1
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Dong X, Xu M, Wu M, Wang Y, Cheng X, Jiang W, Zheng D, Omar AH, Cheng Y, Li A, Ma L, Xing Q. Structural and catalytic insights into MhpB: A dioxygenase enzyme for degrading catecholic pollutants. JOURNAL OF HAZARDOUS MATERIALS 2025; 488:137431. [PMID: 39892151 DOI: 10.1016/j.jhazmat.2025.137431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2024] [Revised: 01/26/2025] [Accepted: 01/27/2025] [Indexed: 02/03/2025]
Abstract
The increasing environmental pollution from persistent aromatic compounds requires effective biodegradation strategies. In this study, we focused on MhpB, an extradiol dioxygenase (EDO) from Escherichia coli. It is known for its role in the degradation of catechols, key intermediates in the degradation of aromatic compounds. We report the high-resolution structure of MhpB determined by cryo-electron microscopy, revealing a decameric conformation with the catalytic chamber at the side. The structure-based analysis allowed us to investigate the substrate-enzyme interaction and the substrate selectivity, which are crucial for its catalytic function. Site-directed mutagenesis was used to modulate the in vitro and in vivo substrate preference of MhpB, enhancing its potential for industrial applications in pollutant degradation. The study provides insight into the mechanism of the enzyme and paves the way for the development of engineered EDOs for environmental remediation of aromatic pollutants.
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Affiliation(s)
- Xu Dong
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China.
| | - Manli Xu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China
| | - Miao Wu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China
| | - Ying Wang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China
| | - Xiaoqi Cheng
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China
| | - Wenxue Jiang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China
| | - Dule Zheng
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China
| | - Ahmed Habiba Omar
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China
| | - Yibin Cheng
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China
| | - Aitao Li
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China
| | - Lixin Ma
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China
| | - Qiong Xing
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan 430074, China.
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2
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Kuatsjah E, Schwartz A, Zahn M, Tornesakis K, Kellermyer ZA, Ingraham MA, Woodworth SP, Ramirez KJ, Cox PA, Pickford AR, Salvachúa D. Biochemical and structural characterization of enzymes in the 4-hydroxybenzoate catabolic pathway of lignin-degrading white-rot fungi. Cell Rep 2024; 43:115002. [PMID: 39589922 DOI: 10.1016/j.celrep.2024.115002] [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: 05/17/2024] [Revised: 09/15/2024] [Accepted: 11/06/2024] [Indexed: 11/28/2024] Open
Abstract
White-rot fungi (WRF) are the most efficient lignin-degrading organisms in nature. However, their capacity to use lignin-related aromatic compounds, such as 4-hydroxybenzoate, as carbon sources has only been described recently. Previously, the hydroxyquinol pathway was proposed for the bioconversion of these compounds in fungi, but gene- and structure-function relationships of the full enzymatic pathway remain uncharacterized in any single fungal species. Here, we characterize seven enzymes from two WRF, Trametes versicolor and Gelatoporia subvermispora, which constitute a four-enzyme cascade from 4-hydroxybenzoate to β-ketoadipate via the hydroxyquinol pathway. Furthermore, we solve the crystal structure of four of these enzymes and identify mechanistic differences with the closest bacterial and fungal structural homologs. Overall, this research expands our understanding of aromatic catabolism by WRF and establishes an alternative strategy for the conversion of lignin-related compounds to the valuable molecule β-ketoadipate, contributing to the development of biological processes for lignin valorization.
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Affiliation(s)
- Eugene Kuatsjah
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Alexa Schwartz
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA; Advanced Energy Systems Graduate Program, Colorado School of Mines, Golden, CO 80401, USA
| | - Michael Zahn
- Centre for Enzyme Innovation, School of the Environment and Life Sciences, University of Portsmouth, PO1 2DT Portsmouth, UK
| | - Konstantinos Tornesakis
- Centre for Enzyme Innovation, School of the Environment and Life Sciences, University of Portsmouth, PO1 2DT Portsmouth, UK
| | - Zoe A Kellermyer
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Morgan A Ingraham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Sean P Woodworth
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Kelsey J Ramirez
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
| | - Paul A Cox
- Centre for Enzyme Innovation, School of the Environment and Life Sciences, University of Portsmouth, PO1 2DT Portsmouth, UK
| | - Andrew R Pickford
- Centre for Enzyme Innovation, School of the Environment and Life Sciences, University of Portsmouth, PO1 2DT Portsmouth, UK
| | - Davinia Salvachúa
- Renewable Resources and Enabling Sciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA.
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3
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McWhorter KL, Purohit V, Ambarian JA, Jhunjhunwala R, Davis KM. The common chemical logic of 'bridged' peroxo species in mononuclear non-heme iron systems. Crit Rev Biochem Mol Biol 2024; 59:418-433. [PMID: 39878573 DOI: 10.1080/10409238.2025.2455084] [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: 10/31/2024] [Revised: 01/10/2025] [Accepted: 01/14/2025] [Indexed: 01/31/2025]
Abstract
Mononuclear non-heme iron enzymes catalyze a wide array of important oxidative transformations. They are correspondingly diverse in both structure and mechanism. Despite significant evolutionary distance, it is becoming increasingly apparent that these enzymes nonetheless illustrate a compelling case of mechanistic convergence via the formation of peroxo species bridging metal and substrate. Aromatic amino acid hydroxylases and 2-oxoglutarate (2OG)-dependent enzymes, for example, form bridged acyl- or alkylperoxo intermediates en route to highly oxidizing ferryl species, while catechol dioxygenases utilize such 'bridged' peroxos directly. Analogous acylperoxoiron intermediates have also been demonstrated to precede a perferryl oxidant in biomimetic systems. Herein, we synthesize the results of structural, spectroscopic and computational studies on these systems to gain insight into the shared chemical logic that drives iron-peracid formation and reactivity. In all cases, reactions are tuned via the electron-donating properties of coordinating ligands. Second-sphere residues have also been demonstrated to modulate the orientation of the bridge, thereby influencing reaction outcomes. The effect of carboxylic acid addition to relevant biomimetic catalyst reactions further underscores these fundamental chemical principles. Altogether, we provide a comprehensive analysis of the cross-cutting mechanisms that guide peroxo formation and subsequent oxidative chemistry performed by non-heme mononuclear iron catalysts.
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Affiliation(s)
| | - Vatsal Purohit
- Department of Chemistry, Emory University, Atlanta, GA, USA
| | - Joseph A Ambarian
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
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4
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Marques HM. Electron transfer in biological systems. J Biol Inorg Chem 2024; 29:641-683. [PMID: 39424709 PMCID: PMC11638306 DOI: 10.1007/s00775-024-02076-8] [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: 04/21/2024] [Accepted: 09/27/2024] [Indexed: 10/21/2024]
Abstract
Examples of how metalloproteins feature in electron transfer processes in biological systems are reviewed. Attention is focused on the electron transport chains of cellular respiration and photosynthesis, and on metalloproteins that directly couple electron transfer to a chemical reaction. Brief mention is also made of extracellular electron transport. While covering highlights of the recent and the current literature, this review is aimed primarily at introducing the senior undergraduate and the novice postgraduate student to this important aspect of bioinorganic chemistry.
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Affiliation(s)
- Helder M Marques
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, 2050, South Africa.
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5
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Xiong J, Reed C, Lavina B, Hu MY, Zhao J, Alp EE, Agapie T, Guo Y. 57Fe nuclear resonance vibrational spectroscopic studies of tetranuclear iron clusters bearing terminal iron(iii)-oxido/hydroxido moieties. Chem Sci 2024; 15:d4sc03396e. [PMID: 39296996 PMCID: PMC11403573 DOI: 10.1039/d4sc03396e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Accepted: 09/08/2024] [Indexed: 09/21/2024] Open
Abstract
57Fe nuclear resonance vibrational spectroscopy (NRVS) has been applied to study a series of tetranuclear iron ([Fe4]) clusters based on a multidentate ligand platform (L3-) anchored by a 1,3,5-triarylbenzene linker and pyrazolate or (tertbutylamino)pyrazolate ligand (PzNH t Bu-). These clusters bear a terminal Fe(iii)-O/OH moiety at the apical position and three additional iron centers forming the basal positions. The three basal irons are connected with the apical iron center via a μ4-oxido ligand. Detailed vibrational analysis via density functional theory calculations revealed that strong NRVS spectral features below 400 cm-1 can be used as an oxidation state marker for the overall [Fe4] cluster core. The terminal Fe(iii)-O/OH stretching frequencies, which were observed in the range of 500-700 cm-1, can be strongly modulated (energy shifts of 20-40 cm-1 were observed) upon redox events at the three remote basal iron centers of the [Fe4] cluster without the change of the terminal Fe(iii) oxidation state and its coordination environment. Therefore, the current study provides a quantitative vibrational analysis of how the remote iron centers within the same iron cluster exert exquisite control of the chemical reactivities and thermodynamic properties of the specific iron site that is responsible for small molecule activation.
