1
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Yu K, Ward TR. C-H functionalization reactions catalyzed by artificial metalloenzymes. J Inorg Biochem 2024; 258:112621. [PMID: 38852295 DOI: 10.1016/j.jinorgbio.2024.112621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 05/23/2024] [Accepted: 05/25/2024] [Indexed: 06/11/2024]
Abstract
CH functionalization, a promising frontier in modern organic chemistry, facilitates the direct conversion of inert CH bonds into many valuable functional groups. Despite its merits, traditional homogeneous catalysis, often faces challenges in efficiency, selectivity, and sustainability towards this transformation. In this context, artificial metalloenzymes (ArMs), resulting from the incorporation of a catalytically-competent metal cofactor within an evolvable protein scaffold, bridges the gap between the efficiency of enzymatic transformations and the versatility of transition metal catalysis. Accordingly, ArMs have emerged as attractive tools for various challenging catalytic transformations. Additionally, the coming of age of directed evolution has unlocked unprecedented avenues for optimizing enzymatic catalysis. Taking advantage of their genetically-encoded protein scaffold, ArMs have been evolved to catalyze various CH functionalization reactions. This review delves into the recent developments of ArM-catalyzed CH functionalization reactions, highlighting the benefits of engineering the second coordination sphere around a metal cofactor within a host protein.
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Affiliation(s)
- Kun Yu
- Department of Chemistry, University of Basel, Mattenstrasse 22, Basel CH-4058, Switzerland
| | - Thomas R Ward
- Department of Chemistry, University of Basel, Mattenstrasse 22, Basel CH-4058, Switzerland.
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2
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Jain S, Ospina F, Hammer SC. A New Age of Biocatalysis Enabled by Generic Activation Modes. JACS AU 2024; 4:2068-2080. [PMID: 38938808 PMCID: PMC11200230 DOI: 10.1021/jacsau.4c00247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 06/29/2024]
Abstract
Biocatalysis is currently undergoing a profound transformation. The field moves from relying on nature's chemical logic to a discipline that exploits generic activation modes, allowing for novel biocatalytic reactions and, in many instances, entirely new chemistry. Generic activation modes enable a wide range of reaction types and played a pivotal role in advancing the fields of organo- and photocatalysis. This perspective aims to summarize the principal activation modes harnessed in enzymes to develop new biocatalysts. Although extensively researched in the past, the highlighted activation modes, when applied within enzyme active sites, facilitate chemical transformations that have largely eluded efficient and selective catalysis. This advance is attributed to multiple tunable interactions in the substrate binding pocket that precisely control competing reaction pathways and transition states. We will highlight cases of new synthetic methodologies achieved by engineered enzymes and will provide insights into potential future developments in this rapidly evolving field.
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Affiliation(s)
| | | | - Stephan C. Hammer
- Research Group for Organic Chemistry
and Biocatalysis, Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615 Bielefeld, Germany
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3
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Schülke KH, Fröse JS, Klein A, Garcia-Borràs M, Hammer SC. Efficient Transferase Engineering for SAM Analog Synthesis from Iodoalkanes. Chembiochem 2024; 25:e202400079. [PMID: 38477872 DOI: 10.1002/cbic.202400079] [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: 01/29/2024] [Revised: 03/12/2024] [Accepted: 03/13/2024] [Indexed: 03/14/2024]
Abstract
S-Adenosyl-l-methionine (SAM) is an important cosubstrate in various biochemical processes, including selective methyl transfer reactions. Simple methods for the (re)generation of SAM analogs could expand the chemistry accessible with SAM-dependent transferases and go beyond methylation reactions. Here we present an efficient enzyme engineering strategy to synthesize different SAM analogs from "off-the-shelf" iodoalkanes through enzymatic alkylation of S-adenosyl-l-homocysteine (SAH). This was achieved by mutating multiple hydrophobic and structurally dynamic amino acids simultaneously. Combinatorial mutagenesis was guided by the natural amino acid diversity and generated a highly functional mutant library. This approach increased the speed as well as the scale of enzyme engineering by providing a panel of optimized enzymes with orders of magnitude higher activities for multiple substrates in just one round of enzyme engineering. The optimized enzymes exhibit catalytic efficiencies up to 31 M-1 s-1, convert various iodoalkanes, including substrates bearing cyclopropyl or aromatic moieties, and catalyze S-alkylation of SAH with very high stereoselectivities (>99 % de). We further report a high throughput chromatographic screening system for reliable and rapid SAM analog analysis. We believe that the methods and enzymes described herein will further advance the field of selective biocatalytic alkylation chemistry by enabling SAM analog regeneration with "off-the-shelf" reagents.
