28 results on '"Manfred T. Reetz"'
Search Results
2. Book review of 'Enzyme engineering: Selective catalysts for applications in biotechnology, organic chemistry, and life science'
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Manfred T. Reetz, Zhoutong Sun, and Ge Qu
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Directed evolution ,Rational design ,Enzyme engineering ,Methodology ,Biocatalysis ,Chemical technology ,TP1-1185 ,Biochemistry ,QD415-436 - Published
- 2023
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3. Pervasive cooperative mutational effects on multiple catalytic enzyme traits emerge via long-range conformational dynamics
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Carlos G. Acevedo-Rocha, Aitao Li, Lorenzo D’Amore, Sabrina Hoebenreich, Joaquin Sanchis, Paul Lubrano, Matteo P. Ferla, Marc Garcia-Borràs, Sílvia Osuna, and Manfred T. Reetz
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Science - Abstract
Connecting conformational dynamics and epistasis has so far been limited to a few proteins and a single fitness trait. Here, the authors provide evidence of positive epistasis on multiple catalytic traits in the evolution and dynamics of engineered cytochrome P450 monooxygenase, offering insights for in silico protein design.
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- 2021
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4. Artificial cysteine-lipases with high activity and altered catalytic mechanism created by laboratory evolution
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Yixin Cen, Warispreet Singh, Mamatjan Arkin, Thomas S. Moody, Meilan Huang, Jiahai Zhou, Qi Wu, and Manfred T. Reetz
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Science - Abstract
Candida antarctica lipase B (CALB) is a serine lipase. Here, the authors use directed evolution to exchange serine with cysteine in the catalytic triad of the enzyme, thereby obtaining a highly active CALB variant that — unlike the wild type — accommodates bulky substrates.
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- 2019
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5. A breakthrough in protein engineering of a glycosyltransferase
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Manfred T. Reetz
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Rational design ,FRISM ,Regioselectivity ,Glycosyltransferase ,Chemical technology ,TP1-1185 ,Biochemistry ,QD415-436 - Abstract
An intriguing advance in the rational protein engineering of a newly identified glycosyltransferase from Siraitia grosvenorii (UGT74AC2) has been accomplished by Zhoutong Sun, Yuanxia Sun and coworkers for the targeted pharmaceutically significant glucosylation of the polyhydroxy substrate silybin. Using an advanced version of Focused Rational Iterative Site-specific Mutagenesis (FRISM), they were able to evolve mutants that allow the formation of the 3-OH, 7-OH and the 3,7-O-diglycoside products with 94%, > 99% and > 99% regioselectivity, respectively. This can be viewed as a breakthrough because the wildtype UGT74AC2 delivers a difficult to separate mixture of products in a ratio of 22%:39%:39%. Even N- and S-glucosylations were achieved, a likewise unusual accomplishment.
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- 2021
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6. Publisher Correction: A machine learning approach for reliable prediction of amino acid interactions and its application in the directed evolution of enantioselective enzymes
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Frédéric Cadet, Nicolas Fontaine, Guangyue Li, Joaquin Sanchis, Matthieu Ng Fuk Chong, Rudy Pandjaitan, Iyanar Vetrivel, Bernard Offmann, and Manfred T. Reetz
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Medicine ,Science - Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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- 2021
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7. A redox-mediated Kemp eliminase
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Aitao Li, Binju Wang, Adriana Ilie, Kshatresh D. Dubey, Gert Bange, Ivan V. Korendovych, Sason Shaik, and Manfred T. Reetz
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Science - Abstract
The majority of enzymatic Kemp elimination reactions proceed via a well-established acid-base mechanism. Here, the authors show that cytochrome P450 is able to metabolize the leflunomide drug via a redox Kemp elimination, offering new insights into enzyme catalysis.
