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Thomas R. Ward - One of the best experts on this subject based on the ideXlab platform.
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Biomacromolecules as Ligands for Artificial Metalloenzymes
Comprehensive Inorganic Chemistry II, 2020Co-Authors: Didier R Hamels, Thomas R. WardAbstract:First coordination sphere interactions usually are involved in metal-catalyzed enantioselective transformations: a chiral ligand directly linked to the metal dictates the enantiomeric outcome of a given reaction. A novel concept has emerged in the past 30 years: achiral metal complexes are inserted into proteins or DNA and the resulting artificial Metalloenzymes catalyze various enantioselective transformations. In these hybrid catalysts, enantioselection is achieved with the help of the second coordination sphere, that is, a subtle combination of secondary interactions between the biomolecular scaffold, the catalyst, and the substrate. This chapter discusses the design of artificial Metalloenzymes and their use in homogeneous catalysis.
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Supramolecular Enzyme Mimics
Comprehensive Supramolecular Chemistry II, 2020Co-Authors: Yasunori Okamoto, Thomas R. WardAbstract:Artificial Metalloenzymes result from the incorporation of an organometallic moiety within a macromolecule. In this article, we review the field of artificial Metalloenzymes. These are classified according to the host that accommodates the organometallic cofactor: cyclodextrins (“Cyclodextrin-Based Artificial Enzymes” section), ligands bearing a substrate recognition motif (“Artificial Enzymes With Ligands Bearing Substrate Recognition Motifs” section), supramolecular cages (“Cage Molecules as Artificial Enzymes” section), nucleic acids (“DNA-Based Artificial Metalloenzymes” section), and proteins (“Protein-Based Artificial Enzymes” section). Both dative and supramolecular anchoring strategies are reviewed.
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Chimeric Streptavidins as Host Proteins for Artificial Metalloenzymes
ACS Catalysis, 2018Co-Authors: Michela Pellizzoni, Fabian Schwizer, Christopher W. Wood, Valerio Sabatino, Yoann Cotelle, Stefan Matile, Derek N. Woolfson, Thomas R. WardAbstract:The streptavidin scaffold was expanded with well-structured naturally occurring motifs. These chimeric scaffolds were tested as hosts for biotinylated catalysts as artificial Metalloenzymes (ArM) for asymmetric transfer hydrogenation, ring-closing metathesis and anion−π catalysis. The additional second coordination sphere elements significantly influence both the activity and the selectivity of the resulting hybrid catalysts. These findings lead to the identification of propitious chimeric streptavidins for future directed evolution efforts of artificial Metalloenzymes.
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directed evolution of artificial Metalloenzymes for in vivo metathesis
Nature, 2016Co-Authors: Markus Jeschek, Raphael Reuter, Christian Trindler, Juliane Klehr, Sven Panke, Tillmann Heinisch, Thomas R. WardAbstract:An artificial metalloenzyme is compartmentalized and evolved in vivo for olefin metathesis—an archetypal organometallic reaction without equivalent in nature; the evolved metathase reveals broad substrate scope and compares favourably with commercial catalysts. Artificial Metalloenzymes—made by incorporating an abiotic cofactor within a protein scaffold—have the potential to engineer non-natural in vivo reactions. To be of practical use, such catalysts must maintain their activity in a cellular environment, which means overcoming the tendency of introduced metal cofactors to be inhibited by cellular components. This paper demonstrates that directed evolution can overcome this difficulty. Markus Jeschek et al. report on the in vivo evolution of a ruthenium–protein complex that can catalyse olefin metathesis—an archetypal organometallic reaction with no equivalent in nature—in the periplasm of Escherichia coli. The evolved metathase compares favorably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in different directions by adjusting the protocol. The field of biocatalysis has advanced from harnessing natural enzymes to using directed evolution to obtain new biocatalysts with tailor-made functions1. Several tools have recently been developed to expand the natural enzymatic repertoire with abiotic reactions2,3. For example, artificial Metalloenzymes, which combine the versatile reaction scope of transition metals with the beneficial catalytic features of enzymes, offer an attractive means to engineer new reactions. Three complementary strategies exist3: repurposing natural Metalloenzymes for abiotic transformations2,4; in silico metalloenzyme (re-)design5,6,7; and incorporation of abiotic cofactors into proteins8,9,10,11. The third strategy offers the opportunity to design a wide variety of artificial Metalloenzymes for non-natural reactions. However, many metal cofactors are inhibited by cellular