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Affiliation(s)
- Kai H Schülke
- Organic Chemistry and Biocatalysis, Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Jana S Fröse
- Organic Chemistry and Biocatalysis, Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Alina Klein
- Organic Chemistry and Biocatalysis, Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
| | - Marc Garcia-Borràs
- Department Institut de Química Computacional i Catàlisi (IQCC), Departament de Química, Universitat de Girona, 17003, Girona, Catalonia, Spain
| | - Stephan C Hammer
- Organic Chemistry and Biocatalysis, Faculty of Chemistry, Bielefeld University, Universitätsstraße 25, 33615, Bielefeld, Germany
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4
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Fu H, Hyster TK. From Ground-State to Excited-State Activation Modes: Flavin-Dependent "Ene"-Reductases Catalyzed Non-natural Radical Reactions. Acc Chem Res 2024; 57:1446-1457. [PMID: 38603772 DOI: 10.1021/acs.accounts.4c00129] [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] [Indexed: 04/13/2024]
Abstract
Enzymes are desired catalysts for chemical synthesis, because they can be engineered to provide unparalleled levels of efficiency and selectivity. Yet, despite the astonishing array of reactions catalyzed by natural enzymes, many reactivity patterns found in small molecule catalysts have no counterpart in the living world. With a detailed understanding of the mechanisms utilized by small molecule catalysts, we can identify existing enzymes with the potential to catalyze reactions that are currently unknown in nature. Over the past eight years, our group has demonstrated that flavin-dependent "ene"-reductases (EREDs) can catalyze various radical-mediated reactions with unparalleled levels of selectivity, solving long-standing challenges in asymmetric synthesis.This Account presents our development of EREDs as general catalysts for asymmetric radical reactions. While we have developed multiple mechanisms for generating radicals within protein active sites, this account will focus on examples where flavin mononucleotide hydroquinone (FMNhq) serves as an electron transfer radical initiator. While our initial mechanistic hypotheses were rooted in electron-transfer-based radical initiation mechanisms commonly used by synthetic organic chemists, we ultimately uncovered emergent mechanisms of radical initiation that are unique to the protein active site. We will begin by covering intramolecular reactions and discussing how the protein activates the substrate for reduction by altering the redox-potential of alkyl halides and templating the charge transfer complex between the substrate and flavin-cofactor. Protein engineering has been used to modify the fundamental photophysics of these reactions, highlighting the opportunity to tune these systems further by using directed evolution. This section highlights the range of coupling partners and radical termination mechanisms available to intramolecular reactions.The next section will focus on intermolecular reactions and the role of enzyme-templated ternary charge transfer complexes among the cofactor, alkyl halide, and coupling partner in gating electron transfer to ensure that it only occurs when both substrates are bound within the protein active site. We will highlight the synthetic applications available to this activation mode, including olefin hydroalkylation, carbohydroxylation, arene functionalization, and nitronate alkylation. This section also discusses how the protein can favor mechanistic steps that are elusive in solution for the asymmetric reductive coupling of alkyl halides and nitroalkanes. We are aware of several recent EREDs-catalyzed photoenzymatic transformations from other groups. We will discuss results from these papers in the context of understanding the nuances of radical initiation with various substrates.These biocatalytic asymmetric radical reactions often complement the state-of-the-art small-molecule-catalyzed reactions, making EREDs a valuable addition to a chemist's synthetic toolbox. Moreover, the underlying principles studied with these systems are potentially operative with other cofactor-dependent proteins, opening the door to different types of enzyme-catalyzed radical reactions. We anticipate that this Account will serve as a guide and inspire broad interest in repurposing existing enzymes to access new transformations.
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Affiliation(s)
- Haigen Fu
- NHC Key Laboratory of Biotechnology for Microbial Drugs, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, China
| | - Todd K Hyster
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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5
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Ju S, Li D, Mai BK, Liu X, Vallota-Eastman A, Wu J, Valentine DL, Liu P, Yang Y. Stereodivergent photobiocatalytic radical cyclization through the repurposing and directed evolution of fatty acid photodecarboxylases. Nat Chem 2024:10.1038/s41557-024-01494-0. [PMID: 38632367 DOI: 10.1038/s41557-024-01494-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 02/28/2024] [Indexed: 04/19/2024]
Abstract
Despite their intriguing photophysical and photochemical activities, naturally occurring photoenzymes have not yet been repurposed for new-to-nature activities. Here we engineered fatty acid photodecarboxylases to catalyse unnatural photoredox radical C-C bond formation by leveraging the strongly oxidizing excited-state flavoquinone cofactor. Through genome mining, rational engineering and directed evolution, we developed a panel of radical photocyclases to facilitate decarboxylative radical cyclization with excellent chemo-, enantio- and diastereoselectivities. Our high-throughput experimental workflow allowed for the directed evolution of fatty acid photodecarboxylases. An orthogonal set of radical photocyclases was engineered to access all four possible stereoisomers of the stereochemical dyad, affording fully diastereo- and enantiodivergent biotransformations in asymmetric radical biocatalysis. Molecular dynamics simulations show that our evolved radical photocyclases allow near-attack conformations to be easily accessed, enabling chemoselective radical cyclization. The development of stereoselective radical photocyclases provides unnatural C-C-bond-forming activities in natural photoenzyme families, which can be used to tame the stereochemistry of free-radical-mediated reactions.
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Affiliation(s)
- Shuyun Ju
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Dian Li
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Binh Khanh Mai
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xin Liu
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - Alec Vallota-Eastman
- Interdepartmental Graduate Program for Marine Science, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Jianping Wu
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
| | - David L Valentine
- Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, USA
- Department of Earth Science, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, USA.
| | - Yang Yang
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA.
- Biomolecular Science and Engineering (BMSE) Program, University of California Santa Barbara, Santa Barbara, CA, USA.
