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Guo Y, Alvigini L, Trajkovic M, Alonso-Cotchico L, Monza E, Savino S, Marić I, Mattevi A, Fraaije MW. Structure- and computational-aided engineering of an oxidase to produce isoeugenol from a lignin-derived compound. Nat Commun 2022; 13:7195. [PMID: 36418310 PMCID: PMC9684555 DOI: 10.1038/s41467-022-34912-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 11/11/2022] [Indexed: 11/26/2022] Open
Abstract
Various 4-alkylphenols can be easily obtained through reductive catalytic fractionation of lignocellulosic biomass. Selective dehydrogenation of 4-n-propylguaiacol results in the formation of isoeugenol, a valuable flavor and fragrance molecule and versatile precursor compound. Here we present the engineering of a bacterial eugenol oxidase to catalyze this reaction. Five mutations, identified from computational predictions, are first introduced to render the enzyme more thermostable. Other mutations are then added and analyzed to enhance chemoselectivity and activity. Structural insight demonstrates that the slow catalytic activity of an otherwise promising enzyme variant is due the formation of a slowly-decaying covalent substrate-flavin cofactor adduct that can be remedied by targeted residue changes. The final engineered variant comprises eight mutations, is thermostable, displays good activity and acts as a highly chemoselective 4-n-propylguaiacol oxidase. We lastly use our engineered biocatalyst in an illustrative preparative reaction at gram-scale. Our findings show that a natural enzyme can be redesigned into a tailored biocatalyst capable of valorizing lignin-based monophenols.
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Affiliation(s)
- Yiming Guo
- grid.4830.f0000 0004 0407 1981Molecular Enzymology Group, University of Groningen, Groningen, the Netherlands
| | - Laura Alvigini
- grid.8982.b0000 0004 1762 5736Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Pavia, Italy
| | - Milos Trajkovic
- grid.4830.f0000 0004 0407 1981Molecular Enzymology Group, University of Groningen, Groningen, the Netherlands
| | | | | | - Simone Savino
- grid.4830.f0000 0004 0407 1981Molecular Enzymology Group, University of Groningen, Groningen, the Netherlands
| | - Ivana Marić
- grid.4830.f0000 0004 0407 1981Molecular Enzymology Group, University of Groningen, Groningen, the Netherlands
| | - Andrea Mattevi
- grid.8982.b0000 0004 1762 5736Department of Biology and Biotechnology “Lazzaro Spallanzani”, University of Pavia, Pavia, Italy
| | - Marco W. Fraaije
- grid.4830.f0000 0004 0407 1981Molecular Enzymology Group, University of Groningen, Groningen, the Netherlands
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2
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Alvigini L, Gran‐Scheuch A, Guo Y, Trajkovic M, Saifuddin M, Fraaije MW, Mattevi A. Discovery, Biocatalytic Exploration and Structural Analysis of a 4-Ethylphenol Oxidase from Gulosibacter chungangensis. Chembiochem 2021; 22:3225-3233. [PMID: 34523783 PMCID: PMC9293466 DOI: 10.1002/cbic.202100457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/14/2021] [Indexed: 11/21/2022]
Abstract
The vanillyl-alcohol oxidase (VAO) family is a rich source of biocatalysts for the oxidative bioconversion of phenolic compounds. Through genome mining and sequence comparisons, we found that several family members lack a generally conserved catalytic aspartate. This finding led us to study a VAO-homolog featuring a glutamate residue in place of the common aspartate. This 4-ethylphenol oxidase from Gulosibacter chungangensis (Gc4EO) shares 42 % sequence identity with VAO from Penicillium simplicissimum, contains the same 8α-N3 -histidyl-bound FAD and uses oxygen as electron acceptor. However, Gc4EO features a distinct substrate scope and product specificity as it is primarily effective in the dehydrogenation of para-substituted phenols with little generation of hydroxylated products. The three-dimensional structure shows that the characteristic glutamate side chain creates a closely packed environment that may limit water accessibility and thereby protect from hydroxylation. With its high thermal stability, well defined structural properties and high expression yields, Gc4EO may become a catalyst of choice for the specific dehydrogenation of phenolic compounds bearing small substituents.