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- 2017
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8. Chemical and Biocatalytic Routes to Arbutin †
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Hangyu Zhou, Jing Zhao, Aitao Li, and Manfred T. Reetz
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arbutin ,glycosyltransferases ,glucosides ,shikimate pathway ,cosmetics ,directed evolution ,Chinese folk medicines ,Organic chemistry ,QD241-441 - Abstract
Arbutin (also called β-arbutin) is a natural product occurring in the leaves of a variety of different plants, the bearberries of the Ericaceae and Saxifragaceae families being prominent examples. It is a β-glucoside derived from hydroquinone (HQ; 1,4-dihydroxybenzene). Arbutin has been identified in traditional Chinese folk medicines as having, inter alia, anti-microbial, anti-oxidant, and anti-inflammatory properties that useful in the treatment of different ailments including urinary diseases. Today, it is also used worldwide for the treatment of skin ailments by way of depigmenting, which means that arbutin is a component of many products in the cosmetics and healthcare industries. It is also relevant in the food industry. Hundreds of publications have appeared describing the isolation, structure determination, toxicology, synthesis, and biological properties of arbutin as well as the molecular mechanism of melanogenesis (tyrosinase inhibition). This review covers the most important aspects with special emphasis on the chemical and biocatalytic methods for the production of arbutin.
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- 2019
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9. Crystal structure of 7,8,9,10-tetrahydrobenzo[b]naphtho[2,1-d]furan
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Zhongyuan Wu, Manfred T. Reetz, and Klaus Harms
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crystal structure ,Diels–Alder reaction ,Friedel–Crafts reaction ,furan ,tetrahydrobenzonaphthofuran ,C—H...π interactions ,Crystallography ,QD901-999 - Abstract
In the title compound, C16H14O, the cyclohexene ring has a half-chair conformation. The mean plane, calculated through all non-H atoms of the molecule, except for the central CH2 atoms of the cyclohexene ring, which deviate by 0.340 (3) and −0.369 (3) Å from this mean plane, has an r.m.s. deviation of 0.012 Å. In the crystal, there are C—H...π contacts present, resulting in the formation of zigzag chains propagating along the [010] direction.
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- 2016
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10. Evolution in the Test-Tube as a Means to Create Selective Biocatalysts
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Manfred T. Reetz
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Asymmetric catalysis ,Directed evolution ,Enantioselectivity ,Enzymes ,Gene mutagenesis ,High-throughput screening ,Chemistry ,QD1-999 - Abstract
The development of chiral catalysts for use in synthetic organic chemistry is traditionally associated with progress in asymmetric transition metal catalysis or organocatalysis. In addition to these options chemists have employed enzymes for a number of asymmetric transformations for a long time. However, limited substrate acceptance and insufficient enantioselectivity are the crucial factors which prevent the general exploitation of biocatalysis in organic chemistry. In order to solve this long-standing problem, we proposed some time ago the concept of directed evolution of enantioselective enzymes. This report constitutes a short overview of the principle involved, together with a description of the first examples and the illumination of the present and future challenges.
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- 2007
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11. Platinum-Nanoparticles on Different Types of Carbon Supports: Correlation of Electrocatalytic Activity with Carrier Morphology
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Manfred T. Reetz, Hendrik Schulenburg, Marco Lopez, Bernd Spliethoff, and Bernd Tesche
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Electrocatalysis ,Fuel cells ,Nanoparticles ,Platinum ,Transmission electron microscopy ,Chemistry ,QD1-999 - Abstract
The electrocatalytic activity of Pt-nanoparticles used in fuel cells increases by 34% upon going from the usual Pt/Vulcan XC72 to support systems such as Pt/Printex XE2 which have a relatively rough surface structure.
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- 2004
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12. Chiral Phosphoric Acid Diesters as Ligands in Asymmetric Transition Metal Catalyzed Hydrogenation
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Manfred T. Reetz, Thorsten Sell, and Richard Goddard
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Asymmetric catalysis ,Chirality ,Hydrogenation ,Iridium ,Palladium ,Phosphorus ligands ,Chemistry ,QD1-999 - Abstract
A chiral phosphoric acid diester, specifically the BINOL-based derivative, has been used for the first time in Rh-, Ir-, and Pd-catalyzed hydrogenation of olefins and imines, giving ee-values of up to 85%.
