1
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Pan J, Wenger ES, Lin CY, Zhang B, Sil D, Schaperdoth I, Saryazdi S, Grossman RB, Krebs C, Bollinger JM. An Unusual Ferryl Intermediate and Its Implications for the Mechanism of Oxacyclization by the Loline-Producing Iron(II)- and 2-Oxoglutarate-Dependent Oxygenase, LolO. Biochemistry 2024. [PMID: 38898603 DOI: 10.1021/acs.biochem.4c00166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
N-Acetylnorloline synthase (LolO) is one of several iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenases that catalyze sequential reactions of different types in the biosynthesis of valuable natural products. LolO hydroxylates C2 of 1-exo-acetamidopyrrolizidine before coupling the C2-bonded oxygen to C7 to form the tricyclic loline core. Each reaction requires cleavage of a C-H bond by an oxoiron(IV) (ferryl) intermediate; however, different carbons are targeted, and the carbon radicals have different fates. Prior studies indicated that the substrate-cofactor disposition (SCD) controls the site of H· abstraction and can affect the reaction outcome. These indications led us to determine whether a change in SCD from the first to the second LolO reaction might contribute to the observed reactivity switch. Whereas the single ferryl complex in the C2 hydroxylation reaction was previously shown to have typical Mössbauer parameters, one of two ferryl complexes to accumulate during the oxacyclization reaction has the highest isomer shift seen to date for such a complex and abstracts H· from C7 ∼ 20 times faster than does the first ferryl complex in its previously reported off-pathway hydroxylation of C7. The detectable hydroxylation of C7 in competition with cyclization by the second ferryl complex is not enhanced in 2H2O solvent, suggesting that the C2 hydroxyl is deprotonated prior to C7-H cleavage. These observations are consistent with the coordination of the C2 oxygen to the ferryl complex, which may reorient its oxo ligand, the substrate, or both to positions more favorable for C7-H cleavage and oxacyclization.
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Affiliation(s)
- Juan Pan
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Eliott S Wenger
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Chi-Yun Lin
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Bo Zhang
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Debangsu Sil
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Irene Schaperdoth
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Setareh Saryazdi
- Department of Chemistry, The University of Kentucky, Lexington, Kentucky 40506, United States
| | - Robert B Grossman
- Department of Chemistry, The University of Kentucky, Lexington, Kentucky 40506, United States
| | - Carsten Krebs
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - J Martin Bollinger
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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2
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Panth N, Wenger ES, Krebs C, Bollinger JM, Grossman RB. Synthesis of 6,6- and 7,7-difluoro-1-acetamidopyrrolizidines and their oxidation catalyzed by the nonheme Fe oxygenase LolO. Chembiochem 2022; 23:e202200081. [PMID: 35482316 DOI: 10.1002/cbic.202200081] [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: 02/05/2022] [Revised: 03/26/2022] [Indexed: 11/11/2022]
Abstract
LolO, a 2-oxoglutarate-dependent nonheme Fe oxygenase, catalyzes both the hydroxylation and cycloetherification of 1- exo -acetamidopyrrolizidine (AcAP), a pathway intermediate in the biosynthesis of the loline alkaloids. We have prepared fluorinated AcAP analogs to aid in continued mechanistic investigation of the unusual LolO-catalyzed cycloetherification step. LolO was able to first hydroxylate and then cycloetherify 6,6-difluoro-AcAP (prepared from N , O -protected 4-oxoproline), forming a difluorinated analog of N -acetylnorloline (NANL) and providing evidence for a cycloetherification mechanism involving a C(7) radical as opposed to a C(7) carbocation. By contrast, LolO was able to hydroxylate 7,7-difluoro-AcAP (prepared from 3-oxoproline) but failed to cycloetherify it, forming (1 R , 2 R , 8 S )-7,7-difluoro-2-hydroxy-AcAP as the sole product. Because it completely blocks the cycloetherification step, 7,7-difluoro-AcAP has the potential to become an important tool for accumulating and characterizing the LolO intermediate responsible for catalyzing cycloetherification of 2-hydroxy-AcAP.