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6
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Zhao Q, Chen Z, Rui J, Huang X. Radical fluorine transfer catalysed by an engineered nonheme iron enzyme. Methods Enzymol 2024; 696:231-247. [PMID: 38658081 PMCID: PMC11232670 DOI: 10.1016/bs.mie.2024.03.004] [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] [Indexed: 04/26/2024]
Abstract
Nonheme iron enzymes stand out as one of the most versatile biocatalysts for molecular functionalization. They facilitate a wide array of chemical transformations within biological processes, including hydroxylation, chlorination, epimerization, desaturation, cyclization, and more. Beyond their native biological functions, these enzymes possess substantial potential as powerful biocatalytic platforms for achieving abiological metal-catalyzed reactions, owing to their functional and structural diversity and high evolvability. To this end, our group has recently engineered a series of nonheme iron enzymes to employ non-natural radical-relay mechanisms for abiological radical transformations not previously known in biology. Notably, we have demonstrated that a nonheme iron enzyme, (S)-2-hydroxypropylphosphonate epoxidase from Streptomyces viridochromogenes (SvHppE), can be repurposed into an efficient and selective biocatalyst for radical fluorine transfer reactions. This marks the first known instance of a redox enzymatic process for C(sp3)F bond formation. This chapter outlines the detailed experimental protocol for engineering SvHPPE for fluorination reactions. Furthermore, the provided protocol could serve as a general guideline that might facilitate other engineering endeavors targeting nonheme iron enzymes for novel catalytic functions.
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Affiliation(s)
- Qun Zhao
- School of Biotechnology, Jiangnan University, Wuxi, P.R. China.
| | - Zhenhong Chen
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, United States
| | - Jinyan Rui
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, United States
| | - Xiongyi Huang
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, United States.
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7
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Hooson JF, Tran HN, Bian KJ, West JG. Simple, catalytic C(sp 3)-H azidation using the C-H donor as the limiting reagent. Chem Commun (Camb) 2024. [PMID: 38477139 DOI: 10.1039/d3cc04728h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
C-N bonds play a critical role in pharmaceutical, agrochemical, and materials sciences, necessitating ever-better methods to forge this linkage. Here we report a simple procedure for direct C(sp3)-H azidation using iron or manganese catalysis and a nucleophilic azide source. All reagents are commercially available, the experimental procedure is simple, and we can use the C-H donor substrate as the limiting reagent, a challenge for many C-H azidation methods. Preliminary experiments are consistent with a hydrogen atom transfer (HAT)/radical ligand transfer (RLT) radical cascade mechanism and a wide variety of substrates can be azidated in moderate to high yields.
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Affiliation(s)
- James F Hooson
- Department of Chemistry, Rice University, 6500 Main St, Houston, TX, USA.
| | - Hai N Tran
- Department of Chemistry, Rice University, 6500 Main St, Houston, TX, USA.
| | - Kang-Jie Bian
- Department of Chemistry, Rice University, 6500 Main St, Houston, TX, USA.
| | - Julian G West
- Department of Chemistry, Rice University, 6500 Main St, Houston, TX, USA.
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8
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Yin HN, Wang PC, Liu Z. Recent advances in biocatalytic C-N bond-forming reactions. Bioorg Chem 2024; 144:107108. [PMID: 38244379 DOI: 10.1016/j.bioorg.2024.107108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/25/2023] [Accepted: 01/06/2024] [Indexed: 01/22/2024]
Abstract
Molecules containing C-N bonds are of paramount importance in a diverse array of organic-based materials, natural products, pharmaceutical compounds, and agricultural chemicals. Biocatalytic C-N bond-forming reactions represent powerful strategies for producing these valuable targets, and their significance in the field of synthetic chemistry has steadily increased over the past decade. In this review, we provide a concise overview of recent advancements in the development of C-N bond-forming enzymes, with a particular emphasis on the inherent chemistry involved in these enzymatic processes. Overall, these enzymatic systems have proven their potential in addressing long-standing challenges in traditional small-molecule catalysis.
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Affiliation(s)
- Hong-Ning Yin
- National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China
| | - Peng-Cheng Wang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Zhen Liu
- National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China.
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9
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Hopiavuori A, McKinnie SMK. Algal Kainoid Synthases Exhibit Substrate-Dependent Hydroxylation and Cyclization Activities. ACS Chem Biol 2023; 18:2457-2463. [PMID: 38047879 PMCID: PMC10728896 DOI: 10.1021/acschembio.3c00596] [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: 09/26/2023] [Revised: 11/28/2023] [Accepted: 11/29/2023] [Indexed: 12/05/2023]
Abstract
FeII/α-ketoglutarate-dependent dioxygenases (Fe/αKG) make up a large enzyme family that functionalize C-H bonds on diverse organic substrates. Although Fe/αKG homologues catalyze an array of chemically useful reactions, hydroxylation typically predominates. Microalgal DabC uniquely forms a novel C-C bond to construct the bioactive pyrrolidine ring in domoic acid biosynthesis; however, we have identified that this kainoid synthase exclusively performs a stereospecific hydroxylation reaction on its cis substrate regioisomer. Mechanistic and kinetic analyses with native and alternative substrates identified a 20-fold rate increase in DabC radical cyclization over β-hydroxylation with no observable 1,5-hydrogen atom transfer. Moreover, this dual activity was conserved among macroalgal RadC1 and KabC homologues and provided insight into substrate recognition and reactivity trends. Investigation of this substrate-dependent chemistry improves our understanding of kainoid synthases and their biocatalytic application.
