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Masuda T, Baba S, Matsuo K, Ito S, Mikami B. The high-resolution crystal structure of lobster hemocyanin shows its enzymatic capability as a phenoloxidase. Arch Biochem Biophys 2020; 688:108370. [DOI: 10.1016/j.abb.2020.108370] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 04/07/2020] [Accepted: 04/08/2020] [Indexed: 02/04/2023]
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2
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Adam SM, Wijeratne GB, Rogler PJ, Diaz DE, Quist DA, Liu JJ, Karlin KD. Synthetic Fe/Cu Complexes: Toward Understanding Heme-Copper Oxidase Structure and Function. Chem Rev 2018; 118:10840-11022. [PMID: 30372042 PMCID: PMC6360144 DOI: 10.1021/acs.chemrev.8b00074] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heme-copper oxidases (HCOs) are terminal enzymes on the mitochondrial or bacterial respiratory electron transport chain, which utilize a unique heterobinuclear active site to catalyze the 4H+/4e- reduction of dioxygen to water. This process involves a proton-coupled electron transfer (PCET) from a tyrosine (phenolic) residue and additional redox events coupled to transmembrane proton pumping and ATP synthesis. Given that HCOs are large, complex, membrane-bound enzymes, bioinspired synthetic model chemistry is a promising approach to better understand heme-Cu-mediated dioxygen reduction, including the details of proton and electron movements. This review encompasses important aspects of heme-O2 and copper-O2 (bio)chemistries as they relate to the design and interpretation of small molecule model systems and provides perspectives from fundamental coordination chemistry, which can be applied to the understanding of HCO activity. We focus on recent advancements from studies of heme-Cu models, evaluating experimental and computational results, which highlight important fundamental structure-function relationships. Finally, we provide an outlook for future potential contributions from synthetic inorganic chemistry and discuss their implications with relevance to biological O2-reduction.
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Affiliation(s)
- Suzanne M. Adam
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Gayan B. Wijeratne
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Patrick J. Rogler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Daniel E. Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David A. Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Jeffrey J. Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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3
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Hu S, He B, Du KJ, Wang XJ, Gao SQ, Lin YW. Peroxidase Activity of a c-Type Cytochrome b5 in the Non-Native State is Comparable to that of Native Peroxidases. ChemistryOpen 2017. [PMID: 28638761 PMCID: PMC5474653 DOI: 10.1002/open.201700055] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The design of artificial metalloenzymes has achieved tremendous progress, although few designs can achieve catalytic performances comparable to that of native enzymes. Moreover, the structure and function of artificial metalloenzymes in non‐native states has rarely been explored. Herein, we found that a c‐type cytochrome b5 (Cyt b5), N57C/S71C Cyt b5, with heme covalently attached to the protein matrix through two Cys–heme linkages, adopts a non‐native state with an open heme site after guanidine hydrochloride (Gdn⋅HCl)‐induced unfolding, which facilitates H2O2 activation and substrate binding. Stopped‐flow kinetic studies further revealed that c‐type Cyt b5 in the non‐native state exhibited impressive peroxidase activity comparable to that of native peroxidases, such as the most efficient horseradish peroxidase. This study presents an alternative approach to the design of functional artificial metalloenzymes by exploring enzymatic functions in non‐native states.
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Affiliation(s)
- Shan Hu
- School of Chemistry and Chemical Engineering University of South China Hengyang 421001 P.R. China
| | - Bo He
- School of Chemistry and Chemical Engineering University of South China Hengyang 421001 P.R. China
| | - Ke-Jie Du
- School of Chemistry and Chemical Engineering University of South China Hengyang 421001 P.R. China
| | - Xiao-Juan Wang
- School of Chemistry and Chemical Engineering University of South China Hengyang 421001 P.R. China
| | - Shu-Qin Gao
- Laboratory of Protein Structure and Function University of South China Hengyang 421001 P.R. China
| | - Ying-Wu Lin
- School of Chemistry and Chemical Engineering University of South China Hengyang 421001 P.R. China.,Laboratory of Protein Structure and Function University of South China Hengyang 421001 P.R. China
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4
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Quist DA, Diaz DE, Liu JJ, Karlin KD. Activation of dioxygen by copper metalloproteins and insights from model complexes. J Biol Inorg Chem 2017; 22:253-288. [PMID: 27921179 PMCID: PMC5600896 DOI: 10.1007/s00775-016-1415-2] [Citation(s) in RCA: 163] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2016] [Accepted: 11/11/2016] [Indexed: 02/08/2023]
Abstract
Nature uses dioxygen as a key oxidant in the transformation of biomolecules. Among the enzymes that are utilized for these reactions are copper-containing metalloenzymes, which are responsible for important biological functions such as the regulation of neurotransmitters, dioxygen transport, and cellular respiration. Enzymatic and model system studies work in tandem in order to gain an understanding of the fundamental reductive activation of dioxygen by copper complexes. This review covers the most recent advancements in the structures, spectroscopy, and reaction mechanisms for dioxygen-activating copper proteins and relevant synthetic models thereof. An emphasis has also been placed on cofactor biogenesis, a fundamentally important process whereby biomolecules are post-translationally modified by the pro-enzyme active site to generate cofactors which are essential for the catalytic enzymatic reaction. Significant questions remaining in copper-ion-mediated O2-activation in copper proteins are addressed.