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Affiliation(s)
- Nabin Panth
- University of Kentucky, Chemistry, UNITED STATES
| | | | - Carsten Krebs
- The Pennsylvania State University, Chemistry; Biochemistry and Molecular Biology, UNITED STATES
| | - J Martin Bollinger
- The Pennsylvania State University, Chemistry; Biochemistry and Molecular Biology, UNITED STATES
| | - Robert B Grossman
- University of Kentucky, Chemistry, Chemistry-Physics Building, 40506-0055, Lexington, UNITED STATES
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3
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Wojdyla Z, Borowski T. Properties of the Reactants and Their Interactions within and with the Enzyme Binding Cavity Determine Reaction Selectivities. The Case of Fe(II)/2-Oxoglutarate Dependent Enzymes. Chemistry 2022; 28:e202104106. [PMID: 34986268 DOI: 10.1002/chem.202104106] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Indexed: 12/12/2022]
Abstract
Fe(II)/2-oxoglutarate dependent dioxygenases (ODDs) share a double stranded beta helix (DSBH) fold and utilise a common reactive intermediate, ferryl species, to catalyse oxidative transformations of substrates. Despite the structural similarities, ODDs accept a variety of substrates and facilitate a wide range of reactions, that is hydroxylations, desaturations, (oxa)cyclisations and ring rearrangements. In this review we present and discuss the factors contributing to the observed (regio)selectivities of ODDs. They span from inherent properties of the reactants, that is, substrate molecule and iron cofactor, to the interactions between the substrate and the enzyme's binding cavity; the latter can counterbalance the effect of the former. Based on results of both experimental and computational studies dedicated to ODDs, we also line out the properties of the reactants which promote reaction outcomes other than the "default" hydroxylation. It turns out that the reaction selectivity depends on a delicate balance of interactions between the components of the investigated system.
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Affiliation(s)
- Zuzanna Wojdyla
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Kraków, Niezapominajek 8, 30239 Krakow, Poland
| | - Tomasz Borowski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Kraków, Niezapominajek 8, 30239 Krakow, Poland
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4
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Ye Y, Fu H, Hyster TK. Activation modes in biocatalytic radical cyclization reactions. J Ind Microbiol Biotechnol 2021; 48:6155068. [PMID: 33674826 PMCID: PMC8210684 DOI: 10.1093/jimb/kuab021] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 02/26/2021] [Indexed: 12/17/2022]
Abstract
Radical cyclizations are essential reactions in the biosynthesis of secondary metabolites and the chemical synthesis of societally valuable molecules. In this review, we highlight the general mechanisms utilized in biocatalytic radical cyclizations. We specifically highlight cytochrome P450 monooxygenases (P450s) involved in the biosynthesis of mycocyclosin and vancomycin, nonheme iron- and α-ketoglutarate-dependent dioxygenases (Fe/αKGDs) used in the biosynthesis of kainic acid, scopolamine, and isopenicillin N, and radical S-adenosylmethionine (SAM) enzymes that facilitate the biosynthesis of oxetanocin A, menaquinone, and F420. Beyond natural mechanisms, we also examine repurposed flavin-dependent “ene”-reductases (ERED) for non-natural radical cyclization. Overall, these general mechanisms underscore the opportunity for enzymes to augment and enhance the synthesis of complex molecules using radical mechanisms.
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Affiliation(s)
- Yuxuan Ye
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Haigen Fu
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
| | - Todd K Hyster
- Department of Chemistry, Princeton University, Princeton, NJ 08544, USA
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5
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Wojdyla Z, Borowski T. Enzyme Multifunctionality by Control of Substrate Positioning Within the Catalytic Cycle—A QM/MM Study of Clavaminic Acid Synthase. Chemistry 2020; 27:2196-2211. [DOI: 10.1002/chem.202004426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Zuzanna Wojdyla
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences Niezapominajek 8 30239 Krakow Poland
| | - Tomasz Borowski
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences Niezapominajek 8 30239 Krakow Poland
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6
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Kluza A, Wojdyla Z, Mrugala B, Kurpiewska K, Porebski PJ, Niedzialkowska E, Minor W, Weiss MS, Borowski T. Regioselectivity of hyoscyamine 6β-hydroxylase-catalysed hydroxylation as revealed by high-resolution structural information and QM/MM calculations. Dalton Trans 2020; 49:4454-4469. [PMID: 32182320 DOI: 10.1039/d0dt00302f] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Hyoscyamine 6β-hydroxylase (H6H) is a bifunctional non-heme 2-oxoglutarate/Fe2+-dependent dioxygenase that catalyzes the two final steps in the biosynthesis of scopolamine. Based on high resolution crystal structures of H6H from Datura metel, detailed information on substrate binding was obtained that provided insights into the onset of the enzymatic process. In particular, the role of two prominent residues was revealed - Glu-116 that interacts with the tertiary amine located on the hyoscyamine tropane moiety and Tyr-326 that forms CH-π hydrogen bonds with the hyoscyamine phenyl ring. The structures were used as the basis for QM/MM calculations that provided an explanation for the regioselectivity of the hydroxylation reaction on the hyoscyamine tropane moiety (C6 vs. C7) and quantified contributions of active site residues to respective barrier heights.