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Affiliation(s)
- Jin Xiong
- Department of Chemistry, Carnegie Mellon University Pittsburgh PA 15213 USA
| | - Christopher Reed
- Division of Chemistry and Chemical Engineering, California Institute of Technology CA 91125 USA
| | - Barbara Lavina
- Advanced Photon Source, Argonne National Laboratory Argonne Illinois 60439 USA
- Center for Advanced Radiation Source, University of Chicago Chicago Illinois 60439 USA
| | - Michael Y Hu
- Advanced Photon Source, Argonne National Laboratory Argonne Illinois 60439 USA
| | - Jiyong Zhao
- Advanced Photon Source, Argonne National Laboratory Argonne Illinois 60439 USA
| | - Esen E Alp
- Advanced Photon Source, Argonne National Laboratory Argonne Illinois 60439 USA
| | - Theodor Agapie
- Division of Chemistry and Chemical Engineering, California Institute of Technology CA 91125 USA
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University Pittsburgh PA 15213 USA
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6
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Li JY, Si DH, Mi FQ, Xu WL, Zhang T, Cao R. A Bioinspired Copper-Pair Catalyst in Metal-Organic Frameworks for Molecular Dioxygen Activation and Aerobic Oxidative C-N Coupling. J Am Chem Soc 2024; 146:12444-12453. [PMID: 38680118 DOI: 10.1021/jacs.3c14794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2024]
Abstract
Open Cu sites were loaded to the UiO-67 metal-organic framework (MOF) skeleton by introduction of flexible Cu-binding pyridylmethylamine (pyma) side chains to the biphenyldicarboxylate linkers. Distance between Cu centers in the MOF pores was tuned by controlling the density of metal-binding side chains. "Interacted" Cu-pair or "isolated" monomeric Cu sites were achieved with high and low (pyma)Cu side chain loading, respectively. Spectroscopic and theoretical studies indicate that "interacted" Cu pairs can effectively bind and activate molecular dioxygen to form Cu2O2 clusters, which showed high catalytic activity for aerobic oxidative C-N coupling. On the contrary, MOF catalyst bearing isolated monomeric Cu sites only showed modest catalytic activity. Enhancement in catalytic performance for the Cu-pair catalyst is attributed to the remote synergistic effect of the paired Cu site, which binds molecular dioxygen and cleaves the O═O bond in a collaborative manner. This work demonstrates that noncovalently interacted metal-pair sites can effectively activate inert small molecules and promote heterogeneous catalytic processes.
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Affiliation(s)
- Jun-Yu Li
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Duan-Hui Si
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian 350108, China
| | - Fu-Qi Mi
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Wang-Lan Xu
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- Fujian College, University of the Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- College of Chemistry and Materials Science, Fujian Normal University, Fuzhou, Fujian 350007, China
| | - Teng Zhang
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
- Fujian College, University of the Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
| | - Rong Cao
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
- University of the Chinese Academy of Sciences, Beijing 100049, China
- Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, Fujian 350108, China
- Fujian College, University of the Chinese Academy of Sciences, Fuzhou, Fujian 350002, China
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7
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Babicz JT, Rogers MS, DeWeese DE, Sutherlin KD, Banerjee R, Böttger LH, Yoda Y, Nagasawa N, Saito M, Kitao S, Kurokuzu M, Kobayashi Y, Tamasaku K, Seto M, Lipscomb JD, Solomon EI. Nuclear Resonance Vibrational Spectroscopy Definition of Peroxy Intermediates in Catechol Dioxygenases: Factors that Determine Extra- versus Intradiol Cleavage. J Am Chem Soc 2023; 145:15230-15250. [PMID: 37414058 PMCID: PMC10804917 DOI: 10.1021/jacs.3c02242] [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: 07/08/2023]
Abstract
The extradiol dioxygenases (EDOs) and intradiol dioxygenases (IDOs) are nonheme iron enzymes that catalyze the oxidative aromatic ring cleavage of catechol substrates, playing an essential role in the carbon cycle. The EDOs and IDOs utilize very different FeII and FeIII active sites to catalyze the regiospecificity in their catechol ring cleavage products. The factors governing this difference in cleavage have remained undefined. The EDO homoprotocatechuate 2,3-dioxygenase (HPCD) and IDO protocatechuate 3,4-dioxygenase (PCD) provide an opportunity to understand this selectivity, as key O2 intermediates have been trapped for both enzymes. Nuclear resonance vibrational spectroscopy (in conjunction with density functional theory calculations) is used to define the geometric and electronic structures of these intermediates as FeII-alkylhydroperoxo (HPCD) and FeIII-alkylperoxo (PCD) species. Critically, in both intermediates, the initial peroxo bond orientation is directed toward extradiol product formation. Reaction coordinate calculations were thus performed to evaluate both the extra- and intradiol O-O cleavage for the simple organic alkylhydroperoxo and for the FeII and FeIII metal catalyzed reactions. These results show the FeII-alkylhydroperoxo (EDO) intermediate undergoes facile extradiol O-O bond homolysis due to its extra e-, while for the FeIII-alkylperoxo (IDO) intermediate the extradiol cleavage involves a large barrier and would yield the incorrect extradiol product. This prompted our evaluation of a viable mechanism to rearrange the FeIII-alkylperoxo IDO intermediate for intradiol cleavage, revealing a key role in the rebinding of the displaced Tyr447 ligand in this rearrangement, driven by the proton delivery necessary for O-O bond cleavage.
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Affiliation(s)
- Jeffrey T. Babicz
- Department of Chemistry, Stanford University, 380 Roth Way, Stanford, California 94305, United States
| | - Melanie S. Rogers
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55391, United States
| | - Dory E. DeWeese
- Department of Chemistry, Stanford University, 380 Roth Way, Stanford, California 94305, United States
| | - Kyle D. Sutherlin
- Department of Chemistry, Stanford University, 380 Roth Way, Stanford, California 94305, United States
| | - Rahul Banerjee
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55391, United States
| | - Lars H. Böttger
- Department of Chemistry, Stanford University, 380 Roth Way, Stanford, California 94305, United States
| | - Yoshitaka Yoda
- Japan Synchrotron Radiation Research Institute, Hyogo 679-5198, Japan
| | - Nobumoto Nagasawa
- Japan Synchrotron Radiation Research Institute, Hyogo 679-5198, Japan
| | - Makina Saito
- Department of Physics, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Shinji Kitao
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494, Japan
| | - Masayuki Kurokuzu
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494, Japan
| | - Yasuhiro Kobayashi
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494, Japan
| | - Kenji Tamasaku
- RIKEN SPring-8 Center, RIKEN, Sayo, Hyogo 679-5148, Japan
| | - Makoto Seto
- Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494, Japan
| | - John D. Lipscomb
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota 55391, United States
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, 380 Roth Way, Stanford, California 94305, United States
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
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8
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Lu X, Wang S, Qin JH. Isolating Fe-O 2 Intermediates in Dioxygen Activation by Iron Porphyrin Complexes. Molecules 2022; 27:4690. [PMID: 35897870 PMCID: PMC9332324 DOI: 10.3390/molecules27154690] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/12/2022] [Accepted: 07/18/2022] [Indexed: 11/30/2022] Open
Abstract
Dioxygen (O2) is an environmentally benign and abundant oxidant whose utilization is of great interest in the design of bioinspired synthetic catalytic oxidation systems to reduce energy consumption. However, it is unfortunate that utilization of O2 is a significant challenge because of the thermodynamic stability of O2 in its triplet ground state. Nevertheless, nature is able to overcome the spin state barrier using enzymes, which contain transition metals with unpaired d-electrons facilitating the activation of O2 by metal coordination. This inspires bioinorganic chemists to synthesize biomimetic small-molecule iron porphyrin complexes to carry out the O2 activation, wherein Fe-O2 species have been implicated as the key reactive intermediates. In recent years, a number of Fe-O2 intermediates have been synthesized by activating O2 at iron centers supported on porphyrin ligands. In this review, we focus on a few examples of these advances with emphasis in each case on the particular design of iron porphyrin complexes and particular reaction environments to stabilize and isolate metal-O2 intermediates in dioxygen activation, which will provide clues to elucidate structures of reactive intermediates and mechanistic insights in biological processes.