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Affiliation(s)
- Laura Alvigini
- Department of Biology and Biotechnology “Lazzaro Spallanzani”University of PaviaVia Ferrata 927100PaviaItaly
| | - Alejandro Gran‐Scheuch
- Molecular Enzymology GroupUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Yiming Guo
- Molecular Enzymology GroupUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Milos Trajkovic
- Molecular Enzymology GroupUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Mohammad Saifuddin
- Molecular Enzymology GroupUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Marco W. Fraaije
- Molecular Enzymology GroupUniversity of GroningenNijenborgh 49747 AGGroningenThe Netherlands
| | - Andrea Mattevi
- Department of Biology and Biotechnology “Lazzaro Spallanzani”University of PaviaVia Ferrata 927100PaviaItaly
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3
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Abstract
Enzymatic methods for the oxidation of alcohols are critically reviewed. Dehydrogenases and oxidases are the most prominent biocatalysts, enabling the selective oxidation of primary alcohols into aldehydes or acids. In the case of secondary alcohols, region and/or enantioselective oxidation is possible. In this contribution, we outline the current state-of-the-art and discuss current limitations and promising solutions.
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4
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Abstract
This review presents a historical outline of the research on vanillyl alcohol oxidase (VAO) from Penicillium simplicissimum, one of the canonical members of the VAO/PCMH flavoprotein family. After describing its discovery and initial biochemical characterization, we discuss the physiological role, substrate scope, and catalytic mechanism of VAO, and review its three-dimensional structure and mechanism of covalent flavinylation. We also explain how protein engineering provided a deeper insight into the role of certain amino acid residues in determining the substrate specificity and enantioselectivity of the enzyme. Finally, we summarize recent computational studies about the migration of substrates and products through the enzyme's structure and the phylogenetic distribution of VAO and related enzymes.
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Affiliation(s)
- Tom A Ewing
- Wageningen Food & Biobased Research, Wageningen University & Research, Wageningen, The Netherlands
| | - Gudrun Gygli
- Institute for Biological Interfaces, Karlsruhe Institute of Technology, Karlsruhe, Germany
| | - Marco W Fraaije
- Molecular Enzymology Group, University of Groningen, Groningen, The Netherlands
| | - Willem J H van Berkel
- Laboratory of Food Chemistry, Wageningen University & Research, Wageningen, The Netherlands.
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5
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Nguyen QT, de Gonzalo G, Binda C, Rioz-Martínez A, Mattevi A, Fraaije MW. Biocatalytic Properties and Structural Analysis of Eugenol Oxidase from Rhodococcus jostii RHA1: A Versatile Oxidative Biocatalyst. Chembiochem 2016; 17:1359-66. [PMID: 27123962 PMCID: PMC5089669 DOI: 10.1002/cbic.201600148] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Indexed: 11/15/2022]
Abstract
Eugenol oxidase (EUGO) from Rhodococcus jostii RHA1 had previously been shown to convert only a limited set of phenolic compounds. In this study, we have explored the biocatalytic potential of this flavoprotein oxidase, resulting in a broadened substrate scope and a deeper insight into its structural properties. In addition to the oxidation of vanillyl alcohol and the hydroxylation of eugenol, EUGO can efficiently catalyze the dehydrogenation of various phenolic ketones and the selective oxidation of a racemic secondary alcohol-4-(1-hydroxyethyl)-2-methoxyphenol. EUGO was also found to perform the kinetic resolution of a racemic secondary alcohol. Crystal structures of the enzyme in complexes with isoeugenol, coniferyl alcohol, vanillin, and benzoate have been determined. The catalytic center is a remarkable solvent-inaccessible cavity on the si side of the flavin cofactor. Structural comparison with vanillyl alcohol oxidase from Penicillium simplicissimum highlights a few localized changes that correlate with the selectivity of EUGO for phenolic substrates bearing relatively small p-substituents while tolerating o-methoxy substituents.
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Affiliation(s)
- Quoc-Thai Nguyen
- Molecular Enzymology, Groningen Biomolecular Sciences and, Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, NL
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 1, 27100, Pavia, Italy
| | - Gonzalo de Gonzalo
- Departmento de Química Orgánica, Universidad de Sevilla, c/Profesor García González 1, 41012, Sevilla, Spain
| | - Claudia Binda
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 1, 27100, Pavia, Italy
| | - Ana Rioz-Martínez
- Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, NL
| | - Andrea Mattevi
- Department of Biology and Biotechnology, University of Pavia, Via Ferrata 1, 27100, Pavia, Italy.
| | - Marco W Fraaije
- Molecular Enzymology, Groningen Biomolecular Sciences and, Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, NL.