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Affiliation(s)
- Anna Kluza
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
| | - Zuzanna Wojdyla
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
| | - Beata Mrugala
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
| | - Katarzyna Kurpiewska
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland. and Department of Crystal Chemistry and Crystal Physics, Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, PL-30387 Krakow, Poland
| | - Przemyslaw J Porebski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland. and Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue Pinn Hall, Charlottesville, VA 22908, USA
| | - Ewa Niedzialkowska
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland. and Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue Pinn Hall, Charlottesville, VA 22908, USA
| | - Wladek Minor
- Department of Molecular Physiology and Biological Physics, University of Virginia, 1340 Jefferson Park Avenue Pinn Hall, Charlottesville, VA 22908, USA
| | - Manfred S Weiss
- Macromolecular Crystallography, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Str. 15, D-12489, Berlin, Germany
| | - Tomasz Borowski
- Jerzy Haber Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 8, PL-30239 Krakow, Poland.
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7
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Dunham NP, Arnold FH. Nature's Machinery, Repurposed: Expanding the Repertoire of Iron-Dependent Oxygenases. ACS Catal 2020; 10:12239-12255. [PMID: 33282461 PMCID: PMC7710332 DOI: 10.1021/acscatal.0c03606] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Iron is an especially important redox-active cofactor in biology because of its ability to mediate reactions with atmospheric O2. Iron-dependent oxygenases exploit this earth-abundant transition metal for the insertion of oxygen atoms into organic compounds. Throughout the astounding diversity of transformations catalyzed by these enzymes, the protein framework directs reactive intermediates toward the precise formation of products, which, in many cases, necessitates the cleavage of strong C-H bonds. In recent years, members of several iron-dependent oxygenase families have been engineered for new-to-nature transformations that offer advantages over conventional synthetic methods. In this Perspective, we first explore what is known about the reactivity of heme-dependent cytochrome P450 oxygenases and nonheme iron-dependent oxygenases bearing the 2-His-1-carboxylate facial triad by reviewing mechanistic studies with an emphasis on how the protein scaffold maximizes the catalytic potential of the iron-heme and iron cofactors. We then review how these cofactors have been repurposed for abiological transformations by engineering the protein frameworks of these enzymes. Finally, we discuss contemporary challenges associated with engineering these platforms and comment on their roles in biocatalysis moving forward.
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Affiliation(s)
- Noah P. Dunham
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, MC 210-41, Pasadena, California 91125, United States
| | - Frances H. Arnold
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, MC 210-41, Pasadena, California 91125, United States
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8
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Tang S, Zhang X, Sun J, Niu D, Chruma JJ. 2-Azaallyl Anions, 2-Azaallyl Cations, 2-Azaallyl Radicals, and Azomethine Ylides. Chem Rev 2018; 118:10393-10457. [PMID: 30302999 DOI: 10.1021/acs.chemrev.8b00349] [Citation(s) in RCA: 164] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This review covers the use of 2-azaallyl anions, 2-azaallyl cations, and 2-azaallyl radicals in organic synthesis up through June 2018. Particular attention is paid to both foundational studies and recent advances over the past decade involving semistabilized and nonstabilized 2-azaallyl anions as key intermediates in various carbon-carbon and carbon-heteroatom bond-forming processes. Both transition-metal-catalyzed and transition-metal-free transformations are covered. Azomethine ylides, which have received significant attention elsewhere, are discussed briefly with the primary focus on critical comparisons with 2-azaallyl anions in regard to generation and use.
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Affiliation(s)
- Shaojian Tang
- Key Laboratory of Green Chemistry & Technology (MOE), College of Chemistry, Sino-British Materials Research Institute, College of Physical Sciences & Technology, and State Key Laboratory of Biotherapy, West China Hospital , Sichuan University , Chengdu , Sichuan 610064 , People's Republic of China
| | - Xia Zhang
- Key Laboratory of Green Chemistry & Technology (MOE), College of Chemistry, Sino-British Materials Research Institute, College of Physical Sciences & Technology, and State Key Laboratory of Biotherapy, West China Hospital , Sichuan University , Chengdu , Sichuan 610064 , People's Republic of China
| | - Jiayue Sun
- Key Laboratory of Green Chemistry & Technology (MOE), College of Chemistry, Sino-British Materials Research Institute, College of Physical Sciences & Technology, and State Key Laboratory of Biotherapy, West China Hospital , Sichuan University , Chengdu , Sichuan 610064 , People's Republic of China
| | - Dawen Niu
- Key Laboratory of Green Chemistry & Technology (MOE), College of Chemistry, Sino-British Materials Research Institute, College of Physical Sciences & Technology, and State Key Laboratory of Biotherapy, West China Hospital , Sichuan University , Chengdu , Sichuan 610064 , People's Republic of China
| | - Jason J Chruma
- Key Laboratory of Green Chemistry & Technology (MOE), College of Chemistry, Sino-British Materials Research Institute, College of Physical Sciences & Technology, and State Key Laboratory of Biotherapy, West China Hospital , Sichuan University , Chengdu , Sichuan 610064 , People's Republic of China
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9
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Rabe P, Kamps JJAG, Schofield CJ, Lohans CT. Roles of 2-oxoglutarate oxygenases and isopenicillin N synthase in β-lactam biosynthesis. Nat Prod Rep 2018; 35:735-756. [PMID: 29808887 PMCID: PMC6097109 DOI: 10.1039/c8np00002f] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Indexed: 01/01/2023]
Abstract
Covering: up to 2017 2-Oxoglutarate (2OG) dependent oxygenases and the homologous oxidase isopenicillin N synthase (IPNS) play crucial roles in the biosynthesis of β-lactam ring containing natural products. IPNS catalyses formation of the bicyclic penicillin nucleus from a tripeptide. 2OG oxygenases catalyse reactions that diversify the chemistry of β-lactams formed by both IPNS and non-oxidative enzymes. Reactions catalysed by the 2OG oxygenases of β-lactam biosynthesis not only involve their typical hydroxylation reactions, but also desaturation, epimerisation, rearrangement, and ring-forming reactions. Some of the enzymes involved in β-lactam biosynthesis exhibit remarkable substrate and product selectivities. We review the roles of 2OG oxygenases and IPNS in β-lactam biosynthesis, highlighting opportunities for application of knowledge of their roles, structures, and mechanisms.
