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Li H, Zhang Y, Huang Y, Duan P, Ge R, Han X, Zhang W. A Simple Access to γ- and ε-Keto Arenes via Enzymatic Divergent C─H Bond Oxyfunctionalization. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2304605. [PMID: 37870171 DOI: 10.1002/advs.202304605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/28/2023] [Indexed: 10/24/2023]
Abstract
Performing divergent C─H bond functionalization on molecules with multiple reaction sites is a significant challenge in organic chemistry. Biocatalytic oxyfunctionalization reactions of these compounds to the corresponding ketones/aldehydes are typically hindered by selectivity issues. To address these challenges, the catalytic performance of oxidoreductases is explored. The results show that combining the peroxygenase-catalyzed propargylic C─H bond oxidation with the Old Yellow Enzyme-catalyzed reduction of conjugated C─C triple bonds in one-pot enables the regio- and chemoselective oxyfunctionalization of sp3 C─H bonds that are distant from benzylic sites. This enzymatic approach yielded a variety of γ-keto arenes with diverse structural and electronic properties in yields of up to 99% and regioselectivity of 100%, which are difficult to achieve using other chemocatalysis and enzymes. By adjusting the C─C triple bond, the carbonyl group's position can be further tuned to yield ε-keto arenes. This enzymatic approach can be combined with other biocatalysts to establish new synthetic pathways for accessing various challenging divergent C─H bond functionalization reactions.
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Affiliation(s)
- Huanhuan Li
- School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, 710049, China
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin, 300308, China
| | - Yalan Zhang
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin, 300308, China
| | - Yawen Huang
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin, 300308, China
| | - Peigao Duan
- School of Chemical Engineering and Technology, Xi'an Jiaotong University, Xi'an, 710049, China
| | - Ran Ge
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin, 300308, China
| | - Xiaofeng Han
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin, 300308, China
| | - Wuyuan Zhang
- Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, 32 West 7th Avenue, Tianjin, 300308, China
- National Innovation Center for Synthetic Biotechnology, 32 West 7th Avenue, Tianjin, 300308, China
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Ahmad R, Rizaldo S, Gohari M, Shanahan J, Shaner SE, Stone KL, Kissel DS. Buffer Effects in Zirconium-Based UiO Metal-Organic Frameworks (MOFs) That Influence Enzyme Immobilization and Catalytic Activity in Enzyme/MOF Biocatalysts. ACS OMEGA 2023; 8:22545-22555. [PMID: 37396281 PMCID: PMC10308582 DOI: 10.1021/acsomega.3c00703] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 05/11/2023] [Indexed: 07/04/2023]
Abstract
Novel biocatalysts that feature enzymes immobilized onto solid supports have recently become a major research focus in an effort to create more sustainable and greener chemistries in catalysis. Many of these novel biocatalyst systems feature enzymes immobilized onto metal-organic frameworks (MOFs), which have been shown to increase enzyme activity, stability, and recyclability in industrial processes. While the strategies used for immobilizing enzymes onto MOFs can vary, the conditions always require a buffer to maintain the functionality of the enzymes during immobilization. This report brings attention to critical buffer effects important to consider when developing enzyme/MOF biocatalysts, specifically for buffering systems containing phosphate ions. A comparative analysis of different enzyme/MOF biocatalysts featuring horseradish peroxidase and/or glucose oxidase immobilized onto the MOFs UiO-66, UiO-66-NH2, and UiO-67 using a noncoordinate buffering system (MOPSO buffer) and a phosphate buffering system (PBS) show that phosphate ions can have an inhibitory effect. Previous studies utilizing phosphate buffers for enzyme immobilization onto MOFs have shown Fourier transform infrared (FT-IR) spectra that have been assigned stretching frequencies associated with enzymes after immobilization. Analyses and characterizations using zeta potential measurements, scanning electron microscopy, Brunauer-Emmett-Teller surface area, powder X-ray diffraction, Energy Dispersive X-ray Spectroscopy, and FT-IR show concerning differences in enzyme loading and activity based on the buffering system used during immobilization.
