On the formation and role of reactive oxygen species in light-driven LPMO oxidation of phosphoric acid swollen cellulose

Möllers, K. Benedikt; Mikkelsen, Hanne B.; Simonsen, Tor I.; Cannella, David; Johansen, Katja Salomon; Bjerrum, Morten J.; Felby, Claus

doi:10.1016/j.carres.2017.03.013

Cited by 35 publications

(32 citation statements)

References 26 publications

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“…As shown by agreement with several studies published since the discovery of the role of H 2 O 2 in LPMO catalysis 22,[25][26][27][28][29]41 22,42 . The dualistic impact of H 2 O 2 could also explain why our present conclusions differ from those of Möllers and colleagues 43 , who concluded that reactive oxygen species (ROS) are not part of light-driven LPMO catalysis. On the one hand, these authors observed that exposure of Chl/AscA to light leads to consumption of O 2 .…”

Section: Resultscontrasting

confidence: 80%

Controlled depolymerization of cellulose by light-driven lytic polysaccharide oxygenases

et al. 2020

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Lytic polysaccharide (mono)oxygenases (LPMOs) perform oxidative cleavage of polysaccharides, and are key enzymes in biomass processing and the global carbon cycle. It has been shown that LPMO reactions may be driven by light, using photosynthetic pigments or photocatalysts, but the mechanism behind this highly attractive catalytic route remains unknown. Here, prompted by the discovery that LPMOs catalyze a peroxygenase reaction more efficiently than a monooxygenase reaction, we revisit these light-driven systems, using an LPMO from Streptomyces coelicolor (ScAA10C) as model cellulolytic enzyme. By using coupled enzymatic assays, we show that H 2 O 2 is produced and necessary for efficient lightdriven activity of ScAA10C. Importantly, this activity is achieved without addition of reducing agents and proportional to the light intensity. Overall, the results highlight the importance of controlling fluxes of reactive oxygen species in LPMO reactions and demonstrate the feasibility of light-driven, tunable enzymatic peroxygenation to degrade recalcitrant polysaccharides.

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Section: Resultscontrasting

confidence: 80%

Controlled depolymerization of cellulose by light-driven lytic polysaccharide oxygenases

et al. 2020

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“…2G). This is also apparent in lightdriven reduction of PMOs, where the addition of reactive oxygen species scavengers had no effect on PASC oxidation (35).…”

Section: Discussionmentioning

confidence: 86%

Reactivity of O ₂ versus H ₂ O ₂ with polysaccharide monooxygenases

Hangasky

Iavarone

Marletta

2018

Proc. Natl. Acad. Sci. U.S.A.

154

170

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Enzymatic conversion of polysaccharides into lower-molecular-weight, soluble oligosaccharides is dependent on the action of hydrolytic and oxidative enzymes. Polysaccharide monooxygenases (PMOs) use an oxidative mechanism to break the glycosidic bond of polymeric carbohydrates, thereby disrupting the crystalline packing and creating new chain ends for hydrolases to depolymerize and degrade recalcitrant polysaccharides. PMOs contain a mononuclear Cu(II) center that is directly involved in C-H bond hydroxylation. Molecular oxygen was the accepted cosubstrate utilized by this family of enzymes until a recent report indicated reactivity was dependent on HO Reported here is a detailed analysis of PMO reactivity with HO and O, in conjunction with high-resolution MS measurements. The cosubstrate utilized by the enzyme is dependent on the assay conditions. PMOs will directly reduce O in the coupled hydroxylation of substrate (monooxygenase activity) and will also utilize HO (peroxygenase activity) produced from the uncoupled reduction of O Both cosubstrates require Cu reduction to Cu(I), but the reaction with HO leads to nonspecific oxidation of the polysaccharide that is consistent with the generation of a hydroxyl radical-based mechanism in Fenton-like chemistry, while the O reaction leads to regioselective substrate oxidation using an enzyme-bound Cu/O reactive intermediate. Moreover, HO does not influence the ability of secretome from to degrade Avicel, providing evidence that molecular oxygen is a physiologically relevant cosubstrate for PMOs.

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“…TaLPMO9A catalyzed oxidation of PASC contains TaLPMO9A (0.1 m m ), ascorbate (2 m m ), and PASC (0.4 %, w/v) . Reaction was carried out in absence or presence of H 2 O 2 (0.1 m m / 2 m m ) in 20 m m phosphate buffer (pH 6.0) at 25 °C for 30 min.…”

Section: Methodsmentioning

confidence: 99%

Detection and Characterization of a Novel Copper‐Dependent Intermediate in a Lytic Polysaccharide Monooxygenase

Singh

Blossom

Russo

et al. 2019

Chemistry A European J

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Lytic polysaccharide monooxygenases (LPMOs) are copper‐containing enzymes capable of oxidizing crystalline cellulose which have large practical application in the process of refining biomass. The catalytic mechanism of LPMOs still remains debated despite several proposed reaction mechanisms. Here, we report a long‐lived intermediate (t1/2=6–8 minutes) observed in an LPMO from Thermoascus aurantiacus (TaLPMO9A). The intermediate with a strong absorption around 420 nm is formed when reduced LPMO‐CuI reacts with sub‐equimolar amounts of H2O2. UV/Vis absorption spectroscopy, electron paramagnetic resonance, resonance Raman and stopped‐flow spectroscopy suggest that the observed long‐lived intermediate involves the copper center and a nearby tyrosine (Tyr175). Additionally, activity assays in the presence of sub‐equimolar amounts of H2O2 showed an increase in the LPMO oxidation of phosphoric acid swollen cellulose. Accordingly, this suggests that the long‐lived copper‐dependent intermediate could be part of the catalytic mechanism for LPMOs. The observed intermediate offers a new perspective into the oxidative reaction mechanism of TaLPMO9A and hence for the biomass oxidation and the reactivity of copper in biological systems.

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On the formation and role of reactive oxygen species in light-driven LPMO oxidation of phosphoric acid swollen cellulose

Cited by 35 publications

References 26 publications

Controlled depolymerization of cellulose by light-driven lytic polysaccharide oxygenases

Controlled depolymerization of cellulose by light-driven lytic polysaccharide oxygenases

Reactivity of O ₂ versus H ₂ O ₂ with polysaccharide monooxygenases

Detection and Characterization of a Novel Copper‐Dependent Intermediate in a Lytic Polysaccharide Monooxygenase

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On the formation and role of reactive oxygen species in light-driven LPMO oxidation of phosphoric acid swollen cellulose

Cited by 35 publications

References 26 publications

Controlled depolymerization of cellulose by light-driven lytic polysaccharide oxygenases

Controlled depolymerization of cellulose by light-driven lytic polysaccharide oxygenases

Reactivity of O 2 versus H 2 O 2 with polysaccharide monooxygenases

Detection and Characterization of a Novel Copper‐Dependent Intermediate in a Lytic Polysaccharide Monooxygenase

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Reactivity of O ₂ versus H ₂ O ₂ with polysaccharide monooxygenases