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Affiliation(s)
- Xiaoyan Lu
- College of Chemistry and Chemical Engineering, Luoyang Normal University, Luoyang 471934, China; (S.W.); (J.-H.Q.)
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9
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Abstract
Here, the choice of the first coordination shell of the metal center is analyzed from the perspective of charge maintenance in a binary enzyme-substrate complex and an O2-bound ternary complex in the nonheme iron oxygenases. Comparing homogentisate 1,2-dioxygenase and gentisate dioxygenase highlights the significance of charge maintenance after substrate binding as an important factor that drives the reaction coordinate. We then extend the charge analysis to several common types of nonheme iron oxygenases containing either a 2-His-1-carboxylate facial triad or a 3-His or 4-His ligand motif, including extradiol and intradiol ring-cleavage dioxygenases, thiol dioxygenases, α-ketoglutarate-dependent oxygenases, and carotenoid cleavage oxygenases. After forming the productive enzyme-substrate complex, the overall charge of the iron complex at the 0, +1, or +2 state is maintained in the remaining catalytic steps. Hence, maintaining a constant charge is crucial to promote the reaction of the iron center beginning from the formation of the Michaelis or ternary complex. The charge compensation to the iron ion is tuned not only by protein-derived carboxylate ligands but also by substrates. Overall, these analyses indicate that charge maintenance at the iron center is significant when all the necessary components form a productive complex. This charge maintenance concept may apply to most oxygen-activating metalloenzymes systems that do not draw electrons and protons step-by-step from a separate reactant, such as NADH, via a reductase. The charge maintenance perception may also be useful in proposing catalytic pathways or designing prototypical reactions using artificial or engineered enzymes for biotechnological applications.
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Affiliation(s)
- Ephrahime S. Traore
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
| | - Aimin Liu
- Department of Chemistry, The University of Texas at San Antonio, San Antonio, Texas 78249, United States
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10
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Theoretical perspective on mononuclear copper-oxygen mediated C–H and O–H activations: A comparison between biological and synthetic systems. CHINESE JOURNAL OF CATALYSIS 2022. [DOI: 10.1016/s1872-2067(21)63974-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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11
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Csizi K, Eckert L, Brunken C, Hofstetter TB, Reiher M. The Apparently Unreactive Substrate Facilitates the Electron Transfer for Dioxygen Activation in Rieske Dioxygenases. Chemistry 2022; 28:e202103937. [PMID: 35072969 PMCID: PMC9306888 DOI: 10.1002/chem.202103937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Indexed: 12/29/2022]
Abstract
Rieske dioxygenases belong to the non-heme iron family of oxygenases and catalyze important cis-dihydroxylation as well as O-/N-dealkylation and oxidative cyclization reactions for a wide range of substrates. The lack of substrate coordination at the non-heme ferrous iron center, however, makes it particularly challenging to delineate the role of the substrate for productive O 2 activation. Here, we studied the role of the substrate in the key elementary reaction leading to O 2 activation from a theoretical perspective by systematically considering (i) the 6-coordinate to 5-coordinate conversion of the non-heme FeII upon abstraction of a water ligand, (ii) binding of O 2 , and (iii) transfer of an electron from the Rieske cluster. We systematically evaluated the spin-state-dependent reaction energies and structural effects at the active site for all combinations of the three elementary processes in the presence and absence of substrate using naphthalene dioxygenase as a prototypical Rieske dioxygenase. We find that reaction energies for the generation of a coordination vacancy at the non-heme FeII center through thermoneutral H2 O reorientation and exothermic O 2 binding prior to Rieske cluster oxidation are largely insensitive to the presence of naphthalene and do not lead to formation of any of the known reactive Fe-oxygen species. By contrast, the role of the substrate becomes evident after Rieske cluster oxidation and exclusively for the 6-coordinate non-heme FeII sites in that the additional electron is found at the substrate instead of at the iron and oxygen atoms. Our results imply an allosteric control of the substrate on Rieske dioxygenase reactivity to happen prior to changes at the non-heme FeII in agreement with a strategy that avoids unproductive O 2 activation.
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Affiliation(s)
- Katja‐Sophia Csizi
- EawagSwiss Federal Institute of Aquatic Science and TechnologyÜberlandstrasse 1338600DübendorfSwitzerland
- ETH ZürichLaboratory for Physical ChemistryVladimir-Prelog-Weg 28093ZürichSwitzerland
| | - Lina Eckert
- ETH ZürichLaboratory for Physical ChemistryVladimir-Prelog-Weg 28093ZürichSwitzerland
| | - Christoph Brunken
- EawagSwiss Federal Institute of Aquatic Science and TechnologyÜberlandstrasse 1338600DübendorfSwitzerland
- ETH ZürichLaboratory for Physical ChemistryVladimir-Prelog-Weg 28093ZürichSwitzerland
| | - Thomas B. Hofstetter
- EawagSwiss Federal Institute of Aquatic Science and TechnologyÜberlandstrasse 1338600DübendorfSwitzerland
| | - Markus Reiher
- ETH ZürichLaboratory for Physical ChemistryVladimir-Prelog-Weg 28093ZürichSwitzerland
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12
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Chen M, Zhu JY, Mu WJ, Guo L. Cysteine dioxygenase type 1 (CDO1): its functional role in physiological and pathophysiological processes. Genes Dis 2022. [DOI: 10.1016/j.gendis.2021.12.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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13
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Cook EN, Machan CW. Bioinspired mononuclear Mn complexes for O 2 activation and biologically relevant reactions. Dalton Trans 2021; 50:16871-16886. [PMID: 34730590 DOI: 10.1039/d1dt03178c] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
A general interest in harnessing the oxidizing power of dioxygen (O2) continues to motivate research efforts on bioinspired and biomimetic complexes to better understand how metalloenzymes mediate these reactions. The ubiquity of Fe- and Cu-based enzymes attracts significant attention and has resulted in many noteworthy developments for abiotic systems interested in direct O2 reduction and small molecule activation. However, despite the existence of Mn-based metalloenzymes with important O2-dependent activity, there has been comparatively less focus on the development of these analogues relative to Fe- and Cu-systems. In this Perspective, we summarize important contributions to the development of bioinspired mononuclear Mn complexes for O2 activation and studies on their reactivity, emphasizing important design parameters in the primary and secondary coordination spheres and outlining mechanistic trends.
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Affiliation(s)
- Emma N Cook
- Department of Chemistry, University of Virginia, PO Box 400319, Charlottesville, VA 22904-4319, USA.
| | - Charles W Machan
- Department of Chemistry, University of Virginia, PO Box 400319, Charlottesville, VA 22904-4319, USA.
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14
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Wang J, Dai X, Wang H, Liu H, Rabeah J, Brückner A, Shi F, Gong M, Yang X. Dihydroxyacetone valorization with high atom efficiency via controlling radical oxidation pathways over natural mineral-inspired catalyst. Nat Commun 2021; 12:6840. [PMID: 34824262 PMCID: PMC8617048 DOI: 10.1038/s41467-021-27240-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 11/08/2021] [Indexed: 11/21/2022] Open
Abstract
Diminishing fossil fuel resources and calls for sustainability are driving the urgent need for efficient valorization of renewable resources with high atom efficiency. Inspired from the natural goethite mineral with Mn paragenesis, we develop cost-effective MnO2/goethite catalysts for the efficient valorization of dihydroxyacetone, an important biomass-based platform molecule, into value-added glycolic acid and formic acid with 83.2% and 93.4% yields. The DHA substrates first undergo C-C cleavage to selectively form glycolic acid and hydroxymethyl (·CH2OH) radicals, which are further oxidized into formic acid. The kinetic and isotopic labeling experiments reveal that the catalase-like activity of MnO2 turns the oxidative radicals into oxygen, which then switches towards a hydroxymethyl peroxide (HMOO) pathway for formic acid generation and prevents formic acid over-oxidation. This nature-inspired catalyst design not only significantly improves the carbon efficiency to 86.6%, but also enhances the oxygen atom utilization efficiency from 11.2% to 46.6%, indicating a promising biomass valorization process.
