1
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Williams TL, Taily IM, Hatton L, Berezin AA, Wu YL, Moliner V, Świderek K, Tsai YH, Luk LYP. Secondary Amine Catalysis in Enzyme Design: Broadening Protein Template Diversity through Genetic Code Expansion. Angew Chem Int Ed Engl 2024; 63:e202403098. [PMID: 38545954 DOI: 10.1002/anie.202403098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Indexed: 04/20/2024]
Abstract
Secondary amines, due to their reactivity, can transform protein templates into catalytically active entities, accelerating the development of artificial enzymes. However, existing methods, predominantly reliant on modified ligands or N-terminal prolines, impose significant limitations on template selection. In this study, genetic code expansion was used to break this boundary, enabling secondary amines to be incorporated into alternative proteins and positions of choice. Pyrrolysine analogues carrying different secondary amines could be incorporated into superfolder green fluorescent protein (sfGFP), multidrug-binding LmrR and nucleotide-binding dihydrofolate reductase (DHFR). Notably, the analogue containing a D-proline moiety demonstrated both proteolytic stability and catalytic activity, conferring LmrR and DHFR with the desired transfer hydrogenation activity. While the LmrR variants were confined to the biomimetic 1-benzyl-1,4-dihydronicotinamide (BNAH) as the hydride source, the optimal DHFR variant favorably used the pro-R hydride from NADPH for stereoselective reactions (e.r. up to 92 : 8), highlighting that a switch of protein template could broaden the nucleophile option for catalysis. Owing to the cofactor compatibility, the DHFR-based secondary amine catalysis could be integrated into an enzymatic recycling scheme. This established method shows substantial potential in enzyme design, applicable from studies on enzyme evolution to the development of new biocatalysts.
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Affiliation(s)
- Thomas L Williams
- School of Chemistry and Cardiff Catalysis Institute, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, United Kingdom
| | - Irshad M Taily
- School of Chemistry and Cardiff Catalysis Institute, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, United Kingdom
| | - Lewis Hatton
- School of Chemistry and Cardiff Catalysis Institute, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, United Kingdom
| | - Andrey A Berezin
- School of Chemistry and Cardiff Catalysis Institute, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, United Kingdom
| | - Yi-Lin Wu
- School of Chemistry and Cardiff Catalysis Institute, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, United Kingdom
| | - Vicent Moliner
- BioComp Group, Institute of Advanced Materials (INAM), Universitat Jaume I, 12071, Castelló, Spain
| | - Katarzyna Świderek
- BioComp Group, Institute of Advanced Materials (INAM), Universitat Jaume I, 12071, Castelló, Spain
| | - Yu-Hsuan Tsai
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Gaoke International Innovation Center, Guangming District, 518132, Shenzhen, Guangdong, China
| | - Louis Y P Luk
- School of Chemistry and Cardiff Catalysis Institute, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, United Kingdom
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2
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Thorpe T, Marshall JR, Turner NJ. Multifunctional Biocatalysts for Organic Synthesis. J Am Chem Soc 2024; 146:7876-7884. [PMID: 38489244 PMCID: PMC10979396 DOI: 10.1021/jacs.3c09542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 02/13/2024] [Accepted: 02/15/2024] [Indexed: 03/17/2024]
Abstract
Biocatalysis is becoming an indispensable tool in organic synthesis due to high enzymatic catalytic efficiency as well as exquisite chemo- and stereoselectivity. Some biocatalysts display great promiscuity including a broad substrate scope as well as the ability to catalyze more than one type of transformation. These promiscuous activities have been applied individually to efficiently access numerous valuable target molecules. However, systems in which enzymes possessing multiple different catalytic activities are applied in the synthesis are less well developed. Such multifunctional biocatalysts (MFBs) would simplify chemical synthesis by reducing the number of operational steps and enzyme count, as well as simplifying the sequence space that needs to be engineered to develop an efficient biocatalyst. In this Perspective, we highlight recently reported MFBs focusing on their synthetic utility and mechanism. We also offer insight into their origin as well as comment on potential strategies for their discovery and engineering.
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Affiliation(s)
- Thomas
W. Thorpe
- Department
of Chemistry, University of Manchester,
Manchester Institute of Biotechnology, 131 Princess Street, Manchester, United Kingdom, M1
7DN
| | - James R. Marshall
- Department
of Chemistry, University of Manchester,
Manchester Institute of Biotechnology, 131 Princess Street, Manchester, United Kingdom, M1
7DN
| | - Nicholas J. Turner
- Department
of Chemistry, University of Manchester,
Manchester Institute of Biotechnology, 131 Princess Street, Manchester, United Kingdom, M1
7DN
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3
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Yu MZ, Chen KY, Zhang YB, Zhang CX, Xiang Z. Enantioselective conjugate addition of malonates to α,β-unsaturated aldehydes catalysed by 4-oxalocrotonate tautomerase. Org Biomol Chem 2023; 21:2086-2090. [PMID: 36806856 DOI: 10.1039/d3ob00111c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The enantioselective conjugate addition of malonates to α,β-unsaturated aldehydes catalysed by 4-oxalocrotonate tautomerase is described. High conversions, high enantioselectivities, and good isolation yields were achieved for a range of substrates. We further completed a four-step synthesis of the antidepressant (+)-femoxetine by utilizing this reaction and an enzymatic reductive amination reaction.
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Affiliation(s)
- Ming-Zhu Yu
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| | - Kai-Yue Chen
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| | - Yi-Bin Zhang
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| | - Chang-Xuan Zhang
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China.
| | - Zheng Xiang
- State Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China. .,Institute of Chemical Biology, Shenzhen Bay Laboratory, Shenzhen 518132, China.,AI for Science (AI4S) Preferred Program, Peking University Shenzhen Graduate School, Shenzhen 518055, China
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4
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John T, Pires E, Hester SS, Salah E, Hopkinson RJ, Schofield CJ. Formaldehyde reacts with N-terminal proline residues to give bicyclic aminals. Commun Chem 2023; 6:12. [PMID: 36698022 PMCID: PMC9839752 DOI: 10.1038/s42004-022-00801-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 12/20/2022] [Indexed: 01/15/2023] Open
Abstract
Formaldehyde (HCHO) is a potent electrophile that is toxic above threshold levels, but which is also produced in the nuclei of eukaryotic cells by demethylases. We report studies with the four canonical human histones revealing that histone H2B reacts with HCHO, including as generated by a histone demethylase, to give a stable product. NMR studies show that HCHO reacts with the N-terminal proline and associated amide of H2B to give a 5,5-bicyclic aminal that is relatively stable to competition with HCHO scavengers. While the roles of histone modification by this reaction require further investigation, we demonstrated the potential of N-terminal aminal formation to modulate protein function by conducting biochemical and cellular studies on the effects of HCHO on catalysis by 4-oxalocrotonate tautomerase, which employs a nucleophilic N-terminal proline. The results suggest that reactions of N-terminal residues with HCHO and other aldehydes have potential to alter protein function.