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- 2003
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13. Towards the Directed Evolution of Hybrid Catalysts
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Manfred T. Reetz, Martin Rentzsch, Andreas Pletsch, and Matthias Maywald
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Chemical modification ,Directed evolution ,Enzymes ,Hybrid catalysts ,Transition metal catalysis ,Chemistry ,QD1-999 - Abstract
The first step in applying the recently proposed concept concerning the application of directed evolution to the creation of selective hybrid catalysts is described, specifically the covalent attachment of Mn-salen moieties and of Cu-, Pd-, and Rh-complexes of dipyridine derivatives as well as the implantation of a diphosphine moiety in a protein, future steps being cycles of mutagenesis/screening.
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- 2002
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14. Lipase-Catalyzed Dynamic Kinetic Resolution of Chiral Amines: Use of Palladium as the Racemization Catalyst
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Manfred T. Reetz and Klaus Schimossek
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Chemistry ,QD1-999 - Abstract
The simultaneous use of a biocatalyst (lipase Candida antarctica) and a transition-metal catalyst (palladium) makes the dynamic kinetic resolution of racemic phenylethylamine possible, conversion to the enantiomerically pure N-acylated form being 75–77% (ee = 99%).
- Published
- 1996
15. Preparation and Catalytic Activity of Boron-Substituted Zirconocenes
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Manfred T. Reetz, Ranno Brümmer, Magnus Kessler, and Jörg Kuhnigk
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Chemistry ,QD1-999 - Abstract
Borylated zirconocenes of the type (L2B–C5H4)2ZrCl2 and (L2B–C5H4)(C5H5)ZrCl2 are readily available in two steps. In the polymerization of ethylene and propylene in the presence of AlEt3 or methylalumoxan (MAO), these zirconocenes are more active than the unsubstituted reagent Cp2ZrCl2.
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- 1995
16. Highly Efficient Lipase-Catalyzed Kinetic Resolution of Chiral Amines
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Manfred T. Reetz and Claus Dreisbach
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Chemistry ,QD1-999 - Abstract
The lipase Candida antarctica catalyzes the enantioselective acetylation of chiral primary amines, kinetic resolution leading to an enantiomeric excess (ee) of 90–98%.
- Published
- 1994
17. Supercritical Carbon Dioxide as a Reaction Medium and Reaction Partner
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Manfred T. Reetz, Werner Könen, and Thomas Strack
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Chemistry ,QD1-999 - Abstract
The [Ni(cod)2]/Ph2P(CH2)4PPh2-catalyzed reaction of hex-3-yne with CO2 under supercritical conditions affords tetraethylpyrone
- Published
- 1993
18. Mixtures of monodentate P-ligands as a means to control the diastereoselectivity in Rh-catalyzed hydrogenation of chiral alkenes
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Manfred T. Reetz and Hongchao Guo
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Science ,Organic chemistry ,QD241-441 - Abstract
The previously reported concept of using mixtures of monodentate ligands in a combinatorial manner in order to influence enantio- or regioselectivity of transition metal catalyzed processes has been extended to include diastereoselectivity. Accordingly, 1,2- and 1,3-asymmetric induction in the Rh-catalyzed hydrogenation of a chiral allylic alcohol and a chiral homo-allylic alcohol has been studied by using mixtures of monodentate P-ligands. It was found that appropriate 1:1 mixtures of two different P-ligands enhance the degree of diastereoselectivity relative to the use of the respective pure ligands themselves. Here, as in the previous cases regarding enantio- or regioselectivity, this type of combinatorial catalysis leads to improved catalytic profiles without the need to prepare new ligands.
