1
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Perna V, Agger JW. Transesterification with CE15 glucuronoyl esterase from Cerrena unicolor reveals substrate preferences. Biotechnol Lett 2024; 46:107-114. [PMID: 38150097 PMCID: PMC10787888 DOI: 10.1007/s10529-023-03456-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 11/21/2023] [Accepted: 11/25/2023] [Indexed: 12/28/2023]
Abstract
PURPOSE Glucuronoyl esterases (GE, family CE15) catalyse the cleavage of ester linkages in lignin-carbohydrate complexes (LCCs), and this study demonstrate how transesterification reactions with a fungal GE from Cerrena unicolor (CuGE) can reveal the enzyme's preference for the alcohol-part of the ester-bond. METHODS This alcohol-preference relates to where the ester-LCCs are located on the lignin molecule, and has consequences for how the enzymes potentially interact with lignin. It is unknown exactly what the enzymes prefer; either the α-benzyl or the γ-benzyl position. By providing the enzyme with a donor substrate (the methyl ester of either glucuronate or 4-O-methyl-glucuronate) and either one of two acceptor molecules (benzyl alcohol or 3-phenyl-1-propanol) we demonstrate that the enzyme can perform transesterification and it serves as a method for assessing the enzyme's alcohol preferences. CONCLUSION CuGE preferentially forms the γ-ester from the methyl ester of 4-O-methyl-glucuronate and 3-phenyl-1-propanol and the enzyme's substrate preferences are primarily dictated by the presence of the 4-O-methylation on the glucuronoyl donor, and secondly on the type of alcohol.
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Affiliation(s)
- Valentina Perna
- Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800, Kgs Lyngby, Denmark
| | - Jane Wittrup Agger
- Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800, Kgs Lyngby, Denmark.
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2
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Agger JW, Madsen MS, Martinsen LK, Martins PA, Barrett K, Meyer AS. New insights to diversity and enzyme-substrate interactions of fungal glucuronoyl esterases. Appl Microbiol Biotechnol 2023:10.1007/s00253-023-12575-4. [PMID: 37256329 DOI: 10.1007/s00253-023-12575-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/05/2023] [Accepted: 05/09/2023] [Indexed: 06/01/2023]
Abstract
Glucuronoyl esterases (GEs) (EC 3.1.1.117) catalyze the cleavage of ester-linked lignin-carbohydrate complexes that has high impact on the plant cell wall integrity. The GEs are among the very few known types of hydrolytic enzymes that act at the interface of lignin, or which may potentially interact with lignin itself. In this review, we provide the latest update of the current knowledge on GEs with a special focus on the fungal variants. In addition, we have established the phylogenetic relationship between all GEs and this reveals that the fungal enzymes largely fall into one major branch, together with only a minor subset of bacterial enzymes. About 22% of the fungal proteins carry an additional domain, which is almost exclusively a CBM1 binding domain. We address how GEs may interact with the lignin-side of their substrate by molecular docking experiments based on the known structure of the Cerrena unicolor GE (CuGE). The docking studies indicate that there are no direct interactions between the enzyme and the lignin polymer, that the lignin-moiety is facing away from the protein surface and that an elongated carbon-chain between the ester-linkage and the first phenyl of lignin is preferable. Much basic research on these enzymes has been done over the past 15 years, but the next big step forward for these enzymes is connected to application and how these enzymes can facilitate the use of lignocellulose as a renewable resource. KEY POINTS: Fungal GEs are closely related and are sometimes linked to a binding module Molecular docking suggests good accommodation of lignin-like substructures GEs could be among the first expressed enzymes during fungal growth on biomass.
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Affiliation(s)
- Jane Wittrup Agger
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark.