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Affiliation(s)
- Tobias John
- Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Elisabete Pires
- Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Svenja S Hester
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford, UK
| | - Eidarus Salah
- Chemistry Research Laboratory, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Richard J Hopkinson
- Leicester Institute for Structural and Chemical Biology and School of Chemistry, University of Leicester, Henry Wellcome Building, Lancaster Road, Leicester, LE1 7RH, UK.
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5
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Sigmund M, Xu G, Grandi E, Poelarends GJ. Enhancing the Peroxygenase Activity of a Cofactor-Independent Peroxyzyme by Directed Evolution Enabling Gram-Scale Epoxide Synthesis. Chemistry 2022; 28:e202201651. [PMID: 35861144 PMCID: PMC9804992 DOI: 10.1002/chem.202201651] [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: 05/28/2022] [Indexed: 01/09/2023]
Abstract
Peroxygenases selectively incorporate oxygen into organic molecules making use of the environmentally friendly oxidant H2 O2 with water being the sole by-product. These biocatalysts can provide 'green' routes for the synthesis of enantioenriched epoxides, which are fundamental intermediates in the production of pharmaceuticals. The peroxyzyme 4-oxalocrotonate tautomerase (4-OT), catalysing the epoxidation of a variety of α,β-unsaturated aldehydes with H2 O2 , is outstanding because of its independence from any cost-intensive cofactor. However, its low-level peroxygenase activity and the decrease in the enantiomeric excess of the corresponding α,β-epoxy-aldehydes under preparative-scale conditions is limiting the potential of 4-OT. Herein we report the directed evolution of a tandem-fused 4-OT variant, which showed an ∼150-fold enhanced peroxygenase activity compared to 4-OT wild type, enabling the synthesis of α,β-epoxy-aldehydes in milligram- and gram-scale with high enantiopurity (up to 98 % ee) and excellent conversions. This engineered cofactor-independent peroxyzyme can provide new opportunities for the eco-friendly and practical synthesis of enantioenriched epoxides at large scale.
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Affiliation(s)
- Marie‐Cathérine Sigmund
- Department of Chemical and Pharmaceutical BiologyUniversity of GroningenAntonius Deusignlaan 19713 AVGroningenThe Netherlands
| | - Guangcai Xu
- Department of Chemical and Pharmaceutical BiologyUniversity of GroningenAntonius Deusignlaan 19713 AVGroningenThe Netherlands
| | - Eleonora Grandi
- Department of Chemical and Pharmaceutical BiologyUniversity of GroningenAntonius Deusignlaan 19713 AVGroningenThe Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical BiologyUniversity of GroningenAntonius Deusignlaan 19713 AVGroningenThe Netherlands
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6
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Tseliou V, Faraone A, Kqiku L, Vilím J, Simionato G, Melchiorre P. Enantioselective Biocascade Catalysis with a Single Multifunctional Enzyme. Angew Chem Int Ed Engl 2022; 61:e202212176. [DOI: 10.1002/anie.202212176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Indexed: 12/12/2022]
Affiliation(s)
- Vasilis Tseliou
- ICIQ, Institute of Chemical Research of Catalonia The Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | - Adriana Faraone
- University Rovira i Virgili 43007 Tarragona Spain
- ICIQ, Institute of Chemical Research of Catalonia The Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | - Laura Kqiku
- University Rovira i Virgili 43007 Tarragona Spain
- ICIQ, Institute of Chemical Research of Catalonia The Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | - Jan Vilím
- ICIQ, Institute of Chemical Research of Catalonia The Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | - Gianluca Simionato
- ICIQ, Institute of Chemical Research of Catalonia The Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
| | - Paolo Melchiorre
- ICREA Passeig Lluís Companys 23 08010 Barcelona Spain
- ICIQ, Institute of Chemical Research of Catalonia The Barcelona Institute of Science and Technology Avenida Països Catalans 16 43007 Tarragona Spain
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7
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Tseliou V, Faraone A, Kqiku L, Vilím J, Simionato G, Melchiorre P. Enantioselective Biocascade Catalysis with a Single Multifunctional Enzyme. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202212176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Vasilis Tseliou
- ICIQ: Institut Catala d'Investigacio Quimica Melchiorre group 43007 Tarragona SPAIN
| | - Adriana Faraone
- ICIQ: Institut Catala d'Investigacio Quimica Melchiorre group SPAIN
| | - Laura Kqiku
- ICIQ: Institut Catala d'Investigacio Quimica Melchiorre group SPAIN
| | - Jan Vilím
- ICIQ: Institut Catala d'Investigacio Quimica Melchiorre group SPAIN
| | | | - Paolo Melchiorre
- Institute of Chemical Research of Catalonia (ICIQ) ICIQ Av. Països Catalans 16 43007 Tarragona SPAIN
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8
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Baas BJ, Medellin BP, LeVieux JA, Erwin K, Lancaster EB, Johnson WH, Kaoud TS, Moreno RY, de Ruijter M, Babbitt PC, Zhang YJ, Whitman CP. Kinetic and Structural Analysis of Two Linkers in the Tautomerase Superfamily: Analysis and Implications. Biochemistry 2021; 60:1776-1786. [PMID: 34019384 DOI: 10.1021/acs.biochem.1c00220] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The tautomerase superfamily (TSF) is a collection of enzymes and proteins that share a simple β-α-β structural scaffold. Most members are constructed from a single-core β-α-β motif or two consecutively fused β-α-β motifs in which the N-terminal proline (Pro-1) plays a key and unusual role as a catalytic residue. The cumulative evidence suggests that a gene fusion event took place in the evolution of the TSF followed by duplication (of the newly fused gene) to result in the diversification of activity that is seen today. Analysis of the sequence similarity network (SSN) for the TSF identified several linking proteins ("linkers") whose similarity links subgroups of these contemporary proteins that might hold clues about structure-function relationship changes accompanying the emergence of new activities. A previously uncharacterized pair of linkers (designated N1 and N2) was identified in the SSN that connected the 4-oxalocrotonate tautomerase (4-OT) and cis-3-chloroacrylic acid dehalogenase (cis-CaaD) subgroups. N1, in the cis-CaaD subgroup, has the full complement of active site residues for cis-CaaD activity, whereas N2, in the 4-OT subgroup, lacks a key arginine (Arg-39) for canonical 4-OT activity. Kinetic characterization and nuclear magnetic resonance analysis show that N1 has activities observed for other characterized members of the cis-CaaD subgroup with varying degrees of efficiencies. N2 is a modest 4-OT but shows enhanced hydratase activity using allene and acetylene compounds, which might be due to the presence of Arg-8 along with Arg-11. Crystallographic analysis provides a structural context for these observations.
