Download MendeleyElectrochemical Insight into the Copper Redox Chemistry and H 2 O 2 and O 2 Reducing Capability of Two AA10 Lytic Polysaccharide Monooxygenases.
Reid, E.K., Miles, C.G., Lloyd-Laney, H.O., Nairn, A.K., Branch, J., Garland, N., Yates, N.D.J., Ascham, A., Walton, P.H., Hemsworth, G., Parkin, A.(2026) ACS Electrochem 2: 239-257
- PubMed: 41669087 Search on PubMedSearch on PubMed Central
- DOI: https://doi.org/10.1021/acselectrochem.5c00266
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9I1U - PubMed Abstract:
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 Cu 2+/1+ redox chemistry and the polysaccharide-free catalytic activity of two AA10 LPMOs: Cj AA10B from Cellvibrio japonicus and Cf AA10 from Cellulomonas fimi . Immobilisation of these enzymes on the surface of a graphite electrode allows for direct electrochemical measurements of Cu 2+/1+ redox cycling as well as the ability of both LPMOs to reduce H 2 O 2 vs O 2 . 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 H 2 O 2 and O 2 reduction by Cj AA10B and Cf AA10 from pH 5-7, with Cf AA10 consistently outperforming Cj AA10B. Both enzymes perform faster catalysis with H 2 O 2 but when comparing the affinity-coupled specificity constant ( k cat / K M ), the LPMOs perform similarly with both H 2 O 2 and O 2 , 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
K a ∼ 4.6). The increase in signal size with decreasing pH that is seen for the non-catalytic Cu 2+/1+ transition is interpreted in light of an increasing proportion of electroactive species at low pH; such a change in activity with pH is notably not observed in the presence of substrate (H 2 O 2 or O 2 ). This suggests that substrate binding modulates the active site, disrupting the effect of protonation. These findings establish electrochemistry as a powerful tool for probing LPMO activity. - Department of Chemistry, University of York, Heslington, York YO10 5DD, U.K.
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