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Fan XY, Yu Y, Yao Y, Li WD, Tao FY, Wang N. Applications of Ene-Reductases in the Synthesis of Flavors and Fragrances. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:18305-18320. [PMID: 38966982 PMCID: PMC11342376 DOI: 10.1021/acs.jafc.4c02897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 06/26/2024] [Accepted: 06/28/2024] [Indexed: 07/06/2024]
Abstract
Flavors and fragrances (F&F) are interesting organic compounds in chemistry. These compounds are widely used in the food, cosmetic, and medical industries. Enzymatic synthesis exhibits several advantages over natural extraction and chemical preparation, including a high yield, stable quality, mildness, and environmental friendliness. To date, many oxidoreductases and hydrolases have been used to biosynthesize F&F. Ene-reductases (ERs) are a class of biocatalysts that can catalyze the asymmetric reduction of α,β-unsaturated compounds and offer superior specificity and selectivity; therefore, ERs have been increasingly considered an ideal alternative to their chemical counterparts. This review summarizes the research progress on the use of ERs in F&F synthesis over the past 20 years, including the achievements of various scholars, the differences and similarities among the findings, and the discussions of future research trends related to ERs. We hope this review can inspire researchers to promote the development of biotechnology in the F&F industry.
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Affiliation(s)
- Xin-Yue Fan
- Key
Laboratory of Green Chemistry & Technology, Ministry of Education,
College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People’s
Republic of China
| | - Yuan Yu
- Key
Laboratory of Green Chemistry & Technology, Ministry of Education,
College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People’s
Republic of China
| | - Yao Yao
- Key
Laboratory of Green Chemistry & Technology, Ministry of Education,
College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People’s
Republic of China
| | - Wen-Dian Li
- Harmful
Components and Tar Reduction in Cigarette Key Laboratory of Sichuan
Province, China Tobacco Sichuan Industrial
Company, Limited, Chengdu, Sichuan 610066, People’s Republic of China
- Sichuan
Sanlian New Material Company, Limited, Chengdu, Sichuan 610041, People’s Republic
of China
| | - Fei-Yan Tao
- Harmful
Components and Tar Reduction in Cigarette Key Laboratory of Sichuan
Province, China Tobacco Sichuan Industrial
Company, Limited, Chengdu, Sichuan 610066, People’s Republic of China
- Sichuan
Sanlian New Material Company, Limited, Chengdu, Sichuan 610041, People’s Republic
of China
| | - Na Wang
- Key
Laboratory of Green Chemistry & Technology, Ministry of Education,
College of Chemistry, Sichuan University, Chengdu, Sichuan 610064, People’s
Republic of China
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2
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Kattula B, Munakala A, Kashyap R, Nallamilli T, Nagendla NK, Naza S, Mudiam MKR, Chegondi R, Addlagatta A. Strategic enzymatic enantioselective desymmetrization of prochiral cyclohexa-2,5-dienones. Chem Commun (Camb) 2024; 60:6647-6650. [PMID: 38856301 DOI: 10.1039/d4cc02181a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Asymmetric desymmetrization through the selective reduction of one double bond of prochiral 2,5-cyclohexadienones is highly challenging. A novel method has been developed for synthesizing chiral cyclohexenones by employing an ene-reductase (Bacillus subtilis YqjM) enzyme that belongs to the OYE family. Our strategy demonstrates high substrate scope and enantioselectivity towards substrates containing all-carbon as well as heteroatom (O, N)-containing quaternary centers. The mechanistic studies (kH/D = ∼1.8) indicate that hydride transfer is probably the rate-limiting step. Mutation of several active site residues did not affect the stereochemical outcomes. This work provides a convenient way of synthesizing various enantioselective γ,γ-disubstituted cyclohexanones using enzymes.
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Affiliation(s)
- Bhavita Kattula
- Department of Applied Biology, Hyderabad, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Anandarao Munakala
- Department of Organic Synthesis and Process Chemistry, Hyderabad, Telangana, India.
| | | | - Tarun Nallamilli
- Department of Organic Synthesis and Process Chemistry, Hyderabad, Telangana, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Narendra Kumar Nagendla
- Department of Analytical and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad-500 007, Telangana, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Surabhi Naza
- Department of Applied Biology, Hyderabad, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Mohana Krishna Reddy Mudiam
- Department of Analytical and Structural Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad-500 007, Telangana, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Rambabu Chegondi
- Department of Organic Synthesis and Process Chemistry, Hyderabad, Telangana, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
| | - Anthony Addlagatta
- Department of Applied Biology, Hyderabad, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India
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3
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Wu S, Ma X, Yan H. Identification and characterization of an ene-reductase from Corynebacterium casei. Int J Biol Macromol 2024; 264:130427. [PMID: 38428763 DOI: 10.1016/j.ijbiomac.2024.130427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 02/12/2024] [Accepted: 02/22/2024] [Indexed: 03/03/2024]
Abstract
The asymmetric reduction of α, β-unsaturated compounds conjugated with electron-withdrawing group by ene-reductases (ERs) is a valuable method for the synthesis of enantiopure chiral compounds. This study introduced an ER from Corynebacterium casei (CcER) which was heterologously expressed in Escherichia coli BL21(DE3), and the purified recombinant CcER was characterized for its biocatalytic properties. CcER exhibited the highest specific activity at 40 °C and pH 6.5, and showcased appreciable stability below 40 °C over a pH range of 6.0-7.0. The enzyme displayed high resistance to methanol. CcER accepted NADH or NADPH as a cofactor and exhibited a broad substrate spectrum towards α, β-unsaturated compounds. It achieved complete conversion of 2-cyclohexen-1-one and good performance for stereoselective reduction of (R)-carvone (conversion 98 %, diastereoselectivity 96 %). This study highlights the robustness and potential of CcER.