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Affiliation(s)
- Austin
R. Hopiavuori
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
| | - Shaun M. K. McKinnie
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, California 95064, United States
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10
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Boucher DG, Carroll E, Nguyen ZA, Jadhav RG, Simoska O, Beaver K, Minteer SD. Bioelectrocatalytic Synthesis: Concepts and Applications. Angew Chem Int Ed Engl 2023; 62:e202307780. [PMID: 37428529 DOI: 10.1002/anie.202307780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/08/2023] [Accepted: 07/10/2023] [Indexed: 07/11/2023]
Abstract
Bioelectrocatalytic synthesis is the conversion of electrical energy into value-added products using biocatalysts. These methods merge the specificity and selectivity of biocatalysis and energy-related electrocatalysis to address challenges in the sustainable synthesis of pharmaceuticals, commodity chemicals, fuels, feedstocks and fertilizers. However, the specialized experimental setups and domain knowledge for bioelectrocatalysis pose a significant barrier to adoption. This review introduces key concepts of bioelectrosynthetic systems. We provide a tutorial on the methods of biocatalyst utilization, the setup of bioelectrosynthetic cells, and the analytical methods for assessing bioelectrocatalysts. Key applications of bioelectrosynthesis in ammonia production and small-molecule synthesis are outlined for both enzymatic and microbial systems. This review serves as a necessary introduction and resource for the non-specialist interested in bioelectrosynthetic research.
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Affiliation(s)
- Dylan G Boucher
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Emily Carroll
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Zachary A Nguyen
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Rohit G Jadhav
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Olja Simoska
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
| | - Kevin Beaver
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Shelley D Minteer
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
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11
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Yadav V, Wen L, Yadav S, Siegler MA, Goldberg DP. Selective Radical Transfer in a Series of Nonheme Iron(III) Complexes. Inorg Chem 2023; 62:17830-17842. [PMID: 37857315 DOI: 10.1021/acs.inorgchem.3c02617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
A series of nonheme iron complexes, FeIII(BNPAPh2O)(Lax)(Leq) (Lax/eq = N3-, NCS-, NCO-, and Cl-) have been synthesized using the previously reported BNPAPh2O- ligand. The ferrous analogs FeII(BNPAPh2O)(Lax) (Lax = N3-, NCS-, and NCO-) were also prepared. The complexes were structurally characterized using single crystal X-ray diffraction, which shows that all the FeIII complexes are six-coordinate, with one anionic ligand (Lax) in the H-bonding axial site and the other anionic ligand (Leq) in the equatorial plane, cis to the Lax ligand. The reaction of FeIII(BNPAPh2O-)(Lax)(Leq) with Ph3C• shows that one ligand is selectively transferred in each case. A selectivity trend emerges that shows •N3 is the most favored for transfer in each case to the carbon radical, whereas Cl• is the least favored. The NCO and NCS ligands showed an intermediate propensity for radical transfer, with NCS > NCO. The overall order of selectivity is N3 > NCS > NCO > Cl. In addition, we also demonstrated that H-bonding has a small effect on governing product selectivity by using a non-H-bonded ligand (DPAPh2O-). This study demonstrates the inherent radical transfer selectivity of nonhydroxo-ligated nonheme iron(III) complexes, which could be useful for efforts in synthetic and (bio)catalytic C-H functionalization.
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Affiliation(s)
- Vishal Yadav
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Lyupeng Wen
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Sudha Yadav
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - David P Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
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12
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Abstract
The ability to site-selectively modify equivalent functional groups in a molecule has the potential to streamline syntheses and increase product yields by lowering step counts. Enzymes catalyze site-selective transformations throughout primary and secondary metabolism, but leveraging this capability for non-native substrates and reactions requires a detailed understanding of the potential and limitations of enzyme catalysis and how these bounds can be extended by protein engineering. In this review, we discuss representative examples of site-selective enzyme catalysis involving functional group manipulation and C-H bond functionalization. We include illustrative examples of native catalysis, but our focus is on cases involving non-native substrates and reactions often using engineered enzymes. We then discuss the use of these enzymes for chemoenzymatic transformations and target-oriented synthesis and conclude with a survey of tools and techniques that could expand the scope of non-native site-selective enzyme catalysis.
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Affiliation(s)
- Dibyendu Mondal
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Harrison M Snodgrass
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Christian A Gomez
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
| | - Jared C Lewis
- Department of Chemistry, Indiana University, Bloomington, Indiana 47405, United States
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13
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Mao Y, Zhang W, Fu Z, Liu Y, Chen L, Lian X, Zhuo D, Wu J, Zheng M, Liao C. Versatile Biocatalytic C(sp 3 )-H Oxyfunctionalization for the Site- Selective and Stereodivergent Synthesis of α- and β-Hydroxy Acids. Angew Chem Int Ed Engl 2023; 62:e202305250. [PMID: 37340543 DOI: 10.1002/anie.202305250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/03/2023] [Accepted: 06/20/2023] [Indexed: 06/22/2023]
Abstract
C(sp3 )-H oxyfunctionalization, the insertion of an O-atom into C(sp3 )-H bonds, streamlines the synthesis of complex molecules from easily accessible precursors and represents one of the most challenging tasks in organic chemistry with regard to site and stereoselectivity. Biocatalytic C(sp3 )-H oxyfunctionalization has the potential to overcome limitations inherent to small-molecule-mediated approaches by delivering catalyst-controlled selectivity. Through enzyme repurposing and activity profiling of natural variants, we have developed a subfamily of α-ketoglutarate-dependent iron dioxygenases that catalyze the site- and stereodivergent oxyfunctionalization of secondary and tertiary C(sp3 )-H bonds, providing concise synthetic routes towards four types of 92 α- and β-hydroxy acids with high efficiency and selectivity. This method provides a biocatalytic approach for the production of valuable but synthetically challenging chiral hydroxy acid building blocks.