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9
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Xu G, Crotti M, Saravanan T, Kataja KM, Poelarends GJ. Enantiocomplementary Epoxidation Reactions Catalyzed by an Engineered Cofactor-Independent Non-natural Peroxygenase. Angew Chem Int Ed Engl 2020; 59:10374-10378. [PMID: 32160395 PMCID: PMC7317984 DOI: 10.1002/anie.202001373] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 03/06/2020] [Indexed: 11/29/2022]
Abstract
Peroxygenases are heme-dependent enzymes that use peroxide-borne oxygen to catalyze a wide range of oxyfunctionalization reactions. Herein, we report the engineering of an unusual cofactor-independent peroxygenase based on a promiscuous tautomerase that accepts different hydroperoxides (t-BuOOH and H2 O2 ) to accomplish enantiocomplementary epoxidations of various α,β-unsaturated aldehydes (citral and substituted cinnamaldehydes), providing access to both enantiomers of the corresponding α,β-epoxy-aldehydes. High conversions (up to 98 %), high enantioselectivity (up to 98 % ee), and good product yields (50-80 %) were achieved. The reactions likely proceed via a reactive enzyme-bound iminium ion intermediate, allowing tweaking of the enzyme's activity and selectivity by protein engineering. Our results underscore the potential of catalytic promiscuity for the engineering of new cofactor-independent oxidative enzymes.
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Affiliation(s)
- Guangcai Xu
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713AVGroningenThe Netherlands
| | - Michele Crotti
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713AVGroningenThe Netherlands
| | - Thangavelu Saravanan
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713AVGroningenThe Netherlands
- Present address: School of ChemistryUniversity of HyderabadP.O. Central University, GachibowliHyderabad500046India
| | - Kim M. Kataja
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713AVGroningenThe Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713AVGroningenThe Netherlands
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10
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Biewenga L, Kunzendorf A, Poelarends GJ. In Situ Acetaldehyde Synthesis for Carboligation Reactions. Chembiochem 2020; 21:1505-1509. [PMID: 31868962 PMCID: PMC7318290 DOI: 10.1002/cbic.201900666] [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: 11/01/2019] [Indexed: 11/24/2022]
Abstract
The enzyme 4-oxalocrotonate tautomerase (4-OT) can promiscuously catalyze various carboligation reactions using acetaldehyde as a nucleophile. However, the highly reactive nature of acetaldehyde requires intricate handling, which can impede its usage in practical synthesis. Therefore, we investigated three enzymatic routes to synthesize acetaldehyde in situ in one-pot cascade reactions with 4-OT. Two routes afforded practical acetaldehyde concentrations, using an environmental pollutant, trans-3-chloroacrylic acid, or a bio-renewable, ethanol, as starting substrate. These routes can be combined with 4-OT catalyzed Michael-type additions and aldol condensations in one pot. This modular systems biocatalysis methodology provides a stepping stone towards the development of larger artificial metabolic networks for the practical synthesis of important chemical synthons.
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Affiliation(s)
- Lieuwe Biewenga
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713 AVGroningenThe Netherlands
| | - Andreas Kunzendorf
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713 AVGroningenThe Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713 AVGroningenThe Netherlands
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11
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Nödling AR, Santi N, Williams TL, Tsai YH, Luk LYP. Enabling protein-hosted organocatalytic transformations. RSC Adv 2020; 10:16147-16161. [PMID: 33184588 PMCID: PMC7654312 DOI: 10.1039/d0ra01526a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Accepted: 03/25/2020] [Indexed: 12/30/2022] Open
Abstract
In this review, the development of organocatalytic artificial enzymes will be discussed. This area of protein engineering research has underlying importance, as it enhances the biocompatibility of organocatalysis for applications in chemical and synthetic biology research whilst expanding the catalytic repertoire of enzymes. The approaches towards the preparation of organocatalytic artificial enzymes, techniques used to improve their performance (selectivity and reactivity) as well as examples of their applications are presented. Challenges and opportunities are also discussed.
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Affiliation(s)
- Alexander R Nödling
- School of Chemistry, Cardiff University, Main Building, Cardiff, CF10 3AT, UK.
| | - Nicolò Santi
- School of Chemistry, Cardiff University, Main Building, Cardiff, CF10 3AT, UK.
| | - Thomas L Williams
- School of Chemistry, Cardiff University, Main Building, Cardiff, CF10 3AT, UK.
| | - Yu-Hsuan Tsai
- School of Chemistry, Cardiff University, Main Building, Cardiff, CF10 3AT, UK.
| | - Louis Y P Luk
- School of Chemistry, Cardiff University, Main Building, Cardiff, CF10 3AT, UK.
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12
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Xu G, Crotti M, Saravanan T, Kataja KM, Poelarends GJ. Enantiocomplementary Epoxidation Reactions Catalyzed by an Engineered Cofactor‐Independent Non‐natural Peroxygenase. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202001373] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Guangcai Xu
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Michele Crotti
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Thangavelu Saravanan
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
- Present address: School of Chemistry University of Hyderabad P.O. Central University, Gachibowli Hyderabad 500046 India
| | - Kim M. Kataja
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical Biology Groningen Research Institute of Pharmacy University of Groningen Antonius Deusinglaan 1 9713 AV Groningen The Netherlands
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13
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Guo C, Biewenga L, Lubberink M, van Merkerk R, Poelarends GJ. Tuning Enzyme Activity for Nonaqueous Solvents: Engineering an Enantioselective "Michaelase" for Catalysis in High Concentrations of Ethanol. Chembiochem 2020; 21:1499-1504. [PMID: 31886617 PMCID: PMC7317446 DOI: 10.1002/cbic.201900721] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Indexed: 01/22/2023]
Abstract
Enzymes have evolved to function under aqueous conditions and may not exhibit features essential for biocatalytic application, such as the ability to function in high concentrations of an organic solvent. Consequently, protein engineering is often required to tune an enzyme for catalysis in non‐aqueous solvents. In this study, we have used a collection of nearly all single mutants of 4‐oxalocrotonate tautomerase, which promiscuously catalyzes synthetically useful Michael‐type additions of acetaldehyde to various nitroolefins, to investigate the effect of each mutation on the ability of this enzyme to retain its “Michaelase” activity in elevated concentrations of ethanol. Examination of this mutability landscape allowed the identification of two hotspot positions, Ser30 and Ala33, at which mutations are beneficial for catalysis in high ethanol concentrations. The “hotspot” position Ala33 was then randomized in a highly enantioselective, but ethanol‐sensitive 4‐OT variant (L8F/M45Y/F50A) to generate an improved enzyme variant (L8F/A33I/M45Y/F50A) that showed great ethanol stability and efficiently catalyzes the enantioselective addition of acetaldehyde to nitrostyrene in 40 % ethanol (permitting high substrate loading) to give the desired γ‐nitroaldehyde product in excellent isolated yield (89 %) and enantiopurity (ee=98 %). The presented work demonstrates the power of mutability‐landscape‐guided enzyme engineering for efficient biocatalysis in non‐aqueous solvents.
