TY - JOUR

T1 - A frontier-orbital view of the initial steps of lytic polysaccharide monooxygenase reactions

AU - Wieduwilt, Erna Katharina

AU - Lo Leggio, Leila

AU - Hedegård, Erik Donovan

PY - 2024

Y1 - 2024

N2 - 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.

AB - 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.

KW - Mixed Function Oxygenases/chemistry

KW - Hydrogen Peroxide

KW - Copper/chemistry

KW - Polysaccharides/metabolism

KW - Oxidation-Reduction

U2 - 10.1039/d3dt04275h

DO - 10.1039/d3dt04275h

M3 - Journal article

C2 - 38445349

VL - 53

SP - 5796

EP - 5807

JO - Dalton Transactions (Online)

JF - Dalton Transactions (Online)

SN - 1477-9234

IS - 13

ER -