1
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Selvakumaran B, Murali M, Shanmugavadivel S, Sindhuja V, Sathya V. Impressive promiscuous biomimetic models of ascorbate, amine, and catechol oxidases. J Inorg Biochem 2024; 259:112671. [PMID: 39059176 DOI: 10.1016/j.jinorgbio.2024.112671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2024] [Revised: 07/14/2024] [Accepted: 07/21/2024] [Indexed: 07/28/2024]
Abstract
Copper metalloenzymes ascorbate oxidase (AOase), amine oxidase (AmOase), and catechol oxidase (COase) possess copper(II) sites of coordination, which are trimeric, homodimeric, and dimeric, respectively. Two newly mononuclear copper(II) complexes, namely, [Cu(L)(bpy)](ClO4) (1) and [Cu(L)(phen)](ClO4) (2) where HL = Schiff base, have been synthesized. UV-visible, EPR and single-crystal X-ray diffraction examinations were used to validate the geometry in solution and solid state. For complex 1, the metal exhibits a coordination sphere between square pyramidal and trigonal bipyramidal geometry (τ, 0.49). A positive CuII/I redox potential indicates a stable switching between CuII and CuI redox states. Despite the monomeric origin, both homogeneous catalysts (1 or 2) in MeOH were found to favor three distinct chemical transformations, namely, ascorbic acid (H2A) to dehydroascorbic acid (DA), benzylamine (Ph-CH2-NH2) to benzaldehyde (Ph-CHO), and 3,5-di-tert-butylcatechol (3,5-DTBC) to 3,5-di-tert-butylquinone (3,5-DTBQ) [kcat: AOase, 9.6 (1) or 2.0 × 106 h-1(2); AmOase, 13.4 (1) or 9.4 × 106 h-1 (2); COase, 2.0 (1) or 1.9 × 103 h-1 (2)]. They exhibit higher levels of AOase activity as indicated by their kcat values compared to the AOase enzyme. The kcat values for COase activity in buffer solution [5.93 (1) or 2.95 × 105 h-1 (2)] are one order lower than those of the enzymes. This is because of the labile nature of the coordinated donor, the flexibility of the ligand, the simplicity of the catalyst-substrate interaction, and the positive CuII/I redox potential. Interestingly, more efficient catalysis is promoted by 1 and 2 concerning that of other mono- and dicopper(II) complexes.
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Affiliation(s)
- Balasubramaniam Selvakumaran
- Coordination and Bioinorganic Chemistry Research Laboratory, Department of Chemistry, National College (Autonomous), Tiruchirappalli 620 001, Tamil Nadu, India
| | - Mariappan Murali
- Coordination and Bioinorganic Chemistry Research Laboratory, Department of Chemistry, National College (Autonomous), Tiruchirappalli 620 001, Tamil Nadu, India.
| | - Selvaraj Shanmugavadivel
- Coordination and Bioinorganic Chemistry Research Laboratory, Department of Chemistry, National College (Autonomous), Tiruchirappalli 620 001, Tamil Nadu, India
| | - Venkatesan Sindhuja
- Coordination and Bioinorganic Chemistry Research Laboratory, Department of Chemistry, National College (Autonomous), Tiruchirappalli 620 001, Tamil Nadu, India
| | - Velusamy Sathya
- Coordination and Bioinorganic Chemistry Research Laboratory, Department of Chemistry, National College (Autonomous), Tiruchirappalli 620 001, Tamil Nadu, India
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2
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Chaussy L, Chilkuri VG, Humbel S, Nava P. Spectroscopy of End-On Copper(II) Superoxido Complexes: A Wave Function-Based Analysis. Inorg Chem 2024; 63:8038-8049. [PMID: 38659336 DOI: 10.1021/acs.inorgchem.3c04401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
Wave function methods are employed to analyze the ground and low-lying excited states of bipyramid trigonal copper(II) superoxido complexes, up to their characteristic ligand to metal charge transfer band. Several multireference methods have been combined to provide new insights into the interpretation of their experimental absorption spectra. We show that the intraligand transition on the dioxygen leads to a dark state. Among the results, we shall highlight the finding of doubly excited states in the region of the d-d transitions and the subtle interplay between Cu(I) and Cu(II) in the ground and excited states. Some of these findings could be obtained only with multireference methods.
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Affiliation(s)
- Léo Chaussy
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Marseille 13397, France
| | | | - Stéphane Humbel
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Marseille 13397, France
| | - Paola Nava
- Aix Marseille Univ, CNRS, Centrale Marseille, iSm2, Marseille 13397, France
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3
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Mohapatra D, Patra SA, Pattanayak PD, Sahu G, Sasamori T, Dinda R. Monomeric copper(II) complexes with unsymmetrical salen environment: Synthesis, characterization and study of biological activities. J Inorg Biochem 2024; 253:112497. [PMID: 38290220 DOI: 10.1016/j.jinorgbio.2024.112497] [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: 10/19/2023] [Revised: 01/23/2024] [Accepted: 01/23/2024] [Indexed: 02/01/2024]
Abstract
Three new ONNO-donor tetradentate unsymmetrical salen ligands were synthesized by using o-phenyl diamine with substituted salicylaldehydes followed by a two-step reaction methodology. These three ligands by reaction with Cu(OAc)2.4H2O produced three new monomeric Cu(II) complexes, [CuII(L1-3)] (1-3). Elemental analysis, IR, UV-vis, NMR, and HR-ESI-MS techniques were used to analyze and characterize all the synthesized ligands and their corresponding metal complexes. Molecular structures of 1-3 were confirmed by the single-crystal-XRD analysis. Furthermore, the DNA binding ability of these complexes was checked through UV-vis, fluorescence spectroscopy, and also by circular dichroism studies. All the complexes were found to show an intercalation mode of binding with the Kb value in the range of 104-105 M-1. Finally, 1-3 was tested against two malignant (HeLa and A549) and non-cancerous (NIH-3T3) cell lines to check their in vitro antiproliferative activities. Among all, 1 is the most cytotoxic of the series having IC50 values of 5.7 ± 0.9 and 6.0 ± 0.3 μM against HeLa and A549 cell lines, respectively. This result is also consistent with the DNA binding order. Furthermore, the apoptotic mode of cell death of all the complexes was also evaluated by DAPI, AO/EB, and Annexin V-FITC/PI double staining assays.
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Affiliation(s)
- Deepika Mohapatra
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | - Sushree Aradhana Patra
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | | | - Gurunath Sahu
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India
| | - Takahiro Sasamori
- University of Tsukuba, Institute of Natural Sciences B-506, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8571, Japan
| | - Rupam Dinda
- Department of Chemistry, National Institute of Technology, Rourkela 769008, Odisha, India.
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4
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Rush KW, Eastman KAS, Welch EF, Bandarian V, Blackburn NJ. Capturing the Binuclear Copper State of Peptidylglycine Monooxygenase Using a Peptidyl-Homocysteine Lure. J Am Chem Soc 2024; 146:5074-5080. [PMID: 38363651 PMCID: PMC11096088 DOI: 10.1021/jacs.3c14705] [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: 02/18/2024]
Abstract
Peptidylglycine monooxygenase is a copper-dependent enzyme that catalyzes C-alpha hydroxylation of glycine extended pro-peptides, a critical post-translational step in peptide hormone processing. The canonical mechanism posits that dioxygen binds at the mononuclear M-center to generate a Cu(II)-superoxo species capable of H atom abstraction from the peptidyl substrate, followed by long-range electron tunneling from the CuH center. Recent crystallographic and biochemical data have challenged this mechanism, suggesting instead that an "open-to-closed" transition brings the copper centers closer, allowing reactivity within a binuclear intermediate. Here we present the first direct observation of an enzyme-bound binuclear copper species, captured by the use of an Ala-Ala-Phe-hCys inhibitor complex. This molecule reacts with the fully reduced enzyme to form a thiolate-bridged binuclear species characterized by EXAFS of the WT and its M314H variant and with the oxidized enzyme to form a novel mixed valence entity characterized by UV/vis and EPR. Mechanistic implications are discussed.