| | - Michael Schmidt Madsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark
| | - Line Korte Martinsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark
| | - Pedro Alves Martins
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark
| | - Kristian Barrett
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark
| | - Anne S Meyer
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark
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3
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Lin S, Xu X, Holck J, Wittrup Agger J, Wilkens C, Xie Z, Khakimov B, Nielsen DS, Meyer AS. Soluble, Diferuloylated Corn Bran Glucuronoarabinoxylans Modulate the Human Gut Microbiota In Vitro. J Agric Food Chem 2023; 71:3885-3897. [PMID: 36787634 DOI: 10.1021/acs.jafc.2c08338] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Corn bran is exceptionally rich in substituted glucuronoarabinoxylan polysaccharides, which are monoferuloylated and cross-linked by diferulic acid moieties. Here, we assessed the potential prebiotic activity of three enzymatically solubilized corn bran glucuronoarabinoxylans: medium feruloylated (FGAX-M), laccase cross-linked FGAX-M (FGAX-H), and alkali-treated FGAX-M devoid of feruloyl substitutions (FGAX-B). We examined the influence of these soluble FGAX samples on the gut microbiome composition and functionality during in vitro simulated colon fermentations, determined by 16S rRNA gene amplicon sequencing and assessment of short-chain fatty acid (SCFAs) production. All FGAX samples induced changes in the relative composition of the microbiota and the SCFA levels after 24 h of in vitro fermentation. The changes induced by FGAX-M and FGAX-H tended to be more profound and more similar to the changes induced by inulin than changes conferred by FGAX-B. The microbiota changes induced by FGAX-M and FGAX-H correlated with an increase in the relative abundance of Anaerostipes and with increased butyric acid production, while the changes induced by the FGAX-B sample were less compelling. The results imply that solubilized, substituted diferuloylated corn bran glucuronoarabinoxylans may be potential prebiotic candidates and that both single feruloylations and diferuloyl cross-links influence the prebiotic potential of these arabinoxylan compounds.
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Affiliation(s)
- Shang Lin
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, DK-2800 Kongens Lyngby, Denmark
| | - Xinming Xu
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, DK-2800 Kongens Lyngby, Denmark
| | - Jesper Holck
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, DK-2800 Kongens Lyngby, Denmark
| | - Jane Wittrup Agger
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, DK-2800 Kongens Lyngby, Denmark
| | - Casper Wilkens
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, DK-2800 Kongens Lyngby, Denmark
| | - Zhuqing Xie
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark
| | - Bekzod Khakimov
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark
| | - Dennis S Nielsen
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, DK-1958 Frederiksberg C, Denmark
| | - Anne S Meyer
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 221, DK-2800 Kongens Lyngby, Denmark
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4
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Westereng B, Arntzen MØ, Østby H, Agger JW, Vaaje-Kolstad G, Eijsink VGH. Analyzing Activities of Lytic Polysaccharide Monooxygenases by Liquid Chromatography and Mass Spectrometry. Methods Mol Biol 2023; 2657:27-51. [PMID: 37149521 DOI: 10.1007/978-1-0716-3151-5_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Lytic polysaccharide monooxygenases perform oxidative cleavage of glycosidic bonds in various polysaccharides. The majority of LMPOs studied so far possess activity on either cellulose or chitin and analysis of these activities is therefore the main focus of this review. Notably, however, the number of LPMOs that are active on other polysaccharides is increasing. The products generated by LPMOs from cellulose are either oxidized in the downstream end (at C1) or upstream end (at C4), or at both ends. These modifications only result in small structural changes, which makes both chromatographic separation and product identification by mass spectrometry challenging. The changes in physicochemical properties that are associated with oxidation need to be considered when choosing analytical approaches. C1 oxidation leads to a sugar that is no longer reducing but instead has an acidic functionality, whereas C4 oxidation leads to products that are inherently labile at high and low pH and that exist in a keto-gemdiol equilibrium that is strongly shifted towards the gemdiol in aqueous solutions. Partial degradation of C4-oxidized products leads to the formation of native products, which could explain why some authors claim to have observed glycoside hydrolase activity for LPMOs. Notably, apparent glycoside hydrolase activity may also be due to small amounts of contaminating glycoside hydrolases since these normally have much higher catalytic rates than LPMOs. The low catalytic turnover rates of LPMOs necessitate the use of sensitive product detection methods, which limits the analytical possibilities considerably. Modern liquid chromatography and mass spectrometry have become essential tools for evaluating LPMO activity and this chapter provides an overview of available methods together with a few novel tools. The methods described constitute a suite of techniques for analyzing oxidized carbohydrate products, which can be applied to LPMOs as well as other carbohydrate-active redox enzymes.
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Affiliation(s)
- Bjørge Westereng
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, Norway.