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- 2005
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19. Machine Learning Enables Selection of Epistatic Enzyme Mutants for Stability Against Unfolding and Detrimental Aggregation
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Xavier F. Cadet, Nicolas Fontaine, Frédéric Cadet, Youcai Qin, Ferran Feixas, Manfred T. Reetz, Matthieu Ng Fuk Chong, Rudy Pandjaitan, Miguel A. Maria-Solano, Marc Garcia-Borràs, and Guangyue Li
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epistasis ,Protein Folding ,Stability (learning theory) ,Context (language use) ,innov'SAR ,Molecular Dynamics Simulation ,010402 general chemistry ,Machine learning ,computer.software_genre ,Protein Engineering ,01 natural sciences ,Biochemistry ,Machine Learning ,Molecular dynamics ,Protein sequencing ,Rhodococcus ,Molecular Biology ,Mathematics ,Epoxide Hydrolases ,Full Paper ,010405 organic chemistry ,business.industry ,Organic Chemistry ,Robustness (evolution) ,Protein engineering ,molecular dynamics simulations ,Full Papers ,artificial intelligence ,0104 chemical sciences ,epoxide hydrolase ,Order (biology) ,Mutation ,Molecular Medicine ,Epistasis ,Artificial intelligence ,Protein Multimerization ,business ,computer ,Limonene - Abstract
Machine learning (ML) has pervaded most areas of protein engineering, including stability and stereoselectivity. Using limonene epoxide hydrolase as the model enzyme and innov'SAR as the ML platform, comprising a digital signal process, we achieved high protein robustness that can resist unfolding with concomitant detrimental aggregation. Fourier transform (FT) allows us to take into account the order of the protein sequence and the nonlinear interactions between positions, and thus to grasp epistatic phenomena. The innov'SAR approach is interpolative, extrapolative and makes outside‐the‐box, predictions not found in other state‐of‐the‐art ML or deep learning approaches. Equally significant is the finding that our approach to ML in the present context, flanked by advanced molecular dynamics simulations, uncovers the connection between epistatic mutational interactions and protein robustness., A quick learner: Machine learning based on the innov'SAR algorithm leads to efficient selection of highly robust limonene epoxide hydrolase mutants with enhanced unfolding stability and resistance to aggregation by recognizing epistatic mutational interactions.
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- 2020
20. Artificial cysteine-lipases with high activity and altered catalytic mechanism created by laboratory evolution
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Thomas S. Moody, Qi Wu, Manfred T. Reetz, Warispreet Singh, Jiahai Zhou, Yixin Cen, Mamatjan Arkin, and Meilan Huang
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0301 basic medicine ,Models, Molecular ,Stereochemistry ,Protein Conformation ,Science ,Protein design ,General Physics and Astronomy ,02 engineering and technology ,Crystallography, X-Ray ,Protein Engineering ,General Biochemistry, Genetics and Molecular Biology ,Catalysis ,Article ,Substrate Specificity ,Fungal Proteins ,03 medical and health sciences ,Enzyme activator ,Catalytic Domain ,Hydrolase ,Catalytic triad ,Cysteine ,Lipase ,lcsh:Science ,Candida ,chemistry.chemical_classification ,Multidisciplinary ,Binding Sites ,biology ,Hydrolysis ,General Chemistry ,021001 nanoscience & nanotechnology ,Directed evolution ,biology.organism_classification ,C700 ,Enzyme Activation ,Kinetics ,030104 developmental biology ,Enzyme ,chemistry ,Mutation ,Enzyme mechanisms ,biology.protein ,Biocatalysis ,lcsh:Q ,Candida antarctica ,0210 nano-technology - Abstract
Engineering artificial enzymes with high activity and catalytic mechanism different from naturally occurring enzymes is a challenge in protein design. For example, many attempts have been made to obtain active hydrolases by introducing a Ser → Cys exchange at the respective catalytic triads, but this generally induced a breakdown of activity. We now report that this long-standing dogma no longer pertains, provided additional mutations are introduced by directed evolution. By employing Candida antarctica lipase B (CALB) as the model enzyme with the Ser-His-Asp catalytic triad, a highly active cysteine-lipase having a Cys-His-Asp catalytic triad and additional mutations W104V/A281Y/A282Y/V149G can be evolved, showing a 40-fold higher catalytic efficiency than wild-type CALB in the hydrolysis of 4-nitrophenyl benzoate, and tolerating bulky substrates. Crystal structures, kinetics, MD simulations and QM/MM calculations reveal dynamic features and explain all results, including the preference of a two-step mechanism involving the zwitterionic pair Cys105−/His224+ rather than a concerted process., Candida antarctica lipase B (CALB) is a serine lipase. Here, the authors use directed evolution to exchange serine with cysteine in the catalytic triad of the enzyme, thereby obtaining a highly active CALB variant that — unlike the wild type — accommodates bulky substrates.