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Affiliation(s)
- Jinling Wang
- National Engineering Laboratory for Industrial Wastewater Treatment, East China University of Science and Technology (ECUST), Shanghai, 200237, China
- State Key Laboratory of Chemical Engineering, ECUST, Shanghai, 200237, China
| | - Xingchao Dai
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), 18059, Rostock, Germany
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Hualin Wang
- National Engineering Laboratory for Industrial Wastewater Treatment, East China University of Science and Technology (ECUST), Shanghai, 200237, China
| | - Honglai Liu
- State Key Laboratory of Chemical Engineering, ECUST, Shanghai, 200237, China
| | - Jabor Rabeah
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), 18059, Rostock, Germany
| | - Angelika Brückner
- Leibniz-Institut für Katalyse e.V. an der Universität Rostock (LIKAT), 18059, Rostock, Germany.
| | - Feng Shi
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Ming Gong
- Department of Chemistry, Fudan University, Shanghai, 200438, China
| | - Xuejing Yang
- National Engineering Laboratory for Industrial Wastewater Treatment, East China University of Science and Technology (ECUST), Shanghai, 200237, China.
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15
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Sigmund LM, Ehlert C, Enders M, Graf J, Gryn'ova G, Greb L. Disauerstoffaktivierung und Pyrrol‐α‐Spaltung mit Calix[4]pyrrolatoaluminaten: Enzymmodell durch strukturellen Zwang. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202104916] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Lukas Maximilian Sigmund
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Christopher Ehlert
- Heidelberger Institut für Theoretische Studien (HITS gGmbH) Schloss-Wolfsbrunnenweg 35 69118 Heidelberg Deutschland
- Interdisziplinäres Zentrum für wissenschaftliches Rechnen (IWR) Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 205 69120 Heidelberg Deutschland
| | - Markus Enders
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Jürgen Graf
- Organisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
| | - Ganna Gryn'ova
- Heidelberger Institut für Theoretische Studien (HITS gGmbH) Schloss-Wolfsbrunnenweg 35 69118 Heidelberg Deutschland
- Interdisziplinäres Zentrum für wissenschaftliches Rechnen (IWR) Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 205 69120 Heidelberg Deutschland
| | - Lutz Greb
- Anorganisch-Chemisches Institut Ruprecht-Karls-Universität Heidelberg Im Neuenheimer Feld 270 69120 Heidelberg Deutschland
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16
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Sigmund LM, Ehlert C, Enders M, Graf J, Gryn'ova G, Greb L. Dioxygen Activation and Pyrrole α-Cleavage with Calix[4]pyrrolato Aluminates: Enzyme Model by Structural Constraint. Angew Chem Int Ed Engl 2021; 60:15632-15640. [PMID: 33955154 PMCID: PMC8362023 DOI: 10.1002/anie.202104916] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Indexed: 01/30/2023]
Abstract
The present work describes the reaction of triplet dioxygen with the porphyrinogenic calix[4]pyrrolato aluminates to alkylperoxido aluminates in high selectivity. Multiconfigurational quantum chemical computations disclose the mechanism for this spin‐forbidden process. Despite a negligible spin–orbit coupling constant, the intersystem crossing (ISC) is facilitated by singlet and triplet state degeneracy and spin–vibronic coupling. The formed peroxides are stable toward external substrates but undergo an unprecedented oxidative pyrrole α‐cleavage by ligand aromatization/dearomatization‐initiated O−O σ‐bond scission. A detailed comparison of the calix[4]pyrrolato aluminates with dioxygen‐related enzymology provides insights into the ISC of metal‐ or cofactor‐free enzymes. It substantiates the importance of structural constraint and element–ligand cooperativity for the functions of aerobic life.
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Affiliation(s)
- Lukas Maximilian Sigmund
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Christopher Ehlert
- Heidelberg Institute for Theoretical Studies (HITS gGmbH), Schloss-Wolfsbrunnenweg 35, 69118, Heidelberg, Germany.,Interdisciplinary Center for Scientific Computing (IWR), Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 205, 69120, Heidelberg, Germany
| | - Markus Enders
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Jürgen Graf
- Organisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
| | - Ganna Gryn'ova
- Heidelberg Institute for Theoretical Studies (HITS gGmbH), Schloss-Wolfsbrunnenweg 35, 69118, Heidelberg, Germany.,Interdisciplinary Center for Scientific Computing (IWR), Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 205, 69120, Heidelberg, Germany
| | - Lutz Greb
- Anorganisch-Chemisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany
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17
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Monika, Yadav O, Chauhan H, Ansari A. Electronic structures, bonding, and spin state energetics of biomimetic mononuclear and bridged dinuclear iron complexes: a computational examination. Struct Chem 2021. [DOI: 10.1007/s11224-020-01690-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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18
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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: 89] [Impact Index Per Article: 17.8] [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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19
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Shan C, Yao S, Driess M. Where silylene–silicon centres matter in the activation of small molecules. Chem Soc Rev 2020; 49:6733-6754. [DOI: 10.1039/d0cs00815j] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Small molecules such as H2, N2, CO, NH3, O2 are ubiquitous stable species and their activation and role in the formation of value-added products are of fundamental importance in nature and industry.
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Affiliation(s)
- Changkai Shan
- Department of Chemistry
- Metalorganics and Inorganic Materials
- Technische Universität Berlin
- 10623 Berlin
- Germany
| | - Shenglai Yao
- Department of Chemistry
- Metalorganics and Inorganic Materials
- Technische Universität Berlin
- 10623 Berlin
- Germany
| | - Matthias Driess
- Department of Chemistry
- Metalorganics and Inorganic Materials
- Technische Universität Berlin
- 10623 Berlin
- Germany
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20
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Comba P, Faltermeier D, Krieg S, Martin B, Rajaraman G. Spin state and reactivity of iron(iv)oxido complexes with tetradentate bispidine ligands. Dalton Trans 2020; 49:2888-2894. [DOI: 10.1039/c9dt04578c] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The iron(iv)oxido complex [(bispidine)FeIVO(Cl)]+is shown by experiment and high-level DLPNO-CCSD(T) quantum-chemical calculations to be an extremely short-lived and very reactive intermediate-spin (S= 1) species.
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Affiliation(s)
- Peter Comba
- Universität Heidelberg
- Anorganisch-Chemisches Institut
- D-69120 Heidelberg
- Germany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR)
| | - Dieter Faltermeier
- Universität Heidelberg
- Anorganisch-Chemisches Institut
- D-69120 Heidelberg
- Germany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR)
| | - Saskia Krieg
- Universität Heidelberg
- Anorganisch-Chemisches Institut
- D-69120 Heidelberg
- Germany
| | - Bodo Martin
- Universität Heidelberg
- Anorganisch-Chemisches Institut
- D-69120 Heidelberg
- Germany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR)
| | - Gopalan Rajaraman
- Department of Chemistry
- Indian Institute of Technology Bombay
- Mumbai-400076
- India
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21
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Wu P, Fan F, Song J, Peng W, Liu J, Li C, Cao Z, Wang B. Theory Demonstrated a "Coupled" Mechanism for O 2 Activation and Substrate Hydroxylation by Binuclear Copper Monooxygenases. J Am Chem Soc 2019; 141:19776-19789. [PMID: 31746191 DOI: 10.1021/jacs.9b09172] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Multiscale simulations have been performed to address the longstanding issue of "dioxygen activation" by the binuclear copper monooxygenases (PHM and DβM), which have been traditionally classified as "noncoupled" binuclear copper enzymes. Our QM/MM calculations rule out that CuM(II)-O2• is an active species for H-abstraction from the substrate. In contrast, CuM(II)-O2• would abstract an H atom from the cosubstrate ascorbate to form a CuM(II)-OOH intermediate in PHM and DβM. Consistent with the recently reported structural features of DβM, the umbrella sampling shows that the "open" conformation of the CuM(II)-OOH intermediate could readily transform into the "closed" conformation in PHM, in which we located a mixed-valent μ-hydroperoxodicopper(I,II) intermediate, (μ-OOH)Cu(I)Cu(II). The subsequent O-O cleavage and OH moiety migration to CuH generate the unexpected species (μ-O•)(μ-OH)Cu(II)Cu(II), which is revealed to be the reactive intermediate responsible for substrate hydroxylation. We also demonstrate that the flexible Met ligand is favorable for O-O cleavage reactions, while the replacement of Met with the strongly bound His ligand would inhibit the O-O cleavage reactivity. As such, the study not only demonstrates a "coupled" mechanism for O2 activation by binuclear copper monooxygenases but also deciphers the full catalytic cycle of PHM and DβM in accord with the available experimental data. These findings of O2 activation and substrate hydroxylation by binuclear copper monooxygenases could expand our understanding of the reactivities of the synthetic monocopper complexes.
