scholarly journals The role of the active site tyrosine in the mechanism of lytic polysaccharide monooxygenase

2021 ◽  
Vol 12 (1) ◽  
pp. 352-362
Author(s):  
Aina McEvoy ◽  
Joel Creutzberg ◽  
Raushan K. Singh ◽  
Morten J. Bjerrum ◽  
Erik D. Hedegård
Keyword(s):  
Active Site ◽  
Lytic Polysaccharide Monooxygenase ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases ◽  
Active Site Tyrosine ◽  
Polysaccharide Monooxygenase

With QM/MM, we investigate the mechanism of tyrosine deprotonation in lytic polysaccharide monooxygenases. Our results support deprotonation and our calculated UV-vis spectra show that two isomers must be formed to match recent experiments.

scholarly journals The Role of the Active Site Tyrosine in the Mechanism of Lytic Polysaccharide Monooxygenase

2020 ◽  
Author(s):  
Aina McEvoy ◽  
Joel Creutzberg ◽  
Raushan Kumar Singh ◽  
Morten J. Bjerrum ◽  
Erik Hedegård
Keyword(s):  
Active Site ◽  
Density Functional ◽  
Renewable Resource ◽  
Lytic Polysaccharide Monooxygenase ◽  
Functional Theory ◽  
Polysaccharide Monooxygenases ◽  
Active Site Tyrosine ◽  
The Difference ◽  
First Time

Natural polysaccharides (such as cellulose) comprise a large bio-renewable resource. However, exploitation of this resource requires energy-efficient polysaccharide degradation, which is currently limited by the inherent recalcitrance of many naturally occurring polysaccharides. Catalytic breakdown of polysaccharides can be achieved more efficiently by means of the enzymes lytic polysaccharide monooxygenases (LPMOs). However, the LPMO mechanism has remained controversial, preventing full exploitation of their potential. One of the controversies has centered around an active site tyrosine, present in most LPMOs. Different roles for this tyrosine have been proposed without direct evidence, but two recent investigations have for the first time obtained direct (spectroscopic) evidence for that chemical modification of this tyrosine is possible. Surprisingly, the spectroscopic features obtained in the two investigations are remarkably different. In this paper we use density functional theory (DFT) in a QM/MM formulation to reconcile these (apparently) conflicting results. By modeling the spectroscopy as well as the underlying reaction mechanism we can show how formation of two isomers (both involving deprotonation of tyrosine) explain the difference in the experimental observed spectroscopic features. The link between our structures and the observed spectroscopy provides a firm ground to investigate the role of tyrosine.

scholarly journals The Role of the Active Site Tyrosine in the Mechanism of Lytic Polysaccharide Monooxygenase

2020 ◽  
Author(s):  
Aina McEvoy ◽  
Joel Creutzberg ◽  
Raushan Kumar Singh ◽  
Morten J. Bjerrum ◽  
Erik Hedegård
Keyword(s):  
Active Site ◽  
Density Functional ◽  
Protective Role ◽  
Lytic Polysaccharide Monooxygenase ◽  
Functional Theory ◽  
Polysaccharide Monooxygenases ◽  
Active Site Tyrosine ◽  
The Difference ◽  
First Time

<p>Catalytic breakdown of polysaccharides can be achieved more efficiently by means of the enzymes lytic polysaccharide monooxygenases (LPMOs). However, the LPMO mechanism has remained controversial, preventing full exploitation of their potential. One of the controversies has centered around an active site tyrosine, present in most LPMO classes. Recent investigations have for the first time obtained direct (spectroscopic) evidence for that chemical modification of this tyrosine is possible. However, the spectroscopic features obtained in the different investigations are remarkably different, with absorption maximum at 420 and 490 nm, respectively. In this paper we use density functional theory (DFT) in a QM/MM formulation to reconcile these (apparently) conflicting results. By modeling the spectroscopy as well as the underlying reaction mechanism we can show how formation of two isomers (both involving deprotonation of tyrosine) explain the difference in the observed spectroscopic features. Both isomers have a [TyrO-Cu–OH]<sup>+</sup> moiety with the OH in either <i>cis</i>- or <i>trans</i>-position to a deprotonated tyrosine. Although the <i>cis</i>-[TyrO-Cu–OH]<sup>+</sup> moiety is well positioned for oxidation of the substrate, preliminary calculations with substrate reveal that the reactivity is at best moderate, making a protective role of tyrosine more likely.</p>

scholarly journals Recent Advances in Screening Methods for the Functional Investigation of Lytic Polysaccharide Monooxygenases

2021 ◽  
Vol 9 ◽  
Author(s):  
Damao Wang ◽  
Yanping Li ◽  
Yuting Zheng ◽  
Yves S. Y. Hsieh
Keyword(s):  
Copper Ions ◽  
Biomass Conversion ◽  
Screening Methods ◽  
Lytic Polysaccharide Monooxygenase ◽  
Indirect Measurements ◽  
Glycosidic Bonds ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases ◽  
Functional Investigation ◽  
Polysaccharide Monooxygenase