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Affiliation(s)
- Katherine W. Rush
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA
| | | | - Evan F. Welch
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA
| | - Vahe Bandarian
- Department of Chemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Ninian J. Blackburn
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA
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5
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Kim B, Karlin KD. Ligand-Copper(I) Primary O 2-Adducts: Design, Characterization, and Biological Significance of Cupric-Superoxides. Acc Chem Res 2023; 56:2197-2212. [PMID: 37527056 PMCID: PMC11152209 DOI: 10.1021/acs.accounts.3c00297] [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: 08/03/2023]
Abstract
In this Account, we overview and highlight synthetic bioinorganic chemistry focused on initial adducts formed from the reaction of reduced ligand-copper(I) coordination complexes with molecular oxygen, reactions that produce ligand-CuII(O2•-) complexes (O2•- ≡ superoxide anion). We provide mostly a historical perspective, starting in the Karlin research group in the 1980s, emphasizing the ligand design and ligand effects, structure, and spectroscopy of these O2 adducts and subsequent further reactivity with substrates, including the interaction with a second ligand-CuI complex to form binuclear species. The Account emphasizes the approach, evolution, and results obtained in the Karlin group, a synthetic bioinorganic research program inspired by the state of knowledge and insights obtained on enzymes possessing copper ion active sites which process molecular oxygen. These constitute an important biochemistry for all levels/types of organisms, bacteria, fungi, insects, and mammals, including humans.Copper is earth abundant, and its redox properties in complexes allow for facile CuII/CuI interconversions. Simple salts or coordination complexes have been well known to serve as oxidants for the stoichiometric or catalytic oxidation or oxygenation (i.e., O-atom insertion) of organic substrates. Thus, copper dioxygen- or peroxide-centered synthetic bioinorganic studies provide strong relevance and potential application to synthesis or even the development of cathodic catalysts for dioxygen reduction to hydrogen peroxide or water, as in fuel cells. The Karlin group's focus however was primarily oriented toward bioinorganic chemistry with the goal to provide fundamental insights into the nature of copper-dioxygen adducts and further reduced and/or protonated derivatives, species likely occurring in enzyme turnover or related in one or more aspects of formation, structure, spectroscopic properties, and scope of reactivity toward organic/biochemical substrates.Prior to this time, the 1980s, O2 adducts of redox-active first-row transition-metal ions focused on iron, such as the porphyrinate-Fe centers occurring in the oxygen carrier proteins myoglobin and hemoglobin and that determined to occur in cytochrome P-450 monooxygenase turnover. Deoxy (i.e., reduced Fe(II)) heme proteins react with O2, giving FeIII-superoxo complexes (preferably referred to by traditional biochemists as ferrous-oxy species). And, it was in the 1970s that great strides were made by synthetic chemists in generating hemes capable of forming O2 adducts, their physiochemical characterization providing critical insights to enzyme (bio)chemistry and providing ideas and important goals leading to countless person years of future research.
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Affiliation(s)
- Bohee Kim
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D Karlin
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
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6
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Okamoto Y, Mabuchi T, Nakane K, Ueno A, Sato S. Switching Type I/Type II Reactions by Turning a Photoredox Catalyst into a Photo-Driven Artificial Metalloenzyme. ACS Catal 2023. [DOI: 10.1021/acscatal.2c05946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Affiliation(s)
- Yasunori Okamoto
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Aramaki aza Aoba 6-3, Aoba-ku, Sendai 980-8578, Japan
| | - Takuya Mabuchi
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Aramaki aza Aoba 6-3, Aoba-ku, Sendai 980-8578, Japan
- Institute of Fluid Science, Tohoku University, 2-1-1 Katahira,
Aoba-ku, Sendai 980-8577, Japan
| | - Keita Nakane
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira,
Aoba-ku, Sendai 980-8577, Japan
| | - Akiko Ueno
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Aramaki aza Aoba 6-3, Aoba-ku, Sendai 980-8578, Japan
| | - Shinichi Sato
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Aramaki aza Aoba 6-3, Aoba-ku, Sendai 980-8578, Japan
- Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira,
Aoba-ku, Sendai 980-8577, Japan
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7
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Interplay of electronic and geometric structure on Cu phenanthroline, bipyridine and derivative complexes, synthesis, characterization, and reactivity towards oxygen. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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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: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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9
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Davydov R, Herzog AE, Jodts RJ, Karlin KD, Hoffman BM. End-On Copper(I) Superoxo and Cu(II) Peroxo and Hydroperoxo Complexes Generated by Cryoreduction/Annealing and Characterized by EPR/ENDOR Spectroscopy. J Am Chem Soc 2022; 144:377-389. [PMID: 34981938 PMCID: PMC8785356 DOI: 10.1021/jacs.1c10252] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
In this report, we investigate the physical and chemical properties of monocopper Cu(I) superoxo and Cu(II) peroxo and hydroperoxo complexes. These are prepared by cryoreduction/annealing of the parent [LCuI(O2)]+ Cu(I) dioxygen adducts with the tripodal, N4-coordinating, tetradentate ligands L = PVtmpa, DMMtmpa, TMG3tren and are best described as [LCuII(O2•-)]+ Cu(II) complexes that possess end-on (η1-O2•-) superoxo coordination. Cryogenic γ-irradiation (77 K) of the EPR-silent parent complexes generates mobile electrons from the solvent that reduce the [LCuII(O2•-)]+ within the frozen matrix, trapping the reduced form fixed in the structure of the parent complex. Cryoannealing, namely progressively raising the temperature of a frozen sample in stages and then cooling back to low temperature at each stage for examination, tracks the reduced product as it relaxes its structure and undergoes chemical transformations. We employ EPR and ENDOR (electron-nuclear double resonance) as powerful spectroscopic tools for examining the properties of the states that form. Surprisingly, the primary products of reduction of the Cu(II) superoxo species are metastable cuprous superoxo [LCuI(O2•-)]+ complexes. During annealing to higher temperatures this state first undergoes internal electron transfer (IET) to form the end-on Cu(II) peroxo state, which is then protonated to form Cu(II)-OOH species. This is the first time these methods, which have been used to determine key details of metalloenzyme catalytic cycles and are a powerful tools for tracking PCET reactions, have been applied to copper coordination compounds.
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Affiliation(s)
- Roman Davydov
- Department of Chemistry, Northwestern University, Evanston, Illinois 60201, United States
| | - Austin E Herzog
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Richard J Jodts
- Department of Chemistry, Northwestern University, Evanston, Illinois 60201, United States
| | - Kenneth D Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Brian M Hoffman
- Department of Chemistry, Northwestern University, Evanston, Illinois 60201, United States
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10
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Selvakumaran B, Murali M. Functional mimic for amine and catechol oxidases: Structural, spectral, electrochemical and catalytic properties of mononuclear copper(II) complex. Inorganica Chim Acta 2022. [DOI: 10.1016/j.ica.2022.120819] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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11
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Quek SY, Debnath S, Laxmi S, van Gastel M, Krämer T, England J. Sterically Stabilized End-On Superoxocopper(II) Complexes and Mechanistic Insights into Their Reactivity with O-H, N-H, and C-H Substrates. J Am Chem Soc 2021; 143:19731-19747. [PMID: 34783549 DOI: 10.1021/jacs.1c07837] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Instability of end-on superoxocopper(II) complexes, with respect to conversion to peroxo-bridged dicopper(II) complexes, has largely constrained their study to very low temperatures. This limits their kinetic capacity to oxidize substrates. In response, we have developed a series of bulky ligands, Ar3-TMPA (Ar = tpb, dpb, dtbpb), and used them to support copper(I) complexes that react with O2 to yield [CuII(η1-O2•-)(Ar3-TMPA)]+ species, which are stable against dimerization at all temperatures. Binding of O2 saturates at subambient temperatures and can be reversed by warming. The onset of oxygenation for the Ar = tpb and dpb systems is observed at 25 °C, and all three [CuII(η1-O2•-)(Ar3-TMPA)]+ complexes are stable against self-decay at temperatures of ≤-20 °C. This provides a wide temperature window for study of these complexes, which was exploited by performing extensive reaction kinetics measurements for [CuII(η1-O2•-)(tpb3-TMPA)]+ using a broad range of O-H, N-H, and C-H bond substrates. This includes correlation of second order rate constants (k2) versus oxidation potentials (Eox) for a range of phenols, construction of Eyring plots, and temperature-dependent kinetic isotope effect (KIE) measurements. The data obtained indicate that reaction with all substrates proceeds via H atom transfer (HAT), reaction with the phenols proceeds with significant charge transfer, and full tunneling of both H and D atoms occurs in the case of 1,2-diphenylhydrazine and 4-methoxy-2,6-di-tert-butylphenol. Oxidation of C-H bonds proved to be kinetically challenging, and whereas [CuII(η1-O2•-)(tpb3-TMPA)]+ can oxidize moderately strong O-H and N-H bonds, it is only able to oxidize very weak C-H bonds.