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Affiliation(s)
- Shijin Wu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Xiaojing Ma
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, China
| | - Hongde Yan
- College of Pharmaceutical Engineering and Biotechnology, Zhejiang Pharmaceutical University, Ningbo, China.
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4
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Böhmer S, Marx C, Goss R, Gilbert M, Sasso S, Happe T, Hemschemeier A. Chlamydomonas reinhardtii mutants deficient for Old Yellow Enzyme 3 exhibit increased photooxidative stress. PLANT DIRECT 2023; 7:e480. [PMID: 36685735 PMCID: PMC9840898 DOI: 10.1002/pld3.480] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 11/14/2022] [Accepted: 12/31/2022] [Indexed: 05/12/2023]
Abstract
Old Yellow Enzymes (OYEs) are flavin-containing ene-reductases that have been intensely studied with regard to their biotechnological potential for sustainable chemical syntheses. OYE-encoding genes are found throughout the domains of life, but their physiological role is mostly unknown, one reason for this being the promiscuity of most ene-reductases studied to date. The unicellular green alga Chlamydomonas reinhardtii possesses four genes coding for OYEs, three of which we have analyzed biochemically before. Ene-reductase CrOYE3 stood out in that it showed an unusually narrow substrate scope and converted N-methylmaleimide (NMI) with high rates. This was recapitulated in a C. reinhardtii croye3 mutant that, in contrast to the wild type, hardly degraded externally added NMI. Here we show that CrOYE3-mediated NMI conversion depends on electrons generated photosynthetically by photosystem II (PSII) and that the croye3 mutant exhibits slightly decreased photochemical quenching in high light. Non-photochemical quenching is strongly impaired in this mutant, and it shows enhanced oxidative stress. The phenotypes of the mutant suggest that C. reinhardtii CrOYE3 is involved in the protection against photooxidative stress, possibly by converting reactive carbonyl species derived from lipid peroxides or maleimides from tetrapyrrole degradation.
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Affiliation(s)
- Stefanie Böhmer
- Faculty of Biology and Biotechnology, PhotobiotechnologyRuhr University BochumBochumGermany
| | - Christina Marx
- SolarBioproducts RuhrBusiness Development Agency HerneHerneGermany
| | - Reimund Goss
- Institute of Biology, Plant PhysiologyLeipzig UniversityLeipzigGermany
| | - Matthias Gilbert
- Institute of Biology, Plant PhysiologyLeipzig UniversityLeipzigGermany
| | - Severin Sasso
- Institute of Biology, Plant PhysiologyLeipzig UniversityLeipzigGermany
| | - Thomas Happe
- Faculty of Biology and Biotechnology, PhotobiotechnologyRuhr University BochumBochumGermany
| | - Anja Hemschemeier
- Faculty of Biology and Biotechnology, PhotobiotechnologyRuhr University BochumBochumGermany
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5
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Luan P, Li Y, Huang C, Dong L, Ma T, Liu J, Gao J, Liu Y, Jiang Y. Design of De Novo Three-Enzyme Nanoreactors for Stereodivergent Synthesis of α-Substituted Cyclohexanols. ACS Catal 2022. [DOI: 10.1021/acscatal.2c02136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Pengqian Luan
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China
| | - Yongxing Li
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China
| | - Chen Huang
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China
| | - Lele Dong
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China
| | - Teng Ma
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China
| | - Jianqiao Liu
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China
| | - Jing Gao
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China
| | - Yunting Liu
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China
| | - Yanjun Jiang
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan 430062, China
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6
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Ma T, Kong W, Liu Y, Zhao H, Ouyang Y, Gao J, Zhou L, Jiang Y. Asymmetric Hydrogenation of C = C Bonds in a SpinChem Reactor by Immobilized Old Yellow Enzyme and Glucose Dehydrogenase. Appl Biochem Biotechnol 2022; 194:4999-5016. [PMID: 35687305 DOI: 10.1007/s12010-022-03991-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/27/2022] [Indexed: 11/27/2022]
Abstract
The application of immobilized enzymes in pharmaceutical and bulk chemical production has been shown to be economically viable. We demonstrate the exceptional performance of a method that immobilizes the old yellow enzyme YqjM and glucose dehydrogenase (GDH) on resin for the asymmetric hydrogenation (AH) of C = C bonds in a SpinChem reactor. When immobilized YqjM and GDH are reused 10 times, the conversion of 2-methylcyclopentenone could reach 78%. Which is because the rotor of the SpinChem reactor effectively reduces catalyst damage caused by shear force in the reaction system. When the substrate concentration is 175 mM, an 87% conversion of 2-methylcyclopentenone is obtained. The method is also observed to perform well for the AH of C = C bonds in other unsaturated carbonyl compounds with the SpinChem reactor. Thus, this method has great potential for application in the enzymatic production of chiral compounds.