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Affiliation(s)
- Raneem Ahmad
- Department
of Chemistry, Lewis University, One University Pkwy, Romeoville, Illinois 60446, United States
| | - Sydnie Rizaldo
- Department
of Chemistry, Lewis University, One University Pkwy, Romeoville, Illinois 60446, United States
| | - Mahnaz Gohari
- Department
of Chemistry, Lewis University, One University Pkwy, Romeoville, Illinois 60446, United States
| | - Jordan Shanahan
- Department
of Chemistry, Lewis University, One University Pkwy, Romeoville, Illinois 60446, United States
| | - Sarah E. Shaner
- Department
of Chemistry and Physics, Southeast Missouri
State University, One University Plaza, Cape Girardeau, Missouri 63701, United States
| | - Kari L. Stone
- Department
of Chemistry, Lewis University, One University Pkwy, Romeoville, Illinois 60446, United States
| | - Daniel S. Kissel
- Department
of Chemistry, Lewis University, One University Pkwy, Romeoville, Illinois 60446, United States
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3
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Immobilization of a Bienzymatic System via Crosslinking to a Metal‐Organic Framework. Catalysts 2022. [DOI: 10.3390/catal12090969] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
A leading biotechnological advancement in the field of biocatalysis is the immobilization of enzymes on solid supports to create more stable and recyclable systems. Metal-organic frameworks (MOFs) are porous materials that have been explored as solid supports for enzyme immobilization. Composed of organic linkers and inorganic nodes, MOFs feature empty void space with large surface areas and have the ability to be modified post-synthesis. Our target enzyme system for immobilization is glucose oxidase (GOx) and chloroperoxidase (CPO). Glucose oxidase catalyzes the oxidation of glucose and is used for many applications in biosensing, biofuel cells, and food production. Chloroperoxidase is a fungal heme enzyme that catalyzes peroxide-dependent halogenation, oxidation, and hydroxylation. These two enzymes work sequentially in this enzyme system by GOx producing peroxide, which activates CPO that reacts with a suitable substrate. This study focuses on using a zirconium-based MOF, UiO-66-NH2, to immobilize the enzyme system via crosslinking with the MOF’s amine group on the surface of the MOF. This study investigates two different crosslinkers: disuccinimidyl glutarate (DSG) and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/N-hydroxysuccinidimide (NHS), providing stable crosslinking of the MOF to the enzymes. The two crosslinkers are used to covalently bond CPO and GOx onto UiO-66-NH2, and a comparison of the recyclability and enzymatic activity of the single immobilization of CPO and the doubly immobilized CPO and GOx is discussed through assays and characterization analyses. The DSG-crosslinked composites displayed enhanced activity relative to the free enzyme, and all crosslinked enzyme/MOF composites demonstrated recyclability, with at least 30% of the activity being retained after four catalytic cycles. The results of this report will aid researchers in utilizing CPO as a biocatalyst that is more active and has greater recyclability.
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Hobisch M, Holtmann D, Gomez de Santos P, Alcalde M, Hollmann F, Kara S. Recent developments in the use of peroxygenases - Exploring their high potential in selective oxyfunctionalisations. Biotechnol Adv 2021; 51:107615. [PMID: 32827669 PMCID: PMC8444091 DOI: 10.1016/j.biotechadv.2020.107615] [Citation(s) in RCA: 67] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 08/10/2020] [Accepted: 08/14/2020] [Indexed: 12/11/2022]
Abstract
Peroxygenases are an emerging new class of enzymes allowing selective oxyfunctionalisation reactions in a cofactor-independent way different from well-known P450 monooxygenases. Herein, we focused on recent developments from organic synthesis, molecular biotechnology and reaction engineering viewpoints that are devoted to bring these enzymes in industrial applications. This covers natural diversity from different sources, protein engineering strategies for expression, substrate scope, activity and selectivity, stabilisation of enzymes via immobilisation, and the use of peroxygenases in low water media. We believe that peroxygenases have much to offer for selective oxyfunctionalisations and we have much to study to explore the full potential of these versatile biocatalysts in organic synthesis.