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Affiliation(s)
- Patrick Rabe
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Jos J A G Kamps
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Christopher J Schofield
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Christopher T Lohans
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
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10
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Nishizaki D, Iwahashi H. Oxygen-Centered Radicals Formed in the Reaction Mixtures Containing Chloroiron Tetraphenylporphyrin, Iodosylbenzene, and Ethanol. Inorg Chem 2017; 56:13166-13173. [DOI: 10.1021/acs.inorgchem.7b01949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daisuke Nishizaki
- Department of Chemistry, Wakayama Medical University, 580 Mikazura, Wakayama 6410011, Japan
| | - Hideo Iwahashi
- Department of Chemistry, Wakayama Medical University, 580 Mikazura, Wakayama 6410011, Japan
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11
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The UbiX-UbiD system: The biosynthesis and use of prenylated flavin (prFMN). Arch Biochem Biophys 2017; 632:209-221. [DOI: 10.1016/j.abb.2017.07.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 07/19/2017] [Accepted: 07/24/2017] [Indexed: 12/17/2022]
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12
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Abstract
Oxidative cyclizations are important transformations that occur widely during natural product biosynthesis. The transformations from acyclic precursors to cyclized products can afford morphed scaffolds, structural rigidity, and biological activities. Some of the most dramatic structural alterations in natural product biosynthesis occur through oxidative cyclization. In this Review, we examine the different strategies used by nature to create new intra(inter)molecular bonds via redox chemistry. This Review will cover both oxidation- and reduction-enabled cyclization mechanisms, with an emphasis on the former. Radical cyclizations catalyzed by P450, nonheme iron, α-KG-dependent oxygenases, and radical SAM enzymes are discussed to illustrate the use of molecular oxygen and S-adenosylmethionine to forge new bonds at unactivated sites via one-electron manifolds. Nonradical cyclizations catalyzed by flavin-dependent monooxygenases and NAD(P)H-dependent reductases are covered to show the use of two-electron manifolds in initiating cyclization reactions. The oxidative installations of epoxides and halogens into acyclic scaffolds to drive subsequent cyclizations are separately discussed as examples of "disappearing" reactive handles. Last, oxidative rearrangement of rings systems, including contractions and expansions, will be covered.
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Affiliation(s)
- Man-Cheng Tang
- Department of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Yi Zou
- Department of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, CA 90095, USA
| | - Kenji Watanabe
- Department of Pharmaceutical Sciences, University of Shizuoka, Shizuoka 422-8526, Japan
| | - Christopher T. Walsh
- Stanford University Chemistry, Engineering, and Medicine for Human Health (ChEM-H), Stanford University, 443 Via Ortega, Stanford, CA 94305
| | - Yi Tang
- Department of Chemical and Biomolecular Engineering, Department of Chemistry and Biochemistry, University of California, Los Angeles, 420 Westwood Plaza, Los Angeles, CA 90095, USA
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13
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Peck SC, Wang C, Dassama LMK, Zhang B, Guo Y, Rajakovich LJ, Bollinger JM, Krebs C, van der Donk WA. O-H Activation by an Unexpected Ferryl Intermediate during Catalysis by 2-Hydroxyethylphosphonate Dioxygenase. J Am Chem Soc 2017; 139:2045-2052. [PMID: 28092705 PMCID: PMC5302023 DOI: 10.1021/jacs.6b12147] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Activation
of O–H bonds by inorganic metal-oxo complexes
has been documented, but no cognate enzymatic process is known. Our
mechanistic analysis of 2-hydroxyethylphosphonate dioxygenase
(HEPD), which cleaves the C1–C2 bond of its substrate to afford
hydroxymethylphosphonate on the biosynthetic pathway to
the commercial herbicide phosphinothricin, uncovered an example
of such an O–H-bond-cleavage event. Stopped-flow UV–visible
absorption and freeze-quench Mössbauer experiments identified
a transient iron(IV)-oxo (ferryl) complex. Maximal accumulation of
the intermediate required both the presence of deuterium in the substrate
and, importantly, the use of 2H2O as solvent.