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6
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Wuensch C, Pavkov-Keller T, Steinkellner G, Gross J, Fuchs M, Hromic A, Lyskowski A, Fauland K, Gruber K, Glueck SM, Faber K. Regioselective Enzymatic β-Carboxylation of para-Hydroxy- styrene Derivatives Catalyzed by Phenolic Acid Decarboxylases. Adv Synth Catal 2015; 357:1909-1918. [PMID: 26190963 PMCID: PMC4498466 DOI: 10.1002/adsc.201401028] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 01/07/2015] [Indexed: 11/17/2022]
Abstract
We report on a 'green' method for the utilization of carbon dioxide as C1 unit for the regioselective synthesis of (E)-cinnamic acids via regioselective enzymatic carboxylation of para-hydroxystyrenes. Phenolic acid decarboxylases from bacterial sources catalyzed the β-carboxylation of para-hydroxystyrene derivatives with excellent regio- and (E/Z)-stereoselectivity by exclusively acting at the β-carbon atom of the C=C side chain to furnish the corresponding (E)-cinnamic acid derivatives in up to 40% conversion at the expense of bicarbonate as carbon dioxide source. Studies on the substrate scope of this strategy are presented and a catalytic mechanism is proposed based on molecular modelling studies supported by mutagenesis of amino acid residues in the active site.
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Affiliation(s)
- Christiane Wuensch
- Austrian Centre of Industrial Biotechnology, c/o Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria ; Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria, ; phone: (+43)-316-380-5332 ; e-mail: or
| | - Tea Pavkov-Keller
- Austrian Centre of Industrial Biotechnology, c/o Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria ; Institute of Molecular Biosciences, Humboldtstrasse 50, University of Graz 8010 Graz, Austria
| | - Georg Steinkellner
- Austrian Centre of Industrial Biotechnology, c/o Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria ; Institute of Molecular Biosciences, Humboldtstrasse 50, University of Graz 8010 Graz, Austria
| | - Johannes Gross
- Austrian Centre of Industrial Biotechnology, c/o Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria ; Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria, ; phone: (+43)-316-380-5332 ; e-mail: or
| | - Michael Fuchs
- Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria, ; phone: (+43)-316-380-5332 ; e-mail: or
| | - Altijana Hromic
- Austrian Centre of Industrial Biotechnology, c/o Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria ; Institute of Molecular Biosciences, Humboldtstrasse 50, University of Graz 8010 Graz, Austria
| | - Andrzej Lyskowski
- Austrian Centre of Industrial Biotechnology, c/o Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria ; Institute of Molecular Biosciences, Humboldtstrasse 50, University of Graz 8010 Graz, Austria
| | - Kerstin Fauland
- Austrian Centre of Industrial Biotechnology, c/o Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria ; Institute of Molecular Biosciences, Humboldtstrasse 50, University of Graz 8010 Graz, Austria
| | - Karl Gruber
- Institute of Molecular Biosciences, Humboldtstrasse 50, University of Graz 8010 Graz, Austria
| | - Silvia M Glueck
- Austrian Centre of Industrial Biotechnology, c/o Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria ; Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria, ; phone: (+43)-316-380-5332 ; e-mail: or
| | - Kurt Faber
- Department of Chemistry, Organic & Bioorganic Chemistry, Heinrichstrasse 28, University of Graz 8010 Graz, Austria, ; phone: (+43)-316-380-5332 ; e-mail: or
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7
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Wuensch C, Gross J, Steinkellner G, Gruber K, Glueck SM, Faber K. Asymmetric enzymatic hydration of hydroxystyrene derivatives. Angew Chem Int Ed Engl 2013; 52:2293-7. [PMID: 23335002 DOI: 10.1002/anie.201207916] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Revised: 12/10/2012] [Indexed: 11/05/2022]