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Affiliation(s)
- Teng Ma
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin, 300130, People's Republic of China.,Tianjin Key Laboratory of Chemical Process Safety, Hebei University of Technology, Tianjin, 300130, People's Republic of China
| | - Weixi Kong
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin, 300130, People's Republic of China.,Tianjin Key Laboratory of Chemical Process Safety, Hebei University of Technology, Tianjin, 300130, People's Republic of China
| | - Yunting Liu
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin, 300130, People's Republic of China.,Tianjin Key Laboratory of Chemical Process Safety, Hebei University of Technology, Tianjin, 300130, People's Republic of China
| | - Hao Zhao
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin, 300130, People's Republic of China.,Tianjin Key Laboratory of Chemical Process Safety, Hebei University of Technology, Tianjin, 300130, People's Republic of China
| | - Yaping Ouyang
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin, 300130, People's Republic of China.,Tianjin Key Laboratory of Chemical Process Safety, Hebei University of Technology, Tianjin, 300130, People's Republic of China
| | - Jing Gao
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin, 300130, People's Republic of China.,Tianjin Key Laboratory of Chemical Process Safety, Hebei University of Technology, Tianjin, 300130, People's Republic of China
| | - Liya Zhou
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin, 300130, People's Republic of China. .,Tianjin Key Laboratory of Chemical Process Safety, Hebei University of Technology, Tianjin, 300130, People's Republic of China.
| | - Yanjun Jiang
- School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin, 300130, People's Republic of China. .,Tianjin Key Laboratory of Chemical Process Safety, Hebei University of Technology, Tianjin, 300130, People's Republic of China.
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7
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Robescu MS, Cendron L, Bacchin A, Wagner K, Reiter T, Janicki I, Merusic K, Illek M, Aleotti M, Bergantino E, Hall M. Asymmetric Proton Transfer Catalysis by Stereocomplementary Old Yellow Enzymes for C═C Bond Isomerization Reaction. ACS Catal 2022. [DOI: 10.1021/acscatal.2c01110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Marina S. Robescu
- Department of Biology, University of Padova, Padova, Province of Padova 35131, Italy
| | - Laura Cendron
- Department of Biology, University of Padova, Padova, Province of Padova 35131, Italy
| | - Arianna Bacchin
- Institute of Chemistry, University of Graz, Graz, Styria 8010, Austria
| | - Karla Wagner
- Institute of Chemistry, University of Graz, Graz, Styria 8010, Austria
| | - Tamara Reiter
- Institute of Chemistry, University of Graz, Graz, Styria 8010, Austria
| | - Ignacy Janicki
- Department of Heteroorganic Chemistry, Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Lodz, Lodz Province 90-001, Poland
| | - Kemal Merusic
- Institute of Chemistry, University of Graz, Graz, Styria 8010, Austria
| | - Maximilian Illek
- Institute of Chemistry, University of Graz, Graz, Styria 8010, Austria
| | - Matteo Aleotti
- Institute of Chemistry, University of Graz, Graz, Styria 8010, Austria
| | - Elisabetta Bergantino
- Department of Biology, University of Padova, Padova, Province of Padova 35131, Italy
| | - Mélanie Hall
- Institute of Chemistry, University of Graz, Graz, Styria 8010, Austria
- Field of Excellence BioHealth, University of Graz, Graz, Styria 8010, Austria
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8
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Jongkind EPJ, Fossey‐Jouenne A, Mayol O, Zaparucha A, Vergne‐Vaxelaire C, Paul CE. Synthesis of Chiral Amines via a Bi‐Enzymatic Cascade Using an Ene‐Reductase and Amine Dehydrogenase. ChemCatChem 2021. [DOI: 10.1002/cctc.202101576] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Ewald P. J. Jongkind
- Biocatalysis Department of Biotechnology Delft University of Technology Van der Maasweg 9 2629 HZ Delft The Netherlands
| | - Aurélie Fossey‐Jouenne
- Génomique Métabolique Genoscope Institut François Jacob CEA CNRS Univ Evry Université Paris-Saclay 2 rue Gaston Crémieux 91057 Evry France
| | - Ombeline Mayol
- Génomique Métabolique Genoscope Institut François Jacob CEA CNRS Univ Evry Université Paris-Saclay 2 rue Gaston Crémieux 91057 Evry France
| | - Anne Zaparucha
- Génomique Métabolique Genoscope Institut François Jacob CEA CNRS Univ Evry Université Paris-Saclay 2 rue Gaston Crémieux 91057 Evry France
| | - Carine Vergne‐Vaxelaire
- Génomique Métabolique Genoscope Institut François Jacob CEA CNRS Univ Evry Université Paris-Saclay 2 rue Gaston Crémieux 91057 Evry France
| | - Caroline E. Paul
- Biocatalysis Department of Biotechnology Delft University of Technology Van der Maasweg 9 2629 HZ Delft The Netherlands