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Affiliation(s)
- Peng Wu
- State Key Laboratory of Structural Chemistry , Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou , Fujian 350002 , People's Republic of China.,University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China
| | - Fangfang Fan
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 360015 , People's Republic of China
| | - Jinshuai Song
- College of Chemistry, and Institute of Green Catalysis , Zhengzhou University , Zhengzhou 450001 , People's Republic of China
| | - Wei Peng
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 360015 , People's Republic of China
| | - Jia Liu
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 360015 , People's Republic of China
| | - Chunsen Li
- State Key Laboratory of Structural Chemistry , Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences , Fuzhou , Fujian 350002 , People's Republic of China.,Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry , Xiamen , Fujian 361005 , People's Republic of China
| | - Zexing Cao
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 360015 , People's Republic of China
| | - Binju Wang
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering , Xiamen University , Xiamen 360015 , People's Republic of China
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22
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Guo M, Corona T, Ray K, Nam W. Heme and Nonheme High-Valent Iron and Manganese Oxo Cores in Biological and Abiological Oxidation Reactions. ACS CENTRAL SCIENCE 2019; 5:13-28. [PMID: 30693322 PMCID: PMC6346628 DOI: 10.1021/acscentsci.8b00698] [Citation(s) in RCA: 259] [Impact Index Per Article: 43.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Indexed: 05/23/2023]
Abstract
Utilization of O2 as an abundant and environmentally benign oxidant is of great interest in the design of bioinspired synthetic catalytic oxidation systems. Metalloenzymes activate O2 by employing earth-abundant metals and exhibit diverse reactivities in oxidation reactions, including epoxidation of olefins, functionalization of alkane C-H bonds, arene hydroxylation, and syn-dihydroxylation of arenes. Metal-oxo species are proposed as reactive intermediates in these reactions. A number of biomimetic metal-oxo complexes have been synthesized in recent years by activating O2 or using artificial oxidants at iron and manganese centers supported on heme or nonheme-type ligand environments. Detailed reactivity studies together with spectroscopy and theory have helped us understand how the reactivities of these metal-oxygen intermediates are controlled by the electronic and steric properties of the metal centers. These studies have provided important insights into biological reactions, which have contributed to the design of biologically inspired oxidation catalysts containing earth-abundant metals like iron and manganese. In this Outlook article, we survey a few examples of these advances with particular emphasis in each case on the interplay of catalyst design and our understanding of metalloenzyme structure and function.
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Affiliation(s)
- Mian Guo
- Department
of Chemistry and Nano Science, Ewha Womans
University, Seoul 03760, Korea
| | - Teresa Corona
- Department
of Chemistry, Humboldt-Universität
zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Kallol Ray
- Department
of Chemistry, Humboldt-Universität
zu Berlin, Brook-Taylor-Strasse 2, 12489 Berlin, Germany
| | - Wonwoo Nam
- Department
of Chemistry and Nano Science, Ewha Womans
University, Seoul 03760, Korea
- State
Key Laboratory for Oxo Synthesis and Selective Oxidation, Center for
Excellence in Molecular Synthesis, Suzhou
Research Institute of LICP, Lanzhou Institute of Chemical Physics
(LICP), Chinese Academy of Sciences, Lanzhou, 730000, P. R.
China
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23
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Abstract
Aerobic life is possible because the molecular structure of oxygen (O2) makes direct reaction with most organic materials at ambient temperatures an exceptionally slow process. Of course, these reactions are inherently very favorable, and they occur rapidly with the release of a great deal of energy at high temperature. Nature has been able to tap this sequestered reservoir of energy with great spatial and temporal selectivity at ambient temperatures through the evolution of oxidase and oxygenase enzymes. One mechanism used by these enzymes for O2 activation has been studied in detail for the soluble form of the enzyme methane monooxygenase. These studies have revealed the step-by-step process of O2 activation and insertion into the ultimately stable C-H bond of methane. Additionally, an elegant regulatory mechanism has been defined that enlists size selection and quantum tunneling to allow methane oxidation to occur specifically in the presence of more easily oxidized substrates.
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Affiliation(s)
- Rahul Banerjee
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA; , ,
| | - Jason C Jones
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA; , ,
| | - John D Lipscomb
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455, USA; , ,
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24
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Chang WC, Liu P, Guo Y. Mechanistic Elucidation of Two Catalytically Versatile Iron(II)- and α-Ketoglutarate-Dependent Enzymes: Cases Beyond Hydroxylation. COMMENT INORG CHEM 2018. [DOI: 10.1080/02603594.2018.1509856] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Wei-chen Chang
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina, USA
| | - Pinghua Liu
- Department of Chemistry, Boston University, Boston, Massachusetts, USA
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
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25
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Huang X, Groves JT. Oxygen Activation and Radical Transformations in Heme Proteins and Metalloporphyrins. Chem Rev 2018; 118:2491-2553. [PMID: 29286645 PMCID: PMC5855008 DOI: 10.1021/acs.chemrev.7b00373] [Citation(s) in RCA: 658] [Impact Index Per Article: 94.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Indexed: 12/20/2022]
Abstract
As a result of the adaptation of life to an aerobic environment, nature has evolved a panoply of metalloproteins for oxidative metabolism and protection against reactive oxygen species. Despite the diverse structures and functions of these proteins, they share common mechanistic grounds. An open-shell transition metal like iron or copper is employed to interact with O2 and its derived intermediates such as hydrogen peroxide to afford a variety of metal-oxygen intermediates. These reactive intermediates, including metal-superoxo, -(hydro)peroxo, and high-valent metal-oxo species, are the basis for the various biological functions of O2-utilizing metalloproteins. Collectively, these processes are called oxygen activation. Much of our understanding of the reactivity of these reactive intermediates has come from the study of heme-containing proteins and related metalloporphyrin compounds. These studies not only have deepened our understanding of various functions of heme proteins, such as O2 storage and transport, degradation of reactive oxygen species, redox signaling, and biological oxygenation, etc., but also have driven the development of bioinorganic chemistry and biomimetic catalysis. In this review, we survey the range of O2 activation processes mediated by heme proteins and model compounds with a focus on recent progress in the characterization and reactivity of important iron-oxygen intermediates. Representative reactions initiated by these reactive intermediates as well as some context from prior decades will also be presented. We will discuss the fundamental mechanistic features of these transformations and delineate the underlying structural and electronic factors that contribute to the spectrum of reactivities that has been observed in nature as well as those that have been invented using these paradigms. Given the recent developments in biocatalysis for non-natural chemistries and the renaissance of radical chemistry in organic synthesis, we envision that new enzymatic and synthetic transformations will emerge based on the radical processes mediated by metalloproteins and their synthetic analogs.