components and therefore require purification of the scaffold protein12,13,14,15. This limits the throughput of genetic optimization schemes applied to artificial Metalloenzymes and their applicability in vivo to expand natural metabolism. Here we report the compartmentalization and in vivo evolution of an artificial metalloenzyme for olefin metathesis, which represents an archetypal organometallic reaction16,17,18,19,20,21,22 without equivalent in nature. Building on previous work6 on an artificial metallohydrolase, we exploit the periplasm of Escherichia coli as a reaction compartment for the ‘metathase’ because it offers an auspicious environment for artificial Metalloenzymes, mainly owing to low concentrations of inhibitors such as glutathione, which has recently been identified as a major inhibitor15. This strategy facilitated the assembly of a functional metathase in vivo and its directed evolution with substantially increased throughput compared to conventional approaches that rely on purified protein variants. The evolved metathase compares favourably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in different directions by adjusting the workflow. Our results represent the systematic implementation and evolution of an artificial metalloenzyme that catalyses an abiotic reaction in vivo, with potential applications in, for example, non-natural metabolism.
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Directed evolution of artificial Metalloenzymes for in vivo metathesis
Nature, 2016Co-Authors: Markus Jeschek, Raphael Reuter, Christian Trindler, Juliane Klehr, Sven Panke, Tillmann Heinisch, Thomas R. WardAbstract:The field of biocatalysis has advanced from harnessing natural enzymes to using directed evolution to obtain new biocatalysts with tailor-made functions. Several tools have recently been developed to expand the natural enzymatic repertoire with abiotic reactions. For example, artificial Metalloenzymes, which combine the versatile reaction scope of transition metals with the beneficial catalytic features of enzymes, offer an attractive means to engineer new reactions. Three complementary strategies exist: repurposing natural Metalloenzymes for abiotic transformations; in silico metalloenzyme (re-)design; and incorporation of abiotic cofactors into proteins. The third strategy offers the opportunity to design a wide variety of artificial Metalloenzymes for non-natural reactions. However, many metal cofactors are inhibited by cellular components and therefore require purification of the scaffold protein. This limits the throughput of genetic optimization schemes applied to artificial Metalloenzymes and their applicability in vivo to expand natural metabolism. Here we report the compartmentalization and in vivo evolution of an artificial metalloenzyme for olefin metathesis, which represents an archetypal organometallic reaction without equivalent in nature. Building on previous work on an artificial metallohydrolase, we exploit the periplasm of Escherichia coli as a reaction compartment for the 'metathase' because it offers an auspicious environment for artificial Metalloenzymes, mainly owing to low concentrations of inhibitors such as glutathione, which has recently been identified as a major inhibitor. This strategy facilitated the assembly of a functional metathase in vivo and its directed evolution with substantially increased throughput compared to conventional approaches that rely on purified protein variants. The evolved metathase compares favourably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in different directions by adjusting the workflow. Our results represent the systematic implementation and evolution of an artificial metalloenzyme that catalyses an abiotic reaction in vivo, with potential applications in, for example, non-natural metabolism.
Kenneth M. Merz - One of the best experts on this subject based on the ideXlab platform.
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qm mm x ray refinement of zinc Metalloenzymes
Journal of Inorganic Biochemistry, 2010Co-Authors: Xue Li, Seth A. Hayik, Kenneth M. MerzAbstract:Abstract Zinc Metalloenzymes play an important role in biology. However, due to the limitation of molecular force field energy restraints used in X-ray refinement at medium or low resolutions, the precise geometry of the zinc coordination environment can be difficult to distinguish from ambiguous electron density maps. Due to the difficulties involved in defining accurate force fields for metal ions, the QM/MM (quantum-mechanical/molecular-mechanical) method provides an attractive and more general alternative for the study and refinement of metalloprotein active sites. Herein we present three examples that indicate that QM/MM based refinement yields a superior description of the crystal structure based on R and Rfree values and on the inspection of the zinc coordination environment. It is concluded that QM/MM refinement is an useful general tool for the improvement of the metal coordination sphere in metalloenzyme active sites.