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Raj K, Venayak N, Diep P, Golla SA, Yakunin AF, Mahadevan R. Automation assisted anaerobic phenotyping for metabolic engineering. Microb Cell Fact 2021; 20:184. [PMID: 34556155 PMCID: PMC8461876 DOI: 10.1186/s12934-021-01675-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 09/10/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Microorganisms can be metabolically engineered to produce a wide range of commercially important chemicals. Advancements in computational strategies for strain design and synthetic biological techniques to construct the designed strains have facilitated the generation of large libraries of potential candidates for chemical production. Consequently, there is a need for high-throughput laboratory scale techniques to characterize and screen these candidates to select strains for further investigation in large scale fermentation processes. Several small-scale fermentation techniques, in conjunction with laboratory automation have enhanced the throughput of enzyme and strain phenotyping experiments. However, such high throughput experimentation typically entails large operational costs and generate massive amounts of laboratory plastic waste. RESULTS In this work, we develop an eco-friendly automation workflow that effectively calibrates and decontaminates fixed-tip liquid handling systems to reduce tip waste. We also investigate inexpensive methods to establish anaerobic conditions in microplates for high-throughput anaerobic phenotyping. To validate our phenotyping platform, we perform two case studies-an anaerobic enzyme screen, and a microbial phenotypic screen. We used our automation platform to investigate conditions under which several strains of E. coli exhibit the same phenotypes in 0.5 L bioreactors and in our scaled-down fermentation platform. We also propose the use of dimensionality reduction through t-distributed stochastic neighbours embedding (t-SNE) in conjunction with our phenotyping platform to effectively cluster similarly performing strains at the bioreactor scale. CONCLUSIONS Fixed-tip liquid handling systems can significantly reduce the amount of plastic waste generated in biological laboratories and our decontamination and calibration protocols could facilitate the widespread adoption of such systems. Further, the use of t-SNE in conjunction with our automation platform could serve as an effective scale-down model for bioreactor fermentations. Finally, by integrating an in-house data-analysis pipeline, we were able to accelerate the 'test' phase of the design-build-test-learn cycle of metabolic engineering.
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Affiliation(s)
- Kaushik Raj
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, M5S 3E5 Canada
| | - Naveen Venayak
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, M5S 3E5 Canada
| | - Patrick Diep
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, M5S 3E5 Canada
| | - Sai Akhil Golla
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, M5S 3E5 Canada
| | - Alexander F. Yakunin
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, M5S 3E5 Canada
- School of Natural Sciences, Bangor University, Bangor, LL57 2DG UK
| | - Radhakrishnan Mahadevan
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, M5S 3E5 Canada
- Institute of Biomedical Engineering, University of Toronto, 164 College Street, Toronto, M5S 3G9 Canada
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10
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Mantel M, Giesler M, Guder M, Rüthlein E, Hartmann L, Pietruszka J. Lewis‐Base‐Brønsted‐Säure‐Enzym‐Katalyse in enantioselektiven mehrstufigen Eintopf‐Synthesen. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202103406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Marvin Mantel
- Institut für Bioorganische Chemie Heinrich-Heine-Universität Düsseldorf im Forschungszentrum Jülich Stetternicher Forst, Geb. 15.8 52426 Jülich Deutschland
| | - Markus Giesler
- Institut für Organische und Makromolekulare Chemie Heinrich-Heine-Universität Düsseldorf 40225 Düsseldorf Deutschland
| | - Marian Guder
- Institut für Bio- und Geowissenschaften: Biotechnologie (IBG-1) Forschungszentrum Jülich GmbH 52428 Jülich Deutschland
| | - Elisabeth Rüthlein
- Institut für Bioorganische Chemie Heinrich-Heine-Universität Düsseldorf im Forschungszentrum Jülich Stetternicher Forst, Geb. 15.8 52426 Jülich Deutschland
| | - Laura Hartmann
- Institut für Organische und Makromolekulare Chemie Heinrich-Heine-Universität Düsseldorf 40225 Düsseldorf Deutschland
| | - Jörg Pietruszka
- Institut für Bioorganische Chemie Heinrich-Heine-Universität Düsseldorf im Forschungszentrum Jülich Stetternicher Forst, Geb. 15.8 52426 Jülich Deutschland
- Institut für Bio- und Geowissenschaften: Biotechnologie (IBG-1) Forschungszentrum Jülich GmbH 52428 Jülich Deutschland
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11
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Mantel M, Giesler M, Guder M, Rüthlein E, Hartmann L, Pietruszka J. Lewis Base-Brønsted Acid-Enzyme Catalysis in Enantioselective Multistep One-Pot Syntheses. Angew Chem Int Ed Engl 2021; 60:16700-16706. [PMID: 33856095 PMCID: PMC8360128 DOI: 10.1002/anie.202103406] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 04/08/2021] [Indexed: 12/23/2022]
Abstract
Establishing one-pot, multi-step protocols combining different types of catalysts is one important goal for increasing efficiency in modern organic synthesis. In particular, the high potential of biocatalysts still needs to be harvested. Based on an in-depth mechanistic investigation of a new organocatalytic protocol employing two catalysts {1,4-diazabicyclo[2.2.2]octane (DABCO); benzoic acid (BzOH)}, a sequence was established providing starting materials for enzymatic refinement (ene reductase; alcohol dehydrogenase): A gram-scale access to a variety of enantiopure key building blocks for natural product syntheses was enabled utilizing up to six catalytic steps within the same reaction vessel.