Affiliation(s)
- Christiane Wuensch
- ACIB GmbH c/o Department of Chemistry, Organic & Bioorganic Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria
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8
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Wuensch C, Gross J, Steinkellner G, Gruber K, Glueck SM, Faber K. Asymmetric Enzymatic Hydration of Hydroxystyrene Derivatives. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201207916] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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9
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Gabriel FLP, Cyris M, Giger W, Kohler HPE. ipso-substitution: a general biochemical and biodegradation mechanism to cleave alpha-quaternary alkylphenols and bisphenol A. Chem Biodivers 2007; 4:2123-37. [PMID: 17886831 DOI: 10.1002/cbdv.200790170] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Sphingobium xenophagum Bayram is capable of metabolizing 4-alkoxyphenols and endocrine disruptive alpha-quaternary 4-nonylphenols by an ipso-substitution mechanism that involves ring hydroxylation at the site of the substituent. Here, we show that Bayram's ipso-hydroxylating activity was able to transform also bisphenol A (= dimethyl-4,4'-methylenediphenol; BPA) and 4-isopropylphenol. We identified six metabolites when resting cells of strain Bayram were incubated with BPA. They were unambiguously characterized by HPLC-UV, HPLC/MS, and HPLC/MS/MS as hydroquinone, 2-(4-hydroxyphenyl)isopropanol, 4-isopropenylphenol, 4-isopropylphenol, 4-hydroxy-4-isopropenylcyclohexa-2,5-dien-1-one, and 4-hydroxy-4-isopropylcyclohexa-2,5-dien-1-one. In experiments with 4-isopropylphenol as a substrate, 4-hydroxy-4-isopropylcyclohexa-2,5-dien-1-one, one of the metabolites from BPA, accumulated to a high degree. We could rationalize the formation of all metabolites by invoking ipso-hydroxylation and ipso-substitution mechanisms. On closer view, also classical bacterial metabolism of BPA can be well rationalized by an ipso-substitution mechanism, albeit with ipso-attack of an internal alkyl radical instead of an activated oxygen species. This highlights the important role of ipso-substitution as a versatile degradative principle utilized by diverse organisms to degrade alpha-quaternary 4-nonylphenols, 4-alkoxyphenols, and BPA.
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Affiliation(s)
- Frédéric L P Gabriel
- Swiss Federal Institute for Aquatic Science and Technology (Eawag), CH-8600 Dübendorf
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10
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van Berkel WJH, Kamerbeek NM, Fraaije MW. Flavoprotein monooxygenases, a diverse class of oxidative biocatalysts. J Biotechnol 2006; 124:670-89. [PMID: 16712999 DOI: 10.1016/j.jbiotec.2006.03.044] [Citation(s) in RCA: 518] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 02/21/2006] [Accepted: 03/29/2006] [Indexed: 10/24/2022]
Abstract
During the last decades a large number of flavin-dependent monooxygenases have been isolated and studied. This has revealed that flavoprotein monooxygenases are able to catalyze a remarkable wide variety of oxidative reactions such as regioselective hydroxylations and enantioselective sulfoxidations. These oxidation reactions are often difficult, if not impossible, to be achieved using chemical approaches. Analysis of the available genome sequences has indicated that many more flavoprotein monooxygenases exist and await biocatalytic exploration. Based on the known biochemical properties of a number of flavoprotein monooxygenases and sequence and structural analyses, flavoprotein monooxygenases can be classified into six distinct flavoprotein monooxygenase subclasses. This review provides an inventory of known flavoprotein monooxygenases belonging to these different enzyme subclasses. Furthermore, the biocatalytic potential of a selected number of flavoprotein monooxygenases is highlighted.
