Issue 13, 2024

A frontier-orbital view of the initial steps of lytic polysaccharide monooxygenase reactions

Abstract

Lytic polysaccharide monooxygenases (LPMOs) are copper enzymes that oxidatively cleave the strong C–H bonds in recalcitrant polysaccharide substrates, thereby playing a crucial role in biomass degradation. Recently, LPMOs have also been shown to be important for several pathogens. It is well established that the Cu(II) resting state of LPMOs is inactive, and the electronic structure of the active site needs to be altered to transform the enzyme into an active form. Whether this transformation occurs due to substrate binding or due to a unique priming reduction has remained speculative. Starting from four different crystal structures of the LPMO LsAA9A with well-defined oxidation states, we use a frontier molecular orbital approach to elucidate the initial steps of the LPMO reaction. We give an explanation for the requirement of the unique priming reduction and analyse electronic structure changes upon substrate binding. We further investigate how the presence of the substrate could facilitate an electron transfer from the copper active site to an H2O2 co-substrate. Our findings could help to control experimental LPMO reactions.

Graphical abstract: A frontier-orbital view of the initial steps of lytic polysaccharide monooxygenase reactions

Supplementary files

Article information

Article type
Paper
Submitted
20 Dec. 2023
Accepted
23 Febr. 2024
First published
26 Febr. 2024

Dalton Trans., 2024,53, 5796-5807

A frontier-orbital view of the initial steps of lytic polysaccharide monooxygenase reactions

E. K. Wieduwilt, L. Lo Leggio and E. D. Hedegård, Dalton Trans., 2024, 53, 5796 DOI: 10.1039/D3DT04275H

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