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QM/MM X-ray refinement of zinc Metalloenzymes
2010Co-Authors: Xue Li, Seth A. Hayik, Kenneth M. MerzAbstract:Zinc Metalloenzymes play an important role in biology. However, due to the limitation of molecular force field energy restraints used in X-ray refinement at medium or low resolutions, the precise geometry of the zinc coordination environment can be difficult to distinguish from ambiguous electron density maps. Due to the difficulties involved in defining accurate force fields for metal ions, the QM/MM (quantum-mechanical/molecular-mechanical) method provides an attractive and more general alternative for the study and refinement of metalloprotein active sites. Herein we present three examples that indicate that QM/MM based refinement yields a superior description of the crystal structure based on R and Rfree values and on the inspection of the zinc coordination environment. It is concluded that QM/MM refinement is an useful general tool for the improvement of the metal coordination sphere in metalloenzyme active sites. ?? 2010 Elsevier Inc.
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PM3-compatible zinc parameters optimized for metalloenzyme active sites.
Journal of Computational Chemistry, 2004Co-Authors: Dimas Suárez, David W. Deerfield, Kenneth M. MerzAbstract:Recent studies have shown that semiempirical methods (e.g., PM3 and AM1) for zinc-containing compounds are unreliable for modeling structures containing zinc ions with ligand environments similar to those observed in zinc Metalloenzymes. To correct these deficiencies a reparameterization of zinc at the PM3 level was undertaken. In this effort we included frequency corrected B3LYP/6-311G* zinc metalloenzyme ligand environments along with previously utilized experimental data. Average errors for the heats of formation have been reduced from 46.9 kcal/mol (PM3) to 14.2 kcal/mol for this new parameter set, termed ZnB for "Zinc, Biological." In addition, the new parameter sets predict geometries for the Bacillus fragilis active site model and other zinc metalloenzyme mimics that are qualitatively in agreement with high-level ab initio results, something existing parameter sets failed to do.
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A Quantum Mechanics-Based Scoring Function: Study of Zinc Ion-Mediated Ligand Binding
Journal of the American Chemical Society, 2004Co-Authors: Kaushik Raha, Kenneth M. MerzAbstract:In this communication, we report the development of a novel quantum mechanics-based scoring function to predict free energy of ligand binding in the zinc Metalloenzymes carbonic anhydrase (CA) and carboxypeptidase A (CPA). In particular, the AM1 method is used in conjunction with solvation modeling to predict the relative binding affinities of 18 CA and 5 CPA inhibitors. The effect of metal-ligand charge transfer is also discussed and shown to be different in CPA and CA, providing a further challenge to computing metalloenzyme binding affinities.
Tillmann Heinisch - One of the best experts on this subject based on the ideXlab platform.