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- 2019
21. Stereodivergent Protein Engineering of a Lipase to Access All Possible Stereoisomers of Chiral Esters with Two Stereo-centers
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Jian Xu, Jiahai Zhou, Meilan Huang, Lian Wu, Xianfu Lin, Manfred T. Reetz, Jiajie Fan, Warispreet Singh, Yixin Cen, and Qi Wu
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Stereochemistry ,Protein Conformation ,F100 ,Stereoisomerism ,Molecular Dynamics Simulation ,010402 general chemistry ,Protein Engineering ,01 natural sciences ,Biochemistry ,Catalysis ,Stereocenter ,Fungal Proteins ,Colloid and Surface Chemistry ,Hydrolase ,Lipase ,biology ,Chemistry ,Esters ,Protein engineering ,General Chemistry ,Directed evolution ,biology.organism_classification ,C700 ,0104 chemical sciences ,Mutation ,biology.protein ,Candida antarctica ,Stereoselectivity ,Protein Binding - Abstract
Enzymatic stereodivergent synthesis to access all possible product stereoisomers bearing multiple stereocenters is relatively undeveloped, although enzymes are being increasingly used in both academic and industrial areas. When two stereocenters and thus four stereoisomeric products are involved, obtaining stereodivergent enzyme mutants for individually accessing all four stereoisomers would be ideal. Although significant success has been achieved in directed evolution of enzymes in general, stereodivergent engineering of one enzyme into four highly stereocomplementary variants for obtaining the full complement of stereoisomers bearing multiple stereocenters remains a challenge. Using Candida antarctica lipase B (CALB) as a model, we report the protein engineering of this enzyme into four highly stereocomplementary variants needed for obtaining all four stereoisomers in transesterification reactions between racemic acids and racemic alcohols in organic solvents. By generating and screening less than 25 variants of each isomer, we achieved >90% selectivity for all of the four possible stereoisomers in the model reaction. This difficult feat was accomplished by developing a strategy dubbed "focused rational iterative site-specific mutagenesis" (FRISM) at sites lining the enzyme's binding pocket. The accumulation of single mutations by iterative site-specific mutagenesis using a restricted set of rationally chosen amino acids allows the formation of ultrasmall mutant libraries requiring minimal screening for stereoselectivity. The crystal structure of all stereodivergent CALB variants, flanked by MD simulations, uncovered the source of selectivity.
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- 2019
22. P450-Catalyzed Regio- and Diastereoselective Steroid Hydroxylation: Efficient Directed Evolution Enabled by Mutability Landscaping
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Richard Lonsdale, Kirsty J. McLean, Charles G. Gamble, Yuval Nov, Christophe Farès, Aitao Li, Julia B. Lingnau, Adrian J. Mulholland, Manfred T. Reetz, David Leys, Heike Hinrichs, Alfred Deege, Sabrina Hoebenreich, Carlos G. Acevedo-Rocha, Nathalie Nett, Cornelia Wirtz, and Andrew W. Munro
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medicine.medical_treatment ,010402 general chemistry ,01 natural sciences ,Catalysis ,Steroid ,Hydroxylation ,chemistry.chemical_compound ,Regioselectivity ,Manchester Institute of Biotechnology ,medicine ,Saturated mutagenesis ,C-H activation ,010405 organic chemistry ,Cytochrome P450 monooxygenase ,Rational design ,Stereoselectivity ,General Chemistry ,Protein engineering ,iterative saturation mutagenesis ,Directed evolution ,ResearchInstitutes_Networks_Beacons/03/05 ,ResearchInstitutes_Networks_Beacons/manchester_institute_of_biotechnology ,Combinatorial chemistry ,0104 chemical sciences ,mutability landscapes ,chemistry ,Steroids ,Biotechnology - Abstract
Cytochrome P450 monooxygenases play a crucial role in the biosynthesis of many natural products and in the human metabolism of numerous pharmaceuticals. This has inspired synthetic organic and medicinal chemists to exploit them as catalysts in regio- and stereoselective CH-activating oxidation of structurally simple and complex organic compounds such as steroids. However, levels of regio- and stereoselectivity as well as activity are not routinely high enough for real applications. Protein engineering using rational design or directed evolution has helped in many respects, but simultaneous engineering of multiple catalytic traits such as activity, regioselectivity, and stereoselectivity, while overcoming trade-offs and diminishing returns, remains a challenge. Here we show that the exploitation of information derived from mutability landscapes and molecular dynamics simulations for rationally designing iterative saturation mutagenesis constitutes a viable directed evolution strategy. This combined approac...