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Affiliation(s)
- Yingle Mao
- Chemical Biology Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Science, 201203, Shanghai, China
| | - Weijie Zhang
- School of Pharmaceutical Science, Guangzhou University of Chinese Medicine, 510006, Guangzhou, China
| | - Zunyun Fu
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 201203, Shanghai, China
| | - Yanqiong Liu
- Chemical Biology Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Science, 201203, Shanghai, China
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, 210023, Nanjing, China
| | - Lin Chen
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 201203, Shanghai, China
| | - Xin Lian
- School of Pharmaceutical Science, Guangzhou University of Chinese Medicine, 510006, Guangzhou, China
| | - Dan Zhuo
- Chemical Biology Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Science, 201203, Shanghai, China
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, 210023, Nanjing, China
| | - Jiewei Wu
- School of Pharmaceutical Science, Guangzhou University of Chinese Medicine, 510006, Guangzhou, China
| | - Mingyue Zheng
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 201203, Shanghai, China
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, 210023, Nanjing, China
| | - Cangsong Liao
- Chemical Biology Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Science, 201203, Shanghai, China
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, 210023, Nanjing, China
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14
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Ouyang Y, Turek-Herman J, Qiao T, Hyster TK. Asymmetric Carbohydroxylation of Alkenes Using Photoenzymatic Catalysis. J Am Chem Soc 2023; 145:17018-17022. [PMID: 37498747 PMCID: PMC10875682 DOI: 10.1021/jacs.3c06618] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Alkene difunctionalizations enable the synthesis of structurally elaborated products from simple and ubiquitous starting materials in a single chemical step. Carbohydroxylations of olefins represent a family of reactivity that furnish structurally complex alcohols. While examples of this type of three-component coupling have been reported, catalytic asymmetric examples remain elusive. Here, we report an enzyme-catalyzed asymmetric carbohydroxylation of alkenes catalyzed by flavin-dependent "ene"-reductases to produce enantioenriched tertiary alcohols. Seven rounds of protein engineering reshape the enzyme's active site to increase activity and enantioselectivity. Mechanistic studies suggest that C-O bond formation occurs via a 5-endo-trig cyclization with the pendant ketone to afford an α-oxy radical which is oxidized and hydrolyzed to form the product. This work demonstrates photoenzymatic reactions involving "ene"-reductases can terminate radicals via mechanisms other than hydrogen atom transfer, expanding their utility in chemical synthesis.
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Affiliation(s)
- Yao Ouyang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Joshua Turek-Herman
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Tianzhang Qiao
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Todd K. Hyster
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
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15
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Cheng L, Li D, Mai BK, Bo Z, Cheng L, Liu P, Yang Y. Stereoselective amino acid synthesis by synergistic photoredox-pyridoxal radical biocatalysis. Science 2023; 381:444-451. [PMID: 37499030 PMCID: PMC10444520 DOI: 10.1126/science.adg2420] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Accepted: 06/20/2023] [Indexed: 07/29/2023]
Abstract
Developing synthetically useful enzymatic reactions that are not known in biochemistry and organic chemistry is an important challenge in biocatalysis. Through the synergistic merger of photoredox catalysis and pyridoxal 5'-phosphate (PLP) biocatalysis, we developed a pyridoxal radical biocatalysis approach to prepare valuable noncanonical amino acids, including those bearing a stereochemical dyad or triad, without the need for protecting groups. Using engineered PLP enzymes, either enantiomeric product could be produced in a biocatalyst-controlled fashion. Synergistic photoredox-pyridoxal radical biocatalysis represents a powerful platform with which to discover previously unknown catalytic reactions and to tame radical intermediates for asymmetric catalysis.
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Affiliation(s)
- Lei Cheng
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Dian Li
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Binh Khanh Mai
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Zhiyu Bo
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Lida Cheng
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Yang Yang
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
- Biomolecular Science and Engineering (BMSE) Program, University of California Santa Barbara, Santa Barbara, California 93106, USA
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16
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Fu W, Neris NM, Fu Y, Zhao Y, Krohn-Hansen B, Liu P, Yang Y. Enzyme-controlled stereoselective radical cyclization to arenes enabled by metalloredox biocatalysis. Nat Catal 2023; 6:628-636. [PMID: 38404758 PMCID: PMC10882986 DOI: 10.1038/s41929-023-00986-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 06/13/2023] [Indexed: 02/27/2024]
Abstract
The effective induction of high levels of stereocontrol for free radical-mediated transformations represents a notorious challenge in asymmetric catalysis. Herein, we describe a novel metalloredox biocatalysis strategy to repurpose natural cytochromes P450 to catalyse asymmetric radical cyclisation to arenes through an unnatural electron transfer mechanism. Empowered by directed evolution, engineered P450s allowed diverse radical cyclisation selectivities to be accomplished in a catalyst-controlled fashion: P450arc1 and P450arc2 facilitated enantioconvergent transformations of racemic substrates, giving rise to either enantiomer of the product with excellent total turnover numbers (up to 12,000). In addition to these enantioconvergent variants, another engineered radical cyclase, P450arc3, permitted efficient kinetic resolution of racemic chloride substrates (S factor = 18). Furthermore, computational studies revealed a proton-coupled electron transfer (PCET) mechanism for the radical-polar crossover step, suggesting the potential role of the haem carboxylate as a base catalyst. Collectively, the excellent tunability of this metalloenzyme family provides an exciting platform for harnessing free radical intermediates for asymmetric catalysis.
