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Zhang Z, Feng J, Yang C, Cui H, Harrison W, Zhong D, Wang B, Zhao H. Photoenzymatic Enantioselective Intermolecular Radical Hydroamination. Nat Catal 2023; 6:687-694. [PMID: 38501052 PMCID: PMC10948044 DOI: 10.1038/s41929-023-00994-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 06/30/2023] [Indexed: 03/20/2024]
Abstract
Since the discovery of Hofmann-Löffler-Freytag reaction more than 130 years ago, nitrogen-centered radicals have been widely studied in both structures and reactivities1-2. Nevertheless, catalytic enantioselective intermolecular radical hydroamination remains a challenge due to the existence of side reactions, short lifetime of nitrogen-centered radicals, and lack of understanding of the fundamental catalytic steps. In chemistry, nitrogen-centered radicals are produced with radical initiators, photocatalysts, or electrocatalysts. On the other hand, the generation and reaction of nitrogen-centered radicals are unknown in nature. Here we report a pure biocatalytic system by successfully repurposing an ene-reductase through directed evolution for the photoenzymatic production of nitrogen-centered radicals and enantioselective intermolecular radical hydroaminations. These reactions progress efficiently at room temperature under visible light without any external photocatalysts and exhibit excellent enantioselectivities. Detailed mechanistic study reveals that the enantioselectivity originates from the radical-addition step while the reactivity originates from the ultrafast photoinduced electron transfer (ET) from reduced flavin mononucleotide (FMNH-) to nitrogen-containing substrates.
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Affiliation(s)
- Zhengyi Zhang
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- These authors contributed equally
| | - Jianqiang Feng
- State Key Laboratory Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
- These authors contributed equally
| | - Chao Yang
- Department of Physics, Programs of Biophysics, Chemical Physics and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Haiyang Cui
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- NSF Molecular Maker Lab Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Wesley Harrison
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Dongping Zhong
- Department of Physics, Programs of Biophysics, Chemical Physics and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
- Department of Chemistry and Biochemistry, Programs of Biophysics, Chemical Physics and Biochemistry, The Ohio State University, Columbus, OH 43210, USA
| | - Binju Wang
- State Key Laboratory Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, P. R. China
| | - Huimin Zhao
- DOE Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- Carl Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
- NSF Molecular Maker Lab Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Zhuang B, Liebl U, Vos MH. Flavoprotein Photochemistry: Fundamental Processes and Photocatalytic Perspectives. J Phys Chem B 2022; 126:3199-3207. [PMID: 35442696 DOI: 10.1021/acs.jpcb.2c00969] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Flavins are highly versatile redox-active and colored cofactors in a large variety of proteins. These do include photoenzymes and photoreceptors, although the vast majority performs non-light-driven physiological functions. Nevertheless, electron transfer between flavins and specific nearby amino acid residues (in particular tyrosine, tryptophan, and presumably histidine and arginine) takes place upon excitation of flavin in many flavoproteins. For oxidized flavoproteins these reactions potentially have a photoprotective role. In this Perspective, we outline work on the characterization of early reaction intermediates not only in the relatively well-studied resting oxidized forms but also in the fully reduced and the intrinsically unstable semireduced forms, where ultrafast photooxidation of flavin was recently demonstrated. Along different lines, flavoprotein-based novel photocatalysts for biotechnological applications are presently emerging, employing both substrate photooxidation and photoreduction strategies. Deep insight into the fundamental flavin photochemical reactions may help in guiding and optimizing their development and in the exploration of novel photocatalytic approaches.
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Affiliation(s)
- Bo Zhuang
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau Cedex, France
| | - Ursula Liebl
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau Cedex, France
| | - Marten H Vos
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau Cedex, France
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Nicholls BT, Oblinsky DG, Kurtoic SI, Grosheva D, Ye Y, Scholes GD, Hyster TK. Engineering a Non‐Natural Photoenzyme for Improved Photon Efficiency**. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202113842] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Bryce T. Nicholls
- Department of Chemistry and Chemical Biology Cornell University Ithaca NY 14853 USA
- Department of Chemistry Princeton University Princeton NJ 08544 USA
| | | | - Sarah I. Kurtoic
- Department of Chemistry Princeton University Princeton NJ 08544 USA
| | - Daria Grosheva
- Department of Chemistry Princeton University Princeton NJ 08544 USA
| | - Yuxuan Ye
- Department of Chemistry and Chemical Biology Cornell University Ithaca NY 14853 USA
| | | | - Todd K. Hyster
- Department of Chemistry and Chemical Biology Cornell University Ithaca NY 14853 USA
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Nicholls BT, Oblinsky DG, Kurtoic SI, Grosheva D, Ye Y, Scholes GD, Hyster TK. Engineering a Non-Natural Photoenzyme for Improved Photon Efficiency. Angew Chem Int Ed Engl 2022; 61:e202113842. [PMID: 34739168 DOI: 10.1002/anie.202113842] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Indexed: 11/08/2022]
Abstract
Photoenzymes are biological catalysts that use light to convert starting materials into products. These catalysts require photon absorption for each turnover, making quantum efficiency an important optimization parameter. Flavin-dependent "ene"-reductases (EREDs) display latent photoenzymatic activity for synthetically valuable hydroalkylations; however, protein engineering has not been used to optimize this non-natural function. We describe a protein engineering platform for the high throughput optimization of photoenzymes. A single round of engineering results in improved catalytic function toward the synthesis of γ, δ, ϵ-lactams, and acyclic amides. Mechanistic studies show that key mutations can alter the enzyme's excited state dynamics, enhance its photon efficiency, and ultimately increase catalyst performance. Transient absorption spectroscopy reveals that engineered variants display dramatically decreased radical lifetimes, indicating an evolution toward a concerted mechanism.
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Affiliation(s)
- Bryce T Nicholls
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Daniel G Oblinsky
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Sarah I Kurtoic
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Daria Grosheva
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Yuxuan Ye
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Gregory D Scholes
- Department of Chemistry, Princeton University, Princeton, NJ, 08544, USA
| | - Todd K Hyster
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
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Meech S. Virtual Issue on Ultrafast Spectroscopy. J Phys Chem B 2021; 125:6037-6039. [PMID: 34134490 DOI: 10.1021/acs.jpcb.1c04148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Steve Meech
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, U.K
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