- Published
- 2018
23. Crystal structure of 7,8,9,10-tetrahydrobenzo[b]naphtho[2,1-d]furan
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Manfred T. Reetz, Klaus Harms, and Zhongyuan Wu
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crystal structure ,furan ,Nanotechnology ,Crystal structure ,C—H⋯π interactions ,010402 general chemistry ,010403 inorganic & nuclear chemistry ,Ring (chemistry) ,01 natural sciences ,Research Communications ,tetrahydrobenzonaphthofuran ,Crystal ,lcsh:Chemistry ,chemistry.chemical_compound ,C—H...π interactions ,Furan ,General Materials Science ,Friedel–Crafts reaction ,biology ,Chemistry ,Plane (geometry) ,General Chemistry ,Condensed Matter Physics ,biology.organism_classification ,0104 chemical sciences ,Crystallography ,tetrahydrobenzonaphthofuran ,Zigzag ,lcsh:QD1-999 ,Diels–Alder reaction ,Tetra - Abstract
The reaction of 1-naphthol with cyclohexadiene in the presence of catalytic amounts of Lewis acid, which interacts with 1-naphthol with release of protons, does not afford the Diels–Alder adduct but the Friedel–Crafts products followed by aromatization. The crystal structure of the final tetrahydrobenzonaphthofuran product is described., In the title compound, C16H14O, the cyclohexene ring has a half-chair conformation. The mean plane, calculated through all non-H atoms of the molecule, except for the central CH2 atoms of the cyclohexene ring, which deviate by 0.340 (3) and −0.369 (3) Å from this mean plane, has an r.m.s. deviation of 0.012 Å. In the crystal, there are C—H⋯π contacts present, resulting in the formation of zigzag chains propagating along the [010] direction.
- Published
- 2016
24. A redox-mediated Kemp eliminase
- Author
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Manfred T. Reetz, Binju Wang, Aitao Li, Ivan V. Korendovych, Gert Bange, Sason Shaik, Kshatresh Dutta Dubey, and Adriana Ilie
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Chemical Phenomena ,Stereochemistry ,Science ,General Physics and Astronomy ,Molecular Dynamics Simulation ,010402 general chemistry ,Protein Engineering ,01 natural sciences ,Heterolysis ,Redox ,General Biochemistry, Genetics and Molecular Biology ,Article ,Catalysis ,Substrate Specificity ,Electron transfer ,chemistry.chemical_compound ,Cytochrome P-450 Enzyme System ,Catalytic Domain ,Moiety ,Humans ,Isoxazole ,Multidisciplinary ,010405 organic chemistry ,General Chemistry ,Protein engineering ,Isoxazoles ,0104 chemical sciences ,3. Good health ,Kinetics ,Biochemistry ,chemistry ,Biocatalysis ,Bacillus megaterium ,Quantum Theory ,Oxidation-Reduction ,Leflunomide - Abstract
The acid/base-catalysed Kemp elimination of 5-nitro-benzisoxazole forming 2-cyano-4-nitrophenol has long served as a design platform of enzymes with non-natural reactions, providing new mechanistic insights in protein science. Here we describe an alternative concept based on redox catalysis by P450-BM3, leading to the same Kemp product via a fundamentally different mechanism. QM/MM computations show that it involves coordination of the substrate's N-atom to haem-Fe(II) with electron transfer and concomitant N–O heterolysis liberating an intermediate having a nitrogen radical moiety Fe(III)–N· and a phenoxyl anion. Product formation occurs by bond rotation and H-transfer. Two rationally chosen point mutations cause a notable increase in activity. The results shed light on the prevailing mechanistic uncertainties in human P450-catalysed metabolism of the immunomodulatory drug leflunomide, which likewise undergoes redox-mediated Kemp elimination by P450-BM3. Other isoxazole-based pharmaceuticals are probably also metabolized by a redox mechanism. Our work provides a basis for designing future artificial enzymes., The majority of enzymatic Kemp elimination reactions proceed via a well-established acid-base mechanism. Here, the authors show that cytochrome P450 is able to metabolize the leflunomide drug via a redox Kemp elimination, offering new insights into enzyme catalysis.