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Affiliation(s)
- Sebastian Y Quek
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Suman Debnath
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Shoba Laxmi
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr D-45470, Germany
| | - Tobias Krämer
- Department of Chemistry, Maynooth University, Maynooth, Co. Kildare W23 F2H6, Ireland.,Hamilton Institute, Maynooth University, Maynooth, Co. Kildare W23 F2H6, Ireland
| | - Jason England
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.,Department of Chemistry, University of Lincoln, Lincoln LN6 7TW, U.K
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12
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Bhadra M, Transue WJ, Lim H, Cowley RE, Lee JYC, Siegler MA, Josephs P, Henkel G, Lerch M, Schindler S, Neuba A, Hodgson KO, Hedman B, Solomon EI, Karlin KD. A Thioether-Ligated Cupric Superoxide Model with Hydrogen Atom Abstraction Reactivity. J Am Chem Soc 2021; 143:3707-3713. [PMID: 33684290 DOI: 10.1021/jacs.1c00260] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The central role of cupric superoxide intermediates proposed in hormone and neurotransmitter biosynthesis by noncoupled binuclear copper monooxygenases like dopamine-β-monooxygenase has drawn significant attention to the unusual methionine ligation of the CuM ("CuB") active site characteristic of this class of enzymes. The copper-sulfur interaction has proven critical for turnover, raising still-unresolved questions concerning Nature's selection of an oxidizable Met residue to facilitate C-H oxygenation. We describe herein a model for CuM, [(TMGN3S)CuI]+ ([1]+), and its O2-bound analog [(TMGN3S)CuII(O2•-)]+ ([1·O2]+). The latter is the first reported cupric superoxide with an experimentally proven Cu-S bond which also possesses demonstrated hydrogen atom abstraction (HAA) reactivity. Introduction of O2 to a precooled solution of the cuprous precursor [1]B(C6F5)4 (-135 °C, 2-methyltetrahydrofuran (2-MeTHF)) reversibly forms [1·O2]B(C6F5)4 (UV/vis spectroscopy: λmax 442, 642, 742 nm). Resonance Raman studies (413 nm) using 16O2 [18O2] corroborated the identity of [1·O2]+ by revealing Cu-O (446 [425] cm-1) and O-O (1105 [1042] cm-1) stretches, and extended X-ray absorption fine structure (EXAFS) spectroscopy showed a Cu-S interatomic distance of 2.55 Å. HAA reactivity between [1·O2]+ and TEMPO-H proceeds rapidly (1.28 × 10-1 M-1 s-1, -135 °C, 2-MeTHF) with a primary kinetic isotope effect of kH/kD = 5.4. Comparisons of the O2-binding behavior and redox activity of [1]+ vs [2]+, the latter a close analog of [1]+ but with all N atom ligation (i.e., N3S vs N4), are presented.
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Affiliation(s)
- Mayukh Bhadra
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Wesley J Transue
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Hyeongtaek Lim
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Ryan E Cowley
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Jung Yoon C Lee
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Maxime A Siegler
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Patrick Josephs
- Department of Chemistry, University of Paderborn, Paderborn D-33098, Germany
| | - Gerald Henkel
- Department of Chemistry, University of Paderborn, Paderborn D-33098, Germany
| | - Markus Lerch
- Institute of Inorganic and Analytical Chemistry, Justus-Liebig University of Gießen, Giessen D-35392, Germany
| | - Siegfried Schindler
- Institute of Inorganic and Analytical Chemistry, Justus-Liebig University of Gießen, Giessen D-35392, Germany
| | - Adam Neuba
- Department of Chemistry, University of Paderborn, Paderborn D-33098, Germany
| | - Keith O Hodgson
- Department of Chemistry, Stanford University, Stanford, California 94305, United States.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Britt Hedman
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Kenneth D Karlin
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
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13
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Davis HJ, Häussinger D, Ward TR, Okamoto Y. A Visible-Light Promoted Amine Oxidation Catalyzed by a Cp*Ir Complex. ChemCatChem 2020; 12:4512-4516. [PMID: 33777249 PMCID: PMC7984327 DOI: 10.1002/cctc.202000488] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 06/11/2020] [Indexed: 12/21/2022]
Abstract
Through a rapid screening of Cp*Ir complexes based on a turn-on type fluorescence readout, a [Cp*Ir(dipyrido[3,2-a : 2',3'-c]phenazine)Cl]+ complex was found to catalyze the blue-light promoted dehydrogenation of N-heterocycles under physiological conditions. In the dehydrogenation of tetrahydroisoquinolines, the catalyst preferentially yielded the monodehydrogenated product, accompanying H2O2 generation. We surmise that this mechanism may be reminiscent of flavin-dependent oxidases.
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Affiliation(s)
- Holly Jane Davis
- Department of ChemistryUniversity of BaselMattenstrasse 24a BRP 1096 RosentalCH-4058BaselSwitzerland
| | - Daniel Häussinger
- Department of ChemistryUniversity of BaselSt. Johanns-Ring 19CH-4056BaselSwitzerland
| | - Thomas R. Ward
- Department of ChemistryUniversity of BaselMattenstrasse 24a BRP 1096 RosentalCH-4058BaselSwitzerland
| | - Yasunori Okamoto
- Department of ChemistryUniversity of BaselMattenstrasse 24a BRP 1096 RosentalCH-4058BaselSwitzerland
- Frontier Research Institute for Interdisciplinary SciencesTohoku University6-3 Aramaki aza AobaAoba-kuSendai980-8578Japan
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14
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Lin YH, Kutin Y, van Gastel M, Bill E, Schnegg A, Ye S, Lee WZ. A Manganese(IV)-Hydroperoxo Intermediate Generated by Protonation of the Corresponding Manganese(III)-Superoxo Complex. J Am Chem Soc 2020; 142:10255-10260. [PMID: 32412757 DOI: 10.1021/jacs.0c02756] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Earlier work revealed that metal-superoxo species primarily function as radicals and/or electrophiles. Herein, we present ambiphilicity of a MnIII-superoxo complex revealed by its proton- and metal-coupled electron-transfer processes. Specifically, a MnIV-hydroperoxo intermediate, [Mn(BDPBrP)(OOH)]+ (1, H2BDPBrP = 2,6-bis((2-(S)-di(4-bromo)phenylhydroxylmethyl-1-pyrrolidinyl)methyl)pyridine) was generated by treatment of a MnIII-superoxo complex, Mn(BDPBrP)(O2•) (2) with trifluoroacetic acid at -120 °C. Detailed insights into the electronic structure of 1 are obtained using resonance Raman and multi-frequency electron paramagnetic resonance spectroscopies coupled with density functional theory calculations. Similarly, the reaction of 2 with scandium(III) triflate was shown to give a Mn(IV)/Sc(III) bridging peroxo species, [Mn(BDPBrP)(OO)Sc(OTf)n](3-n)+ (4). Furthermore, it is found that deprotonation of 1 quantitatively regenerates 2, and that one-electron oxidation of the corresponding MnIII-hydroperoxo species, Mn(BDPBrP)(OOH) (3), also yields 1.