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Affiliation(s)
- David A Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Daniel E Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Jeffrey J Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA
| | - Kenneth D Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218, USA.
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5
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Immunological properties of oxygen-transport proteins: hemoglobin, hemocyanin and hemerythrin. Cell Mol Life Sci 2016; 74:293-317. [PMID: 27518203 PMCID: PMC5219038 DOI: 10.1007/s00018-016-2326-7] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 07/17/2016] [Accepted: 08/03/2016] [Indexed: 01/22/2023]
Abstract
It is now well documented that peptides with enhanced or alternative functionality (termed cryptides) can be liberated from larger, and sometimes inactive, proteins. A primary example of this phenomenon is the oxygen-transport protein hemoglobin. Aside from respiration, hemoglobin and hemoglobin-derived peptides have been associated with immune modulation, hematopoiesis, signal transduction and microbicidal activities in metazoans. Likewise, the functional equivalents to hemoglobin in invertebrates, namely hemocyanin and hemerythrin, act as potent immune effectors under certain physiological conditions. The purpose of this review is to evaluate the true extent of oxygen-transport protein dynamics in innate immunity, and to impress upon the reader the multi-functionality of these ancient proteins on the basis of their structures. In this context, erythrocyte-pathogen antibiosis and the immune competences of various erythroid cells are compared across diverse taxa.
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6
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Fujieda N, Itoh S. Controlling Dicopper Protein Functions. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2016. [DOI: 10.1246/bcsj.20150444] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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7
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Askari MS, Esguerra KVN, Lumb JP, Ottenwaelder X. A Biomimetic Mechanism for the Copper-Catalyzed Aerobic Oxygenation of 4-tert-Butylphenol. Inorg Chem 2015; 54:8665-72. [PMID: 26302341 DOI: 10.1021/acs.inorgchem.5b01297] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Controlling product selectivity during the catalytic aerobic oxidation of phenols remains a significant challenge that hinders reaction development. This work provides a mechanistic picture of a Cu-catalyzed, aerobic functionalization of phenols that is selective for phenoxy-coupled ortho-quinones. We show that the immediate product of the reaction is a Cu(II)-semiquinone radical complex and reveal that ortho-oxygenation precedes oxidative coupling. This complex is the resting state of the Cu catalyst during turnover at room temperature. A mechanistic study of the formation of this complex at low temperatures demonstrates that the oxygenation pathway mimics the dinuclear Cu enzyme tyrosinase by involving a dinuclear side-on peroxodicopper(II) oxidant. Unlike the enzyme, however, the rate-limiting step of the ortho-oxygenation reaction is the self-assembly of the oxidant from Cu(I) and O2. We provide details for all steps in the cycle and demonstrate that turnover is contingent upon proton-transfer events that are mediated by a slight excess of ligand. Finally, our knowledge of the reaction mechanism can be leveraged to diversify the reaction outcome. Thus, uncoupled ortho-quinones are favored in polar, coordinating media, highlighting unusually high levels of chemoselectivity for a catalytic aerobic oxidation of a phenol.