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Affiliation(s)
- Marvin Mantel
- Institut für Bioorganische ChemieHeinrich-Heine-Universität Düsseldorf im Forschungszentrum JülichStetternicher Forst, Geb. 15.852426JülichGermany
| | - Markus Giesler
- Institut für Organische und Makromolekulare ChemieHeinrich-Heine-Universität Düsseldorf40225DüsseldorfGermany
| | - Marian Guder
- Institut für Bio- und Geowissenschaften: Biotechnologie (IBG-1)Forschungszentrum Jülich GmbH52428JülichGermany
| | - Elisabeth Rüthlein
- Institut für Bioorganische ChemieHeinrich-Heine-Universität Düsseldorf im Forschungszentrum JülichStetternicher Forst, Geb. 15.852426JülichGermany
| | - Laura Hartmann
- Institut für Organische und Makromolekulare ChemieHeinrich-Heine-Universität Düsseldorf40225DüsseldorfGermany
| | - Jörg Pietruszka
- Institut für Bioorganische ChemieHeinrich-Heine-Universität Düsseldorf im Forschungszentrum JülichStetternicher Forst, Geb. 15.852426JülichGermany
- Institut für Bio- und Geowissenschaften: Biotechnologie (IBG-1)Forschungszentrum Jülich GmbH52428JülichGermany
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12
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The First Step of Biodegradation of 7-Hydroxycoumarin in Pseudomonas mandelii 7HK4 Depends on an Alcohol Dehydrogenase-Type Enzyme. Int J Mol Sci 2021; 22:ijms22041552. [PMID: 33557119 PMCID: PMC7913881 DOI: 10.3390/ijms22041552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2021] [Revised: 01/27/2021] [Accepted: 02/01/2021] [Indexed: 11/23/2022] Open
Abstract
Coumarins are well known secondary metabolites widely found in various plants. However, the degradation of these compounds in the environment has not been studied in detail, and, especially, the initial stages of the catabolic pathways of coumarins are not fully understood. A soil isolate Pseudomonas mandelii 7HK4 is able to degrade 7-hydroxycoumarin (umbelliferone) via the formation of 3-(2,4-dihydroxyphenyl)propionic acid, but the enzymes catalyzing the α-pyrone ring transformations have not been characterized. To elucidate an upper pathway of the catabolism of 7-hydroxycoumarin, 7-hydroxycoumarin-inducible genes hcdD, hcdE, hcdF, and hcdG were identified by RT-qPCR analysis. The DNA fragment encoding a putative alcohol dehydrogenase HcdE was cloned, and the recombinant protein catalyzed the NADPH-dependent reduction of 7-hydroxycoumarin both in vivo and in vitro. The reaction product was isolated and characterized as a 7-hydroxy-3,4-dihydrocoumarin based on HPLC-MS and NMR analyses. In addition, the HcdE was active towards 6,7-dihydroxycoumarin, 6-hydroxycoumarin, 6-methylcoumarin and coumarin. Thus, in contrast to the well-known fact that the ene-reductases usually participate in the reduction of the double bond, an alcohol dehydrogenase catalyzing such reaction has been identified, and, for P. mandelii 7HK4, 7-hydroxycoumarin degradation via a 7-hydroxy-3,4-dihydrocoumarin pathway has been proposed.
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Assil-Companioni L, Büchsenschütz HC, Solymosi D, Dyczmons-Nowaczyk NG, Bauer KKF, Wallner S, Macheroux P, Allahverdiyeva Y, Nowaczyk MM, Kourist R. Engineering of NADPH Supply Boosts Photosynthesis-Driven Biotransformations. ACS Catal 2020; 10:11864-11877. [PMID: 33101760 PMCID: PMC7574619 DOI: 10.1021/acscatal.0c02601] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 09/04/2020] [Indexed: 02/08/2023]
Abstract
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Light-driven biocatalysis
in recombinant cyanobacteria provides
highly atom-efficient cofactor regeneration via photosynthesis,
thereby remediating constraints associated with sacrificial cosubstrates.
However, despite the remarkable specific activities of photobiocatalysts,
self-shading at moderate-high cell densities limits efficient space-time-yields
of heterologous enzymatic reactions. Moreover, efficient integration
of an artificial electron sink into the tightly regulated network
of cyanobacterial electron pathways can be highly challenging. Here,
we used C=C bond reduction of 2-methylmaleimide by the NADPH-dependent
ene-reductase YqjM as a model reaction for light-dependent biotransformations.
Time-resolved NADPH fluorescence spectroscopy allowed direct monitoring
of in-cell YqjM activity and revealed differences in NADPH steady-state
levels and oxidation kinetics between different genetic constructs.