The ferryl complex forms and decays rapidly enough to be on the catalytic
pathway. To account for these unanticipated results, a new mechanism
that involves activation of an O–H bond by the ferryl complex
is proposed. This mechanism accommodates all available data on the
HEPD reaction.
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Affiliation(s)
- Spencer C Peck
- Department of Chemistry and Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States.,Institute for Genomic Biology, University of Illinois at Urbana-Champaign , 1206 West Gregory Drive, Urbana, Illinois 61801, United States
| | - Chen Wang
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Laura M K Dassama
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Bo Zhang
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Yisong Guo
- Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Lauren J Rajakovich
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - J Martin Bollinger
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.,Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Carsten Krebs
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States.,Department of Chemistry, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
| | - Wilfred A van der Donk
- Department of Chemistry and Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign , 600 South Mathews Avenue, Urbana, Illinois 61801, United States.,Institute for Genomic Biology, University of Illinois at Urbana-Champaign , 1206 West Gregory Drive, Urbana, Illinois 61801, United States
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14
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Kal S, Que L. Dioxygen activation by nonheme iron enzymes with the 2-His-1-carboxylate facial triad that generate high-valent oxoiron oxidants. J Biol Inorg Chem 2017; 22:339-365. [PMID: 28074299 DOI: 10.1007/s00775-016-1431-2] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 12/13/2016] [Indexed: 11/24/2022]
Abstract
The 2-His-1-carboxylate facial triad is a widely used scaffold to bind the iron center in mononuclear nonheme iron enzymes for activating dioxygen in a variety of oxidative transformations of metabolic significance. Since the 1990s, over a hundred different iron enzymes have been identified to use this platform. This structural motif consists of two histidines and the side chain carboxylate of an aspartate or a glutamate arranged in a facial array that binds iron(II) at the active site. This triad occupies one face of an iron-centered octahedron and makes the opposite face available for the coordination of O2 and, in many cases, substrate, allowing the tailoring of the iron-dioxygen chemistry to carry out a plethora of diverse reactions. Activated dioxygen-derived species involved in the enzyme mechanisms include iron(III)-superoxo, iron(III)-peroxo, and high-valent iron(IV)-oxo intermediates. In this article, we highlight the major crystallographic, spectroscopic, and mechanistic advances of the past 20 years that have significantly enhanced our understanding of the mechanisms of O2 activation and the key roles played by iron-based oxidants.
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Affiliation(s)
- Subhasree Kal
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Lawrence Que
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA.
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15
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Lu J, Hu L, Cheng J, Fang D, Wang C, Yu K, Jiang H, Cui Q, Xu Y, Luo C. A computational investigation on the substrate preference of ten-eleven-translocation 2 (TET2). Phys Chem Chem Phys 2016; 18:4728-38. [PMID: 26799843 DOI: 10.1039/c5cp07266b] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
TET proteins iteratively convert 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC) in a Fe(ii)/α-ketoglutarate-dependent manner. Our previous biochemical studies revealed that TET proteins are more active on 5mC than on 5hmC and 5fC. However, the source of the substrate preference of TET proteins still remains largely elusive. Here, we investigated the substrate binding and catalytic mechanisms of oxidation reactions mediated by TET2 on different substrates through computational approaches. In accordance with previous experimental reports, our computational results suggest that TET2 can bind to different substrates with comparable binding affinities and the hydrogen abstraction step in the catalytic cycle acts as the rate-limiting step. Further structural characterization of the intermediate structures revealed that the 5-substitution groups on 5hmC and 5fC adopt an unfavorable orientation for hydrogen abstraction, which leads to a higher energy barrier for 5hmC and 5fC (compared to 5mC) and thus a lower catalytic efficiency. In summary, our mechanical insights demonstrate that substrate preference is the intrinsic property of TET proteins and our theoretical calculation results can guide further dry-lab or wet-lab studies on the catalytic mechanism of TET proteins as well as other Fe(ii)/α-ketoglutarate (KG)-dependent dioxygenases.