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Affiliation(s)
- Markus Hobisch
- Department of Engineering, Biocatalysis and Bioprocessing Group, Aarhus University, Gustav Wieds Vej 10, Aarhus C 8000, Denmark
| | - Dirk Holtmann
- Institute of Bioprocess Engineering and Pharmaceutical Technology, University of Applied Sciences Mittelhessen, Wiesenstr. 14, Gießen 35390, Germany
| | | | - Miguel Alcalde
- Department of Biocatalysis, Institute of Catalysis, CSIC, C/Marie Curie 2, Madrid 28049, Spain; EvoEnzyme S.L, C/ Marie Curie 2, Madrid 28049, Spain
| | - Frank Hollmann
- Department of Biotechnology, Biocatalysis Group, Delft University of Technology, Van der Maasweg 9, Delft 2629 HZ, The Netherlands
| | - Selin Kara
- Department of Engineering, Biocatalysis and Bioprocessing Group, Aarhus University, Gustav Wieds Vej 10, Aarhus C 8000, Denmark.
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5
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Spectroscopic and QM/MM investigations of Chloroperoxidase catalyzed degradation of orange G. Arch Biochem Biophys 2016; 596:1-9. [DOI: 10.1016/j.abb.2016.02.026] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Revised: 02/05/2016] [Accepted: 02/24/2016] [Indexed: 11/30/2022]
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Bormann S, Gomez Baraibar A, Ni Y, Holtmann D, Hollmann F. Specific oxyfunctionalisations catalysed by peroxygenases: opportunities, challenges and solutions. Catal Sci Technol 2015. [DOI: 10.1039/c4cy01477d] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Peroxygenases are promising oxyfunctionalisation catalysts for organic synthesis.
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Affiliation(s)
| | - Alvaro Gomez Baraibar
- Delft University of Technology
- Department of Biotechnology
- 2628 BL Delft
- The Netherlands
| | - Yan Ni
- Delft University of Technology
- Department of Biotechnology
- 2628 BL Delft
- The Netherlands
| | - Dirk Holtmann
- DECHEMA Research Institute
- 60486 Frankfurt am Main
- Germany
| | - Frank Hollmann
- Delft University of Technology
- Department of Biotechnology
- 2628 BL Delft
- The Netherlands
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7
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Monti D, Ottolina G, Carrea G, Riva S. Redox Reactions Catalyzed by Isolated Enzymes. Chem Rev 2011; 111:4111-40. [DOI: 10.1021/cr100334x] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Daniela Monti
- Istituto di Chimica del Riconoscimento Molecolare, C.N.R., Via Mario Bianco 9, 20131 Milano, Italy
| | - Gianluca Ottolina
- Istituto di Chimica del Riconoscimento Molecolare, C.N.R., Via Mario Bianco 9, 20131 Milano, Italy
| | - Giacomo Carrea
- Istituto di Chimica del Riconoscimento Molecolare, C.N.R., Via Mario Bianco 9, 20131 Milano, Italy
| | - Sergio Riva
- Istituto di Chimica del Riconoscimento Molecolare, C.N.R., Via Mario Bianco 9, 20131 Milano, Italy
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8
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Affiliation(s)
- Lowell P Hager
- Department of Biochemistry, School of Molecular and Cellular Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.
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9
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Perez DI, Grau MM, Arends IWCE, Hollmann F. Visible light-driven and chloroperoxidase-catalyzed oxygenation reactions. Chem Commun (Camb) 2009:6848-50. [PMID: 19885500 DOI: 10.1039/b915078a] [Citation(s) in RCA: 93] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Robust peroxidase-catalyzed enantiospecific oxyfunctionalizations can be achieved by simple light-driven in situ generation of hydrogen peroxide.