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Affiliation(s)
- Mohammad S Askari
- Department of Chemistry and Biochemistry, Concordia University , Montreal, QC H4B 1R6, Canada
| | | | - Jean-Philip Lumb
- Department of Chemistry, McGill University , Montreal, QC H3A 0B8, Canada
| | - Xavier Ottenwaelder
- Department of Chemistry and Biochemistry, Concordia University , Montreal, QC H4B 1R6, Canada
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8
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Synthesis, structure and properties of tris(1-ethyl-4-isopropyl-imidazolyl-κN)phosphine copper(II). Inorganica Chim Acta 2015. [DOI: 10.1016/j.ica.2015.05.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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9
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Coates CJ, Nairn J. Diverse immune functions of hemocyanins. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2014; 45:43-55. [PMID: 24486681 DOI: 10.1016/j.dci.2014.01.021] [Citation(s) in RCA: 192] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2013] [Revised: 01/24/2014] [Accepted: 01/25/2014] [Indexed: 06/03/2023]
Abstract
Substantial evidence gathered recently has revealed the multiple functionalities of hemocyanin. Contrary to previous claims that this ancient protein is involved solely in oxygen transport within the hemolymph of invertebrates, hemocyanin and hemocyanin-derived peptides have been linked to key aspects of innate immunity, in particular, antiviral and phenoloxidase-like activities. Both phenoloxidase and hemocyanin belong to the family of type-3 copper proteins and share a high degree of sequence homology. While the importance of phenoloxidase in immunity and development is well characterised, the contribution of hemocyanin to biological defence systems within invertebrates is not recognised widely. This review focusses on the conversion of hemocyanin into a phenoloxidase-like enzyme and the array of hemocyanin-derived immune responses documented to date.
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Affiliation(s)
- Christopher J Coates
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, Scotland, UK.
| | - Jacqueline Nairn
- Biological and Environmental Sciences, School of Natural Sciences, University of Stirling, Stirling FK9 4LA, Scotland, UK
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10
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Masuda T, Momoji K, Hirata T, Mikami B. The crystal structure of a crustacean prophenoloxidase provides a clue to understanding the functionality of the type 3 copper proteins. FEBS J 2014; 281:2659-73. [PMID: 24720693 DOI: 10.1111/febs.12812] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2014] [Revised: 03/27/2014] [Accepted: 04/08/2014] [Indexed: 11/29/2022]
Abstract
UNLABELLED Phenoloxidase (PO), which is classified as a type 3 copper protein, catalyzes the hydroxylation of monophenol to o-diphenol and subsequent oxidation to the corresponding o-quinone. The geometry and coordination environment of the active site of the arthropod PO are very similar to those of the arthropod hemocyanin (Hc). However, unlike the POs, Hc is an oxygen carrier in crustaceans, and does not possess PO activity in general. Recently, we identified a new type of proPO from a crustacean and designated it proPOβ. This enzyme has many characteristics that are rather similar to those of Hc, such as its maturation, localization, and oligomeric state. Here, we determined the crystal structure of proPOβ prepared from the hemolymph of kuruma prawns (Marsupenaeus japonicus) at 1.8-Å resolution. M. japonicus proPOβ forms a homohexamer rather similar to that of arthropod Hc. The geometry of the active copper site in proPOβ is nearly identical to that of arthropod Hc. Furthermore, the well-characterized 'place-holder' phenylalanine is present (Phe72). However, the accessibility to the active site differs in several ways. First, another phenylalanine, which shields the active site by interacting with a copper-coordinated histidine in crustacean Hc, is replaced by valine in the proPOβ structure. Second, two tyrosines, Tyr208 and Tyr209, both of which are absent in Hc, show the alternative conformations and form a pathway providing access to the reaction center. Thus, the present crystal structure clarifies the similarities and differences in the activity of two closely related proteins, PO and Hc. DATABASE Structural data are available in the RSCB protein data bank under the accession number 3WKY. ray crystallography (View interaction).