This effect correlates with specific activities of whole-cells, which
demonstrated conversions of >99%. Further channelling of electrons
toward heterologous YqjM by inactivation of the flavodiiron proteins
(Flv1/Flv3) led to a 2-fold improvement in specific activity at moderate
cell densities, thereby elucidating the possibility of accelerating
light-driven biotransformations by the removal of natural competing
electron sinks. In the best case, an initial product formation rate
of 18.3 mmol h–1 L–1 was reached,
allowing the complete conversion of a 60 mM substrate solution within
4 h.
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Affiliation(s)
- Leen Assil-Companioni
- Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
- ACIB GmbH, Petersgasse 14, 8010 Graz, Austria
| | - Hanna C. Büchsenschütz
- Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
| | - Dániel Solymosi
- Molecular Plant Biology unit, Department of Biochemistry, Faculty of Science and Engineering, University of Turku, Turku 20014, Finland
| | - Nina G. Dyczmons-Nowaczyk
- Department of Plant Biochemistry, Faculty of Biology & Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany
| | - Kristin K. F. Bauer
- Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
| | - Silvia Wallner
- Institute of Biochemistry, Graz University of Technology, Petersgasse 10, 8010 Graz, Austria
| | - Peter Macheroux
- Institute of Biochemistry, Graz University of Technology, Petersgasse 10, 8010 Graz, Austria
| | - Yagut Allahverdiyeva
- Molecular Plant Biology unit, Department of Biochemistry, Faculty of Science and Engineering, University of Turku, Turku 20014, Finland
| | - Marc M. Nowaczyk
- Department of Plant Biochemistry, Faculty of Biology & Biotechnology, Ruhr University Bochum, 44780 Bochum, Germany
| | - Robert Kourist
- Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14, 8010 Graz, Austria
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14
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Böhmer S, Marx C, Gómez-Baraibar Á, Nowaczyk MM, Tischler D, Hemschemeier A, Happe T. Evolutionary diverse Chlamydomonas reinhardtii Old Yellow Enzymes reveal distinctive catalytic properties and potential for whole-cell biotransformations. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.101970] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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15
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Rauch MCR, Gallou Y, Delorme L, Paul CE, Arends IWCE, Hollmann F. Metals in Biotechnology: Cr-Driven Stereoselective Reduction of Conjugated C=C Double Bonds. Chembiochem 2020; 21:1112-1115. [PMID: 31713969 PMCID: PMC7217005 DOI: 10.1002/cbic.201900685] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Indexed: 11/13/2022]
Abstract
Elemental metals are shown to be suitable sacrificial electron donors to drive the stereoselective reduction of conjugated C=C double bonds using Old Yellow Enzymes as catalysts. Both direct electron transfer from the metal to the enzyme as well as mediated electron transfer is feasible, although the latter excels by higher reaction rates. The general applicability of this new chemoenzymatic reduction method is demonstrated, and current limitations are outlined.
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Affiliation(s)
- Marine C. R. Rauch
- Department of BiotechnologyDelft University of TechnologyVan der Maasweg 92629HZDelftThe Netherlands
| | - Yann Gallou
- Department of BiotechnologyDelft University of TechnologyVan der Maasweg 92629HZDelftThe Netherlands
| | - Léna Delorme
- Department of BiotechnologyDelft University of TechnologyVan der Maasweg 92629HZDelftThe Netherlands
| | - Caroline E. Paul
- Department of BiotechnologyDelft University of TechnologyVan der Maasweg 92629HZDelftThe Netherlands
| | | | - Frank Hollmann
- Department of BiotechnologyDelft University of TechnologyVan der Maasweg 92629HZDelftThe Netherlands
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16
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Abstract
Ene reductases enable the asymmetric hydrogenation of activated alkenes allowing the manufacture of valuable chiral products. The enzymes complement existing metal- and organocatalytic approaches for the stereoselective reduction of activated C=C double bonds, and efforts to expand the biocatalytic toolbox with additional ene reductases are of high academic and industrial interest. Here, we present the characterization of a novel ene reductase from Paenibacillus polymyxa, named Ppo-Er1, belonging to the recently identified subgroup III of the old yellow enzyme family. The determination of substrate scope, solvent stability, temperature, and pH range of Ppo-Er1 is one of the first examples of a detailed biophysical characterization of a subgroup III enzyme. Notably, Ppo-Er1 possesses a wide temperature optimum (Topt: 20–45 °C) and retains high conversion rates of at least 70% even at 10 °C reaction temperature making it an interesting biocatalyst for the conversion of temperature-labile substrates. When assaying a set of different organic solvents to determine Ppo-Er1′s solvent tolerance, the ene reductase exhibited good performance in up to 40% cyclohexane as well as 20 vol% DMSO and ethanol. In summary, Ppo-Er1 exhibited activity for thirteen out of the nineteen investigated compounds, for ten of which Michaelis–Menten kinetics could be determined. The enzyme exhibited the highest specificity constant for maleimide with a kcat/KM value of 287 mM−1 s−1. In addition, Ppo-Er1 proved to be highly enantioselective for selected substrates with measured enantiomeric excess values of 92% or higher for 2-methyl-2-cyclohexenone, citral, and carvone.