- Published
- 2017
25. Directed Evolution of an Enantioselective Epoxide Hydrolase : Uncovering the Source of Enantioselectivity at Each Evolutionary Stage
- Author
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Alain Robert Archelas, Li-Wen Wang, Michael Arand, Joaquin Sanchis, Manfred T. Reetz, Anne Lise Bottalla, Marco Bocola, Sherry L. Mowbray, Jinyu Zou, Annette Cronin, Agata Naworyta, and University of Zurich
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1303 Biochemistry ,Molecular model ,Stereochemistry ,1503 Catalysis ,10050 Institute of Pharmacology and Toxicology ,Ether ,610 Medicine & health ,1600 General Chemistry ,1505 Colloid and Surface Chemistry ,Biochemistry ,Catalysis ,Kinetic resolution ,Substrate Specificity ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Hydrolase ,Epoxide hydrolase ,Epoxide Hydrolases ,biology ,Chemistry ,Enantioselective synthesis ,Biochemistry and Molecular Biology ,Active site ,Stereoisomerism ,General Chemistry ,Directed evolution ,Kinetics ,Mutation ,biology.protein ,570 Life sciences ,Aspergillus niger ,Directed Molecular Evolution ,Biokemi och molekylärbiologi - Abstract
Directed evolution of enzymes as enantioselective catalysts in organic chemistry is an alternative to traditional asymmetric catalysis using chiral transition-metal complexes or organocatalysts, the different approaches often being complementary. Moreover, directed evolution studies allow us to learn more about how enzymes perform mechanistically. The present study concerns a previously evolved highly enantioselective mutant of the epoxide hydrolase from Aspergillus niger in the hydrolytic kinetic resolution of racemic glycidyl phenyl ether. Kinetic data, molecular dynamics calculations, molecular modeling, inhibition experiments, and X-ray structural work for the wild-type (WT) enzyme and the best mutant reveal the basis of the large increase in enantioselectivity (E = 4.6 versus E = 115). The overall structures of the WT and the mutant are essentially identical, but dramatic differences are observed in the active site as revealed by the X-ray structures. All of the experimental and computational results support a model in which productive positioning of the preferred (S)-glycidyl phenyl ether, but not the (R)-enantiomer, forms the basis of enhanced enantioselectivity. Predictions regarding substrate scope and enantioselectivity of the best mutant are shown to be possible.
- Published
- 2009
26. PipPhos and MorfPhos
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Bernard Feringa, M.P. van den Berg, Heiko Bernsmann, de Johannes Vries, Robert Hoen, Gerlinde Mehler, Adriaan J. Minnaard, Manfred T. Reetz, Stratingh Institute of Chemistry, Synthetic Organic Chemistry, and Chemical Biology 2
- Subjects
Cyclic compound ,Phosphoramidite ,DEHYDROAMINO ACID-DERIVATIVES ,PHOSPHORUS LIGANDS ,Denticity ,CYCLIC ENAMIDES ,Ligand ,MONOPHOSPHITE LIGANDS ,Organic Chemistry ,Asymmetric hydrogenation ,Enantioselective synthesis ,CHIRAL LIGANDS ,chemistry.chemical_element ,General Medicine ,REACTION PATHWAYS ,Combinatorial chemistry ,Rhodium ,Catalysis ,PHOSPHITE LIGANDS ,HIGHLY ENANTIOSELECTIVE HYDROGENATION ,chemistry ,Organic chemistry ,CONJUGATE ADDITION ,FINE CHEMICALS - Abstract
A library of 20 monodentate phosphoramidite ligands has been prepared and applied in rhodium-catalyzed asymmetric hydrogenation. This resulted in the identification of two ligands, PipPhos and MorfPhos, that afford excellent and in several cases unprecedented enantioselectivities in the hydrogenation of N-acyldehydroamino acid esters, dimethyl itaconate, acyclic N-acylenamides, and cyclic N-acylenamides. In addition, a method for the parallel enantioselectivity determination of eight acylated amines is presented.