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Affiliation(s)
- Wenzhen Fu
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
| | - Natalia M. Neris
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
| | - Yue Fu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Yunlong Zhao
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
| | - Benjamin Krohn-Hansen
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
| | - Peng Liu
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
| | - Yang Yang
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA
- Biomolecular Science and Engineering (BMSE) Program, University of California, Santa Barbara, California 93106, USA
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17
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Kao SC, Bian KJ, Chen XW, Chen Y, Martí AA, West JG. Photochemical iron-catalyzed decarboxylative azidation via the merger of ligand-to-metal charge transfer and radical ligand transfer catalysis. CHEM CATALYSIS 2023; 3:100603. [PMID: 37720729 PMCID: PMC10501478 DOI: 10.1016/j.checat.2023.100603] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/19/2023]
Abstract
Ligand-to-metal charge transfer (LMCT) using stoichiometric copper salts has recently been shown to permit decarboxylative C-N bond formation via an LMCT/radical polar crossover (RPC) mechanism; however, this method is unable to function catalytically and cannot successfully engage unactivated alkyl carboxylic acids, presenting challenges to the general applicability of this approach. Leveraging the concepts of ligand-to-metal charge transfer (LMCT) and radical-ligand-transfer (RLT), we herein report the first photochemical, iron-catalyzed direct decarboxylative azidation. Simply irradiating an inexpensive iron nitrate catalyst in the presence of azidotrimethylsilane allows for a diverse array of carboxylic acids to be converted to corresponding organic azides directly with broad functional group tolerance and mild conditions. Intriguingly, no additional external oxidant is required for this reaction to proceed, simplifying the reaction protocol. Finally, mechanistic studies are consistent with a radical mechanism and suggest that the nitrate counteranion serves as an internal oxidant for turnover of the iron catalyst.
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Affiliation(s)
- Shih-Chieh Kao
- Department of Chemistry, Rice University, Houston, TX, USA
| | - Kang-Jie Bian
- Department of Chemistry, Rice University, Houston, TX, USA
| | - Xiao-Wei Chen
- Department of Chemistry, Rice University, Houston, TX, USA
| | - Ying Chen
- Department of Chemistry, Rice University, Houston, TX, USA
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, USA
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Angel A. Martí
- Department of Chemistry, Rice University, Houston, TX, USA
- Department of Materials Science and Nanoengineering, Rice University, Houston, TX, USA
- Department of Bioengineering, Rice University, Houston, TX, USA
| | - Julian G. West
- Department of Chemistry, Rice University, Houston, TX, USA
- Lead contact
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18
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Gomez CA, Mondal D, Du Q, Chan N, Lewis JC. Directed Evolution of an Iron(II)- and α-Ketoglutarate-Dependent Dioxygenase for Site-Selective Azidation of Unactivated Aliphatic C-H Bonds. Angew Chem Int Ed Engl 2023; 62:e202301370. [PMID: 36757808 PMCID: PMC10050089 DOI: 10.1002/anie.202301370] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/08/2023] [Accepted: 02/09/2023] [Indexed: 02/10/2023]
Abstract
FeII - and α-ketoglutarate-dependent halogenases and oxygenases can catalyze site-selective functionalization of C-H bonds via a variety of C-X bond forming reactions, but achieving high chemoselectivity for functionalization using non-native functional groups remains rare. The current study shows that directed evolution can be used to engineer variants of the dioxygenase SadX that address this challenge. Site-selective azidation of succinylated amino acids and a succinylated amine was achieved as a result of mutations throughout the SadX structure. The installed azide group was reduced to a primary amine, and the succinyl group required for azidation was enzymatically cleaved to provide the corresponding amine. These results provide a promising starting point for evolving additional SadX variants with activity on structurally distinct substrates and for enabling enzymatic C-H functionalization with other non-native functional groups.
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Affiliation(s)
- Christian A Gomez
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Dibyendu Mondal
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
- Kalsec Inc., 3713W. Main St., Kalamazoo, MI 49006, USA
| | - Qian Du
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Natalie Chan
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
| | - Jared C Lewis
- Department of Chemistry, Indiana University, Bloomington, IN 47405, USA
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19
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Guo H, Sun N, Guo J, Zhou TP, Tang L, Zhang W, Deng Y, Liao RZ, Wu Y, Wu G, Zhong F. Expanding the Promiscuity of a Copper-Dependent Oxidase for Enantioselective Cross-Coupling of Indoles. Angew Chem Int Ed Engl 2023; 62:e202219034. [PMID: 36789864 DOI: 10.1002/anie.202219034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2022] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 02/16/2023]
Abstract
Herein, we disclose the highly enantioselective oxidative cross-coupling of 3-hydroxyindole esters with various nucleophilic partners as catalyzed by copper efflux oxidase. The biocatalytic transformation delivers functionalized 2,2-disubstituted indolin-3-ones with excellent optical purity (90-99 % ee), which exhibited anticancer activity against MCF-7 cell lines, as shown by preliminary biological evaluation. Mechanistic studies and molecular docking results suggest the formation of a phenoxyl radical and enantiocontrol facilitated by a suited enzyme chiral pocket. This study is significant with regard to expanding the catalytic repertoire of natural multicopper oxidases as well as enlarging the synthetic toolbox for sustainable asymmetric oxidative coupling.