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Affiliation(s)
- Daniel I Perez
- Department of Biotechnology, Biocatalysis and Organic Chemistry, Delft University of Technology, Julianalaan 136, Delft, 2628 BL, The Netherlands
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10
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Chen H, Hirao H, Derat E, Schlichting I, Shaik S. Quantum Mechanical/Molecular Mechanical Study on the Mechanisms of Compound I Formation in the Catalytic Cycle of Chloroperoxidase: An Overview on Heme Enzymes. J Phys Chem B 2008; 112:9490-500. [DOI: 10.1021/jp803010f] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hui Chen
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel, and Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Hajime Hirao
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel, and Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Etienne Derat
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel, and Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Ilme Schlichting
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel, and Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - Sason Shaik
- Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Givat Ram Campus, 91904 Jerusalem, Israel, and Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Jahnstrasse 29, 69120 Heidelberg, Germany
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11
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Hofrichter M, Ullrich R. Heme-thiolate haloperoxidases: versatile biocatalysts with biotechnological and environmental significance. Appl Microbiol Biotechnol 2006; 71:276-88. [PMID: 16628447 DOI: 10.1007/s00253-006-0417-3] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Revised: 03/06/2006] [Accepted: 03/06/2006] [Indexed: 11/24/2022]
Abstract
Heme-thiolate haloperoxidases are undoubtedly the most versatile biocatalysts of the hemeprotein family and share catalytic properties with at least three further classes of heme-containing oxidoreductases, namely, classic plant and fungal peroxidases, cytochrome P450 monooxygenases, and catalases. For a long time, only one enzyme of this type--the chloroperoxidase (CPO) of the ascomycete Caldariomyces fumago--has been known. The enzyme is commercially available as a fine chemical and catalyzes the unspecific chlorination, bromination, and iodation (but no fluorination) of a variety of electrophilic organic substrates via hypohalous acid as actual halogenating agent. In the absence of halide, CPO resembles cytochrome P450s and epoxidizes and hydroxylates activated substrates such as organic sulfides and olefins; aromatic rings, however, are not susceptible to CPO-catalyzed oxygen-transfer. Recently, a second fungal haloperoxidase of the heme-thiolate type has been discovered in the agaric mushroom Agrocybe aegerita. The UV-Vis adsorption spectrum of the isolated enzyme shows little similarity to that of CPO but is almost identical to a resting-state P450. The Agrocybe aegerita peroxidase (AaP) has strong brominating as well as weak chlorinating and iodating activities, and catalyzes both benzylic and aromatic hydroxylations (e.g., of toluene and naphthalene). AaP and related fungal peroxidases could become promising biocatalysts in biotechnological applications because they seemingly fill the gap between CPO and P450 enzymes and act as "self-sufficient" peroxygenases. From the environmental point of view, the existence of a halogenating mushroom enzyme is interesting because it could be linked to the multitude of halogenated compounds known from these organisms.
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Affiliation(s)
- Martin Hofrichter
- Unit of Environmental Biotechnology, International Graduate School of Zittau, Germany.
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Yi X, Conesa A, Punt PJ, Hager LP. Examining the role of glutamic acid 183 in chloroperoxidase catalysis. J Biol Chem 2003; 278:13855-9. [PMID: 12576477 DOI: 10.1074/jbc.m210906200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Site-directed mutagenesis has been used to investigate the role of glutamic acid 183 in chloroperoxidase catalysis. Based on the x-ray crystallographic structure of chloroperoxidase, Glu-183 is postulated to function on distal side of the heme prosthetic group as an acid-base catalyst in facilitating the reaction between the peroxidase and hydrogen peroxide with the formation of Compound I. In contrast, the other members of the heme peroxidase family use a histidine residue in this role. Plasmids have now been constructed in which the codon for Glu-183 is replaced with a histidine codon. The mutant recombinant gene has been expressed in Aspergillus niger. An analysis of the produced mutant gene shows that the substitution of Glu-183 with a His residue is detrimental to the chlorination and dismutation activity of chloroperoxidase. The activity is reduced by 85 and 50% of wild type activity, respectively. However, quite unexpectedly, the epoxidation activity of the mutant enzyme is significantly enhanced approximately 2.5-fold. These results show that Glu-183 is important but not essential for the chlorination activity of chloroperoxidase. It is possible that the increased epoxidation of the mutant enzyme is based on an increase in the hydrophobicity of the active site.