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17
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Rauch MCR, Huijbers MME, Pabst M, Paul CE, Pešić M, Arends IWCE, Hollmann F. Photochemical regeneration of flavoenzymes - An Old Yellow Enzyme case-study. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1868:140303. [PMID: 31678192 DOI: 10.1016/j.bbapap.2019.140303] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 10/08/2019] [Accepted: 10/09/2019] [Indexed: 12/01/2022]
Abstract
Direct, NAD(P)H-independent regeneration of Old Yellow Enzymes represents an interesting approach for simplified reaction schemes for the stereoselective reduction of conjugated C=C-double bonds. Simply by illuminating the reaction mixtures with blue light in the presence of sacrificial electron donors enables to circumvent the costly and unstable nicotinamide cofactors and a corresponding regeneration system. In the present study, we characterise the parameters determining the efficiency of this approach and outline the current limitations. Particularly, the photolability of the flavin photocatalyst and the (flavin-containing) biocatalyst represent the major limitation en route to preparative application.
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Affiliation(s)
- M C R Rauch
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - M M E Huijbers
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - M Pabst
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - C E Paul
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - M Pešić
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands
| | - I W C E Arends
- Faculty of Science, Utrecht University, Budapestlaan 6, 3584 CD Utrecht, the Netherlands
| | - F Hollmann
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629 HZ Delft, the Netherlands.
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18
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Pesic M, Willot SJP, Fernández-Fueyo E, Tieves F, Alcalde M, Hollmann F. Multienzymatic in situ hydrogen peroxide generation cascade for peroxygenase-catalysed oxyfunctionalisation reactions. ACTA ACUST UNITED AC 2019; 74:101-104. [PMID: 30379645 DOI: 10.1515/znc-2018-0137] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 10/04/2018] [Indexed: 01/02/2023]
Abstract
There is an increasing interest in the application of peroxygenases in biocatalysis, because of their ability to catalyse the oxyfunctionalisation reaction in a stereoselective fashion and with high catalytic efficiencies, while using hydrogen peroxide or organic peroxides as oxidant. However, enzymes belonging to this class exhibit a very low stability in the presence of peroxides. With the aim of bypassing this fast and irreversible inactivation, we study the use of a gradual supply of hydrogen peroxide to maintain its concentration at stoichiometric levels. In this contribution, we report a multienzymatic cascade for in situ generation of hydrogen peroxide. In the first step, in the presence of NAD+ cofactor, formate dehydrogenase from Candida boidinii (FDH) catalysed the oxidation of formate yielding CO2. Reduced NADH was reoxidised by the reduction of the flavin mononucleotide cofactor bound to an old yellow enzyme homologue from Bacillus subtilis (YqjM), which subsequently reacts with molecular oxygen yielding hydrogen peroxide. Finally, this system was coupled to the hydroxylation of ethylbenzene reaction catalysed by an evolved peroxygenase from Agrocybe aegerita (rAaeUPO). Additionally, we studied the influence of different reaction parameters on the performance of the cascade with the aim of improving the turnover of the hydroxylation reaction.
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Affiliation(s)
- Milja Pesic
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629HZ Delft, The Netherlands
| | - Sébastien Jean-Paul Willot
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629HZ Delft, The Netherlands
| | - Elena Fernández-Fueyo
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629HZ Delft, The Netherlands
| | - Florian Tieves
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629HZ Delft, The Netherlands
| | - Miguel Alcalde
- Department of Biocatalysis, Institute of Catalysis, CSIC, 28049 Madrid, Spain
| | - Frank Hollmann
- Department of Biotechnology, Delft University of Technology, van der Maasweg 9, 2629HZ Delft, The Netherlands
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19
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Peters C, Buller R. Linear enzyme cascade for the production of (-)-iso-isopulegol. ACTA ACUST UNITED AC 2019; 74:63-70. [PMID: 30645192 DOI: 10.1515/znc-2018-0146] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Accepted: 12/09/2018] [Indexed: 01/31/2023]
Abstract
Biocatalysis has developed enormously in the last decade and now offers solutions for the sustainable production of chiral and highly functionalised asset molecules. Products generated by enzymatic transformations are already being used in the food, feed, chemical, pharmaceutical and cosmetic industry, and the accessible compound panoply is expected to expand even further. In particular, the combination of stereo-selective enzymes in linear cascade reactions is an elegant strategy toward enantiomeric pure compounds, as it reduces the number of isolation and purification steps and avoids accumulation of potentially unstable intermediates. Here, we present the set-up of an enzyme cascade to selectively convert citral to (-)-iso-isopulegol by combining an ene reductase and a squalene hopene cyclase. In the initial reaction step, the ene reductase YqjM from Bacillus subtilis selectively transforms citral to (S)-citronellal, which is subsequently cyclised exclusively to (-)-iso-isopulegol by a mutant of the squalene hopene cyclase from Alicyclobacillus acidocaldarius (AacSHC). With this approach, we can convert citral to an enantiopure precursor for isomenthol derivatives.