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Affiliation(s)
- Chao Guo
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Lieuwe Biewenga
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Max Lubberink
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands.,Present address: School of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, UK
| | - Ronald van Merkerk
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
| | - Gerrit J Poelarends
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands
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14
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Biewenga L, Crotti M, Saifuddin M, Poelarends GJ. Selective Colorimetric "Turn-On" Probe for Efficient Engineering of Iminium Biocatalysis. ACS OMEGA 2020; 5:2397-2405. [PMID: 32064400 PMCID: PMC7017405 DOI: 10.1021/acsomega.9b03849] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 01/16/2020] [Indexed: 06/10/2023]
Abstract
The efficient engineering of iminium biocatalysis has drawn considerable attention, with many applications in pharmaceutical synthesis. Here, we report a tailor-made iminium-activated colorimetric "turn-on" probe, specifically designed as a prescreening tool to facilitate engineering of iminium biocatalysis. Upon complexation of the probe with the catalytic Pro-1 residue of the model enzyme 4-oxalocrotonate tautomerase (4-OT), a brightly colored merocyanine-dye-type structure is formed. 4-OT mutants that formed this brightly colored species upon incubation with the probe proved to have a substantial activity for the iminium-based Michael-type addition of nitromethane to cinnamaldehyde, whereas mutants that showed no staining by the probe exhibited no or very low-level "Michaelase" activity. This system was exploited in a solid-phase prescreening assay termed as activated iminium colony staining (AICS) to enrich libraries for active mutants. AICS prescreening reduced the screening effort up to 20-fold. After two rounds of directed evolution, two artificial Michaelases were identified with up to 39-fold improvement in the activity for the addition of nitromethane to cinnamaldehyde, yielding the target γ-nitroaldehyde product with excellent isolated yield (up to 95%) and enantiopurity (up to >99% ee). The colorimetric activation of the turn-on probe could be extended to the class I aldolase 2-deoxy-d-ribose 5-phosphate aldolase, implicating a broader application of AICS in engineering iminium biocatalysis.
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15
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Guo C, Saifuddin M, Saravanan T, Sharifi M, Poelarends GJ. Biocatalytic Asymmetric Michael Additions of Nitromethane to α,β-Unsaturated Aldehydes via Enzyme-bound Iminium Ion Intermediates. ACS Catal 2019; 9:4369-4373. [PMID: 31080691 PMCID: PMC6503466 DOI: 10.1021/acscatal.9b00780] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/09/2019] [Indexed: 11/29/2022]
Abstract
The enzyme 4-oxalocrotonate tautomerase (4-OT) exploits an N-terminal proline as main catalytic residue to facilitate several promiscuous C-C bond-forming reactions via enzyme-bound enamine intermediates. Here we show that the active site of this enzyme can give rise to further synthetically useful catalytic promiscuity. Specifically, the F50A mutant of 4-OT was found to efficiently promote asymmetric Michael additions of nitromethane to various α,β-unsaturated aldehydes to give γ-nitroaldehydes, important precursors to biologically active γ-aminobutyric acids. High conversions, high enantiocontrol, and good isolated product yields were achieved. The reactions likely proceed via iminium ion intermediates formed between the catalytic Pro-1 residue and the α,β-unsaturated aldehydes. In addition, a cascade of three 4-OT(F50A)-catalyzed reactions followed by an enzymatic oxidation step enables assembly of γ-nitrocarboxylic acids from three simple building blocks in one pot. Our results bridge organo- and biocatalysis, and they emphasize the potential of enzyme promiscuity for the preparation of important chiral synthons.
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Affiliation(s)
- Chao Guo
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Mohammad Saifuddin
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Thangavelu Saravanan
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Masih Sharifi
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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16
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Substituting the catalytic proline of 4-oxalocrotonate tautomerase with non-canonical analogues reveals a finely tuned catalytic system. Sci Rep 2019; 9:2697. [PMID: 30804446 PMCID: PMC6389900 DOI: 10.1038/s41598-019-39484-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/03/2019] [Indexed: 12/21/2022] Open
Abstract
The enzyme 4-oxalocrotonate tautomerase shows remarkable catalytic versatility due to the secondary amine of its N-terminal proline moiety. In this work, we incorporated a range of proline analogues into the enzyme and examined the effects on structure and activity. While the structure of the enzyme remained unperturbed, its promiscuous Michael-type activity was severely affected. This finding demonstrates how atomic changes in a biocatalytic system can abolish its activity. Our work provides a toolbox for successful generation of enzyme variants with non-canonical catalytic proline analogues.
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17
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Biewenga L, Saravanan T, Kunzendorf A, van der Meer JY, Pijning T, Tepper PG, van Merkerk R, Charnock SJ, Thunnissen AMWH, Poelarends GJ. Enantioselective Synthesis of Pharmaceutically Active γ-Aminobutyric Acids Using a Tailor-Made Artificial Michaelase in One-Pot Cascade Reactions. ACS Catal 2019; 9:1503-1513. [PMID: 30740262 PMCID: PMC6366683 DOI: 10.1021/acscatal.8b04299] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 01/03/2019] [Indexed: 11/30/2022]
Abstract
![]()
Chiral
γ-aminobutyric acid (GABA) analogues represent abundantly
prescribed drugs, which are broadly applied as anticonvulsants, as
antidepressants, and for the treatment of neuropathic pain. Here we
report a one-pot two-step biocatalytic cascade route for synthesis
of the pharmaceutically relevant enantiomers of γ-nitrobutyric
acids, starting from simple precursors (acetaldehyde and nitroalkenes),
using a tailor-made highly enantioselective artificial “Michaelase”
(4-oxalocrotonate tautomerase mutant L8Y/M45Y/F50A), an aldehyde dehydrogenase
with a broad non-natural substrate scope, and a cofactor recycling
system. We also report a three-step chemoenzymatic cascade route for
the efficient chemical reduction of enzymatically prepared γ-nitrobutyric
acids into GABA analogues in one pot, achieving high enantiopurity
(e.r. up to 99:1) and high overall yields (up to 70%). This chemoenzymatic
methodology offers a step-economic alternative route to important
pharmaceutically active GABA analogues, and highlights the exciting
opportunities available for combining chemocatalysts, natural enzymes,
and designed artificial biocatalysts in multistep syntheses.