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directed evolution of artificial Metalloenzymes for in vivo metathesis
Nature, 2016Co-Authors: Markus Jeschek, Raphael Reuter, Christian Trindler, Juliane Klehr, Sven Panke, Tillmann Heinisch, Thomas R. WardAbstract:An artificial metalloenzyme is compartmentalized and evolved in vivo for olefin metathesis—an archetypal organometallic reaction without equivalent in nature; the evolved metathase reveals broad substrate scope and compares favourably with commercial catalysts. Artificial Metalloenzymes—made by incorporating an abiotic cofactor within a protein scaffold—have the potential to engineer non-natural in vivo reactions. To be of practical use, such catalysts must maintain their activity in a cellular environment, which means overcoming the tendency of introduced metal cofactors to be inhibited by cellular components. This paper demonstrates that directed evolution can overcome this difficulty. Markus Jeschek et al. report on the in vivo evolution of a ruthenium–protein complex that can catalyse olefin metathesis—an archetypal organometallic reaction with no equivalent in nature—in the periplasm of Escherichia coli. The evolved metathase compares favorably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in different directions by adjusting the protocol. The field of biocatalysis has advanced from harnessing natural enzymes to using directed evolution to obtain new biocatalysts with tailor-made functions1. Several tools have recently been developed to expand the natural enzymatic repertoire with abiotic reactions2,3. For example, artificial Metalloenzymes, which combine the versatile reaction scope of transition metals with the beneficial catalytic features of enzymes, offer an attractive means to engineer new reactions. Three complementary strategies exist3: repurposing natural Metalloenzymes for abiotic transformations2,4; in silico metalloenzyme (re-)design5,6,7; and incorporation of abiotic cofactors into proteins8,9,10,11. The third strategy offers the opportunity to design a wide variety of artificial Metalloenzymes for non-natural reactions. However, many metal cofactors are inhibited by cellular components and therefore require purification of the scaffold protein12,13,14,15. This limits the throughput of genetic optimization schemes applied to artificial Metalloenzymes and their applicability in vivo to expand natural metabolism. Here we report the compartmentalization and in vivo evolution of an artificial metalloenzyme for olefin metathesis, which represents an archetypal organometallic reaction16,17,18,19,20,21,22 without equivalent in nature. Building on previous work6 on an artificial metallohydrolase, we exploit the periplasm of Escherichia coli as a reaction compartment for the ‘metathase’ because it offers an auspicious environment for artificial Metalloenzymes, mainly owing to low concentrations of inhibitors such as glutathione, which has recently been identified as a major inhibitor15. This strategy facilitated the assembly of a functional metathase in vivo and its directed evolution with substantially increased throughput compared to conventional approaches that rely on purified protein variants. The evolved metathase compares favourably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in different directions by adjusting the workflow. Our results represent the systematic implementation and evolution of an artificial metalloenzyme that catalyses an abiotic reaction in vivo, with potential applications in, for example, non-natural metabolism.
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Directed evolution of artificial Metalloenzymes for in vivo metathesis
Nature, 2016Co-Authors: Markus Jeschek, Raphael Reuter, Christian Trindler, Juliane Klehr, Sven Panke, Tillmann Heinisch, Thomas R. WardAbstract:The field of biocatalysis has advanced from harnessing natural enzymes to using directed evolution to obtain new biocatalysts with tailor-made functions. Several tools have recently been developed to expand the natural enzymatic repertoire with abiotic reactions. For example, artificial Metalloenzymes, which combine the versatile reaction scope of transition metals with the beneficial catalytic features of enzymes, offer an attractive means to engineer new reactions. Three complementary strategies exist: repurposing natural Metalloenzymes for abiotic transformations; in silico metalloenzyme (re-)design; and incorporation of abiotic cofactors into proteins. The third strategy offers the opportunity to design a wide variety of artificial Metalloenzymes for non-natural reactions. However, many metal cofactors are inhibited by cellular components and therefore require purification of the scaffold protein. This limits the throughput of genetic optimization schemes applied to artificial Metalloenzymes and their applicability in vivo to expand natural metabolism. Here we report the compartmentalization and in vivo evolution of an artificial metalloenzyme for olefin metathesis, which represents an archetypal organometallic reaction without equivalent in nature. Building on previous work on an artificial metallohydrolase, we exploit the periplasm of Escherichia coli as a reaction compartment for the 'metathase' because it offers an auspicious environment for artificial Metalloenzymes, mainly owing to low concentrations of inhibitors such as glutathione, which has recently been identified as a major inhibitor. This strategy facilitated the assembly of a functional metathase in vivo and its directed evolution with substantially increased throughput compared to conventional approaches that rely on purified protein variants. The evolved metathase compares favourably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in different directions by adjusting the workflow. Our results represent the systematic implementation and evolution of an artificial metalloenzyme that catalyses an abiotic reaction in vivo, with potential applications in, for example, non-natural metabolism.