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Affiliation(s)
- Christin Peters
- Competence Center for Biocatalysis, Institute of Chemistry and Biotechnology, Zürich University of Applied Sciences, Einsiedlerstrasse 31, 8820 Wädenswil, Switzerland
| | - Rebecca Buller
- Competence Center for Biocatalysis, Institute of Chemistry and Biotechnology, Zürich University of Applied Sciences, Einsiedlerstrasse 31, 8820 Wädenswil, Switzerland
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20
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Toogood HS, Scrutton NS. Discovery, Characterisation, Engineering and Applications of Ene Reductases for Industrial Biocatalysis. ACS Catal 2019; 8:3532-3549. [PMID: 31157123 PMCID: PMC6542678 DOI: 10.1021/acscatal.8b00624] [Citation(s) in RCA: 158] [Impact Index Per Article: 31.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Recent studies of multiple enzyme families collectively referred to as ene-reductases (ERs) have highlighted potential industrial application of these biocatalysts in the production of fine and speciality chemicals. Processes have been developed whereby ERs contribute to synthetic routes as isolated enzymes, components of multi-enzyme cascades, and more recently in metabolic engineering and synthetic biology programmes using microbial cell factories to support chemicals production. The discovery of ERs from previously untapped sources and the expansion of directed evolution screening programmes, coupled to deeper mechanistic understanding of ER reactions, have driven their use in natural product and chemicals synthesis. Here we review developments, challenges and opportunities for the use of ERs in fine and speciality chemicals manufacture. The ER research field is rapidly expanding and the focus of this review is on developments that have emerged predominantly over the last 4 years.
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Affiliation(s)
- Helen S. Toogood
- School of Chemistry, Faculty of Science and Engineering, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
| | - Nigel S. Scrutton
- School of Chemistry, Faculty of Science and Engineering, University of Manchester, 131 Princess Street, Manchester M1 7DN, U.K
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21
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Peters C, Frasson D, Sievers M, Buller R. Novel Old Yellow Enzyme Subclasses. Chembiochem 2019; 20:1569-1577. [DOI: 10.1002/cbic.201800770] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/12/2019] [Indexed: 11/07/2022]
Affiliation(s)
- Christin Peters
- Competence Center for BiocatalysisInstitute of Chemistry and BiotechnologySchool of Life Sciences and Facility ManagementZurich University of Applied Sciences Einsiedlerstrasse 31 8820 Wädenswil Switzerland
| | - David Frasson
- Molecular BiologyInstitute of Chemistry and BiotechnologySchool of Life Sciences and Facility ManagementZurich University of Applied Sciences Einsiedlerstrasse 31 8820 Wädenswil Switzerland
| | - Martin Sievers
- Molecular BiologyInstitute of Chemistry and BiotechnologySchool of Life Sciences and Facility ManagementZurich University of Applied Sciences Einsiedlerstrasse 31 8820 Wädenswil Switzerland
| | - Rebecca Buller
- Competence Center for BiocatalysisInstitute of Chemistry and BiotechnologySchool of Life Sciences and Facility ManagementZurich University of Applied Sciences Einsiedlerstrasse 31 8820 Wädenswil Switzerland
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22
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Deazaflavins as photocatalysts for the direct reductive regeneration of flavoenzymes. MOLECULAR CATALYSIS 2018. [DOI: 10.1016/j.mcat.2018.04.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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23
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In silico and in vitro studies of the reduction of unsaturated α,β bonds of trans-2-hexenedioic acid and 6-amino-trans-2-hexenoic acid - Important steps towards biobased production of adipic acid. PLoS One 2018; 13:e0193503. [PMID: 29474495 PMCID: PMC5825115 DOI: 10.1371/journal.pone.0193503] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 02/12/2018] [Indexed: 01/31/2023] Open
Abstract
The biobased production of adipic acid, a precursor in the production of nylon, is of great interest in order to replace the current petrochemical production route. Glucose-rich lignocellulosic raw materials have high potential to replace the petrochemical raw material. A number of metabolic pathways have been proposed for the microbial conversion of glucose to adipic acid, but achieved yields and titers remain to be improved before industrial applications are feasible. One proposed pathway starts with lysine, an essential metabolite industrially produced from glucose by microorganisms. However, the drawback of this pathway is that several reactions are involved where there is no known efficient enzyme. By changing the order of the enzymatic reactions, we were able to identify an alternative pathway with one unknown enzyme less compared to the original pathway. One of the reactions lacking known enzymes is the reduction of the unsaturated α,β bond of 6-amino-trans-2-hexenoic acid and trans-2-hexenedioic acid. To identify the necessary enzymes, we selected N-ethylmaleimide reductase from Escherichia coli and Old Yellow Enzyme 1 from Saccharomyces pastorianus. Despite successful in silico docking studies, where both target substrates could fit in the enzyme pockets, and hydrogen bonds with catalytic residues of both enzymes were predicted, no in vitro activity was observed. We hypothesize that the lack of activity is due to a difference in electron withdrawing potential between the naturally reduced aldehyde and the carboxylate groups of our target substrates. Suggestions for protein engineering to induce the reactions are discussed, as well as the advantages and disadvantages of the two metabolic pathways from lysine. We have highlighted bottlenecks associated with the lysine pathways, and proposed ways of addressing them.
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