- Published
- 2005
27. Bacterial biocatalysts: Molecular Biology, Three-Dimensional Structures, and Biotechnological Applications of Lipases
- Author
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Manfred T. Reetz, Bauke W. Dijkstra, Karl-Erich Jaeger, and Groningen Biomolecular Sciences and Biotechnology
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DYNAMIC KINETIC RESOLUTION ,Protein Folding ,Protein Conformation ,PSEUDOMONAS-AERUGINOSA PAO1 ,Triacylglycerol lipase ,ATP-binding cassette transporter ,Microbiology ,Catalysis ,RHAMNOLIPID BIOSURFACTANT SYNTHESIS ,ACINETOBACTER-CALCOACETICUS BD413 ,Hydrolase ,enantioselectivity ,CANDIDA-RUGOSA LIPASE ,Lipase ,directed evolution ,GRAM-NEGATIVE BACTERIA ,Bacteria ,biology ,BACILLUS-SUBTILIS 168 ,ALPHA/BETA-HYDROLASE FOLD ,Gene Expression Regulation, Bacterial ,Directed evolution ,X-RAY ANALYSIS ,secretion ,Quorum sensing ,Biochemistry ,Foldase ,SOL-GEL MATERIALS ,biology.protein ,Protein folding ,Biotechnology - Abstract
▪ Abstract Bacteria produce and secrete lipases, which can catalyze both the hydrolysis and the synthesis of long-chain acylglycerols. These reactions usually proceed with high regioselectivity and enantioselectivity, and, therefore, lipases have become very important stereoselective biocatalysts used in organic chemistry. High-level production of these biocatalysts requires the understanding of the mechanisms underlying gene expression, folding, and secretion. Transcription of lipase genes may be regulated by quorum sensing and two-component systems; secretion can proceed either via the Sec-dependent general secretory pathway or via ABC transporters. In addition, some lipases need folding catalysts such as the lipase-specific foldases and disulfide-bond–forming proteins to achieve a secretion-competent conformation. Three-dimensional structures of bacterial lipases were solved to understand the catalytic mechanism of lipase reactions. Structural characteristics include an α/β hydrolase fold, a catalytic triad consisting of a nucleophilic serine located in a highly conserved Gly-X-Ser-X-Gly pentapeptide, and an aspartate or glutamate residue that is hydrogen bonded to a histidine. Four substrate binding pockets were identified for triglycerides: an oxyanion hole and three pockets accommodating the fatty acids bound at positions sn-1, sn-2, and sn-3. The differences in size and the hydrophilicity/hydrophobicity of these pockets determine the enantiopreference of a lipase. The understanding of structure-function relationships will enable researchers to tailor new lipases for biotechnological applications. At the same time, directed evolution in combination with appropriate screening systems will be used extensively as a novel approach to develop lipases with high stability and enantioselectivity.
- Published
- 1999
28. Electron-beam lithography with metal colloids : Direct writing of metallic nanostructures
- Author
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Eberhard F. Wassermann, J. Lohau, S. Friedrichowski, Martin Winter, Günter Dumpich, and Manfred T. Reetz
- Subjects
endocrine system ,Materials science ,Nanostructure ,Fabrication ,digestive, oral, and skin physiology ,General Engineering ,chemistry.chemical_element ,Nanotechnology ,Physik (inkl. Astronomie) ,complex mixtures ,Metal ,Colloid ,chemistry ,visual_art ,visual_art.visual_art_medium ,Irradiation ,Lithography ,Electron-beam lithography ,Palladium - Abstract
We report on the fabrication of metallic nanostructures in the sub-100 nm region by means of electron-beam lithography with metal colloids. A thin organometallic film consisting of surfactant stabilized Pd-colloids (⩽3 nm) is directly patterned by electron-beam irradiation. Non-exposed colloids are easily removed by rinsing the sample with appropriate dissolvers. The metallic character of the nanostructures is checked by resistance measurements. We find the morphology and the resistance behavior of the present nanostructured Pd-colloids to be similar to those of granular thin Pd/C films. Accordingly, the metal content of the nanostructures fabricated with Pd-colloids can be estimated.
- Published
- 1998
Catalog
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