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artificial Metalloenzymes based on the biotin streptavidin technology challenges and opportunities
Accounts of Chemical Research, 2016Co-Authors: Tillmann Heinisch, Thomas R. WardAbstract:ConspectusThe biotin–streptavidin technology offers an attractive means to engineer artificial Metalloenzymes (ArMs). Initiated over 50 years ago by Bayer and Wilchek, the biotin–(strept)avidin techonology relies on the exquisite supramolecular affinity of either avidin or streptavidin for biotin. This versatile tool, commonly referred to as “molecular velcro”, allows nearly irreversible anchoring of biotinylated probes within a (strept)avidin host protein. Building upon a visionary publication by Whitesides from 1978, several groups have been exploiting this technology to create artificial Metalloenzymes. For this purpose, a biotinylated organometallic catalyst is introduced within (strept)avidin to afford a hybrid catalyst that combines features reminiscent of both enzymes and organometallic catalysts. Importantly, ArMs can be optimized by chemogenetic means. Combining a small collection of biotinylated organometallic catalysts with streptavidin mutants allows generation of significant diversity, thus a...
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Directed evolution of artificial Metalloenzymes for in vivo metathesis
Nature, 2016Co-Authors: Markus Jeschek, Raphael Reuter, Christian Trindler, Juliane Klehr, Sven Panke, Tillmann Heinisch, Thomas R. WardAbstract:The field of biocatalysis has advanced from harnessing natural enzymes to using directed evolution to obtain new biocatalysts with tailor-made functions 1 . Several tools have recently been developed to expand the natural enzymatic repertoire with abiotic reactions 2,3 . For example, artificial Metalloenzymes, which combine the versatile reaction scope of transition metals with the beneficial catalytic features of enzymes, offer an attractive means to engineer new reactions. Three complementary strategies exist 3 : repurposing natural Metalloenzymes for abiotic transformations 2,4 ; in silico metalloenzyme (re-)design 5–7 ; and incorporation of abiotic cofactors into proteins 8–11 . The third strategy offers the opportunity to design a wide variety of artificial Metalloenzymes for non-natural reactions. However, many metal cofactors are inhibited by cellular components and therefore require purification of the scaffold protein 12–15 . This limits the throughput of genetic optimization schemes applied to artificial Metalloenzymes and their applicability in vivo to expand natural metabolism. Here we report the compartmentalization and in vivo evolution of an artificial metalloenzyme for olefin metathesis, which represents an archetypal organometallic reaction 16–22 without equivalent in nature. Building on previous work 6 on an artificial metallohydrolase, we exploit the periplasm of Escherichia coli as a reaction compartment for the 'metathase' because it offers an auspicious environment for artificial Metalloenzymes, mainly owing to low concentrations of inhibitors such as glutathione, which has recently been identified as a major inhibitor 15 . This strategy facilitated the assembly of a functional metathase in vivo and its directed evolution with substantially increased throughput compared to conventional approaches that rely on purified protein variants. The evolved metathase compares favourably with commercial catalysts, shows activity for different metathesis substrates and can be further evolved in different directions by adjusting the workflow. Our results represent the systematic implementation and evolution of an artificial metalloenzyme that catalyses an abiotic reaction in vivo, with potential applications in, for example, non-natural metabolism. In the past decade, the biotin–streptavidin technology has proven to be versatile for generating artificial Metalloenzymes 12,23–26 . This ver-satility may be traced back to the non-covalent affinity of biotinylated organometallic cofactors for streptavidin (SAV), which ensures their quantitative anchoring in an evolvable protein scaffold. To customize this system for in vivo applications, we designed a strain for periplasmic expression of SAV (SAV peri) in E. coli. The resulting strain revealed good secretion of functional SAV into the periplasm with no detectable contamination in the cytoplasm (Fig. 1b). Staining E. coli cells that harbour SAV peri with Atto-565-biotin yielded a persisting