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Affiliation(s)
- Junyan Lu
- Drug Discovery and Design Centre, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
| | - Lulu Hu
- Fudan University Shanghai Cancer Centre, Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China. and State Key Laboratory of Genetic Engineering, Collaborative Innovation Centre of Genetics and Development, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Jingdong Cheng
- Fudan University Shanghai Cancer Centre, Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China.
| | - Dong Fang
- Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin-Madison, 1101 University Ave, Madison, WI 53706, USA
| | - Chen Wang
- Drug Discovery and Design Centre, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
| | - Kunqian Yu
- Drug Discovery and Design Centre, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
| | - Hualiang Jiang
- Drug Discovery and Design Centre, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
| | - Qiang Cui
- Department of Chemistry and Theoretical Chemistry Institute, University of Wisconsin-Madison, 1101 University Ave, Madison, WI 53706, USA
| | - Yanhui Xu
- Fudan University Shanghai Cancer Centre, Institute of Biomedical Sciences, Shanghai Medical College of Fudan University, Shanghai 200032, China. and State Key Laboratory of Genetic Engineering, Collaborative Innovation Centre of Genetics and Development, School of Life Sciences, Fudan University, Shanghai 200433, China
| | - Cheng Luo
- Drug Discovery and Design Centre, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.
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16
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Peck SC, van der Donk WA. Go it alone: four-electron oxidations by mononuclear non-heme iron enzymes. J Biol Inorg Chem 2016; 22:381-394. [PMID: 27783267 DOI: 10.1007/s00775-016-1399-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 10/11/2016] [Indexed: 10/20/2022]
Abstract
This review discusses the current mechanistic understanding of a group of mononuclear non-heme iron-dependent enzymes that catalyze four-electron oxidation of their organic substrates without the use of any cofactors or cosubstrates. One set of enzymes acts on α-ketoacid-containing substrates, coupling decarboxylation to oxygen activation. This group includes 4-hydroxyphenylpyruvate dioxygenase, 4-hydroxymandelate synthase, and CloR involved in clorobiocin biosynthesis. A second set of enzymes acts on substrates containing a thiol group that coordinates to the iron. This group is comprised of isopenicillin N synthase, thiol dioxygenases, and enzymes involved in the biosynthesis of ergothioneine and ovothiol. The final group of enzymes includes HEPD and MPnS that both carry out the oxidative cleavage of the carbon-carbon bond of 2-hydroxyethylphosphonate but generate different products. Commonalities amongst many of these enzymes are discussed and include the initial substrate oxidation by a ferric-superoxo-intermediate and a second oxidation by a ferryl species.
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Affiliation(s)
- Spencer C Peck
- Department of Chemistry and Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA.,Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL, 61801, USA
| | - Wilfred A van der Donk
- Department of Chemistry and Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA. .,Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL, 61801, USA.
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17
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Tamanaha EY, Zhang B, Guo Y, Chang WC, Barr EW, Xing G, St Clair J, Ye S, Neese F, Bollinger JM, Krebs C. Spectroscopic Evidence for the Two C-H-Cleaving Intermediates of Aspergillus nidulans Isopenicillin N Synthase. J Am Chem Soc 2016; 138:8862-74. [PMID: 27193226 PMCID: PMC4956533 DOI: 10.1021/jacs.6b04065] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The enzyme isopenicillin N synthase (IPNS) installs the β-lactam and thiazolidine rings of the penicillin core into the linear tripeptide l-δ-aminoadipoyl-l-Cys-d-Val (ACV) on the pathways to a number of important antibacterial drugs. A classic set of enzymological and crystallographic studies by Baldwin and co-workers established that this overall four-electron oxidation occurs by a sequence of two oxidative cyclizations, with the β-lactam ring being installed first and the thiazolidine ring second. Each phase requires cleavage of an aliphatic C-H bond of the substrate: the pro-S-CCys,β-H bond for closure of the β-lactam ring, and the CVal,β-H bond for installation of the thiazolidine ring. IPNS uses a mononuclear non-heme-iron(II) cofactor and dioxygen as cosubstrate to cleave these C-H bonds and direct the ring closures. Despite the intense scrutiny to which the enzyme has been subjected, the identities of the oxidized iron intermediates that cleave the C-H bonds have been addressed only computationally; no experimental insight into their geometric or electronic structures has been reported. In this work, we have employed a combination of transient-state-kinetic and spectroscopic methods, together with the specifically deuterium-labeled substrates, A[d2-C]V and AC[d8-V], to identify both C-H-cleaving intermediates. The results show that they are high-spin Fe(III)-superoxo and high-spin Fe(IV)-oxo complexes, respectively, in agreement with published mechanistic proposals derived computationally from Baldwin's founding work.