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Affiliation(s)
- Lieuwe Biewenga
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Thangavelu Saravanan
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Andreas Kunzendorf
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Jan-Ytzen van der Meer
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Tjaard Pijning
- Structural Biology Group, Groningen Institute of Biomolecular Sciences and Biotechnology, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Pieter G. Tepper
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Ronald van Merkerk
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Simon J. Charnock
- Prozomix Ltd., Station Court, Haltwhistle, Northumberland NE49 9HN, United Kingdom
| | - Andy-Mark W. H. Thunnissen
- Molecular Enzymology Group, Groningen Institute of Biomolecular Sciences and Biotechnology, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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18
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Rahimi M, Geertsema EM, Miao Y, van der Meer JY, van den Bosch T, de Haan P, Zandvoort E, Poelarends GJ. Inter- and intramolecular aldol reactions promiscuously catalyzed by a proline-based tautomerase. Org Biomol Chem 2018; 15:2809-2816. [PMID: 28277572 DOI: 10.1039/c7ob00302a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The enzyme 4-oxalocrotonate tautomerase (4-OT), which in nature catalyzes a tautomerization step as part of a catabolic pathway for aromatic hydrocarbons, was found to promiscuously catalyze different types of aldol reactions. These include the self-condensation of propanal, the cross-coupling of propanal and benzaldehyde, the cross-coupling of propanal and pyruvate, and the intramolecular cyclizations of hexanedial and heptanedial. Mutation of the catalytic amino-terminal proline (P1A) greatly reduces 4-OT's aldolase activities, whereas mutation of another active site residue (F50A) strongly enhances 4-OT's aldolase activities, indicating that aldolization is an active site process. This catalytic promiscuity of 4-OT could be exploited as starting point to create tailor-made, artificial aldolases for challenging self- and cross-aldolizations.
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Affiliation(s)
- Mehran Rahimi
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Edzard M Geertsema
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Yufeng Miao
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Jan-Ytzen van der Meer
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Thea van den Bosch
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Pim de Haan
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Ellen Zandvoort
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
| | - Gerrit J Poelarends
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands.
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19
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LeVieux JA, Baas BJ, Kaoud TS, Davidson R, Babbitt PC, Zhang YJ, Whitman CP. Kinetic and structural characterization of a cis-3-Chloroacrylic acid dehalogenase homologue in Pseudomonas sp. UW4: A potential step between subgroups in the tautomerase superfamily. Arch Biochem Biophys 2017; 636:50-56. [PMID: 29111295 DOI: 10.1016/j.abb.2017.10.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 10/23/2017] [Accepted: 10/24/2017] [Indexed: 10/18/2022]
Abstract
A Pseudomonas sp. UW4 protein (UniProt K9NIA5) of unknown function was identified as similar to 4-oxalocrotonate tautomerase (4-OT)-like and cis-3-chloroacrylic acid dehalogenase (cis-CaaD)-like subgroups of the tautomerase superfamily (TSF). This protein lacks only Tyr-103 of the amino acids critical for cis-CaaD activity (Pro-1, His-28, Arg-70, Arg-73, Tyr-103, Glu-114). As it may represent an important variant of these enzymes, its kinetic and structural properties have been determined. The protein shows tautomerase activity with phenylenolpyruvate, but lacks native 4-OT activity and dehalogenase activity with the isomers of 3-chloroacrylic acid. It shows mostly low-level hydratase activity at pH 7.0, converting 2-oxo-3-pentynoate to acetopyruvate, consistent with cis-CaaD-like behavior. At pH 9.0, this compound results primarily in covalent modification of Pro-1, which is consistent with 4-OT-like behavior. These observations could reflect a pKa for Pro-1 that is closer to that of cis-CaaD (∼9.2) than to 4-OT (∼6.4). A structure of the native enzyme, at 2.6 Å resolution, highlights differences at the active site from those of 4-OT and cis-CaaD that add to our understanding of how contemporary TSF reactions and mechanisms may have diverged from a common 4-OT-like ancestor.
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Affiliation(s)
- Jake A LeVieux
- Department of Molecular Biosciences, Austin, TX 78712, USA
| | - Bert-Jan Baas
- Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, Austin, TX, 78712, USA
| | - Tamer S Kaoud
- Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, Austin, TX, 78712, USA
| | - Rebecca Davidson
- Departments of Bioengineering and Therapeutic Sciences, San Francisco, CA, 94143, USA
| | - Patricia C Babbitt
- Departments of Bioengineering and Therapeutic Sciences, San Francisco, CA, 94143, USA; Pharmaceutical Chemistry, San Francisco, CA, 94143, USA; Quantitative Biosciences Institute, University of California, San Francisco, CA, 94143, USA
| | - Yan Jessie Zhang
- Department of Molecular Biosciences, Austin, TX 78712, USA; Institute for Cellular and Molecular Biology, University of Texas, Austin, TX, 78712, USA
| | - Christian P Whitman
- Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, Austin, TX, 78712, USA.