strong fluorescent signal as determined by flow cytometric analysis, whereas the dye-treated strain lacking SAV peri exhibited only low fluorescence (Fig. 1b). These experiments con-firm the biotin-binding activity of SAV peri and suggest that large hydrophobic biotinylated probes (weight-averaged molecular mass of Atto-565-biotin, M w (Atto-565-biotin) = 922 Da) are taken up into the periplasm. Next, we selected a biotinylated Hoveyda–Grubbs second-generation catalyst (biot-Ru hereafter) to complete the holoenzyme (Fig. 1c) 27 . Previous experiments using purified SAV revealed that, upon incorpo-ration within SAV, the biot-Ru–SAV complex catalyses the ring-closing metathesis (RCM) of the umbelliferone precursor 1 to afford umbellif-erone 2. Despite its poor performance as an RCM substrate in water 27 , we hypothesized that the formation of fluorescent umbelliferone 2, albeit in low yield, would offer an attractive means to monitor and evolve catalytic performance in vivo. Spiking an aqueous reaction mix-ture with glutathione (GSH; 10 equiv. versus 50 μ M catalyst) led to complete inhibition of biot-Ru–SAV; no umbelliferone 2 was detected. By contrast, upon addition of glutathione disulfide (GSSG) instead of GSH (10 equiv. versus 50 μ M catalyst), the metathesis activity of biot-Ru–SAV was maintained (Extended Data Table 1). This suggests that the periplasm may indeed offer a suitable environment to harbour the artificial metathase, because GSH is present in this compartment mainly in its oxidized GSSG form. To confirm the assembly of the artificial metalloenzyme biot-Ru– SAV within the periplasm, various E. coli strains were treated with the cofactor biot-Ru. Following incubation and washing, the ruthenium content was quantified by inductively coupled plasma optical emis-sion spectrometry (ICP-OES; Fig. 1c). Although some unspecifically bound ruthenium is present in cells either without SAV at all (SAV −
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Latest Developments in Metalloenzyme Design and Repurposing
European Journal of Inorganic Chemistry, 2015Co-Authors: Tillmann Heinisch, Thomas R. WardAbstract:In the past decade, artificial Metalloenzymes (AMEs) have emerged as attractive alternatives to more traditional homogeneous catalysts and enzymes. This microreview presents a selection of recent achievements in the design of such hybrid catalysts. These include artificial zinc hydrolases and metathesases, the heme-protein repurposing for C–H, N–H, and S–H insertion reactions, novel light-driven redox hybrid catalysts, novel scaffold proteins, and metallocofactor anchoring techniques and metalloenzyme models.
Gerard Roelfes - One of the best experts on this subject based on the ideXlab platform.
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Multidrug resistance regulators (MDRs) as scaffolds for the design of artificial Metalloenzymes
Organic and Biomolecular Chemistry, 2017Co-Authors: Manuela Bersellini, Gerard RoelfesAbstract:The choice of protein scaffolds is an important element in the design of artificial Metalloenzymes. Herein, we introduce Multidrug Resistance Regulators (MDRs) from the TetR family as a viable class of protein scaffolds for artificial metalloenzyme design. In vivo incorporation of the metal binding amino acid (2,2-bipyridin-5yl)alanine (BpyA) by stop codon suppression methods was used to create artificial Metalloenzymes from three members of the TetR family of MDRs: QacR, CgmR and RamR. Excellent results were achieved with QacR Y123BpyA in the Cu2+ catalyzed enantioselective vinylogous Friedel-Crafts alkylation reaction with ee's up to 94% of the opposite enantiomer that was achieved with other mutants and the previously reported LmrR-based artificial Metalloenzymes.
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A metal ion regulated artificial metalloenzyme
Dalton Transactions, 2017Co-Authors: Manuela Bersellini, Gerard RoelfesAbstract:Regulation of enzyme activity is essential in living cells. The rapidly increasing number of designer enzymes with new-to-nature activities makes it necessary to develop novel strategies for controlling their catalytic activity. Here we present the development of a metal ion regulated artificial metalloenzyme created by combining two anchoring strategies, covalent and supramolecular, for introducing a regulatory and a catalytic site, respectively. This artificial metalloenzyme is activated in the presence of Fe2+ ions, but only marginally in the presence of Zn2+.