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Affiliation(s)
- Xiongyi Huang
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
- Department
of Chemistry, California Institute of Technology, Pasadena, California 91125, United States
| | - John T. Groves
- Department
of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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26
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Numata T, Saito T, Kawakami T, Yamanaka S, Okumura M. Quantum mechanics study on synthetic model of copper-containing quercetin 2,4-dioxygenase. Polyhedron 2017. [DOI: 10.1016/j.poly.2017.02.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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27
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Ansari A, Ansari M, Singha A, Rajaraman G. Interplay of Electronic Cooperativity and Exchange Coupling in Regulating the Reactivity of Diiron(IV)-oxo Complexes towards C−H and O−H Bond Activation. Chemistry 2017; 23:10110-10125. [DOI: 10.1002/chem.201701059] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Azaj Ansari
- Department of Chemistry; CUH Haryana; Haryana 123031 India
| | | | - Asmita Singha
- Department of Chemistry; IIT Bombay; Mumbai 400076 India
| | - Gopalan Rajaraman
- Department of Chemistry; Indian Institute of Technology Bombay, Powai; Mumbai, Maharashtra 400076 India
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28
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Roy S, Kästner J. Catalytic Mechanism of Salicylate Dioxygenase: QM/MM Simulations Reveal the Origin of Unexpected Regioselectivity of the Ring Cleavage. Chemistry 2017; 23:8949-8962. [DOI: 10.1002/chem.201701286] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Indexed: 11/11/2022]
Affiliation(s)
- Subhendu Roy
- Institute for Theoretical Chemistry; University of Stuttgart; Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Johannes Kästner
- Institute for Theoretical Chemistry; University of Stuttgart; Pfaffenwaldring 55 70569 Stuttgart Germany
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29
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Álvarez-Barcia S, Kästner J. Atom Tunneling in the Hydroxylation Process of Taurine/α-Ketoglutarate Dioxygenase Identified by Quantum Mechanics/Molecular Mechanics Simulations. J Phys Chem B 2017; 121:5347-5354. [PMID: 28490178 DOI: 10.1021/acs.jpcb.7b03477] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Taurine/α-ketoglutarate dioxygenase is one of the most studied α-ketoglutarate-dependent dioxygenases (αKGDs), involved in several biotechnological applications. We investigated the key step in the catalytic cycle of the αKGDs, the hydrogen transfer process, by a quantum mechanics/molecular mechanics approach (B3LYP/CHARMM22). Analysis of the charge and spin densities during the reaction demonstrates that a concerted mechanism takes place, where the H atom transfer happens simultaneously with the electron transfer from taurine to the Fe═O cofactor. We found the quantum tunneling of the hydrogen atom to increase the rate constant by a factor of 40 at 5 °C. As a consequence, a quite high kinetic isotope effect close to 60 is obtained, which is consistent with the experimental value.
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Affiliation(s)
- Sonia Álvarez-Barcia
- Institute for Theoretical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
| | - Johannes Kästner
- Institute for Theoretical Chemistry, University of Stuttgart , Pfaffenwaldring 55, 70569 Stuttgart, Germany
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30
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Hong S, Lee YM, Ray K, Nam W. Dioxygen activation chemistry by synthetic mononuclear nonheme iron, copper and chromium complexes. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2016.07.006] [Citation(s) in RCA: 134] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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31
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Wang Y, Li J, Liu A. Oxygen activation by mononuclear nonheme iron dioxygenases involved in the degradation of aromatics. J Biol Inorg Chem 2017; 22:395-405. [PMID: 28084551 DOI: 10.1007/s00775-017-1436-5] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 01/03/2017] [Indexed: 11/25/2022]
Abstract
Molecular oxygen is utilized in numerous metabolic pathways fundamental for life. Mononuclear nonheme iron-dependent oxygenase enzymes are well known for their involvement in some of these pathways, activating O2 so that oxygen atoms can be incorporated into their primary substrates. These reactions often initiate pathways that allow organisms to use stable organic molecules as sources of carbon and energy for growth. From the myriad of reactions in which these enzymes are involved, this perspective recounts the general mechanisms of aromatic dihydroxylation and oxidative ring cleavage, both of which are ubiquitous chemical reactions found in life-sustaining processes. The organic substrate provides all four electrons required for oxygen activation and insertion in the reactions mediated by extradiol and intradiol ring-cleaving catechol dioxygenases. In contrast, two of the electrons are provided by NADH in the cis-dihydroxylation mechanism of Rieske dioxygenases. The catalytic nonheme Fe center, with the aid of active site residues, facilitates these electron transfers to O2 as key elements of the activation processes. This review discusses some general questions for the catalytic strategies of oxygen activation and insertion into aromatic compounds employed by mononuclear nonheme iron-dependent dioxygenases. These include: (1) how oxygen is activated, (2) whether there are common intermediates before oxygen transfer to the aromatic substrate, and (3) are these key intermediates unique to mononuclear nonheme iron dioxygenases?
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Affiliation(s)
- Yifan Wang
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, 78249, USA
| | - Jiasong Li
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, 78249, USA
| | - Aimin Liu
- Department of Chemistry, University of Texas at San Antonio, San Antonio, TX, 78249, USA.
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Huang X, Groves JT. Beyond ferryl-mediated hydroxylation: 40 years of the rebound mechanism and C-H activation. J Biol Inorg Chem 2016; 22:185-207. [PMID: 27909920 PMCID: PMC5350257 DOI: 10.1007/s00775-016-1414-3] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 11/03/2016] [Indexed: 11/24/2022]
Abstract
Since our initial report in 1976, the oxygen rebound mechanism has become the consensus mechanistic feature for an expanding variety of enzymatic C-H functionalization reactions and small molecule biomimetic catalysts. For both the biotransformations and models, an initial hydrogen atom abstraction from the substrate (R-H) by high-valent iron-oxo species (Fen=O) generates a substrate radical and a reduced iron hydroxide, [Fen-1-OH ·R]. This caged radical pair then evolves on a complicated energy landscape through a number of reaction pathways, such as oxygen rebound to form R-OH, rebound to a non-oxygen atom affording R-X, electron transfer of the incipient radical to yield a carbocation, R+, desaturation to form olefins, and radical cage escape. These various flavors of the rebound process, often in competition with each other, give rise to the wide range of C-H functionalization reactions performed by iron-containing oxygenases. In this review, we first recount the history of radical rebound mechanisms, their general features, and key intermediates involved. We will discuss in detail the factors that affect the behavior of the initial caged radical pair and the lifetimes of the incipient substrate radicals. Several representative examples of enzymatic C-H transformations are selected to illustrate how the behaviors of the radical pair [Fen-1-OH ·R] determine the eventual reaction outcome. Finally, we discuss the powerful potential of "radical rebound" processes as a general paradigm for developing novel C-H functionalization reactions with synthetic, biomimetic catalysts. We envision that new chemistry will continue to arise by bridging enzymatic "radical rebound" with synthetic organic chemistry.
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33
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New insight into cofactor-free oxygenation from combined experimental and computational approaches. Curr Opin Struct Biol 2016; 41:109-118. [DOI: 10.1016/j.sbi.2016.06.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Accepted: 06/22/2016] [Indexed: 01/07/2023]
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Midya L, Pal A, Pal S. Development of Crosslinked Chitosan/Au Nanocomposite, Its Characterization and Application towards Solar Light Driven Photocatalytic Degradation of Toxic Organic Compounds. ChemistrySelect 2016. [DOI: 10.1002/slct.201601337] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Lipi Midya
- Polymer Chemistry Laboratory; Department of Applied Chemistry; Indian Institute of Technology (ISM), Dhanbad; Dhanbad- 826004 India
| | - Aniruddha Pal
- Polymer Chemistry Laboratory; Department of Applied Chemistry; Indian Institute of Technology (ISM), Dhanbad; Dhanbad- 826004 India
| | - Sagar Pal
- Polymer Chemistry Laboratory; Department of Applied Chemistry; Indian Institute of Technology (ISM), Dhanbad; Dhanbad- 826004 India
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Abstract
The non-heme Fe enzymes are ubiquitous in nature and perform a wide range of functions involving O2 activation. These had been difficult to study relative to heme enzymes; however, spectroscopic methods that provide significant insight into the correlation of structure with function have now been developed. This Current Topics article summarizes both the molecular mechanism these enzymes use to control O2 activation in the presence of cosubstrates and the oxygen intermediates these reactions generate. Three types of O2 activation are observed. First, non-heme reactivity is shown to be different from heme chemistry where a low-spin FeIII-OOH non-heme intermediate directly reacts with substrate. Also, two subclasses of non-heme Fe enzymes generate high-spin FeIV═O intermediates that provide both σ and π frontier molecular orbitals that can control selectivity. Finally, for several subclasses of non-heme Fe enzymes, binding of the substrate to the FeII site leads to the one-electron reductive activation of O2 to an FeIII-superoxide capable of H atom abstraction and electrophilic attack.