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20
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Rahimi M, van der Meer J, Geertsema EM, Poelarends GJ. Engineering a Promiscuous Tautomerase into a More Efficient Aldolase for Self-Condensations of Linear Aliphatic Aldehydes. Chembiochem 2017; 18:1435-1441. [PMID: 28426139 PMCID: PMC5575498 DOI: 10.1002/cbic.201700121] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Indexed: 01/04/2023]
Abstract
The enzyme 4-oxalocrotonate tautomerase (4-OT) from Pseudomonas putida mt-2 takes part in a catabolic pathway for aromatic hydrocarbons, where it catalyzes the conversion of 2hydroxyhexa-2,4-dienedioate into 2-oxohexa-3-enedioate. This tautomerase can also promiscuously catalyze carbon-carbon bond-forming reactions, including various types of aldol reactions, by using its amino-terminal proline as a key catalytic residue. Here, we used systematic mutagenesis to identify two hotspots in 4-OT (Met45 and Phe50) at which single mutations give marked improvements in aldolase activity for the self-condensation of propanal. Activity screening of a focused library in which these two hotspots were varied led to the discovery of a 4-OT variant (M45Y/F50V) with strongly enhanced aldolase activity in the self-condensation of linear aliphatic aldehydes, such as acetaldehyde, propanal, and butanal, to yield α,β-unsaturated aldehydes. With both propanal and benzaldehyde, this double mutant, unlike the previously constructed single mutant F50A, mainly catalyzes the self-condensation of propanal rather than the cross-condensation of propanal and benzaldehyde, thus indicating that it indeed has altered substrate specificity. This variant could serve as a template to create new biocatalysts that lack dehydration activity and possess further enhanced aldolase activity, thus enabling the efficient enzymatic self-coupling of aliphatic aldehydes.
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Affiliation(s)
- Mehran Rahimi
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713 AVGroningenThe Netherlands
| | - Jan‐Ytzen van der Meer
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713 AVGroningenThe Netherlands
| | - Edzard M. Geertsema
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713 AVGroningenThe Netherlands
- Present address: Institute for Life Science and TechnologyHanze University of Applied SciencesZernikeplein 119747 ASGroningenThe Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical BiologyGroningen Research Institute of PharmacyUniversity of GroningenAntonius Deusinglaan 19713 AVGroningenThe Netherlands
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21
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Xiang Y, Song J, Zhang Y, Yang DC, Guan Z, He YH. Enzyme-Catalyzed Asymmetric Domino Thia-Michael/Aldol Condensation Using Pepsin. J Org Chem 2016; 81:6042-8. [DOI: 10.1021/acs.joc.6b01132] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Yang Xiang
- Key Laboratory of Applied
Chemistry of Chongqing Municipality, School of Chemistry and Chemical
Engineering, Southwest University, Chongqing 400715, P. R. China
| | - Jian Song
- Key Laboratory of Applied
Chemistry of Chongqing Municipality, School of Chemistry and Chemical
Engineering, Southwest University, Chongqing 400715, P. R. China
| | - Yong Zhang
- Key Laboratory of Applied
Chemistry of Chongqing Municipality, School of Chemistry and Chemical
Engineering, Southwest University, Chongqing 400715, P. R. China
| | - Da-Cheng Yang
- Key Laboratory of Applied
Chemistry of Chongqing Municipality, School of Chemistry and Chemical
Engineering, Southwest University, Chongqing 400715, P. R. China
| | - Zhi Guan
- Key Laboratory of Applied
Chemistry of Chongqing Municipality, School of Chemistry and Chemical
Engineering, Southwest University, Chongqing 400715, P. R. China
| | - Yan-Hong He
- Key Laboratory of Applied
Chemistry of Chongqing Municipality, School of Chemistry and Chemical
Engineering, Southwest University, Chongqing 400715, P. R. China
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22
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Rahimi M, van der Meer JY, Geertsema EM, Poddar H, Baas BJ, Poelarends GJ. Mutations Closer to the Active Site Improve the Promiscuous Aldolase Activity of 4-Oxalocrotonate Tautomerase More Effectively than Distant Mutations. Chembiochem 2016; 17:1225-8. [PMID: 27238293 DOI: 10.1002/cbic.201600149] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Indexed: 01/15/2023]
Abstract
The enzyme 4-oxalocrotonate tautomerase (4-OT), which catalyzes enol-keto tautomerization as part of a degradative pathway for aromatic hydrocarbons, promiscuously catalyzes various carbon-carbon bond-forming reactions. These include the aldol condensation of acetaldehyde with benzaldehyde to yield cinnamaldehyde. Here, we demonstrate that 4-OT can be engineered into a more efficient aldolase for this condensation reaction, with a >5000-fold improvement in catalytic efficiency (kcat /Km ) and a >10(7) -fold change in reaction specificity, by exploring small libraries in which only "hotspots" are varied. The hotspots were identified by systematic mutagenesis (covering each residue), followed by a screen for single mutations that give a strong improvement in the desired aldolase activity. All beneficial mutations were near the active site of 4-OT, thus underpinning the notion that new catalytic activities of a promiscuous enzyme are more effectively enhanced by mutations close to the active site.
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Affiliation(s)
- Mehran Rahimi
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
| | - Jan-Ytzen van der Meer
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
| | - Edzard M Geertsema
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands.,Institute for Life Science & Technology, Hanze University of Applied Sciences, Zernikeplein 11, 9747, AS, Groningen, The Netherlands
| | - Harshwardhan Poddar
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
| | - Bert-Jan Baas
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands
| | - Gerrit J Poelarends
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713, AV, Groningen, The Netherlands.
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23
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van der Meer JY, Poddar H, Baas BJ, Miao Y, Rahimi M, Kunzendorf A, van Merkerk R, Tepper PG, Geertsema EM, Thunnissen AMWH, Quax WJ, Poelarends GJ. Using mutability landscapes of a promiscuous tautomerase to guide the engineering of enantioselective Michaelases. Nat Commun 2016; 7:10911. [PMID: 26952338 PMCID: PMC4786785 DOI: 10.1038/ncomms10911] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 02/02/2016] [Indexed: 01/24/2023] Open
Abstract
The Michael-type addition reaction is widely used in organic synthesis for carbon–carbon bond formation. However, biocatalytic methodologies for this type of reaction are scarce, which is related to the fact that enzymes naturally catalysing carbon–carbon bond-forming Michael-type additions are rare. A promising template to develop new biocatalysts for carbon–carbon bond formation is the enzyme 4-oxalocrotonate tautomerase, which exhibits promiscuous Michael-type addition activity. Here we present mutability landscapes for the expression, tautomerase and Michael-type addition activities, and enantioselectivity of 4-oxalocrotonate tautomerase. These maps of neutral, beneficial and detrimental amino acids for each residue position and enzyme property provide detailed insight into sequence–function relationships. This offers exciting opportunities for enzyme engineering, which is illustrated by the redesign of 4-oxalocrotonate tautomerase into two enantiocomplementary ‘Michaelases'. These ‘Michaelases' catalyse the asymmetric addition of acetaldehyde to various nitroolefins, providing access to both enantiomers of γ-nitroaldehydes, which are important precursors for pharmaceutically active γ-aminobutyric acid derivatives. The Michael-type addition reaction is used for carbon-carbon bond formation; however biocatalytic methods for this reaction are rare. Here, the authors generate and exploit mutability landscapes of 4-oxalocrotonate tautomerase to direct the redesign of this promiscuous enzyme into enantio-complementary Michaelases.