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Affiliation(s)
- Taro Masuda
- Laboratory of Food Quality Design and Development, Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Japan
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11
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Solomon EI, Heppner DE, Johnston EM, Ginsbach JW, Cirera J, Qayyum M, Kieber-Emmons MT, Kjaergaard CH, Hadt RG, Tian L. Copper active sites in biology. Chem Rev 2014; 114:3659-853. [PMID: 24588098 PMCID: PMC4040215 DOI: 10.1021/cr400327t] [Citation(s) in RCA: 1133] [Impact Index Per Article: 113.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
| | - David E. Heppner
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Jordi Cirera
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Munzarin Qayyum
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | | | | | - Ryan G. Hadt
- Department of Chemistry, Stanford University, Stanford, CA, 94305
| | - Li Tian
- Department of Chemistry, Stanford University, Stanford, CA, 94305
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12
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Raynova Y, Doumanova L, Idakieva KN. Phenoloxidase Activity of Helix aspersa Maxima (Garden Snail, Gastropod) Hemocyanin. Protein J 2013; 32:609-18. [DOI: 10.1007/s10930-013-9523-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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13
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Fujieda N, Murata M, Yabuta S, Ikeda T, Shimokawa C, Nakamura Y, Hata Y, Itoh S. Activation mechanism of melB tyrosinase from Aspergillus oryzae by acidic treatment. J Biol Inorg Chem 2012; 18:19-26. [PMID: 23053534 DOI: 10.1007/s00775-012-0945-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Accepted: 09/26/2012] [Indexed: 10/27/2022]
Abstract
The pro form of recombinant tyrosinase from Aspergillus oryzae (melB) shows no catalytic activity, but acid treatment (around pH 3.5) of protyrosinase activates it to induce tyrosinase activity. Circular dichroism spectra, gel filtration analysis, and colorimetric assay have indicated that acid treatment around pH 3.5 induced the disruption of the conformation of the C-terminal domain covering the enzyme active site. These structural changes induced by the acid treatment may open the entrance to the enzyme active site for substrate incorporation. To compare the mechanism of hydroxylation by the acid-treated tyrosinase with that by trypsin-treated tyrosinase, a detailed steady-state kinetic analysis of the phenolase activity was performed by monitoring the O(2)-consumption rate using a Clark-type oxygen electrode. The results clearly show that the phenolase activity (phenol hydroxylation) of the activated tyrosinase involves an electrophilic aromatic substitution mechanism as in the case of mushroom tyrosinase (Yamazaki and Itoh in J. Am. Chem. Soc. 125:13034-13035, 2003) and activated hemocyanin with urea (Morioka et al. in J. Am. Chem. Soc. 128:6788-6789, 2006).
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Affiliation(s)
- Nobutaka Fujieda
- Division of Advanced Science and Biotechnology, Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
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14
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Structure/function correlations among coupled binuclear copper proteins through spectroscopic and reactivity studies of NspF. Proc Natl Acad Sci U S A 2012; 109:10793-7. [PMID: 22711806 DOI: 10.1073/pnas.1208718109] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The terminal step of 4-hydroxy-3-nitrosobenzamide biosynthesis in Streptomyces murayamaensis is performed by NspF, a mono-oxygenase that converts o-aminophenols to the corresponding nitroso product (hydroxyanilinase activity). Previous biochemical characterization of the resting form of NspF suggested that this enzyme belonged to the coupled binuclear copper enzyme (CBC) family. Another member of this enzyme family, tyrosinase, is able to mono-oxygenate monophenols (monophenolase activity) but not o-aminophenols. To gain insight into the unique reactivity of NspF, we have generated and characterized the oxy form of its active site. The observation of spectral features identical to those of oxy-tyrosinase indicates that oxy-NspF contains a Cu(2)O(2) core where peroxide is coordinated in a μ-η(2):η(2) mode, confirming that NspF is a CBC enzyme. This oxy form is found to react with monophenols, indicating that, like tyrosinase, NspF also possesses monophenolase activity. A comparison of the two electrophilic mechanisms for the monophenolase and hydroxyanilinase activity indicates a large geometric change between their respective transition states. The potential for specific interactions between the protein pocket and the substrate in each transition state is discussed within the context of the differential reactivity of this family of enzymes with equivalent μ-η(2):η(2) peroxy bridged coupled binuclear copper active sites.