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Affiliation(s)
- Yen-Hao Lin
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Yury Kutin
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr D-45470, Germany
| | - Maurice van Gastel
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr D-45470, Germany
| | - Eckhard Bill
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr D-45470, Germany
| | - Alexander Schnegg
- Max-Planck-Institut für Chemische Energiekonversion, Mülheim an der Ruhr D-45470, Germany
| | - Shengfa Ye
- Max-Planck-Institut für Kohlenforschung, Mülheim an der Ruhr D-45470, Germany.,State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Way-Zen Lee
- Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan.,Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan
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15
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Squarcina A, Santoro A, Hickey N, De Zorzi R, Carraro M, Geremia S, Bortolus M, Di Valentin M, Bonchio M. Neutralization of Reactive Oxygen Species at Dinuclear Cu(II)-Cores: Tuning the Antioxidant Manifold in Water by Ligand Design. ACS Catal 2020. [DOI: 10.1021/acscatal.0c01955] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
| | | | - Neal Hickey
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy
| | - Rita De Zorzi
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy
| | | | - Silvano Geremia
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy
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16
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Kim H, Rogler PJ, Sharma SK, Schaefer AW, Solomon EI, Karlin KD. Heme-Fe III Superoxide, Peroxide and Hydroperoxide Thermodynamic Relationships: Fe III-O 2•- Complex H-Atom Abstraction Reactivity. J Am Chem Soc 2020; 142:3104-3116. [PMID: 31913628 PMCID: PMC7034651 DOI: 10.1021/jacs.9b12571] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Establishing redox and thermodynamic relationships between metal-ion-bound O2 and its reduced (and protonated) derivatives is critically important for a full understanding of (bio)chemical processes involving dioxygen processing. Here, a ferric heme peroxide complex, [(F8)FeIII-(O22-)]- (P) (F8 = tetrakis(2,6-difluorophenyl)porphyrinate), and a superoxide complex, [(F8)FeIII-(O2•-)] (S), are shown to be redox interconvertible. Using Cr(η-C6H6)2, an equilibrium state where S and P are present is established in tetrahydrofuran (THF) at -80 °C, allowing determination of the reduction potential of S as -1.17 V vs Fc+/0. P could be protonated with 2,6-lutidinium triflate, yielding the low-spin ferric hydroperoxide species, [(F8)FeIII-(OOH)] (HP). Partial conversion of HP back to P using a derivatized phosphazene base gave a P/HP equilibrium mixture, leading to the determination of pKa = 28.8 for HP (THF, -80 °C). With the measured reduction potential and pKa, the O-H bond dissociation free energy (BDFE) of hydroperoxide species HP was calculated to be 73.5 kcal/mol, employing the thermodynamic square scheme and Bordwell relationship. This calculated O-H BDFE of HP, in fact, lines up with an experimental demonstration of the oxidizing ability of S via hydrogen atom transfer (HAT) from TEMPO-H (2,2,6,6-tetramethylpiperdine-N-hydroxide, BDFE = 66.5 kcal/mol in THF), forming the hydroperoxide species HP and TEMPO radical. Kinetic studies carried out with TEMPO-H(D) reveal second-order behavior, kH = 0.5, kD = 0.08 M-1 s-1 (THF, -80 °C); thus, the hydrogen/deuterium kinetic isotope effect (KIE) = 6, consistent with H-atom abstraction by S being the rate-determining step. This appears to be the first case where experimentally derived thermodynamics lead to a ferric heme hydroperoxide OO-H BDFE determination, that FeIII-OOH species being formed via HAT reactivity of the partner ferric heme superoxide complex.
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Affiliation(s)
- Hyun Kim
- 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
| | - Savita K Sharma
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Andrew W Schaefer
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Edward I Solomon
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Kenneth D Karlin
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
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17
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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: 33] [Impact Index Per Article: 6.6] [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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18
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Mononuclear copper(II) complexes containing a macrocyclic ditopic ligand: Synthesis, structures and properties. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2019.119081] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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19
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Will J, Würtele C, Becker J, Walter O, Schindler S. Synthesis, crystal structures and reactivity towards dioxygen of copper(I) complexes with tripodal aliphatic amine ligands. Polyhedron 2019. [DOI: 10.1016/j.poly.2019.07.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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20
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Quist DA, Ehudin MA, Schaefer AW, Schneider GL, Solomon EI, Karlin KD. Ligand Identity-Induced Generation of Enhanced Oxidative Hydrogen Atom Transfer Reactivity for a Cu II2(O 2•-) Complex Driven by Formation of a Cu II2( -OOH) Compound with a Strong O-H Bond. J Am Chem Soc 2019; 141:12682-12696. [PMID: 31299154 DOI: 10.1021/jacs.9b05277] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A superoxide-bridged dicopper(II) complex, [CuII2(XYLO)(O2•-)]2+ (1) (XYLO = binucleating m-xylyl derivative with a bridging phenolate ligand donor and two bis(2-{2-pyridyl}ethyl)amine arms), was generated from chemical oxidation of the peroxide-bridged dicopper(II) complex [CuII2(XYLO)(O22-)]+ (2), using ferrocenium (Fc+) derivatives, in 2-methyltetrahydrofuran (MeTHF) at -125 °C. Using Me10Fc+, a 1 ⇆ 2 equilibrium was established, allowing for calculation of the reduction potential of 1 as -0.525 ± 0.01 V vs Fc+/0. Addition of 1 equiv of strong acid to 2 afforded the hydroperoxide-bridged dicopper(II) species [CuII2(XYLO)(OOH)]2+ (3). An acid-base equilibrium between 3 and 2 was achieved through spectral titrations using a derivatized phosphazene base. The pKa of 3 was thus determined to be 24 ± 0.6 in MeTHF at -125 °C. Using a thermodynamic square scheme and the Bordwell relationship, the hydroperoxo complex (3) O-H bond dissociation free energy (BDFE) was calculated as 81.8 ± 1.5 (BDE = 86.8) kcal/mol. The observed oxidizing capability of [CuII2(XYLO)(O2•-)]2+ (1), as demonstrated in H atom abstraction reactions with certain phenolic ArO-H and hydrocarbon C-H substrates, provides direct support for this experimentally determined O-H BDFE. A kinetic study reveals a very fast reaction of TEMPO-H with 1 in MeTHF, with k (-100 °C) = 5.6 M-1 s-1. Density functional theory (DFT) calculations reveal how the structure of 1 may minimize stabilization of the superoxide moiety, resulting in its enhanced reactivity. The thermodynamic insights obtained herein highlight the importance of the interplay between ligand design and the generation and properties of copper (or other metal ion) bound O2-derived reduced species, such as pKa, reduction potential, and BDFE; these may be relevant to the capabilities (i.e., oxidizing power) of reactive oxygen intermediates in metalloenzyme chemical system mediated oxidative processes.
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Affiliation(s)
- David A Quist
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Melanie A Ehudin
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
| | - Andrew W Schaefer
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Gregory L Schneider
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Edward I Solomon
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Kenneth D Karlin
- Department of Chemistry , Johns Hopkins University , Baltimore , Maryland 21218 , United States
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21
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Alwan KB, Welch EF, Arias RJ, Gambill BF, Blackburn NJ. Rational Design of a Histidine-Methionine Site Modeling the M-Center of Copper Monooxygenases in a Small Metallochaperone Scaffold. Biochemistry 2019; 58:3097-3108. [PMID: 31243953 DOI: 10.1021/acs.biochem.9b00312] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mononuclear copper monooxygenases peptidylglycine monooxygenase (PHM) and dopamine β-monooxygenase (DBM) catalyze the hydroxylation of high energy C-H bonds utilizing a pair of chemically distinct copper sites (CuH and CuM) separated by 11 Å. In earlier work, we constructed single-site PHM variants that were designed to allow the study of the M- and H-centers independently in order to place their reactivity sequentially along the catalytic pathway. More recent crystallographic studies suggest that these single-site variants may not be truly representative of the individual active sites. In this work, we describe an alternative approach that uses a rational design to construct an artificial PHM model in a small metallochaperone scaffold. Using site-directed mutagenesis, we constructed variants that provide a His2Met copper-binding ligand set that mimics the M-center of PHM. The results show that the model accurately reproduces the chemical and spectroscopic properties of the M-center, including details of the methionine coordination, and the properties of Cu(I) and Cu(II) states in the presence of endogenous ligands such as CO and azide. The rate of reduction of the Cu(II) form of the model by the chromophoric reductant N,N'-dimethyl phenylenediamine (DMPD) has been compared with that of the PHM M-center, and the reaction chemistry of the Cu(I) forms with molecular oxygen has also been explored, revealing an unusually low reactivity toward molecular oxygen. This latter finding emphasizes the importance of substrate triggering of oxygen reactivity and implies that the His2Met ligand set, while necessary, is insufficient on its own to activate oxygen in these enzyme systems.