| | - Magnus Ø Arntzen
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, Norway
| | - Heidi Østby
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, Norway
| | - Jane Wittrup Agger
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Lyngby, Denmark
| | - Gustav Vaaje-Kolstad
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, Norway
| | - Vincent G H Eijsink
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Aas, Norway
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5
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Lin S, Brask J, Munk L, Holck J, Krogh KBRM, Meyer AS, Wittrup Agger J, Wilkens C. Enzymatic Cleavage of Diferuloyl Cross-Links in Corn Bran Arabinoxylan by Two Bacterial Feruloyl Esterases. J Agric Food Chem 2022; 70:13349-13357. [PMID: 36205442 DOI: 10.1021/acs.jafc.2c04455] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Corn bran is an abundant coprocessing stream of corn-starch processing, rich in highly substituted, diferuloyl-cross-linked glucurono-arabinoxylan. The diferuloyl cross-links make the glucurono-arabinoxylan recalcitrant to enzymatic conversion and constitute a hindrance for designing selective enzymatic upgrading of corn glucurono-arabinoxylan. Here, we show that two bacterial feruloyl esterases, wtsFae1A and wtsFae1B, each having a carbohydrate-binding module of family 48, are capable of cleaving the ester bonds of the cross-linkages and releasing 5-5', 8-5', 8-5' benzofuran, and 8-O-4' diferulate from soluble and insoluble corn bran glucurono-arabinoxylan. All four diferulic acids were released at similar efficiency, indicating nondiscriminatory enzymatic selectivity for the esterified dimer linkages, the only exception being that wtsFae1B had a surprisingly high propensity for releasing the dimers, especially 8-5' benzofuran diferulate, indicating a potential, unique catalytic selectivity. The data provide evidence of direct enzymatic release of diferulic acids from corn bran by newly discovered feruloyl esterases, i.e., a new enzyme activity. The findings yield new insight and create new opportunities for enzymatic opening of diferuloyl cross-linkages to pave the way for upgrading of recalcitrant arabinoxylans.
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Affiliation(s)
- Shang Lin
- Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800Kgs. Lyngby, Denmark
| | - Jesper Brask
- Novozymes A/S, Biologiens Vej 2, DK-2800Kgs. Lyngby, Denmark
| | - Line Munk
- Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800Kgs. Lyngby, Denmark
| | - Jesper Holck
- Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800Kgs. Lyngby, Denmark
| | | | - Anne S Meyer
- Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800Kgs. Lyngby, Denmark
| | - Jane Wittrup Agger
- Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800Kgs. Lyngby, Denmark
| | - Casper Wilkens
- Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, Building 224, DK-2800Kgs. Lyngby, Denmark
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6
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Mosbech C, Holck J, Meyer A, Agger JW. Enzyme kinetics of fungal glucuronoyl esterases on natural lignin-carbohydrate complexes. Appl Microbiol Biotechnol 2019; 103:4065-4075. [PMID: 30949809 DOI: 10.1007/s00253-019-09797-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/22/2019] [Accepted: 03/23/2019] [Indexed: 12/01/2022]
Abstract
Glucuronoyl esterases (CE15 family) enable targeted cleavage of ester linkages in lignin-carbohydrate complexes (LCCs), particularly those linking lignin and glucuronoyl residues in xylan. A substantial challenge in characterization and kinetic analysis of CE15 enzymes has been the lack of proper substrates. Here, we present an assay using an insoluble LCC-rich lignin fraction from birch; lignin-rich pellet (LRP). The assay employs quantification of enzyme reaction products by LC-MS. The kinetics of four fungal CE15 enzymes, PsGE, CuGE, TtGE, and AfuGE originating from lignocellulose-degrading fungi Punctularia strigosozonata, Cerrena unicolor, Thielavia terrestris, and Armillaria fuscipes respectively were characterized and compared using this new assay. All four enzymes had activity on LRP and showed a clear preference for the insoluble substrate compared with smaller soluble LCC mimicking esters. End-product profiles were near identical for the four enzymes but differences in kinetic parameters were observed. TtGE possesses an alternative active site compared with the three other enzymes as it has the position of the catalytic glutamic acid occupied by a serine. TtGE performed poorly compared with the other enzymes. We speculate that glucuronoyl LCCs are not the preferred substrate of TtGE. Removal of an N-terminal CBM on CuGE affected the catalytic efficiently of the enzyme by reducing Kcat by more than 30%. Reaction products were detected from all four CE15s on a similar substrate from spruce indicating a more generic GE activity not limited to the hardwood. The assay with natural substrate represents a novel tool to study the natural function and kinetics of CE15s.
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Affiliation(s)
- Caroline Mosbech
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, DK-2800, Kongens Lyngby, Denmark
| | - Jesper Holck
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, DK-2800, Kongens Lyngby, Denmark
| | - Anne Meyer
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, DK-2800, Kongens Lyngby, Denmark
| | - Jane Wittrup Agger
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, DK-2800, Kongens Lyngby, Denmark.