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Affiliation(s)
- Edward I Solomon
- Department of Chemistry, Stanford University , Stanford, California 94305, United States.,SLAC National Accelerator Laboratory , Menlo Park, California 94025, United States
| | - Serra Goudarzi
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Kyle D Sutherlin
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
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Abstract
CytP450s have a cysteine-bound heme cofactor that, in its as-isolated resting (oxidized) form, can be conclusively described as a ferric thiolate species. Unlike the native enzyme, most synthetic thiolate-bound ferric porphyrins are unstable in air unless the axial thiolate ligand is sterically protected. Spectroscopic investigations on a series of synthetic mimics of cytP450 indicate that a thiolate-bound ferric porphyrin coexists in organic solutions at room temperature (RT) with a thiyl-radical bound ferrous porphyrin, i.e., its valence tautomer. The ferric thiolate state is favored by greater enthalpy and is air stable. The ferrous thiyl state is favored by entropy, populates at RT, and degrades in air. These ground states can be reversibly interchanged at RT by the addition or removal of water to the apolar medium. It is concluded that hydrogen bonding and local electrostatics protect the resting oxidized cytP450 active site from degradation in air by stabilizing the ferric thiolate ground state in contrast to its synthetic analogs.
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Christian GJ, Neese F, Ye S. Unravelling the Molecular Origin of the Regiospecificity in Extradiol Catechol Dioxygenases. Inorg Chem 2016; 55:3853-64. [PMID: 27050565 DOI: 10.1021/acs.inorgchem.5b02978] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many factors have been suggested to control the selectivity for extradiol or intradiol cleavage in catechol dioxygenases. The varied selectivity of model complexes and the ability to force an extradiol enzyme to do intradiol cleavage indicate that the problem may be complex. In this paper we focus on the regiospecificity of the proximal extradiol dioxygenase, homoprotocatechuate 2,3-dioxygenase (HPCD), for which considerable advances have been made in our understanding of the mechanism from an experimental and computational standpoint. Two key steps in the reaction mechanism were investigated: (1) attack of the substrate by the superoxide moiety and (2) attack of the substrate by the oxyl radical generated by O-O bond cleavage. The selectivity at both steps was investigated through a systematic study of the role of the substrate and the first and second coordination spheres. For the isolated native substrate, intradiol cleavage is calculated to be both kinetically and thermodynamically favored, therefore nature must use the enzyme environment to reverse this preference. Two second sphere residues were found to play key roles in controlling the regiospecificity of the reaction: Tyr257 and His200. Tyr257 controls the selectivity by modulating the electronic structure of the substrate, while His200 controls selectivity through steric effects and by preventing alternative pathways to intradiol cleavage.
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Affiliation(s)
- Gemma J Christian
- Max-Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.,Avondale College of Higher Education , Cooranbong, New South Wales 2265, Australia
| | - Frank Neese
- Max-Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Shengfa Ye
- Max-Planck Institute for Chemical Energy Conversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
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Martin DJ, Liu G, Moniz SJA, Bi Y, Beale AM, Ye J, Tang J. Efficient visible driven photocatalyst, silver phosphate: performance, understanding and perspective. Chem Soc Rev 2016. [PMID: 26204436 DOI: 10.1039/c5cs00380f] [Citation(s) in RCA: 191] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Photocatalysis is a promising technology that can contribute to renewable energy production from water and water purification. In order to further develop the field and meet industrial requirements, it is imperative to focus on advancing high efficiency visible light photocatalysts, such as silver phosphate (Ag3PO4). This review aims to highlight the recent progress made in the field, focusing on oxygen production from water, and organic contaminant decomposition using Ag3PO4. The most important advances are discussed and explained in detail, including semiconductor-semiconductor junctions, metal-semiconductor junctions, exposing facet control, and fundamental understanding using advanced spectroscopies and computational chemistry. The review then concludes by critically summarising both findings and current perspectives, and ultimately how the field might best advance in the near future.
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Affiliation(s)
- David James Martin
- Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK. and Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK
| | - Guigao Liu
- Environmental Remediation Materials Unit and International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, Japan. and Graduate School of Chemical Science and Engineering, Hokkaido University, Sapporo, Japan
| | - Savio J A Moniz
- Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK.
| | - Yingpu Bi
- State Key Laboratory for Oxo Synthesis & Selective Oxidation, National Engineering Research Center for Fine Petrochemical Intermediates, Lanzhou Institute of Chemical Physics, CAS, Lanzhou 730000, China
| | - Andrew M Beale
- Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK and Research Complex at Harwell, Harwell, Didcot, Oxfordshire OX11 0FA, UK
| | - Jinhua Ye
- Environmental Remediation Materials Unit and International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki, Japan. and Graduate School of Chemical Science and Engineering, Hokkaido University, Sapporo, Japan
| | - Junwang Tang
- Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK.
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40
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Roy S, Kästner J. QM/MM-Simulationen ergeben synergetische Substrat- und Sauerstoffaktivierung in Salicylat-Dioxygenase. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201506363] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Subhendu Roy
- Institut für Theoretische Chemie; Universität Stuttgart; Pfaffenwaldring 55 70569 Stuttgart Deutschland
| | - Johannes Kästner
- Institut für Theoretische Chemie; Universität Stuttgart; Pfaffenwaldring 55 70569 Stuttgart Deutschland
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41
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Roy S, Kästner J. Synergistic Substrate and Oxygen Activation in Salicylate Dioxygenase Revealed by QM/MM Simulations. Angew Chem Int Ed Engl 2015; 55:1168-72. [DOI: 10.1002/anie.201506363] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Revised: 09/18/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Subhendu Roy
- Institute for Theoretical Chemistry; University of Stuttgart; Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Johannes Kästner
- Institute for Theoretical Chemistry; University of Stuttgart; Pfaffenwaldring 55 70569 Stuttgart Germany
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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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Light KM, Yamanaka Y, Odaka M, Solomon EI. Spectroscopic and Computational Studies of Nitrile Hydratase: Insights into Geometric and Electronic Structure and the Mechanism of Amide Synthesis. Chem Sci 2015; 6:6280-6294. [PMID: 26508996 PMCID: PMC4618400 DOI: 10.1039/c5sc02012c] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Nitrile hydratases (NHases) are mononuclear nonheme enzymes that catalyze the hydration of nitriles to amides. NHase is unusual in that it utilizes a low-spin (LS) FeIII center and a unique ligand set comprised of two deprotonated backbone amides, cysteine-based sulfenic acid (RSO(H)) and sulfinic acid (RSO2-), and an unmodified cysteine trans to an exogenous ligand site. Electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD) and low-temperature absorption (LT-Abs) spectroscopies are used to determine the geometric and electronic structures of butyrate-bound (NHaseBA) and active (NHaseAq) NHase. These data calibrate DFT models, which are then extended to explore the mechanism of nitrile hydration by NHase. In particular, the nitrile is activated by coordination to the LS FeIII and the sulfenate group is found to be deprotonated and a significantly better nucleophile than water that can attack the coordinated nitrile to form a cyclic species. Attack at the sulfenate S atom of the cyclic species is favorable and leads to a lower kinetic barrier than attack by water on coordinated, uncyclized nitrile, while attack at the C of the cyclic species is unfavorable. The roles of the unique ligand set and low-spin nature of the NHase active site in function are also explored. It is found that the oxidized thiolate ligands are crucial to maintaining the LS state, which is important in the binding and activation of nitrile susbtrates. The dominant role of the backbone amidate ligands appears to be as a chelate in keeping the sulfenate properly oriented for nucleophilic attack on the coordinated substrate.