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Affiliation(s)
- Huan Guo
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
| | - Ningning Sun
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
| | - Juan Guo
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
| | - Tai-Ping Zhou
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
| | - Langyu Tang
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
| | - Wentao Zhang
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
| | - Yaming Deng
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
| | - Rong-Zhen Liao
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
| | - Yuzhou Wu
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
| | - Guojiao Wu
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
| | - Fangrui Zhong
- Hubei Engineering Research Center for Biomaterials and Medical Protective Materials, Hubei Key Laboratory of Bioinorganic Chemistry & Materia Medica, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology (HUST), Luoyu Road 1037, Wuhan, 430074, China
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20
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Zhang J, Maggiolo AO, Alfonzo E, Mao R, Porter NJ, Abney N, Arnold FH. Chemodivergent C(sp 3)-H and C(sp 2)-H Cyanomethylation Using Engineered Carbene Transferases. Nat Catal 2023; 6:152-160. [PMID: 36875868 PMCID: PMC9983643 DOI: 10.1038/s41929-022-00908-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 12/09/2022] [Indexed: 01/21/2023]
Abstract
The ubiquity of C-H bonds presents an attractive opportunity to elaborate and build complexity in organic molecules. Methods for selective functionalization, however, often must differentiate among multiple chemically similar and, in some cases indistinguishable, C-H bonds. An advantage of enzymes is that they can be finely tuned using directed evolution to achieve control over divergent C-H functionalization pathways. Here, we demonstrate engineered enzymes that effect a new-to-nature C-H alkylation with unparalleled selectivity: two complementary carbene C-H transferases derived from a cytochrome P450 from Bacillus megaterium deliver an α-cyanocarbene into the α-amino C(sp3)-H bonds or the ortho-arene C(sp2)-H bonds of N-substituted arenes. These two transformations proceed via different mechanisms, yet only minimal changes to the protein scaffold (nine mutations, less than 2% of the sequence) were needed to adjust the enzyme's control over the site-selectivity of cyanomethylation. The X-ray crystal structure of the selective C(sp3)-H alkylase, P411-PFA, reveals an unprecedented helical disruption which alters the shape and electrostatics in the enzyme active site. Overall, this work demonstrates the advantages of enzymes as C-H functionalization catalysts for divergent molecular derivatization.
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Affiliation(s)
- Juner Zhang
- Division of Chemistry and Chemical Engineering, California Institute of Technology; Pasadena, California, United States
| | - Ailiena O. Maggiolo
- Division of Chemistry and Chemical Engineering, California Institute of Technology; Pasadena, California, United States
| | - Edwin Alfonzo
- Division of Chemistry and Chemical Engineering, California Institute of Technology; Pasadena, California, United States
| | - Runze Mao
- Division of Chemistry and Chemical Engineering, California Institute of Technology; Pasadena, California, United States
| | - Nicholas J. Porter
- Division of Chemistry and Chemical Engineering, California Institute of Technology; Pasadena, California, United States
| | - Nayla Abney
- Division of Chemistry and Chemical Engineering, California Institute of Technology; Pasadena, California, United States
- Present address: Department of Bioengineering, Stanford University; Stanford, California, United States
| | - Frances H. Arnold
- Division of Chemistry and Chemical Engineering, California Institute of Technology; Pasadena, California, United States
- Division of Biology and Bioengineering, California Institute of Technology; Pasadena, California, United States
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21
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Duan X, Cui D, Wang Z, Zheng D, Jiang L, Huang WY, Jia YX, Xu J. A Photoenzymatic Strategy for Radical-Mediated Stereoselective Hydroalkylation with Diazo Compounds. Angew Chem Int Ed Engl 2023; 62:e202214135. [PMID: 36478374 DOI: 10.1002/anie.202214135] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022]
Abstract
Carbene insertion reactions initiated with diazo compounds have been widely used to develop unnatural enzymatic reactions. However, alternative functionalization of diazo compounds in enzymatic processes has been unexploited. Herein, we describe a photoenzymatic strategy for radical-mediated stereoselective hydroalkylation with diazo compounds. This method generates carbon-centered radicals through an ene reductase catalyzed photoinduced electron transfer process from diazo compounds, enabling the synthesis of γ-stereogenic carbonyl compounds in good yields and stereoselectivities. This study further expands the possible reaction patterns in photo-biocatalysis and offers a new approach to solving the selectivity challenges of radical-mediated reactions.