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15
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Garcia-Bosch I, Ribas X, Costas M. Electrophilic arene hydroxylation and phenol O-H oxidations performed by an unsymmetric μ-η(1):η(1)-O2-peroxo dicopper(II) complex. Chemistry 2012; 18:2113-22. [PMID: 22250002 DOI: 10.1002/chem.201102372] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Indexed: 11/09/2022]
Abstract
Reactions of the unsymmetric dicopper(II) peroxide complex [Cu(II)(2)(μ-η(1):η(1)-O(2))(m-XYL(N3N4))](2+) (1 O(2), where m-XYL is a heptadentate N-based ligand), with phenolates and phenols are described. Complex 1 O(2) reacts with p-X-PhONa (X = MeO, Cl, H, or Me) at -90 °C performing tyrosinase-like ortho-hydroxylation of the aromatic ring to afford the corresponding catechol products. Mechanistic studies demonstrate that reactions occur through initial reversible formation of metastable association complexes [Cu(II)(2)(μ-η(1):η(1)-O(2))(p-X-PhO)(m-XYL(N3N4))](+) (1 O(2)⋅X-PhO) that then undergo ortho-hydroxylation of the aromatic ring by the peroxide moiety. Complex 1 O(2) also reacts with 4-X-substituted phenols p-X-PhOH (X = MeO, Me, F, H, or Cl) and with 2,4-di-tert-butylphenol at -90 °C causing rapid decay of 1 O(2) and affording biphenol coupling products, which is indicative that reactions occur through formation of phenoxyl radicals that then undergo radical C-C coupling. Spectroscopic UV/Vis monitoring and kinetic analysis show that reactions take place through reversible formation of ground-state association complexes [Cu(II)(2)(μ-η(1):η(1)-O(2))(X-PhOH)(m-XYL(N3N4))](2+) (1 O(2)⋅X-PhOH) that then evolve through an irreversible rate-determining step. Mechanistic studies indicate that 1 O(2) reacts with phenols through initial phenol binding to the Cu(2)O(2) core, followed by a proton-coupled electron transfer (PCET) at the rate-determining step. Results disclosed in this work provide experimental evidence that the unsymmetric 1 O(2) complex can mediate electrophilic arene hydroxylation and PCET reactions commonly associated with electrophilic Cu(2)O(2) cores, and strongly suggest that the ability to form substrate⋅Cu(2)O(2) association complexes may provide paths to overcome the inherent reactivity of the O(2)-binding mode. This work provides experimental evidence that the presence of a H(+) completely determines the fate of the association complex [Cu(II)(2)(μ-η(1):η(1)-O(2))(X-PhO(H))(m-XYL(N3N4))](n+) between a PCET and an arene hydroxylation reaction, and may provide clues to help understand enzymatic reactions at dicopper sites.
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Affiliation(s)
- Isaac Garcia-Bosch
- QBIS Group, Departament de Química, Universitat de Girona, Campus de Montilivi, 17071 Girona, Catalonia, Spain
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16
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Thorseth MA, Letko CS, Rauchfuss TB, Gewirth AA. Dioxygen and Hydrogen Peroxide Reduction with Hemocyanin Model Complexes. Inorg Chem 2011; 50:6158-62. [DOI: 10.1021/ic200386d] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew A. Thorseth
- Department of Chemistry, University of Illinois at Urbana−Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801, United States
| | - Christopher S. Letko
- Department of Chemistry, University of Illinois at Urbana−Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801, United States
| | - Thomas B. Rauchfuss
- Department of Chemistry, University of Illinois at Urbana−Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801, United States
| | - Andrew A. Gewirth
- Department of Chemistry, University of Illinois at Urbana−Champaign, 600 S. Mathews Avenue, Urbana, Illinois 61801, United States
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17
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Rolff M, Schottenheim J, Decker H, Tuczek F. Copper–O2 reactivity of tyrosinase models towards external monophenolic substrates: molecular mechanism and comparison with the enzyme. Chem Soc Rev 2011; 40:4077-98. [DOI: 10.1039/c0cs00202j] [Citation(s) in RCA: 359] [Impact Index Per Article: 27.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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18
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Fujieda N, Yakiyama A, Itoh S. Five monomeric hemocyanin subunits from Portunus trituberculatus: Purification, spectroscopic characterization, and quantitative evaluation of phenol monooxygenase activity. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1804:2128-35. [DOI: 10.1016/j.bbapap.2010.08.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2010] [Revised: 07/26/2010] [Accepted: 08/10/2010] [Indexed: 11/29/2022]
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19
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Purification and partial characterization of an agglutinin from Octopus maya serum. Comp Biochem Physiol B Biochem Mol Biol 2010; 156:1-5. [PMID: 20105460 DOI: 10.1016/j.cbpb.2010.01.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 01/18/2010] [Accepted: 01/19/2010] [Indexed: 11/24/2022]
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20