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Affiliation(s)
- Jan-Ytzen van der Meer
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Harshwardhan Poddar
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Bert-Jan Baas
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Yufeng Miao
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Mehran Rahimi
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Andreas Kunzendorf
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Ronald van Merkerk
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Pieter G Tepper
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Edzard M Geertsema
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Andy-Mark W H Thunnissen
- Department of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, Groningen 9747 AG, The Netherlands
| | - Wim J Quax
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Gerrit J Poelarends
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
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24
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Poddar H, Rahimi M, Geertsema EM, Thunnissen AMWH, Poelarends GJ. Evidence for the formation of an enamine species during aldol and Michael-type addition reactions promiscuously catalyzed by 4-oxalocrotonate tautomerase. Chembiochem 2015; 16:738-41. [PMID: 25728471 DOI: 10.1002/cbic.201402687] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Indexed: 11/08/2022]
Abstract
The enzyme 4-oxalocrotonate tautomerase (4-OT), which has a catalytic N-terminal proline residue (Pro1), can promiscuously catalyze various carbon-carbon bond-forming reactions, including aldol condensation of acetaldehyde with benzaldehyde to yield cinnamaldehyde, and Michael-type addition of acetaldehyde to a wide variety of nitroalkenes to yield valuable γ-nitroaldehydes. To gain insight into how 4-OT catalyzes these unnatural reactions, we carried out exchange studies in D2 O, and X-ray crystallography studies. The former established that H-D exchange within acetaldehyde is catalyzed by 4-OT and that the Pro1 residue is crucial for this activity. The latter showed that Pro1 of 4-OT had reacted with acetaldehyde to give an enamine species. These results provide evidence of the mechanism of the 4-OT-catalyzed aldol and Michael-type addition reactions in which acetaldehyde is activated for nucleophilic addition by Pro1-dependent formation of an enamine intermediate.
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Affiliation(s)
- Harshwardhan Poddar
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen (The Netherlands)
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Recent developments in enzyme promiscuity for carbon-carbon bond-forming reactions. Curr Opin Chem Biol 2015; 25:115-23. [PMID: 25598537 DOI: 10.1016/j.cbpa.2014.12.020] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2014] [Revised: 12/10/2014] [Accepted: 12/12/2014] [Indexed: 11/22/2022]
Abstract
Numerous enzymes have been found to catalyze additional and completely different types of reactions relative to the natural activity they evolved for. This phenomenon, called catalytic promiscuity, has proven to be a fruitful guide for the development of novel biocatalysts for organic synthesis purposes. As such, enzymes have been identified with promiscuous catalytic activity for, one or more, eminent types of carbon-carbon bond-forming reactions like aldol couplings, Michael(-type) additions, Mannich reactions, Henry reactions, and Knoevenagel condensations. This review focuses on enzymes that promiscuously catalyze these reaction types and exhibit high enantioselectivities (in case chiral products are obtained).
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Baas BJ, Zandvoort E, Wasiel AA, Poelarends GJ. Demethionylation of Pro-1 variants of 4-oxalocrotonate tautomerase in Escherichia coli by co-expression with an engineered methionine aminopeptidase. FEBS Open Bio 2014; 4:651-8. [PMID: 25161874 PMCID: PMC4141196 DOI: 10.1016/j.fob.2014.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/04/2014] [Accepted: 07/04/2014] [Indexed: 11/28/2022] Open
Abstract
The P1S variant of 4-OT was fully demethionylated by wild-type MetAP. The P1H and P1Q variants of 4-OT were partially demethionylated by MetAP-∗TG. Gln-1 is converted into pyro-Glu (pE) by spontaneous intramolecular cyclization. Replacement of Pro-1 by Gln is a unique method to incorporate pE-1 in 4-OT.
4-Oxalocrotonate tautomerase (4-OT) catalyzes the enol-keto tautomerization of 2-hydroxymuconate, utilizing its N-terminal proline (Pro-1) as general base catalyst. Substituting Pro-1 with bulky or charged residues will result in poor or no post-translational removal of the translation-initiating methionine by the methionine aminopeptidase (MetAP) of the Escherichiacoli expression host. Here, we set out to investigate whether co-expression with previously engineered aminopeptidase MetAP-∗TG can be used to produce the P1S, P1H and P1Q variants of 4-OT in a demethionylated form. The P1S variant, which carries a small residue at the penultimate position (the first position after the initiating methionine), was found to be fully processed by wild-type MetAP. The P1S variant has low-level 2-hydroxymuconate tautomerase and promiscuous oxaloacetate decarboxylase activity. The P1Q and P1H variants of 4-OT, which carry bulky residues at the penultimate position, could only be obtained in a demethionylated form (a minor fraction of the purified protein is still composed of methionylated enzyme) by co-expression with MetAP-∗TG. Interestingly, the Gln-1 residue of the demethionylated P1Q variant undergoes intramolecular cyclization to form pyroglutamate (pE), yielding variant P1pE. Whereas the P1H/M1P2H mixture has low-level tautomerase activity, the P1pE/M1P2Q mixture has robust tautomerase activity. The substitution of Pro-1 by Gln, followed by removal of the initiating Met and cyclization of Gln-1 to form pE, is a unique way to obtain a structural analogue of proline on the N-terminus of 4-OT. This opens up new possibilities to study the importance of Pro-1 in recently discovered C–C bond-forming activities of this highly promiscuous tautomerase.
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Affiliation(s)
- Bert-Jan Baas
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Ellen Zandvoort
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Anna A Wasiel
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Gerrit J Poelarends
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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Baas BJ, Zandvoort E, Geertsema EM, Poelarends GJ. Recent Advances in the Study of Enzyme Promiscuity in the Tautomerase Superfamily. Chembiochem 2013; 14:917-26. [DOI: 10.1002/cbic.201300098] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Indexed: 11/06/2022]
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Miao Y, Geertsema EM, Tepper PG, Zandvoort E, Poelarends GJ. Promiscuous catalysis of asymmetric Michael-type additions of linear aldehydes to β-nitrostyrene by the proline-based enzyme 4-oxalocrotonate tautomerase. Chembiochem 2013; 14:191-4. [PMID: 23303727 DOI: 10.1002/cbic.201200676] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Indexed: 11/09/2022]
Abstract
Exploiting catalytic promiscuity: The proline-based enzyme 4-oxalocrotonate tautomerase (4-OT) promiscuously catalyzes asymmetric Michael-type additions of linear aldehydes--ranging from acetaldehyde to octanal--to trans-β-nitrostyrene in aqueous solvent. The presence of 1.4 mol% of 4-OT effected formation of the anticipated γ-nitroaldehydes in fair to good yields with dr values of up to 93:7 and ee values of up to 81 %.