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Affiliation(s)
- Xinyu Duan
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China
| | - Dong Cui
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China
| | - Zhiguo Wang
- Institute of Aging Research, School of Basic Medical Sciences, Hangzhou Normal University, Hangzhou, 311121, P. R. China
| | - Dannan Zheng
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China
| | - Linye Jiang
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China
| | - Wen-Yu Huang
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China
| | - Yi-Xia Jia
- College of Chemical Engineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China.,State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, P. R. China
| | - Jian Xu
- College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, 310014, P. R. China
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22
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Fu H, Qiao T, Carceller JM, MacMillan SN, Hyster TK. Asymmetric C-Alkylation of Nitroalkanes via Enzymatic Photoredox Catalysis. J Am Chem Soc 2023; 145:787-793. [PMID: 36608280 DOI: 10.1021/jacs.2c12197] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Tertiary nitroalkanes and the corresponding α-tertiary amines represent important motifs in bioactive molecules and natural products. The C-alkylation of secondary nitroalkanes with electrophiles is a straightforward strategy for constructing tertiary nitroalkanes; however, controlling the stereoselectivity of this type of reaction remains challenging. Here, we report a highly chemo- and stereoselective C-alkylation of nitroalkanes with alkyl halides catalyzed by an engineered flavin-dependent "ene"-reductase (ERED). Directed evolution of the old yellow enzyme from Geobacillus kaustophilus provided a triple mutant, GkOYE-G7, capable of synthesizing tertiary nitroalkanes in high yield and enantioselectivity. Mechanistic studies indicate that the excitation of an enzyme-templated charge-transfer complex formed between the substrates and cofactor is responsible for radical initiation. Moreover, a single-enzyme two-mechanism cascade reaction was developed to prepare tertiary nitroalkanes from simple nitroalkenes, highlighting the potential to use one enzyme for two mechanistically distinct reactions.
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Affiliation(s)
- Haigen Fu
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Tianzhang Qiao
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Jose M Carceller
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States.,Institute of Chemical Technology (ITQ), Universitat Politècnica de València, València 46022, Spain
| | - Samantha N MacMillan
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
| | - Todd K Hyster
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14850, United States
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23
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Fu W, Yang Y. Undirected biocatalytic amination of unactivated C( sp 3)-H bonds. CHEM CATALYSIS 2022; 2:3287-3289. [PMID: 36873821 PMCID: PMC9980284 DOI: 10.1016/j.checat.2022.11.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Selective catalytic functionalization of C(sp 3)-H bonds represents a powerful means to access valuable products from ubiquitous starting materials. In a recent JACS paper, Arnold and co-workers engineered P450 nitrene transferases to aminate unactivated C(sp 3)-H bonds with excellent site- and stereoselectivities.
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Affiliation(s)
- Wenzhen Fu
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA
| | - Yang Yang
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California 93106, USA.,Biomolecular Science and Engineering (BMSE) Program, University of California Santa Barbara, Santa Barbara, California 93106, USA
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24
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Yadav V, Wen L, Rodriguez RJ, Siegler MA, Goldberg DP. Nonheme Iron(III) Azide and Iron(III) Isothiocyanate Complexes: Radical Rebound Reactivity, Selectivity, and Catalysis. J Am Chem Soc 2022; 144:20641-20652. [PMID: 36382466 PMCID: PMC10226418 DOI: 10.1021/jacs.2c07224] [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] [Indexed: 11/06/2022]
Abstract
The new nonheme iron complexes FeII(BNPAPh2O)(N3) (1), FeIII(BNPAPh2O)(OH)(N3) (2), FeII(BNPAPh2O)(OH) (3), FeIII(BNPAPh2O)(OH)(NCS) (4), FeII(BNPAPh2O)(NCS) (5), FeIII(BNPAPh2O)(NCS)2 (6), and FeIII(BNPAPh2O)(N3)2 (7) (BNPAPh2O = 2-(bis((6-(neopentylamino)pyridin-2-yl) methyl)amino)-1,1-diphenylethanolate) were synthesized and characterized by single crystal X-ray diffraction (XRD), as well as by 1H NMR, 57Fe Mössbauer, and ATR-IR spectroscopies. Complex 2 was reacted with a series of carbon radicals, ArX3C· (ArX = p-X-C6H4), analogous to the proposed radical rebound step for nonheme iron hydroxylases and halogenases. The results show that for ArX3C· (X = Cl, H, tBu), only OH· transfer occurs to give ArX3COH. However, when X = OMe, a mixture of alcohol (ArX3COH) (30%) and azide (ArX3CN3) (40%) products was obtained. These data indicate that the rebound selectivity is influenced by the electron-rich nature of the carbon radicals for the azide complex. Reaction of 2 with Ph3C· in the presence of Sc3+ or H+ reverses the selectivity, giving only the azide product. In contrast to the mixed selectivity seen for 2, the reactivity of cis-FeIII(OH)(NCS) with the X = OMe radical derivative leads only to hydroxylation. Catalytic azidation was achieved with 1 as catalyst, λ3-azidoiodane as oxidant and azide source, and Ph3CH as test substrate, giving Ph3CN3 in 84% (TON = 8). These studies show that hydroxylation is favored over azidation for nonheme iron(III) complexes, but the nature of the carbon radical can alter this selectivity. If an OH· transfer pathway can be avoided, the FeIII(N3) complexes are capable of mediating both stoichiometric and catalytic azidation.
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Affiliation(s)
- Vishal Yadav
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - Lyupeng Wen
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - Rodolfo J. Rodriguez
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - Maxime A. Siegler
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
| | - David P. Goldberg
- Department of Chemistry, The Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland, 21218, USA
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