authors: Reid, EK; Miles, CG; Lloyd-Laney, HO; Nairn, AK; Branch, J

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Chemical Society
• Journal: ACS Electrochemistry
• Volume: 2
• Issue: 2
• Pages: 239-257
• Publication date: 2026-01-15
• Acceptance date: 2025-12-12
• DOI: 10.1021/acselectrochem.5c00266
• EISSN: 2997-0571
• ISSN: 2997-0571
• Language: English
• Keywords: lytic polysaccharide monooxygenases; bioelectrochemical assay; enzyme electrochemistry; type-II copper protein film voltammetry