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Affiliation(s)
- Esta Y. Tamanaha
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Bo Zhang
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Yisong Guo
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Wei-chen Chang
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Eric W. Barr
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Gang Xing
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Jennifer St Clair
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Shengfa Ye
- Max-Planck Institute for Chemical Energy Conversion, Mülheim a. d. Ruhr, Germany
| | - Frank Neese
- Max-Planck Institute for Chemical Energy Conversion, Mülheim a. d. Ruhr, Germany
| | - J. Martin Bollinger
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
| | - Carsten Krebs
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802
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18
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Abstract
Mononuclear non-heme Fe(II)- and 2-oxoglutarate (2OG)-dependent oxygenases comprise a large family of enzymes that utilize an Fe(IV)-oxo intermediate to initiate diverse oxidative transformations with important biological roles. Here, four of the major types of Fe(II)/2OG-dependent reactions are detailed: hydroxylation, halogenation, ring formation, and desaturation. In addition, an atypical epimerization reaction is described. Studies identifying several key intermediates in catalysis are concisely summarized, and the proposed mechanisms are explained. In addition, a variety of other transformations catalyzed by selected family members are briefly described to further highlight the chemical versatility of these enzymes.
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Affiliation(s)
- Salette Martinez
- Departments of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824
| | - Robert P Hausinger
- Departments of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824; Departments of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824.
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19
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Oxidative cyclizations in orthosomycin biosynthesis expand the known chemistry of an oxygenase superfamily. Proc Natl Acad Sci U S A 2015; 112:11547-52. [PMID: 26240321 DOI: 10.1073/pnas.1500964112] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Orthosomycins are oligosaccharide antibiotics that include avilamycin, everninomicin, and hygromycin B and are hallmarked by a rigidifying interglycosidic spirocyclic ortho-δ-lactone (orthoester) linkage between at least one pair of carbohydrates. A subset of orthosomycins additionally contain a carbohydrate capped by a methylenedioxy bridge. The orthoester linkage is necessary for antibiotic activity but rarely observed in natural products. Orthoester linkage and methylenedioxy bridge biosynthesis require similar oxidative cyclizations adjacent to a sugar ring. We have identified a conserved group of nonheme iron, α-ketoglutarate-dependent oxygenases likely responsible for this chemistry. High-resolution crystal structures of the EvdO1 and EvdO2 oxygenases of everninomicin biosynthesis, the AviO1 oxygenase of avilamycin biosynthesis, and HygX of hygromycin B biosynthesis show how these enzymes accommodate large substrates, a challenge that requires a variation in metal coordination in HygX. Excitingly, the ternary complex of HygX with cosubstrate α-ketoglutarate and putative product hygromycin B identified an orientation of one glycosidic linkage of hygromycin B consistent with metal-catalyzed hydrogen atom abstraction from substrate. These structural results are complemented by gene disruption of the oxygenases evdO1 and evdMO1 from the everninomicin biosynthetic cluster, which demonstrate that functional oxygenase activity is critical for antibiotic production. Our data therefore support a role for these enzymes in the production of key features of the orthosomycin antibiotics.
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20
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Krenske EH, Patel A, Houk KN. Does Nature Click? Theoretical Prediction of an Enzyme-Catalyzed Transannular 1,3-Dipolar Cycloaddition in the Biosynthesis of Lycojaponicumins A and B. J Am Chem Soc 2013; 135:17638-42. [DOI: 10.1021/ja409928z] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Elizabeth H. Krenske
- School
of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Ashay Patel
- Department
of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - K. N. Houk
- Department
of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
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21
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Hamed RB, Gomez-Castellanos JR, Henry L, Ducho C, McDonough MA, Schofield CJ. The enzymes of β-lactam biosynthesis. Nat Prod Rep 2013; 30:21-107. [DOI: 10.1039/c2np20065a] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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22
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Lundberg M, Borowski T. Oxoferryl species in mononuclear non-heme iron enzymes: Biosynthesis, properties and reactivity from a theoretical perspective. Coord Chem Rev 2013. [DOI: 10.1016/j.ccr.2012.03.047] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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23
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Structural Insight into the Prolyl Hydroxylase PHD2: A Molecular Dynamics and DFT Study. Eur J Inorg Chem 2012. [DOI: 10.1002/ejic.201200391] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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24