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Affiliation(s)
- Katherine B Alwan
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Evan F Welch
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Renee J Arias
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Ben F Gambill
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
| | - Ninian J Blackburn
- Department of Chemical Physiology and Biochemistry , Oregon Health & Sciences University , Portland , Oregon 97239 , United States
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22
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Hangasky JA, Detomasi TC, Marletta MA. Glycosidic Bond Hydroxylation by Polysaccharide Monooxygenases. TRENDS IN CHEMISTRY 2019. [DOI: 10.1016/j.trechm.2019.01.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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23
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Ehudin MA, Gee LB, Sabuncu S, Braun A, Moenne-Loccoz P, Hedman B, Hodgson KO, Solomon EI, Karlin KD. Tuning the Geometric and Electronic Structure of Synthetic High-Valent Heme Iron(IV)-Oxo Models in the Presence of a Lewis Acid and Various Axial Ligands. J Am Chem Soc 2019; 141:5942-5960. [PMID: 30860832 PMCID: PMC6611672 DOI: 10.1021/jacs.9b00795] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
High-valent ferryl species (e.g., (Por)FeIV═O, Cmpd-II) are observed or proposed key oxidizing intermediates in the catalytic cycles of heme-containing enzymes (P-450s, peroxidases, catalases, and cytochrome c oxidase) involved in biological respiration and oxidative metabolism. Herein, various axially ligated iron(IV)-oxo complexes were prepared to examine the influence of the identity of the base. These were generated by addition of various axial ligands (1,5-dicyclohexylimidazole (DCHIm), a tethered-imidazole system, and sodium derivatives of 3,5-dimethoxyphenolate and imidazolate). Characterization was carried out via UV-vis, electron paramagnetic resonance (EPR), 57Fe Mössbauer, Fe X-ray absorption (XAS), and 54/57Fe resonance Raman (rR) spectroscopies to confirm their formation and compare the axial ligand perturbation on the electronic and geometric structures of these heme iron(IV)-oxo species. Mössbauer studies confirmed that the axially ligated derivatives were iron(IV) and six-coordinate complexes. XAS and 54/57Fe rR data correlated with slight elongation of the iron-oxo bond with increasing donation from the axial ligands. The first reported synthetic H-bonded iron(IV)-oxo heme systems were made in the presence of the protic Lewis acid, 2,6-lutidinium triflate (LutH+), with (or without) DCHIm. Mössbauer, rR, and XAS spectroscopic data indicated the formation of molecular Lewis acid ferryl adducts (rather than full protonation). The reduction potentials of these novel Lewis acid adducts were bracketed through addition of outer-sphere reductants. The oxidizing capabilities of the ferryl species with or without Lewis acid vary drastically; addition of LutH+ to F8Cmpd-II (F8 = tetrakis(2,6-difluorophenyl)porphyrinate) increased its reduction potential by more than 890 mV, experimentally confirming that H-bonding interactions can increase the reactivity of ferryl species.
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Affiliation(s)
- Melanie A. Ehudin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Leland B. Gee
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Sinan Sabuncu
- Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, Oregon 97239-3098, United States
| | - Augustin Braun
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Pierre Moenne-Loccoz
- Department of Biochemistry & Molecular Biology, Oregon Health & Science University, Portland, Oregon 97239-3098, United States
| | - Britt Hedman
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Keith O. Hodgson
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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24
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Bailey WD, Dhar D, Cramblitt AC, Tolman WB. Mechanistic Dichotomy in Proton-Coupled Electron-Transfer Reactions of Phenols with a Copper Superoxide Complex. J Am Chem Soc 2019; 141:5470-5480. [PMID: 30907590 DOI: 10.1021/jacs.9b00466] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The kinetics and mechanism(s) of the reactions of [K(Krypt)][LCuO2] (Krypt = 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane, L = a bis(arylcarboxamido)pyridine ligand) with 2,2,6,6-tetramethylpiperdine- N-hydroxide (TEMPOH) and the para-substituted phenols XArOH (X = para substituent NO2, CF3, Cl, H, Me, tBu, OMe, or NMe2) at low temperatures were studied. The reaction with TEMPOH occurs rapidly ( k = 35.4 ± 0.3 M-1 s-1) by second-order kinetics to yield TEMPO• and [LCuOOH]- on the basis of electron paramagnetic resonance spectroscopy, the production of H2O2 upon treatment with protic acid, and independent preparation from reaction of [NBu4][LCuOH] with H2O2 ( Keq = 0.022 ± 0.007 for the reverse reaction). The reactions with XArOH also follow second-order kinetics, and analysis of the variation of the k values as a function of phenol properties (Hammett σ parameter, O-H bond dissociation free energy, p Ka, E1/2) revealed a change in mechanism across the series, from proton transfer/electron transfer for X = NO2, CF3, Cl to concerted-proton/electron transfer (or hydrogen-atom transfer) for X = OMe, NMe2 (data for X = H, Me, tBu are intermediate between the extremes). Thermodynamic analysis and comparisons to previous results for LCuOH, a different copper-oxygen intermediate with the same supporting ligand, and literature for other [CuO2]+ complexes reveal significant differences in proton-coupled electron-transfer mechanisms that have implications for understanding oxidation catalysis by copper-containing enzymes and abiological catalysts.
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Affiliation(s)
- Wilson D Bailey
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive, Campus Box 1134 , St. Louis , Missouri 63130-4899 , United States
| | - Debanjan Dhar
- Department of Chemistry and Center for Metals in Biocatalysis , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
| | - Anna C Cramblitt
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive, Campus Box 1134 , St. Louis , Missouri 63130-4899 , United States
| | - William B Tolman
- Department of Chemistry , Washington University in St. Louis , One Brookings Drive, Campus Box 1134 , St. Louis , Missouri 63130-4899 , United States.,Department of Chemistry and Center for Metals in Biocatalysis , University of Minnesota , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , United States
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25
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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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27
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Bhadra M, Lee JYC, Cowley RE, Kim S, Siegler MA, Solomon EI, Karlin KD. Intramolecular Hydrogen Bonding Enhances Stability and Reactivity of Mononuclear Cupric Superoxide Complexes. J Am Chem Soc 2018; 140:9042-9045. [PMID: 29957998 PMCID: PMC6217813 DOI: 10.1021/jacs.8b04671] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
[(L)CuII(O2•-)]+ (i.e., cupric-superoxo) complexes, as the first and/or key reactive intermediates in (bio)chemical Cu-oxidative processes, including in the monooxygenases PHM and DβM, have been systematically stabilized by intramolecular hydrogen bonding within a TMPA ligand-based framework. Also, gradual strengthening of ligand-derived H-bonding dramatically enhances the [(L)CuII(O2•-)]+ reactivity toward hydrogen-atom abstraction (HAA) of phenolic O-H bonds. Spectroscopic properties of the superoxo complexes and their azido analogues, [(L)CuII(N3-)]+, also systematically change as a function of ligand H-bonding capability.
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Affiliation(s)
- Mayukh Bhadra
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Jung Yoon C. Lee
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Ryan E. Cowley
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Sunghee Kim
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Maxime A. Siegler
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Kenneth D. Karlin
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
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28
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Paria S, Morimoto Y, Ohta T, Okabe S, Sugimoto H, Ogura T, Itoh S. Copper(I)–Dioxygen Reactivity in the Isolated Cavity of a Nanoscale Molecular Architecture. Eur J Inorg Chem 2018. [DOI: 10.1002/ejic.201800029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Sayantan Paria
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamadaoka 565‐0871 Suita Osaka Japan
| | - Yuma Morimoto
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamadaoka 565‐0871 Suita Osaka Japan
| | - Takehiro Ohta
- Picobiology Institute Graduate School of Life Science University of Hyogo Koto 1‐1‐1 679‐5148 Sayo‐cho Sayo‐gun, Hyogo Japan
| | - Shinsuke Okabe
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamadaoka 565‐0871 Suita Osaka Japan
| | - Hideki Sugimoto
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamadaoka 565‐0871 Suita Osaka Japan
| | - Takashi Ogura
- Picobiology Institute Graduate School of Life Science University of Hyogo Koto 1‐1‐1 679‐5148 Sayo‐cho Sayo‐gun, Hyogo Japan
| | - Shinobu Itoh
- Department of Material and Life Science Division of Advanced Science and Biotechnology Graduate School of Engineering Osaka University 2‐1 Yamadaoka 565‐0871 Suita Osaka Japan
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29
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Meier KK, Jones SM, Kaper T, Hansson H, Koetsier MJ, Karkehabadi S, Solomon EI, Sandgren M, Kelemen B. Oxygen Activation by Cu LPMOs in Recalcitrant Carbohydrate Polysaccharide Conversion to Monomer Sugars. Chem Rev 2018; 118:2593-2635. [PMID: 29155571 PMCID: PMC5982588 DOI: 10.1021/acs.chemrev.7b00421] [Citation(s) in RCA: 116] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Natural carbohydrate polymers such as starch, cellulose, and chitin provide renewable alternatives to fossil fuels as a source for fuels and materials. As such, there is considerable interest in their conversion for industrial purposes, which is evidenced by the established and emerging markets for products derived from these natural polymers. In many cases, this is achieved via industrial processes that use enzymes to break down carbohydrates to monomer sugars. One of the major challenges facing large-scale industrial applications utilizing natural carbohydrate polymers is rooted in the fact that naturally occurring forms of starch, cellulose, and chitin can have tightly packed organizations of polymer chains with low hydration levels, giving rise to crystalline structures that are highly recalcitrant to enzymatic degradation. The topic of this review is oxidative cleavage of carbohydrate polymers by lytic polysaccharide mono-oxygenases (LPMOs). LPMOs are copper-dependent enzymes (EC 1.14.99.53-56) that, with glycoside hydrolases, participate in the degradation of recalcitrant carbohydrate polymers. Their activity and structural underpinnings provide insights into biological mechanisms of polysaccharide degradation.