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supramolecular assembly of artificial Metalloenzymes based on the dimeric protein lmrr as promiscuous scaffold
Journal of the American Chemical Society, 2015Co-Authors: Wesley R Browne, Arnold J M Driessen, Gerard RoelfesAbstract:Supramolecular anchoring of transition metal complexes to a protein scaffold is an attractive approach to the construction of artificial Metalloenzymes since this is conveniently achieved by self-assembly. Here, we report a novel design for supramolecular artificial Metalloenzymes that exploits the promiscuity of the central hydrophobic cavity of the transcription factor Lactococcal multidrug resistance Regulator (LmrR) as a generic binding site for planar coordination complexes that do not provide specific protein binding interactions. The success of this approach is manifested in the excellent enantioselectivities that are achieved in the Cu(II) catalyzed enantioselective Friedel–Crafts alkylation of indoles.
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artificial Metalloenzymes for asymmetric catalysis by creation of novel active sites in protein and dna scaffolds
Israel Journal of Chemistry, 2015Co-Authors: Ivana Drienovska, Gerard RoelfesAbstract:Artificial Metalloenzymes have emerged as a promising new approach to asymmetric catalysis. In our group, we are exploring novel artificial metalloenzyme designs involving creation of a new active site in a protein or DNA scaffold that does not have an existing binding pocket. In this review, we give an overview of the developments in the two approaches to artificial Metalloenzymes for asymmetric catalysis investigated in our group: creation of a novel active site on a peptide or protein dimer interface and using DNA as a scaffold for artificial Metalloenzymes.
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novel artificial Metalloenzymes by in vivo incorporation of metal binding unnatural amino acids
Chemical Science, 2015Co-Authors: Ivana Drienovska, Ana Riozmartinez, Apparao Draksharapu, Gerard RoelfesAbstract:Artificial Metalloenzymes have emerged as an attractive new approach to enantioselective catalysis. Herein, we introduce a novel strategy for preparation of artificial Metalloenzymes utilizing amber stop codon suppression methodology for the in vivo incorporation of metal-binding unnatural amino acids. The resulting artificial Metalloenzymes were applied in catalytic asymmetric Friedel–Crafts alkylation reactions and up to 83% ee for the product was achieved.
Xue Li - One of the best experts on this subject based on the ideXlab platform.
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qm mm x ray refinement of zinc Metalloenzymes
Journal of Inorganic Biochemistry, 2010Co-Authors: Xue Li, Seth A. Hayik, Kenneth M. MerzAbstract:Abstract Zinc Metalloenzymes play an important role in biology. However, due to the limitation of molecular force field energy restraints used in X-ray refinement at medium or low resolutions, the precise geometry of the zinc coordination environment can be difficult to distinguish from ambiguous electron density maps. Due to the difficulties involved in defining accurate force fields for metal ions, the QM/MM (quantum-mechanical/molecular-mechanical) method provides an attractive and more general alternative for the study and refinement of metalloprotein active sites. Herein we present three examples that indicate that QM/MM based refinement yields a superior description of the crystal structure based on R and Rfree values and on the inspection of the zinc coordination environment. It is concluded that QM/MM refinement is an useful general tool for the improvement of the metal coordination sphere in metalloenzyme active sites.
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QM/MM X-ray refinement of zinc Metalloenzymes
2010Co-Authors: Xue Li, Seth A. Hayik, Kenneth M. MerzAbstract:Zinc Metalloenzymes play an important role in biology. However, due to the limitation of molecular force field energy restraints used in X-ray refinement at medium or low resolutions, the precise geometry of the zinc coordination environment can be difficult to distinguish from ambiguous electron density maps. Due to the difficulties involved in defining accurate force fields for metal ions, the QM/MM (quantum-mechanical/molecular-mechanical) method provides an attractive and more general alternative for the study and refinement of metalloprotein active sites. Herein we present three examples that indicate that QM/MM based refinement yields a superior description of the crystal structure based on R and Rfree values and on the inspection of the zinc coordination environment. It is concluded that QM/MM refinement is an useful general tool for the improvement of the metal coordination sphere in metalloenzyme active sites. ?? 2010 Elsevier Inc.