Lytic polysaccharide monooxygenase (LPMO) is a newly discovered and widely studied enzyme in recent years. These enzymes play a key role in the depolymerization of sugar-based biopolymers (including cellulose, hemicellulose, chitin and starch), and have a positive significance for biomass conversion. LPMO is a copper-dependent enzyme that can oxidize and cleave glycosidic bonds in cellulose and other polysaccharides. Their mechanism of action depends on the correct coordination of copper ions in the active site. There are still difficulties in the analysis of LPMO activity, which often requires multiple methods to be used in concert. In this review, we discussed various LPMO activity analysis methods reported so far, including mature mass spectrometry, chromatography, labeling, and indirect measurements, and summarized the advantages, disadvantages and applicability of different methods.

scholarly journals Kinetic insights into the role of the reductant in H2O2-driven degradation of chitin by a bacterial lytic polysaccharide monooxygenase

2018 ◽  
Vol 294 (5) ◽  
pp. 1516-1528 ◽  
Author(s):  
Silja Kuusk ◽  
Riin Kont ◽  
Piret Kuusk ◽  
Agnes Heering ◽  
Morten Sørlie ◽  
...  
Keyword(s):  
Reduction Reaction ◽  
Reaction Conditions ◽  
Lytic Polysaccharide Monooxygenase ◽  
Glycosidic Bonds ◽  
Initial Reduction ◽  
Catalytically Active ◽  
Polysaccharide Monooxygenases ◽  
Theoretical Analyses ◽  
Polysaccharide Monooxygenase

Lytic polysaccharide monooxygenases (LPMOs) are monocopper enzymes that catalyze oxidative cleavage of glycosidic bonds in polysaccharides in the presence of an external electron donor (reductant). In the classical O2-driven monooxygenase reaction, the reductant is needed in stoichiometric amounts. In a recently discovered, more efficient H2O2-driven reaction, the reductant would be needed only for the initial reduction (priming) of the LPMO to its catalytically active Cu(I) form. However, the influence of the reductant on reducing the LPMO or on H2O2 production in the reaction remains undefined. Here, we conducted a detailed kinetic characterization to investigate how the reductant affects H2O2-driven degradation of 14C-labeled chitin by a bacterial LPMO, SmLPMO10A (formerly CBP21). Sensitive detection of 14C-labeled products and careful experimental set-ups enabled discrimination between the effects of the reductant on LPMO priming and other effects, in particular enzyme-independent production of H2O2 through reactions with O2. When supplied with H2O2, SmLPMO10A catalyzed 18 oxidative cleavages per molecule of ascorbic acid, suggesting a “priming reduction” reaction. The dependence of initial rates of chitin degradation on reductant concentration followed hyperbolic saturation kinetics, and differences between the reductants were manifested in large variations in their half-saturating concentrations (KmRapp). Theoretical analyses revealed that KmRapp decreases with a decreasing rate of polysaccharide-independent LPMO reoxidation (by either O2 or H2O2). We conclude that the efficiency of LPMO priming depends on the relative contributions of reductant reactivity, on the LPMO's polysaccharide monooxygenase/peroxygenase and reductant oxidase/peroxidase activities, and on reaction conditions, such as O2, H2O2, and polysaccharide concentrations.

scholarly journals Lytic polysaccharide monooxygenase (LPMO) mediated production of ultra-fine cellulose nanofibres from delignified softwood fibres

2019 ◽  
Vol 21 (21) ◽  
pp. 5924-5933 ◽  
Author(s):  
Salla Koskela ◽  
Shennan Wang ◽  
Dingfeng Xu ◽  
Xuan Yang ◽  
Kai Li ◽  
...  
Keyword(s):  
Efficient Method ◽  
Energy Efficient ◽  
Environmentally Friendly ◽  
Oxidative Enzymes ◽  
Lytic Polysaccharide Monooxygenase ◽  
Lytic Polysaccharide Monooxygenases ◽  
Cellulose Nanofibres ◽  
Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenase

An environmentally friendly, energy-efficient method for cellulose nanofibre (CNF) production from softwood holocellulose utilising oxidative enzymes, lytic polysaccharide monooxygenases (LPMOs).

scholarly journals Mechanism of hydrogen peroxide formation by lytic polysaccharide monooxygenase

2019 ◽  
Vol 10 (2) ◽  
pp. 576-586 ◽  
Author(s):  
Octav Caldararu ◽  
Esko Oksanen ◽  
Ulf Ryde ◽  
Erik D. Hedegård
Keyword(s):  
Hydrogen Peroxide ◽  
Peroxide Formation ◽  
Lytic Polysaccharide Monooxygenase ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases ◽  
Hydrogen Peroxide Formation ◽  
Polysaccharide Monooxygenase

A mechanism for the formation of hydrogen peroxide by lytic polysaccharide monooxygenases (LPMOs) in the absence of substrate is proposed.