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Affiliation(s)
- Katlyn K. Meier
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Stephen M. Jones
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Thijs Kaper
- DuPont Industrial Biosciences, 925 Page Mill Road, Palo Alto, California 94304, United States
| | - Henrik Hansson
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden
| | - Martijn J. Koetsier
- DuPont Industrial Biosciences, Netherlands, Nieuwe Kanaal 7-S, 6709 PA Wageningen, The Netherlands
| | - Saeid Karkehabadi
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O. Box 7015, SE-750 07 Uppsala, Sweden
| | - Bradley Kelemen
- DuPont Industrial Biosciences, 925 Page Mill Road, Palo Alto, California 94304, United States
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30
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Dahl EW, Dong HT, Szymczak NK. Phenylamino derivatives of tris(2-pyridylmethyl)amine: hydrogen-bonded peroxodicopper complexes. Chem Commun (Camb) 2018; 54:892-895. [PMID: 29242872 DOI: 10.1039/c7cc08619a] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
A series of copper complexes bearing new 6-substituted tris(2-pyridylmethyl)amine ligands (LR) appended with NH(p-R-C6H4) groups (R = H, CF3, OMe) were prepared. These ligands are electronically tunable (ΔE1/2 = 160 mV) and CuI(LR)+ complexes react with oxygen to form hydrogen bonded (trans-1,2-peroxo)dicopper species.
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Affiliation(s)
- E W Dahl
- Department of Chemistry, University of Michigan, 930 N. University Ave., Ann Arbor, MI 48109, USA.
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31
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López I, Cao R, Quist DA, Karlin KD, Le Poul N. Direct Determination of Electron-Transfer Properties of Dicopper-Bound Reduced Dioxygen Species by a Cryo-Spectroelectrochemical Approach. Chemistry 2017; 23:18314-18319. [PMID: 29073346 PMCID: PMC5783699 DOI: 10.1002/chem.201705066] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Indexed: 01/10/2023]
Abstract
Direct experimental determination of redox properties of superoxo (O2.- ) and peroxo (O22- ) embedded in dicopper complexes bearing an unsymmetrical binucleating ligand was achieved using cryo-electrochemistry and cryo-spectroelectrochemistry in dichloromethane. Cyclic voltammetry for dicopper(I) (1+ ) oxidation to a CuI CuII mixed-valent species (12+ ) under inert atmosphere at 193 K reveals slow heterogeneous electron-transfer kinetics, indicative of a large reorganization energy. Oxygenation of the dicuprous complex 1+ gives the bridged peroxo dicopper(II) species 3+ , which is reversibly oxidized to the superoxo complex 22+ at E0 =0.11 V (vs. SCE) with a small inner sphere electron-transfer reorganization energy, λi =0.54 eV, determined from variable temperature electrochemical impedance spectroscopy. The data suggest that the O2.- /O22- redox process occurs directly on the O2 -derived core.
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Affiliation(s)
- Isidoro López
- UMR CNRS 6521, Université de Bretagne Occidentale, 6 Avenue Le Gorgeu, CS 93837, 29238, Brest Cedex 3, France
| | - Rui Cao
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, 21218, USA
| | - David A Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, 21218, USA
| | - Kenneth D Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland, 21218, USA
| | - Nicolas Le Poul
- UMR CNRS 6521, Université de Bretagne Occidentale, 6 Avenue Le Gorgeu, CS 93837, 29238, Brest Cedex 3, France
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32
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Shimizu I, Morimoto Y, Faltermeier D, Kerscher M, Paria S, Abe T, Sugimoto H, Fujieda N, Asano K, Suzuki T, Comba P, Itoh S. Tetrahedral Copper(II) Complexes with a Labile Coordination Site Supported by a Tris-tetramethylguanidinato Ligand. Inorg Chem 2017; 56:9634-9645. [DOI: 10.1021/acs.inorgchem.7b01154] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Ikuma Shimizu
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Yuma Morimoto
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Dieter Faltermeier
- Anorganisch-Chemisches Institut and Interdisciplinary
Center for Scientific Computing, Universität Heidelberg, INF 270, 69120 Heidelberg, Germany
| | - Marion Kerscher
- Anorganisch-Chemisches Institut and Interdisciplinary
Center for Scientific Computing, Universität Heidelberg, INF 270, 69120 Heidelberg, Germany
| | - Sayantan Paria
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Tsukasa Abe
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Hideki Sugimoto
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Nobutaka Fujieda
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
| | - Kaori Asano
- Comprehensive Analysis Center, The Institute of Scientific
and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0057, Japan
| | - Takeyuki Suzuki
- Comprehensive Analysis Center, The Institute of Scientific
and Industrial Research (ISIR), Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0057, Japan
| | - Peter Comba
- Anorganisch-Chemisches Institut and Interdisciplinary
Center for Scientific Computing, Universität Heidelberg, INF 270, 69120 Heidelberg, Germany
| | - Shinobu Itoh
- Department of Material
and Life Science, Division of Advanced Science and Biotechnology,
Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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33
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Neisen BD, Gagnon NL, Dhar D, Spaeth AD, Tolman WB. Formally Copper(III)-Alkylperoxo Complexes as Models of Possible Intermediates in Monooxygenase Enzymes. J Am Chem Soc 2017; 139:10220-10223. [PMID: 28722408 DOI: 10.1021/jacs.7b05754] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Reaction of [NBu4][LCuIIOH] with excess ROOH (R = cumyl or tBu) yielded [NBu4][LCuIIOOR], the reversible one-electron oxidation of which generated novel species with [CuOOR]2+ cores (formally CuIIIOOR), identified by spectroscopy and theory for the case R = cumyl. This species reacts with weak O-H bonds in TEMPO-H and 4-dimethylaminophenol (NMe2PhOH), the latter yielding LCu(OPhNMe2), which was also prepared independently. With the identification of [CuOOR]2+ complexes, the first precedent for this core in enzymes is provided, with implications for copper monooxygenase mechanisms.
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Affiliation(s)
- Benjamin D Neisen
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Nicole L Gagnon
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Debanjan Dhar
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - Andrew D Spaeth
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - William B Tolman
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
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34
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Kindermann N, Günes CJ, Dechert S, Meyer F. Hydrogen Atom Abstraction Thermodynamics of a μ-1,2-Superoxo Dicopper(II) Complex. J Am Chem Soc 2017; 139:9831-9834. [PMID: 28691811 DOI: 10.1021/jacs.7b05722] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Pyrazolate-based μ-1,2-peroxo dicopper(II) complex 1 undergoes clean 1e- oxidation at low potential (-0.59 V vs Fc/Fc+) to yield the rather stable μ-1,2-superoxo dicopper(II) complex 3, which was characterized by spectroscopic methods (ν̃(O-O) = 1070 cm-1, Δ(18O-16O) = -59 cm-1) and analyzed by DFT calculations. 3 is also formed via H-atom abstraction from the corresponding μ-1,1-hydroperoxo dicopper(II) complex 2, while 3 itself is able to abstract H-atoms from weaker X-H bonds such as TEMPO-H to re-form 2. Kinetic and thermodynamic analyses evidence a concerted proton-electron transfer pathway for these processes. The thermodynamic square scheme reveals a bond dissociation free energy of 71.7 ± 1.1 kcal mol-1 for the hydroperoxo OO-H bond of 2.