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Muñoz-Muñoz J, García-Molina F, García-Ruiz P, Varon R, Tudela J, García-Cánovas F, Rodríguez-López J. Some kinetic properties of deoxytyrosinase. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.molcatb.2009.10.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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21
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Fujieda N, Yakiyama A, Itoh S. Catalytic oxygenation of phenols by arthropod hemocyanin, an oxygen carrier protein, from Portunus trituberculatus. Dalton Trans 2010; 39:3083-92. [DOI: 10.1039/c000760a] [Citation(s) in RCA: 19] [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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22
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Op't Holt BT, Vance MA, Mirica LM, Heppner DE, Stack TDP, Solomon EI. Reaction coordinate of a functional model of tyrosinase: spectroscopic and computational characterization. J Am Chem Soc 2009; 131:6421-38. [PMID: 19368383 DOI: 10.1021/ja807898h] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mu-eta(2):eta(2)-peroxodicopper(II) complex synthesized by reacting the Cu(I) complex of the bis-diamine ligand N,N'-di-tert-butyl-ethylenediamine (DBED) with O(2) is a functional and spectroscopic model of the coupled binuclear copper protein tyrosinase. This complex reacts with 2,4-di-tert-butylphenolate at low temperature to produce a mixture of the catechol and quinone products, which proceeds through three intermediates (A-C) that have been characterized. A, stabilized at 153 K, is characterized as a phenolate-bonded bis-mu-oxo dicopper(III) species, which proceeds at 193 K to B, presumably a catecholate-bridged coupled bis-copper(II) species via an electrophilic aromatic substitution mechanism wherein aromatic ring distortion is the rate-limiting step. Isotopic labeling shows that the oxygen inserted into the aromatic substrate during hydroxylation derives from dioxygen, and a late-stage ortho-H(+) transfer to an exogenous base is associated with C-O bond formation. Addition of a proton to B produces C, determined from resonance Raman spectra to be a Cu(II)-semiquinone complex. The formation of C (the oxidation of catecholate and reduction to Cu(I)) is governed by the protonation state of the distal bridging oxygen ligand of B. Parallels and contrasts are drawn between the spectroscopically and computationally supported mechanism of the DBED system, presented here, and the experimentally derived mechanism of the coupled binuclear copper protein tyrosinase.
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Affiliation(s)
- Bryan T Op't Holt
- Department of Chemistry, Stanford University, Stanford, California 94305, USA
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Herres-Pawlis S, Verma P, Haase R, Kang P, Lyons CT, Wasinger EC, Flörke U, Henkel G, Stack TDP. Phenolate hydroxylation in a bis(mu-oxo)dicopper(III) complex: lessons from the guanidine/amine series. J Am Chem Soc 2009; 131:1154-69. [PMID: 19119846 PMCID: PMC2663633 DOI: 10.1021/ja807809x] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new hybrid permethylated-amine-guanidine ligand based on a 1,3-propanediamine backbone (2L) and its Cu-O2 chemistry is reported. [(2L)CuI(MeCN)]1+ complex readily oxygenates at low temperatures in polar aprotic solvents to form a bis(mu-oxo)dicopper(III) (O) species (2b), similar to the parent bis-guanidine ligand complex (1b) and permethylated-diamine ligand complex (3b). UV-vis and X-ray absorption spectroscopy experiments confirm this assignment of 2b as an O species, and full formation of the 2:1 Cu-O2 complex is demonstrated by an optical titration with ferrocene-monocarboxylic acid (FcCOOH). The UV-vis spectra of 1b and 2b with guanidine ligation show low-intensity visible features assigned as guanidine pi --> Cu2O2 core transitions by time-dependent density functional theory (TD-DFT) calculations. Comparison of the reactivity among the three related complexes (1b-3b) with phenolate at 195 K is particularly insightful as only 2b hydroxylates 2,4-di-tert-butylphenolate to yield 3,5-di-tert-butylcatecholate (>95% yield) with the oxygen atom derived from O2, reminiscent of tyrosinase reactivity. 1b is unreactive, while 3b yields the C-C radical-coupled bis-phenol product. Attenuated outer-sphere oxidative strength of the O complexes and increased phenolate accessibility to the Cu2O2 core are attributes that correlate with phenolate hydroxylation reactivity observed in 2b. The comparative low-temperature reactivity of 1b-3b with FcCOOH (O-H BDE 71 kcal mol(-1)) to form the two-electron, two-proton reduced bis(mu-hydroxo)dicopper(II,II) complex is quantitative and presumably precedes through two sequential proton-coupled electron transfer (PCET) steps. Optical titrations along with DFT calculations support that the reduced complexes formed in the first step are more powerful oxidants than the parent O complexes. These mechanistic insights aid in understanding the phenol to bis-phenol reactivity exhibited by 2b and 3b.
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