Combination of MALDI-TOF MS and UHPLC-ESI-MS for the characterization of lytic polysaccharide monooxygenase activity

2020 ◽  
Vol 12 (2) ◽  
pp. 149-161 ◽  
Author(s):  
Caio de Oliveira Gorgulho Silva ◽  
Tallyta Santos Teixeira ◽  
Kelly Barreto Rodrigues ◽  
Amanda Araújo Souza ◽  
Antonielle Vieira Monclaro ◽  
...  
Keyword(s):  
Lytic Polysaccharide Monooxygenase ◽  
Monooxygenase Activity ◽  
Maldi Tof Ms ◽  
Esi Ms ◽  
Maldi Tof ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases ◽  
Tof Ms ◽  
Polysaccharide Monooxygenase

Two new mass spectrometry methods, MALDI-TOF MS and hydrophilic interaction UHPLC-ESI-MS, were developed for the characterization of cellulose-active lytic polysaccharide monooxygenases, expanding the analytical toolbox for the study of these enzymes.

scholarly journals Further structural studies of the lytic polysaccharide monooxygenase AoAA13 belonging to the starch-active AA13 family

Amylase ◽  
2019 ◽  
Vol 3 (1) ◽  
pp. 41-54 ◽  
Author(s):  
Sebastian J. Muderspach ◽  
Tobias Tandrup ◽  
Kristian E. H. Frandsen ◽  
Gianluca Santoni ◽  
Jens-Christian N. Poulsen ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Metal Binding ◽  
Binding Studies ◽  
Orthorhombic Crystal ◽  
Lytic Polysaccharide Monooxygenase ◽  
X Ray ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases ◽  
Triclinic Structure ◽  
Polysaccharide Monooxygenase

Abstract Lytic polysaccharide monooxygenases (LPMOs) are recently discovered copper enzymes that cleave recalcitrant polysaccharides by oxidation. The structure of an Aspergillus oryzae LPMO from the starch degrading family AA13 (AoAA13) has previously been determined from an orthorhombic crystal grown in the presence of copper, which is photoreduced in the structure. Here we describe how crystals reliably grown in presence of Zn can be Cu-loaded post crystallization. A partly photoreduced structure was obtained by severely limiting the X-ray dose, showing that this LPMO is much more prone to photoreduction than others. A serial synchrotron crystallography structure was also obtained, showing that this technique may be promising for further studies, to reduce even further photoreduction. We additionally present a triclinic structure of AoAA13, which has less occluded ligand binding site than the orthorhombic one. The availability of the triclinic crystals prompted new ligand binding studies, which lead us to the conclusion that small starch analogues do not bind to AoAA13 to an appreciable extent. A number of disordered conformations of the metal binding histidine brace have been encountered in this and other studies, and we have previously hypothesized that this disorder may be a consequence of loss of copper. We performed molecular dynamics in the absence of active site metal, and showed that the dynamics in solution differ somewhat from the disorder observed in the crystal, though the extent is equally dramatic.

Recent insights into lytic polysaccharide monooxygenases (LPMOs)

2018 ◽  
Vol 46 (6) ◽  
pp. 1431-1447 ◽  
Author(s):  
Tobias Tandrup ◽  
Kristian E. H. Frandsen ◽  
Katja S. Johansen ◽  
Jean-Guy Berrin ◽  
Leila Lo Leggio
Keyword(s):  
Active Site ◽  
Room Temperature ◽  
Experimental Studies ◽  
Binding Mode ◽  
Structural Features ◽  
Oxygen Species ◽  
Animal Kingdom ◽  
X Ray ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases

Lytic polysaccharide monooxygenases (LPMOs) are copper enzymes discovered within the last 10 years. By degrading recalcitrant substrates oxidatively, these enzymes are major contributors to the recycling of carbon in nature and are being used in the biorefinery industry. Recently, two new families of LPMOs have been defined and structurally characterized, AA14 and AA15, sharing many of previously found structural features. However, unlike most LPMOs to date, AA14 degrades xylan in the context of complex substrates, while AA15 is particularly interesting because they expand the presence of LPMOs from the predominantly microbial to the animal kingdom. The first two neutron crystallography structures have been determined, which, together with high-resolution room temperature X-ray structures, have putatively identified oxygen species at or near the active site of LPMOs. Many recent computational and experimental studies have also investigated the mechanism of action and substrate-binding mode of LPMOs. Perhaps, the most significant recent advance is the increasing structural and biochemical evidence, suggesting that LPMOs follow different mechanistic pathways with different substrates, co-substrates and reductants, by behaving as monooxygenases or peroxygenases with molecular oxygen or hydrogen peroxide as a co-substrate, respectively.

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