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Affiliation(s)
- Yufeng Miao
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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Widmann M, Pleiss J, Samland AK. Computational tools for rational protein engineering of aldolases. Comput Struct Biotechnol J 2012; 2:e201209016. [PMID: 24688657 PMCID: PMC3962226 DOI: 10.5936/csbj.201209016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 10/31/2012] [Accepted: 11/07/2012] [Indexed: 11/22/2022] Open
Abstract
In this mini-review we describe the different strategies for rational protein engineering and summarize the computational tools available. Computational tools can either be used to design focused libraries, to predict sequence-function relationships or for structure-based molecular modelling. This also includes de novo design of enzymes. Examples for protein engineering of aldolases and transaldolases are given in the second part of the mini-review.
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Affiliation(s)
- Michael Widmann
- Institute of Technical Biochemistry, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Jürgen Pleiss
- Institute of Technical Biochemistry, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Anne K Samland
- Institute of Microbiology, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
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Baker P, Seah SYK. Rational approaches for engineering novel functionalities in carbon-carbon bond forming enzymes. Comput Struct Biotechnol J 2012; 2:e201209003. [PMID: 24688644 PMCID: PMC3962088 DOI: 10.5936/csbj.201209003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Revised: 09/13/2012] [Accepted: 09/15/2012] [Indexed: 01/17/2023] Open
Abstract
Enzymes that catalyze carbon-carbon bond formation can be exploited as biocatalyst for synthetic organic chemistry. However, natural enzymes frequently do not possess the required properties or specificities to catalyze industrially useful transformations. This mini-review describes recent work using knowledge-guided site-specific mutagenesis of key active site residues to alter substrate specificity, stereospecificity and reaction specificity of these enzymes. In addition, examples of de novo designed enzymes that catalyze C-C bond reactions not found in nature will be discussed.
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Affiliation(s)
- Perrin Baker
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario Canada, N1G 2W1
| | - Stephen Y K Seah
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario Canada, N1G 2W1
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Zandvoort E, Geertsema EM, Baas BJ, Quax WJ, Poelarends GJ. An Unexpected Promiscuous Activity of 4-Oxalocrotonate Tautomerase: Thecis-transIsomerisation of Nitrostyrene. Chembiochem 2012; 13:1869-73. [DOI: 10.1002/cbic.201200371] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Indexed: 11/06/2022]
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Zandvoort E, Geertsema EM, Quax WJ, Poelarends GJ. Enhancement of the Promiscuous Aldolase and Dehydration Activities of 4-Oxalocrotonate Tautomerase by Protein Engineering. Chembiochem 2012; 13:1274-7. [DOI: 10.1002/cbic.201200225] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Indexed: 11/06/2022]
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Zandvoort E, Geertsema EM, Baas BJ, Quax WJ, Poelarends GJ. Bridging between Organocatalysis and Biocatalysis: Asymmetric Addition of Acetaldehyde to β-Nitrostyrenes Catalyzed by a Promiscuous Proline-Based Tautomerase. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201107404] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Zandvoort E, Geertsema EM, Baas BJ, Quax WJ, Poelarends GJ. Bridging between organocatalysis and biocatalysis: asymmetric addition of acetaldehyde to β-nitrostyrenes catalyzed by a promiscuous proline-based tautomerase. Angew Chem Int Ed Engl 2011; 51:1240-3. [PMID: 22190406 DOI: 10.1002/anie.201107404] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Indexed: 11/10/2022]
Affiliation(s)
- Ellen Zandvoort
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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Baas BJ, Zandvoort E, Wasiel AA, Quax WJ, Poelarends GJ. Characterization of a newly identified mycobacterial tautomerase with promiscuous dehalogenase and hydratase activities reveals a functional link to a recently diverged cis-3-chloroacrylic acid dehalogenase. Biochemistry 2011; 50:2889-99. [PMID: 21370851 DOI: 10.1021/bi200071k] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The enzyme cis-3-chloroacrylic acid dehalogenase (cis-CaaD) is found in a bacterial pathway that degrades a synthetic nematocide, cis-1,3-dichloropropene, introduced in the 20th century. The previously determined crystal structure of cis-CaaD and its promiscuous phenylpyruvate tautomerase (PPT) activity link this dehalogenase to the tautomerase superfamily, a group of homologous proteins that are characterized by a catalytic amino-terminal proline and a β-α-β structural fold. The low-level PPT activity of cis-CaaD, which may be a vestige of the function of its progenitor, prompted us to search the databases for a homologue of cis-CaaD that was annotated as a putative tautomerase and test both its PPT and cis-CaaD activity. We identified a mycobacterial cis-CaaD homologue (designated MsCCH2) that shares key sequence and active site features with cis-CaaD. Kinetic and 1H NMR spectroscopic studies show that MsCCH2 functions as an efficient PPT and exhibits low-level promiscuous dehalogenase activity, processing both cis- and trans-3-chloroacrylic acid. To further probe the active site of MsCCH2, the enzyme was incubated with 2-oxo-3-pentynoate (2-OP). At pH 8.5, MsCCH2 is inactivated by 2-OP due to the covalent modification of Pro-1, suggesting that Pro-1 functions as a nucleophile at pH 8.5 and attacks 2-OP in a Michael-type reaction. At pH 6.5, however, MsCCH2 exhibits hydratase activity and converts 2-OP to acetopyruvate, which implies that Pro-1 is cationic at pH 6.5 and not functioning as a nucleophile. At pH 7.5, the hydratase and inactivation reactions occur simultaneously. From these results, it can be inferred that Pro-1 of MsCCH2 has a pKa value that lies in between that of a typical tautomerase (pKa of Pro-1∼6) and that of cis-CaaD (pKa of Pro-1∼9). The shared activities and structural features, coupled with the intermediate pKa of Pro-1, suggest that MsCCH2 could be characteristic of an evolutionary intermediate along the past route for the divergence of cis-CaaD from an unknown superfamily tautomerase. This makes MsCCH2 an ideal candidate for laboratory evolution of its promiscuous dehalogenase activity, which could identify additional features necessary for a fully active cis-CaaD. Such results will provide insight into pathways that could lead to the rapid divergent evolution of an efficient cis-CaaD enzyme.
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Affiliation(s)
- Bert-Jan Baas
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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