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Affiliation(s)
- Nicole Kindermann
- Universität Göttingen , Institut für Anorganische Chemie, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Can-Jerome Günes
- Universität Göttingen , Institut für Anorganische Chemie, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Sebastian Dechert
- Universität Göttingen , Institut für Anorganische Chemie, Tammannstraße 4, D-37077 Göttingen, Germany
| | - Franc Meyer
- Universität Göttingen , Institut für Anorganische Chemie, Tammannstraße 4, D-37077 Göttingen, Germany
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35
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Cheignon C, Jones M, Atrián-Blasco E, Kieffer I, Faller P, Collin F, Hureau C. Identification of key structural features of the elusive Cu-Aβ complex that generates ROS in Alzheimer's disease. Chem Sci 2017; 8:5107-5118. [PMID: 28970897 PMCID: PMC5613283 DOI: 10.1039/c7sc00809k] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 04/29/2017] [Indexed: 12/16/2022] Open
Abstract
Oxidative stress is linked to the etiology of Alzheimer's disease (AD), the most common cause of dementia in the elderly. Redox active metal ions such as copper catalyze the production of Reactive Oxygen Species (ROS) when bound to the amyloid-β (Aβ) peptide encountered in AD. We propose that this reaction proceeds through a low-populated Cu-Aβ state, denoted the "catalytic in-between state" (CIBS), which is in equilibrium with the resting state (RS) of both Cu(i)-Aβ and Cu(ii)-Aβ. The nature of this CIBS is investigated in the present work. We report the use of complementary spectroscopic methods (X-ray absorption spectroscopy, EPR and NMR) to characterize the binding of Cu to a wide series of modified peptides in the RS. ROS production by the resulting Cu-peptide complexes was evaluated using fluorescence and UV-vis based methods and led to the identification of the amino acid residues involved in the Cu-Aβ CIBS species. In addition, a possible mechanism by which the ROS are produced is also proposed. These two main results are expected to affect the current vision of the ROS production mechanism by Cu-Aβ but also in other diseases involving amyloidogenic peptides with weakly structured copper binding sites.
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Affiliation(s)
- Clémence Cheignon
- LCC (Laboratoire de Chimie de Coordination) , CNRS UPR 8241 , 205 route de Narbonne , 31062 Toulouse Cedex 09 , France . ;
- Université de Toulouse , UPS , INPT , 31077 Toulouse , France
- UMR 152 Pharma Dev , Université de Toulouse , IRD , UPS , France
| | - Megan Jones
- LCC (Laboratoire de Chimie de Coordination) , CNRS UPR 8241 , 205 route de Narbonne , 31062 Toulouse Cedex 09 , France . ;
- Université de Toulouse , UPS , INPT , 31077 Toulouse , France
| | - Elena Atrián-Blasco
- LCC (Laboratoire de Chimie de Coordination) , CNRS UPR 8241 , 205 route de Narbonne , 31062 Toulouse Cedex 09 , France . ;
- Université de Toulouse , UPS , INPT , 31077 Toulouse , France
| | - Isabelle Kieffer
- Observatoire des Sciences de l'Univers de Grenoble (OSUG) , CNRS UMS 832 , 414 Rue de la Piscine , 38400 Saint Martin d'Hères , France
- BM30B/FAME , ESRF , The European Synchrotron , 71 Avenue des Martyrs , 38000 Grenoble , France
| | - Peter Faller
- LCC (Laboratoire de Chimie de Coordination) , CNRS UPR 8241 , 205 route de Narbonne , 31062 Toulouse Cedex 09 , France . ;
- Université de Toulouse , UPS , INPT , 31077 Toulouse , France
| | - Fabrice Collin
- LCC (Laboratoire de Chimie de Coordination) , CNRS UPR 8241 , 205 route de Narbonne , 31062 Toulouse Cedex 09 , France . ;
- Université de Toulouse , UPS , INPT , 31077 Toulouse , France
- UMR 152 Pharma Dev , Université de Toulouse , IRD , UPS , France
| | - Christelle Hureau
- LCC (Laboratoire de Chimie de Coordination) , CNRS UPR 8241 , 205 route de Narbonne , 31062 Toulouse Cedex 09 , France . ;
- Université de Toulouse , UPS , INPT , 31077 Toulouse , France
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36
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Devi T, Lee Y, Jung J, Sankaralingam M, Nam W, Fukuzumi S. A Chromium(III)‐Superoxo Complex as a Three‐Electron Oxidant with a Large Tunneling Effect in Multi‐Electron Oxidation of NADH Analogues. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611709] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Tarali Devi
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Yong‐Min Lee
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | - Jieun Jung
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
| | | | - Wonwoo Nam
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
- State Key Laboratory for Oxo Synthesis and Selective Oxidation Lanzhou Institute of Chemical Physics Chinese Academy of Sciences Lanzhou 730000 China
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science Ewha Womans University Seoul 03760 Korea
- Faculty of Science and Engineering SENTAN Japan Science and Technology Agency (JST) Meijo University Nagoya, Aichi 468-8502 Japan
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37
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Devi T, Lee YM, Jung J, Sankaralingam M, Nam W, Fukuzumi S. A Chromium(III)-Superoxo Complex as a Three-Electron Oxidant with a Large Tunneling Effect in Multi-Electron Oxidation of NADH Analogues. Angew Chem Int Ed Engl 2017; 56:3510-3515. [PMID: 28266771 DOI: 10.1002/anie.201611709] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/15/2017] [Indexed: 11/06/2022]
Abstract
Metal-superoxo species are involved in a variety of enzymatic oxidation reactions, and multi-electron oxidation of substrates is frequently observed in those enzymatic reactions. A CrIII -superoxo complex, [CrIII (O2 )(TMC)(Cl)]+ (1; TMC=1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), is described that acts as a novel three-electron oxidant in the oxidation of dihydronicotinamide adenine dinucleotide (NADH) analogues. In the reactions of 1 with NADH analogues, a CrIV -oxo complex, [CrIV (O)(TMC)(Cl)]+ (2), is formed by a heterolytic O-O bond cleavage of a putative CrII -hydroperoxo complex, [CrII (OOH)(TMC)(Cl)], which is generated by hydride transfer from NADH analogues to 1. The comparison of the reactivity of NADH analogues with 1 and p-chloranil (Cl4 Q) indicates that oxidation of NADH analogues by 1 proceeds by proton-coupled electron transfer with a very large tunneling effect (for example, with a kinetic isotope effect of 470 at 233 K), followed by rapid electron transfer.
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Affiliation(s)
- Tarali Devi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea
| | - Jieun Jung
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea
| | | | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea.,State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000, China
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul, 03760, Korea.,Faculty of Science and Engineering, SENTAN Japan Science and Technology Agency (JST), Meijo University, Nagoya, Aichi, 468-8502, Japan
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38
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Elwell CE, Gagnon NL, Neisen BD, Dhar D, Spaeth AD, Yee GM, Tolman WB. Copper-Oxygen Complexes Revisited: Structures, Spectroscopy, and Reactivity. Chem Rev 2017; 117:2059-2107. [PMID: 28103018 PMCID: PMC5963733 DOI: 10.1021/acs.chemrev.6b00636] [Citation(s) in RCA: 445] [Impact Index Per Article: 63.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A longstanding research goal has been to understand the nature and role of copper-oxygen intermediates within copper-containing enzymes and abiological catalysts. Synthetic chemistry has played a pivotal role in highlighting the viability of proposed intermediates and expanding the library of known copper-oxygen cores. In addition to the number of new complexes that have been synthesized since the previous reviews on this topic in this journal (Mirica, L. M.; Ottenwaelder, X.; Stack, T. D. P. Chem. Rev. 2004, 104, 1013-1046 and Lewis, E. A.; Tolman, W. B. Chem. Rev. 2004, 104, 1047-1076), the field has seen significant expansion in the (1) range of cores synthesized and characterized, (2) amount of mechanistic work performed, particularly in the area of organic substrate oxidation, and (3) use of computational methods for both the corroboration and prediction of proposed intermediates. The scope of this review has been limited to well-characterized examples of copper-oxygen species but seeks to provide a thorough picture of the spectroscopic characteristics and reactivity trends of the copper-oxygen cores discussed.