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Barroso-Neto IL, Marques JPC, da Costa RF, Caetano EWS, Cavada BS, Gottfried C, Freire VN. Inactivation of Ovine Cyclooxygenase-1 by Bromoaspirin and Aspirin: A Quantum Chemistry Description. J Phys Chem B 2012; 116:3270-9. [DOI: 10.1021/jp206397z] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Ito L. Barroso-Neto
- Department of Biochemistry, Universidade Federal do Ceará, Fortaleza 60455-760, Ceará, Brazil
| | - João Paulo C. Marques
- Department of Physics, Universidade Federal do Ceará, Fortaleza 60455-760,
Ceará, Brazil
| | - Roner F. da Costa
- Department of Physics, Universidade Federal do Ceará, Fortaleza 60455-760,
Ceará, Brazil
| | - Ewerton W. S. Caetano
- Instituto
Federal de Educação, Ciência e Tecnologia do Ceará, Fortaleza 60040-531, Ceará,
Brazil
| | - Benildo S. Cavada
- Department of Biochemistry, Universidade Federal do Ceará, Fortaleza 60455-760, Ceará, Brazil
| | - Carmem Gottfried
- Department of Biochemistry, Universidade Federal do Rio Grande do Sul, Porto Alegre
90035-003, Rio Grande do Sul, Brazil
| | - Valder N. Freire
- Department of Physics, Universidade Federal do Ceará, Fortaleza 60455-760,
Ceará, Brazil
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25
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Balcells D, Clot E, Eisenstein O. C—H Bond Activation in Transition Metal Species from a Computational Perspective. Chem Rev 2010; 110:749-823. [PMID: 20067255 DOI: 10.1021/cr900315k] [Citation(s) in RCA: 843] [Impact Index Per Article: 60.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- David Balcells
- Institut Charles Gerhardt, Université Montpellier 2, CNRS 5253, cc 1501, Place Eugène Bataillon, 34000 Montpellier, France
| | - Eric Clot
- Institut Charles Gerhardt, Université Montpellier 2, CNRS 5253, cc 1501, Place Eugène Bataillon, 34000 Montpellier, France
| | - Odile Eisenstein
- Institut Charles Gerhardt, Université Montpellier 2, CNRS 5253, cc 1501, Place Eugène Bataillon, 34000 Montpellier, France
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26
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Liu H, Llano J, Gauld JW. A DFT study of nucleobase dealkylation by the DNA repair enzyme AlkB. J Phys Chem B 2009; 113:4887-98. [PMID: 19338370 DOI: 10.1021/jp810715t] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Oxidative dealkylation is a unique mechanistic pathway found in the alpha-ketoglutarate-Fe(II)-dependent AlkB family of enzymes to remove the alkylation damage to DNA bases and regenerate nucleobases to their native state. The B3LYP density functional combined with a self-consistent reaction field was used to explore the triplet, quintet, and septet spin-state potential energy surfaces of the multistep catalytic mechanism of AlkB. The mechanism was found to consist of four stages. First, binding of dioxygen to iron in the active-site complex occurs concerted with electron transfer, thereby yielding a ferric-superoxido species. Second, competing initiation for the activation of oxygen to generate the high-valent iron-oxygen intermediates (ferryl-oxo Fe(IV)O and ferric-oxyl Fe(III)O(*) species) was found to occur on the quintet and septet surfaces. Then, conformational reorientation of the activated iron-oxygen ligand was found to be nearly thermoneutral with a barrier of ca. 50 kJ mol(-1). The final stage is the oxidative dealkylation of the damaged nucleobase with the rate-controlling step being the abstraction of a hydrogen atom from the damaging methyl group by the ferryl-oxo ligand. For this step, the calculated barrier of 87.4 kJ mol(-1) is in good agreement with the experimental activation energy of ca. 83 kJ mol(-1) for the enzyme-catalyzed reaction.
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Affiliation(s)
- Haining Liu
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
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27
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Pandian S, Vincent MA, Hillier IH, Burton NA. Why does the enzyme SyrB2 chlorinate, but does not hydroxylate, saturated hydrocarbons? A density functional theory (DFT) study. Dalton Trans 2009:6201-7. [DOI: 10.1039/b906866j] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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28
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Čondić-Jurkić K, Perchyonok VT, Zipse H, Smith DM. On the modeling of arginine-bound carboxylates: A case study with Pyruvate Formate-Lyase. J Comput Chem 2008; 29:2425-33. [DOI: 10.1002/jcc.20984] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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29
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Lee JK, Tantillo DJ. Reaction mechanisms : Part (ii) Pericyclic reactions. ACTA ACUST UNITED AC 2008. [DOI: 10.1039/b717028a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Ryan JH, Spiccia N, Wong LSM, Holmes AB. Synthesis of 5-Aryloxazolidines via 1,3-Dipolar Cycloaddition Reaction of a Non-Stabilized Azomethine Ylide with Aromatic Aldehydes. Aust J Chem 2007. [DOI: 10.1071/ch07282] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The 1,3-dipolar cycloaddition reaction of a non-stabilized azomethine ylide 4a, formed in situ from N-(methoxymethyl)-N-(trimethylsilylmethyl)benzylamine 5 and a catalytic amount of trifluoroacetic acid, with aromatic aldehydes 3 gives rise to N-benzyl-5-aryloxazolidines 1. Under these conditions, 4-hydroxybenzaldehyde 3p undergoes two-fold addition of azomethine ylide 4a to afford bis adduct 11.
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