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7
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Mosbech C, Holck J, Meyer AS, Agger JW. The natural catalytic function of CuGE glucuronoyl esterase in hydrolysis of genuine lignin-carbohydrate complexes from birch. Biotechnol Biofuels 2018; 11:71. [PMID: 29560026 PMCID: PMC5858132 DOI: 10.1186/s13068-018-1075-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 03/09/2018] [Indexed: 05/08/2023]
Abstract
BACKGROUND Glucuronoyl esterases belong to carbohydrate esterase family 15 and catalyze de-esterification. Their natural function is presumed to be cleavage of ester linkages in lignin-carbohydrate complexes particularly those linking lignin and glucuronoyl residues in xylans in hardwood. RESULTS Here, we show for the first time a detailed product profile of aldouronic acids released from birchwood lignin by a glucuronoyl esterase from the white-rot fungus Cerrena unicolor (CuGE). CuGE releases substrate for GH10 endo-xylanase which results in significantly increased product release compared to the action of endo-xylanase alone. CuGE also releases neutral xylo-oligosaccharides that can be ascribed to the enzymes feruloyl esterase side activity as demonstrated by release of ferulic acid from insoluble wheat arabinoxylan. CONCLUSION The data verify the enzyme's unique ability to catalyze removal of all glucuronoxylan associated with lignin and we propose that this is a direct result of enzymatic cleavage of the ester bonds connecting glucuronoxylan to lignin via 4-O-methyl glucuronoyl-ester linkages. This function appears important for the fungal organism's ability to effectively utilize all available carbohydrates in lignocellulosic substrates. In bioprocess perspectives, this enzyme is a clear candidate for polishing lignin for residual carbohydrates to achieve pure, native lignin fractions after minimal pretreatment.
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Affiliation(s)
- Caroline Mosbech
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads 229, 2800 Kgs. Lyngby, Denmark
| | - Jesper Holck
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads 229, 2800 Kgs. Lyngby, Denmark
| | - Anne S. Meyer
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads 229, 2800 Kgs. Lyngby, Denmark
| | - Jane Wittrup Agger
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads 229, 2800 Kgs. Lyngby, Denmark
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Pierce BC, Agger JW, Zhang Z, Wichmann J, Meyer AS. A comparative study on the activity of fungal lytic polysaccharide monooxygenases for the depolymerization of cellulose in soybean spent flakes. Carbohydr Res 2017; 449:85-94. [PMID: 28750348 DOI: 10.1016/j.carres.2017.07.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 06/21/2017] [Accepted: 07/17/2017] [Indexed: 12/15/2022]
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes capable of the oxidative breakdown of polysaccharides. They are of industrial interest due to their ability to enhance the enzymatic depolymerization of recalcitrant substrates by glycoside hydrolases. In this paper, twenty-four lytic polysaccharide monooxygenases (LPMOs) expressed in Trichoderma reesei were evaluated for their ability to oxidize the complex polysaccharides in soybean spent flakes, an abundant and industrially relevant substrate. TrCel61A, a soy-polysaccharide-active AA9 LPMO from T. reesei, was used as a benchmark in this evaluation. In total, seven LPMOs demonstrated activity on pretreated soy spent flakes, with the products from enzymatic treatments evaluated using mass spectrometry and high performance anion exchange chromatography. The hydrolytic boosting effect of the top-performing enzymes was evaluated in combination with endoglucanase and beta-glucosidase. Two enzymes (TrCel61A and Aspte6) showed the ability to release more than 36% of the pretreated soy spent flake glucose - a greater than 75% increase over the same treatment without LPMO addition.
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Affiliation(s)
- Brian C Pierce
- DuPont™ Nutrition Biosciences ApS, Edwin Rahrs Vej 38 Brabrand, 8220, Denmark; Department of Chemical and Biochemical Engineering, Center for Bioprocess Engineering, Technical University of Denmark, Søltofts Plads, Building 229, Kgs. Lyngby, 2800, Denmark; DuPont™ Nutrition & Health - Protein Solutions, 4300 Duncan Ave., Saint Louis, MO, 63110, USA.
| | - Jane Wittrup Agger
- Department of Chemical and Biochemical Engineering, Center for Bioprocess Engineering, Technical University of Denmark, Søltofts Plads, Building 229, Kgs. Lyngby, 2800, Denmark.
| | - Zhenghong Zhang
- DuPont™ Industrial Biosciences, China Research Center, Building 10, Lane 280, Linhong Road, Shanghai, 200335, PR China; State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, PR China.
| | - Jesper Wichmann
- DuPont™ Nutrition Biosciences ApS, Edwin Rahrs Vej 38 Brabrand, 8220, Denmark.
| | - Anne S Meyer
- Department of Chemical and Biochemical Engineering, Center for Bioprocess Engineering, Technical University of Denmark, Søltofts Plads, Building 229, Kgs. Lyngby, 2800, Denmark.