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Affiliation(s)
- Xianwen Yi
- Department of Biochemistry, University of Illinois at Urbana-Champaign, 61801, USA
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Wang X, Tachikawa H, Yi X, Manoj KM, Hager LP. Two-dimensional NMR study of the heme active site structure of chloroperoxidase. J Biol Chem 2003; 278:7765-74. [PMID: 12488315 DOI: 10.1074/jbc.m209462200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The heme active site structure of chloroperoxidase (CPO), a glycoprotein that displays versatile catalytic activities isolated from the marine mold Caldariomyces fumago, has been characterized by two-dimensional NMR spectroscopic studies. All hyperfine shifted resonances from the heme pocket as well as resonances from catalytically relevant amino acid residues including the heme iron ligand (Cys(29)) attributable to the unique catalytic properties of CPO have been firmly assigned through (a) measurement of nuclear Overhauser effect connectivities, (b) prediction of the Curie intercepts from both one- and two-dimensional variable temperature studies, (c) comparison with assignments made for cyanide derivatives of several well characterized heme proteins such as cytochrome c peroxidase, horseradish peroxidase, and manganese peroxidase, and (d) examination of the crystal structural parameters of CPO. The location of protein modification that differentiates the signatures of the two isozymes of CPO has been postulated. The function of the distal histidine (His(105)) in modulating the catalytic activities of CPO is proposed based on the unique arrangement of this residue within the heme cavity. Contrary to the crystal state, the high affinity Mn(II) binding site in CPO (in solution) is not accessible to externally added Mn(II). The results presented here provide a reasonable explanation for the discrepancies in the literature between spectroscopists and crystallographers concerning the manganese binding site in this unique protein. Our study indicates that results from NMR investigations of the protein in solution can complement the results revealed by x-ray diffraction studies of the crystal form and thus provide a complete and better understanding of the actual structure of the protein.
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Affiliation(s)
- Xiaotang Wang
- Department of Chemistry, Jackson State University, Mississippi 39217, USA.
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16
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Abstract
Recent computational and experimental probes of high-valent intermediates in heme proteins and model compounds reveal a rich spectrum of chemical behavior that is dependent on the nature of the proximal ligand, metal center, distal- and proximal-binding site environment, porphyrin macrocycle architecture, and consequent electronic structure. The results of such studies reveal an underlying complexity, which is simply understood once one is cognizant of the 'chameleon'-like behavior of such intermediates is determined by the high-valent intermediate environment.
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Affiliation(s)
- D L Harris
- Molecular Research Institute, Mountain View, California 94043, USA.
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Rai GP, Zong Q, Hager LP. Isolation of directed evolution mutants of chloroperoxidase resistant to suicide inactivation by primary olefins. Isr J Chem 2000. [DOI: 10.1560/264g-uh9k-meyu-9yhy] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Yi X, Mroczko M, Manoj KM, Wang X, Hager LP. Replacement of the proximal heme thiolate ligand in chloroperoxidase with a histidine residue. Proc Natl Acad Sci U S A 1999; 96:12412-7. [PMID: 10535936 PMCID: PMC22935 DOI: 10.1073/pnas.96.22.12412] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chloroperoxidase is a versatile heme enzyme which can cross over the catalytic boundaries of other oxidative hemoproteins and perform multiple functions. Chloroperoxidase, in addition to catalyzing classical peroxidative reactions, also acts as a P450 cytochrome and a potent catalase. The multiple functions of chloroperoxidase must be derived from its unique active site structure. Chloroperoxidase possesses a proximal cysteine thiolate heme iron ligand analogous to the P450 cytochromes; however, unlike the P450 enzymes, chloroperoxidase possesses a very polar environment distal to its heme prosthetic group and contains a glutamic acid residue in close proximity to the heme iron. The presence of a thiolate ligand in chloroperoxidase has long been thought to play an essential role in its chlorination and epoxidation activities; however, the research reported in this paper proves that hypothesis to be invalid. To explore the role of Cys-29, the amino acid residue supplying the thiolate ligand in chloroperoxidase, Cys-29 has been replaced with a histidine residue. Mutant clones of the chloroperoxidase genome have been expressed in a Caldariomyces fumago expression system by using gene replacement rather than gene insertion technology. C. fumago produces wild-type chloroperoxidase, thus requiring gene replacement of the wild type by the mutant gene. To the best of our knowledge, this is the first time that gene replacement has been reported for this type of fungus. The recombinant histidine mutants retain most of their chlorination, peroxidation, epoxidation, and catalase activities. These results downplay the importance of a thiolate ligand in chloroperoxidase and suggest that the distal environment of the heme active site plays the major role in maintaining the diverse activities of this enzyme.
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Affiliation(s)
- X Yi
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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