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Affiliation(s)
- Kenneth M Light
- Department of Chemistry, Stanford University, Stanford, CA 94305
| | - Yasuaki Yamanaka
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, Japan
| | - Masafumi Odaka
- Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, Japan
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, CA 94305
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44
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Srnec M, Wong SD, Solomon EI. Excited state potential energy surfaces and their interactions in Fe(IV)=O active sites. Dalton Trans 2015; 43:17567-77. [PMID: 24916844 DOI: 10.1039/c4dt01366b] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The non-heme ferryl active sites are of significant interest for their application in biomedical and green catalysis. These sites have been shown to have an S = 1 or S = 2 ground spin state; the latter is functional in biology. Low-temperature magnetic circular dichroism (LT MCD) spectroscopy probes the nature of the excited states in these species including ligand-field (LF) states that are otherwise difficult to study by other spectroscopies. In particular, the temperature dependences of MCD features enable their unambiguous assignment and thus determination of the low-lying excited states in two prototypical S = 1 and S = 2 NHFe(IV)[double bond, length as m-dash]O complexes. Furthermore, some MCD bands exhibit vibronic structures that allow mapping of excited-state interactions and their effects on the potential energy surfaces (PESs). For the S = 2 species, there is also an unusual spectral feature in both near-infrared absorption and MCD spectra - Fano antiresonance (dip in Abs) and Fano resonance (sharp peak in MCD) that indicates the weak spin-orbit coupling of an S = 1 state with the S = 2 LF state. These experimental data are correlated with quantum-chemical calculations that are further extended to analyze the low-lying electronic states and the evolution of their multiconfigurational characters along the Fe-O PESs. These investigations show that the lowest-energy states develop oxyl Fe(III) character at distances that are relevant to the transition state (TS) for H-atom abstraction and define the frontier molecular orbitals that participate in the reactivity of S = 1 vs. S = 2 non-heme Fe(IV)[double bond, length as m-dash]O active sites. The S = 1 species has only one available channel that requires the C-H bond of a substrate to approach perpendicular to the Fe-oxo bond (the π channel). In contrast, there are three channels (one σ and two π) available for the S = 2 non-heme Fe(IV)[double bond, length as m-dash]O system allowing C-H substrate approach both along and perpendicular to the Fe-oxo bond that have important implications for enzymatic selectivity.
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Affiliation(s)
- Martin Srnec
- Department of Chemistry, Stanford University, Stanford, CA 94305-5080, USA.
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Saito T, Kawakami T, Yamanaka S, Okumura M. Computational Study of Catalytic Reaction of Quercetin 2,4-Dioxygenase. J Phys Chem B 2015; 119:6952-62. [PMID: 25990020 DOI: 10.1021/acs.jpcb.5b03564] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We present a quantum mechanics/molecular mechanics (QM/MM) and QM-only study on the oxidative ring-cleaving reaction of quercetin catalyzed by quercetin 2,4-dioxygenase (2,4-QD). 2,4-QD has a mononuclear type 2 copper center and incorporates two oxygen atoms at C2 and C4 positions of the substrate. It has not been clear whether dioxygen reacts with a copper ion or a substrate radical as the first step. We have found that dioxygen is more likely to bind to a Cu(2+) ion, involving the dissociation of the substrate from the copper ion. Then a Cu(2+)-alkylperoxo complex can be generated. Comparison of geometry and stability between QM-only and QM/MM results strongly indicates that steric effects of the protein environment contribute to maintain the orientation of the substrate dissociated from the copper center. The present QM/MM results also highlight that a prior rearrangement of the Cu(2+)-alkylperoxo complex and a subsequent hydrogen bond switching assisted by the movement of Glu73 can facilitate formation of an endoperoxide intermediate selectively.
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Affiliation(s)
- Toru Saito
- †Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.,‡Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology (JST) Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Takashi Kawakami
- †Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Shusuke Yamanaka
- †Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.,‡Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology (JST) Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Mitsutaka Okumura
- †Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan.,‡Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology (JST) Agency, Kawaguchi, Saitama 332-0012, Japan
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Wang B, Zhou X, Wang D, Yin JJ, Chen H, Gao X, Zhang J, Ibrahim K, Chai Z, Feng W, Zhao Y. Structure and catalytic activities of ferrous centers confined on the interface between carbon nanotubes and humic acid. NANOSCALE 2015; 7:2651-2658. [PMID: 25580558 DOI: 10.1039/c4nr06665k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Preparation of heterogeneous catalysts with active ferrous centers is of great significance for industrial and environmental catalytic processes. Nanostructured carbon materials (NCM), which possess free-flowing π electrons, can coordinate with transition metals, provide a confinement environment for catalysis, and act as potential supports or ligands to construct analogous complexes. However, designing such catalysts using NCM is still seldom studied to date. Herein, we synthesized a sandwich structured ternary complex via the coordination of Fe-loaded humic acid (HA) with C=C bonds in the aromatic rings of carbon nanotubes (CNTs), in which the O/N-Fe-C interface configuration provides the confinement environment for the ferrous sites. The experimental and theoretical results revealed octahedrally/tetrahedrally coordinated geometry at Fe centers, and the strong hybridization between CNT C π* and Fe 3d orbitals induces discretization of the atomic charges on aromatic rings of CNTs, which facilitates O2 adsorption and electron transfer from carbon to O2, which enhances O2 activation. The O2 activation by the novel HA/Fe-CNT complex can be applied in the oxidative degradation of phenol red (PR) and bisphenol A (BPA) in aqueous media.
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Affiliation(s)
- Bing Wang
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, CAS Key Laboratory of Nuclear Radiation and Nuclear Energy Technology, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
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Abstract
In order to address how diverse metalloprotein active sites, in particular those containing iron and copper, guide O₂binding and activation processes to perform diverse functions, studies of synthetic models of the active sites have been performed. These studies have led to deep, fundamental chemical insights into how O₂coordinates to mono- and multinuclear Fe and Cu centers and is reduced to superoxo, peroxo, hydroperoxo, and, after O-O bond scission, oxo species relevant to proposed intermediates in catalysis. Recent advances in understanding the various factors that influence the course of O₂activation by Fe and Cu complexes are surveyed, with an emphasis on evaluating the structure, bonding, and reactivity of intermediates involved. The discussion is guided by an overarching mechanistic paradigm, with differences in detail due to the involvement of disparate metal ions, nuclearities, geometries, and supporting ligands providing a rich tapestry of reaction pathways by which O₂is activated at Fe and Cu sites.
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Crystal structures of alkylperoxo and anhydride intermediates in an intradiol ring-cleaving dioxygenase. Proc Natl Acad Sci U S A 2014; 112:388-93. [PMID: 25548185 DOI: 10.1073/pnas.1419118112] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Intradiol aromatic ring-cleaving dioxygenases use an active site, nonheme Fe(3+) to activate O2 and catecholic substrates for reaction. The inability of Fe(3+) to directly bind O2 presents a mechanistic conundrum. The reaction mechanism of protocatechuate 3,4-dioxygenase is investigated here using the alternative substrate 4-fluorocatechol. This substrate is found to slow the reaction at several steps throughout the mechanistic cycle, allowing the intermediates to be detected in solution studies. When the reaction was initiated in an enzyme crystal, it was found to halt at one of two intermediates depending on the pH of the surrounding solution. The X-ray crystal structure of the intermediate at pH 6.5 revealed the key alkylperoxo-Fe(3+) species, and the anhydride-Fe(3+) intermediate was found for a crystal reacted at pH 8.5. Intermediates of these types have not been structurally characterized for intradiol dioxygenases, and they validate four decades of spectroscopic, kinetic, and computational studies. In contrast to our similar in crystallo crystallographic studies of an Fe(2+)-containing extradiol dioxygenase, no evidence for a superoxo or peroxo intermediate preceding the alkylperoxo was found. This observation and the lack of spectroscopic evidence for an Fe(2+) intermediate that could bind O2 are consistent with concerted formation of the alkylperoxo followed by Criegee rearrangement to yield the anhydride and ultimately ring-opened product. Structural comparison of the alkylperoxo intermediates from the intra- and extradiol dioxygenases provides a rationale for site specificity of ring cleavage.
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Balamurugan M, Vadivelu P, Palaniandavar M. Iron(iii) complexes of tripodal tetradentate 4N ligands as functional models for catechol dioxygenases: the electronic vs. steric effect on extradiol cleavage. Dalton Trans 2014; 43:14653-68. [DOI: 10.1039/c3dt52145a] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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50
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Lu L, Zhu C, Xia B, Yi C. Oxidative Demethylation of DNA and RNA Mediated by Non-Heme Iron-Dependent Dioxygenases. Chem Asian J 2014; 9:2018-29. [DOI: 10.1002/asia.201402148] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Indexed: 11/10/2022]
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