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Pierce BC, Agger JW, Wichmann J, Meyer AS. Oxidative cleavage and hydrolytic boosting of cellulose in soybean spent flakes by Trichoderma reesei Cel61A lytic polysaccharide monooxygenase. Enzyme Microb Technol 2017; 98:58-66. [PMID: 28110665 DOI: 10.1016/j.enzmictec.2016.12.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 12/01/2016] [Accepted: 12/26/2016] [Indexed: 01/06/2023]
Abstract
The auxiliary activity family 9 (AA9) copper-dependent lytic polysaccharide monooxygenase (LPMO) from Trichoderma reesei (EG4; TrCel61A) was investigated for its ability to oxidize the complex polysaccharides from soybean. The substrate specificity of the enzyme was assessed against a variety of substrates, including both soy spent flake, a by-product of the soy food industry, and soy spent flake pretreated with sodium hydroxide. Products from enzymatic treatments were analyzed using mass spectrometry and high performance anion exchange chromatography. We demonstrate that TrCel61A is capable of oxidizing cellulose from both pretreated soy spent flake and phosphoric acid swollen cellulose, oxidizing at both the C1 and C4 positions. In addition, we show that the oxidative activity of TrCel61A displays a synergistic effect capable of boosting endoglucanase activity, and thereby substrate depolymerization of soy cellulose, by 27%.
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Affiliation(s)
- Brian C Pierce
- DuPont™ Nutrition Biosciences ApS, Edwin Rahrs Vej 38, Brabrand, 8220, Denmark; Department of Chemical and Biochemical Engineering, Center for Bioprocess Engineering, Technical University of Denmark, Søltofts Plads, Building 229, Kgs. Lyngby 2800, Denmark.
| | - Jane Wittrup Agger
- Department of Chemical and Biochemical Engineering, Center for Bioprocess Engineering, Technical University of Denmark, Søltofts Plads, Building 229, Kgs. Lyngby 2800, Denmark.
| | - Jesper Wichmann
- DuPont™ Nutrition Biosciences ApS, Edwin Rahrs Vej 38, Brabrand, 8220, Denmark.
| | - Anne S Meyer
- Department of Chemical and Biochemical Engineering, Center for Bioprocess Engineering, Technical University of Denmark, Søltofts Plads, Building 229, Kgs. Lyngby 2800, Denmark.
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Westereng B, Arntzen MØ, Agger JW, Vaaje-Kolstad G, Eijsink VGH. Analyzing Activities of Lytic Polysaccharide Monooxygenases by Liquid Chromatography and Mass Spectrometry. Methods Mol Biol 2017; 1588:71-92. [PMID: 28417362 DOI: 10.1007/978-1-4939-6899-2_7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Lytic polysaccharide monooxygenases perform oxidative cleavage of glycosidic bonds in various polysaccharides. The majority of LMPOs studied so far possess activity on either cellulose or chitin and analysis of these activities is therefore the main focus of this review. Notably, however, the number of LPMOs that are active on other polysaccharides is increasing. The products generated by LPMOs from cellulose are either oxidized in the downstream end (at C1) or upstream end (at C4), or at both ends. These modifications only result in small structural changes, which makes both chromatographic separation and product identification by mass spectrometry challenging. The changes in physicochemical properties that are associated with oxidation need to be considered when choosing analytical approaches. C1 oxidation leads to a sugar that is no longer reducing but instead has an acidic functionality, whereas C4 oxidation leads to products that are inherently labile at high and low pH and that exist in a keto-gemdiol equilibrium that is strongly shifted toward the gemdiol in aqueous solutions. Partial degradation of C4-oxidized products leads to the formation of native products, which could explain why some authors claim to have observed glycoside hydrolase activity for LPMOs. Notably, apparent glycoside hydrolase activity may also be due to small amounts of contaminating glycoside hydrolases since these normally have much higher catalytic rates than LPMOs. The low catalytic turnover rates of LPMOs necessitate the use of sensitive product detection methods, which limits the analytical possibilities considerably. Modern liquid chromatography and mass spectrometry have become essential tools for evaluating LPMO activity, and this chapter provides an overview of available methods together with a few novel tools. The methods described constitute a suite of techniques for analyzing oxidized carbohydrate products, which can be applied to LPMOs as well as other carbohydrate-active redox enzymes.
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Affiliation(s)
- Bjørge Westereng
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 5003, Ås Akershus, 1432, Norway.
| | - Magnus Ø Arntzen
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 5003, Ås Akershus, 1432, Norway
| | - Jane Wittrup Agger
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, 2800 Kgs., Lyngby, Denmark
| | - Gustav Vaaje-Kolstad
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 5003, Ås Akershus, 1432, Norway
| | - Vincent G H Eijsink
- Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 5003, Ås Akershus, 1432, Norway
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