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Affiliation(s)
- W J H van Berkel
- Laboratory of Biochemistry, Department of Agrotechnology and Food Sciences, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands
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11
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Zeng GM, Yu HY, Huang HL, Huang DL, Chen YN, Huang GH, Li JB. Laccase activities of a soil fungus Penicillium simplicissimum in relation to lignin degradation. World J Microbiol Biotechnol 2006. [DOI: 10.1007/s11274-005-9025-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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12
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van den Heuvel RHH, van den Berg WAM, Rovida S, van Berkel WJH. Laboratory-evolved vanillyl-alcohol oxidase produces natural vanillin. J Biol Chem 2004; 279:33492-500. [PMID: 15169773 DOI: 10.1074/jbc.m312968200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The flavoenzyme vanillyl-alcohol oxidase was subjected to random mutagenesis to generate mutants with enhanced reactivity to creosol (2-methoxy-4-methylphenol). The vanillyl-alcohol oxidase-mediated conversion of creosol proceeds via a two-step process in which the initially formed vanillyl alcohol (4-hydroxy-3-methoxybenzyl alcohol) is oxidized to the widely used flavor compound vanillin (4-hydroxy-3-methoxybenzaldehyde). The first step of this reaction is extremely slow due to the formation of a covalent FAD N-5-creosol adduct. After a single round of error-prone PCR, seven mutants were generated with increased reactivity to creosol. The single-point mutants I238T, F454Y, E502G, and T505S showed an up to 40-fold increase in catalytic efficiency (kcat/Km) with creosol compared with the wild-type enzyme. This enhanced reactivity was due to a lower stability of the covalent flavin-substrate adduct, thereby promoting vanillin formation. The catalytic efficiencies of the mutants were also enhanced for other ortho-substituted 4-methylphenols, but not for p-cresol (4-methylphenol). The replaced amino acid residues are not located within a distance of direct interaction with the substrate, and the determined three-dimensional structures of the mutant enzymes are highly similar to that of the wild-type enzyme. These results clearly show the importance of remote residues, not readily predicted by rational design, for the substrate specificity of enzymes.
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Affiliation(s)
- Robert H H van den Heuvel
- Department of Genetics and Microbiology, University of Pavia, via Abbiategrasso 207, 27100 Pavia, Italy
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13
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Moonen M, Fraaije M, Rietjens I, Laane C, van Berkel W. Flavoenzyme-Catalyzed Oxygenations and Oxidations of Phenolic Compounds. Adv Synth Catal 2002. [DOI: 10.1002/1615-4169(200212)344:10<1023::aid-adsc1023>3.0.co;2-t] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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15
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Abstract
Nocardia species NRRL 5646 stereospecifically hydrates 4-vinylphenol (15) to S-1-(4'-hydroxyphenyl)ethanol (17), and further oxidizes 17 to 4'-hydroxyacetophenone (18). Labeled metabolites 17 and 18 obtained from incubations in D2O and H218O support initial enzymatic tautomerization of 15 to a reactive quinone methide (16), which adds water in the first reaction. Commitment to catalysis is high in the hydration reaction, while the alcohol dehydrogenation reaction appears to be reversible. The stereochemical features of water addition, alcohol oxidations, and ketone reductions with growing culture biocatalysis were established by chiral HPLC. Alcohol oxidations or ketone reductions in 12 000 × g supernatants preferentially require NADP+NADPH,H+ as co-factors. The alcohol dehydrogenase has broad substrate specificity, favoring the oxidation of primary alkanols and 4-hydroxybenzyl alcohols.Key words : 4-vinylphenol, Nocardia sp., enantiospecific hydration, 1-(4'-hydroxyphenyl)ethanol, 4'-hydroxyacetophenone
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16
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van den Heuvel RH, Partridge J, Laane C, Halling PJ, van Berkel WJ. Tuning of the product spectrum of vanillyl-alcohol oxidase by medium engineering. FEBS Lett 2001; 503:213-6. [PMID: 11513884 DOI: 10.1016/s0014-5793(01)02658-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The flavoenzyme vanillyl-alcohol oxidase (VAO) catalyzes the conversion of 4-alkylphenols through the initial formation of p-quinone methide intermediates. These electrophilic species are stereospecifically attacked by water to yield (R)-1-(4'-hydroxyphenyl)alcohols or rearranged in a competing reaction to 1-(4'-hydroxyphenyl)alkenes. Here, we show that the product spectrum of VAO can be controlled by medium engineering. When the enzymatic conversion of 4-propylphenol was performed in organic solvent, the concentration of the alcohol decreased and the concentration of the cis-alkene, but not the trans-alkene, increased. This change in selectivity occurred in both toluene and acetonitrile and was dependent on the water activity of the reaction medium. A similar shift in alcohol/cis-alkene product ratio was observed when the VAO-mediated conversion of 4-propylphenol was performed in the presence of monovalent anions that bind specifically near the enzyme active site.
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Affiliation(s)
- R H van den Heuvel
- Department of Agrotechnology and Food Sciences, Wageningen University, The Netherlands
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