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Affiliation(s)
- Courtney E Elwell
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Nicole L Gagnon
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Benjamin D Neisen
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Debanjan Dhar
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Andrew D Spaeth
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - Gereon M Yee
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
| | - William B Tolman
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
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39
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Adam SM, Garcia-Bosch I, Schaefer AW, Sharma SK, Siegler MA, Solomon EI, Karlin KD. Critical Aspects of Heme-Peroxo-Cu Complex Structure and Nature of Proton Source Dictate Metal-O(peroxo) Breakage versus Reductive O-O Cleavage Chemistry. J Am Chem Soc 2017; 139:472-481. [PMID: 28029788 PMCID: PMC5274545 DOI: 10.1021/jacs.6b11322] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The 4H+/4e- reduction of O2 to water, a key fuel-cell reaction also carried out in biology by oxidase enzymes, includes the critical O-O bond reductive cleavage step. Mechanistic investigations on active-site model compounds, which are synthesized by rational design to incorporate systematic variations, can focus on and resolve answers to fundamental questions, including protonation and/or H-bonding aspects, which accompany electron transfer. Here, we describe the nature and comparative reactivity of two low-spin heme-peroxo-Cu complexes, LS-4DCHIm, [(DCHIm)F8FeIII-(O22-)-CuII(DCHIm)4]+, and LS-3DCHIm, [(DCHIm)F8FeIII-(O22-)-CuII(DCHIm)3]+ (F8 = tetrakis(2,6-difluorophenyl)-porphyrinate; DCHIm = 1,5-dicyclohexylimidazole), toward different proton (4-nitrophenol and [DMF·H+](CF3SO3-)) (DMF = dimethyl-formamide) or electron (decamethylferrocene (Fc*)) sources. Spectroscopic reactivity studies show that differences in structure and electronic properties of LS-3DCHIm and LS-4DCHIm lead to significant differences in behavior. LS-3DCHIm is resistant to reduction, is unreactive toward weakly acidic 4-NO2-phenol, and stronger acids cleave the metal-O bonds, releasing H2O2. By contrast, LS-4DCHIm forms an adduct with 4-NO2-phenol, which includes an H-bond to the peroxo O-atom distal to Fe (resonance Raman (rR) spectroscopy and DFT). With addition of Fc* (2 equiv overall required), O-O reductive cleavage occurs, giving water, Fe(III), and Cu(II) products; however, a kinetic study reveals a one-electron rate-determining process, ket = 1.6 M-1 s-1 (-90 °C). The intermediacy of a high-valent [(DCHIm)F8FeIV═O] species is thus implied, and separate experiments show that one-electron reduction-protonation of [(DCHIm)F8FeIV═O] occurs faster (ket2 = 5.0 M-1 s-1), consistent with the overall postulated mechanism. The importance of the H-bonding interaction as a prerequisite for reductive cleavage is highlighted.
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Affiliation(s)
- Suzanne M. Adam
- Johns Hopkins University, Baltimore, Maryland 21218, United States
| | | | - Andrew W. Schaefer
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Savita K. Sharma
- Johns Hopkins University, Baltimore, Maryland 21218, United States
| | | | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
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40
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Kline CD, Blackburn NJ. Substrate-Induced Carbon Monoxide Reactivity Suggests Multiple Enzyme Conformations at the Catalytic Copper M-Center of Peptidylglycine Monooxygenase. Biochemistry 2016; 55:6652-6661. [PMID: 27933800 DOI: 10.1021/acs.biochem.6b00845] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present study uses CO as a surrogate for oxygen to probe how substrate binding triggers oxygen activation in peptidylglycine monooygenase (PHM). Infrared stretching frequencies (ν(C ≡ O)) of the carbonyl (CO) adducts of copper proteins are sensitive markers of Cu(I) coordination and are useful in probing oxygen reactivity because the electronic properties of O2 and CO are similar. The carbonyl chemistry has been explored using PHM WT and a number of active site variants in the absence and presence of peptidyl substrates. We have determined that upon carbonylation (i) a major CO band at 2092 cm-1 and a second minor CO band at 2063 cm-1 are observed in the absence of peptide substrate Ac-YVG; (ii) the presence of peptide substrate amplifies the minor CO band and causes it to partially interconvert with the CO band at 2092 cm-1; (iii) the substrate-induced CO band is associated with a second conformer at CuM; and (iv) the CuH-site mutants, which are inactive, fail to generate any substrate-induced CO bands. The total intensity of both bands is constant, suggesting that the Cu(I)M-site partitions between the two carbonylated enzyme states. Together, these data provide evidence for two conformers at CuM, one of which is induced by binding of the peptide substrate with the implication that this represents the conformation that also allows binding and activation of O2.
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Affiliation(s)
- Chelsey D Kline
- Institute of Environmental Health, Oregon Health and Science University , 3181 S.W. Sam Jackson Park Road, Portland, Oregon 97239, United States
| | - Ninian J Blackburn
- Institute of Environmental Health, Oregon Health and Science University , 3181 S.W. Sam Jackson Park Road, Portland, Oregon 97239, United States
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41
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Coordination and redox properties of copper interaction with α-synuclein. J Inorg Biochem 2016; 163:292-300. [DOI: 10.1016/j.jinorgbio.2016.04.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 03/11/2016] [Accepted: 04/04/2016] [Indexed: 11/23/2022]
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42
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Cowley RE, Cirera J, Qayyum MF, Rokhsana D, Hedman B, Hodgson KO, Dooley DM, Solomon EI. Structure of the Reduced Copper Active Site in Preprocessed Galactose Oxidase: Ligand Tuning for One-Electron O 2 Activation in Cofactor Biogenesis. J Am Chem Soc 2016; 138:13219-13229. [PMID: 27626829 DOI: 10.1021/jacs.6b05792] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Galactose oxidase (GO) is a copper-dependent enzyme that accomplishes 2e- substrate oxidation by pairing a single copper with an unusual cysteinylated tyrosine (Cys-Tyr) redox cofactor. Previous studies have demonstrated that the post-translational biogenesis of Cys-Tyr is copper- and O2-dependent, resulting in a self-processing enzyme system. To investigate the mechanism of cofactor biogenesis in GO, the active-site structure of Cu(I)-loaded GO was determined using X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy, and density-functional theory (DFT) calculations were performed on this model. Our results show that the active-site tyrosine lowers the Cu potential to enable the thermodynamically unfavorable 1e- reduction of O2, and the resulting Cu(II)-O2•- is activated toward H atom abstraction from cysteine. The final step of biogenesis is a concerted reaction involving coordinated Tyr ring deprotonation where Cu(II) coordination enables formation of the Cys-Tyr cross-link. These spectroscopic and computational results highlight the role of the Cu(I) in enabling O2 activation by 1e- and the role of the resulting Cu(II) in enabling substrate activation for biogenesis.
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Affiliation(s)
- Ryan E Cowley
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Jordi Cirera
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Munzarin F Qayyum
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Dalia Rokhsana
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States
| | - Britt Hedman
- Department of Chemistry, Stanford University , Stanford, California 94305, United States.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University , Menlo Park, California 94025, United States
| | - Keith O Hodgson
- Department of Chemistry, Stanford University , Stanford, California 94305, United States.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University , Menlo Park, California 94025, United States
| | - David M Dooley
- Department of Chemistry and Biochemistry, Montana State University , Bozeman, Montana 59717, United States.,University of Rhode Island , Kingston, Rhode Island 02881, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University , Stanford, California 94305, United States.,Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University , Menlo Park, California 94025, United States
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43
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Abstract
Primary copper(I)-dioxygen (O2) adducts, cupric-superoxide complexes, have been proposed intermediates in copper-containing dioxygen-activating monooxygenase and oxidase enzymes. Here, mechanisms of C-H activation by reactive copper-(di)oxygen intermediates are discussed, with an emphasis on cupric-superoxide species. Over the past 25 years, many synthetically derived cupric-superoxide model complexes have been reported. Due to the thermal instability of these intermediates, early studies focused on increasing their stability and obtaining physical characterization. More recently, in an effort to gain insight into the possible substrate oxidation step in some copper monooxygenases, several cupric-superoxide complexes have been used as surrogates to probe substrate scope and reaction mechanisms. These cupric superoxides are capable of oxidizing substrates containing weak O-H and C-H bonds. Mechanistic studies for some enzymes and model systems have supported an initial hydrogen-atom abstraction via the cupric-superoxide complex as the first step of substrate oxidation.
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Affiliation(s)
- Jeffrey J Liu
- Department of Chemistry, Johns Hopkins University, Baltimore MD 21218 (USA)
| | - Daniel E Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore MD 21218 (USA)
| | - David A Quist
- 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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44
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Cao R, Saracini C, Ginsbach JW, Kieber-Emmons MT, Siegler MA, Solomon EI, Fukuzumi S, Karlin KD. Peroxo and Superoxo Moieties Bound to Copper Ion: Electron-Transfer Equilibrium with a Small Reorganization Energy. J Am Chem Soc 2016; 138:7055-66. [PMID: 27228314 DOI: 10.1021/jacs.6b02404] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Oxygenation of [Cu2(UN-O(-))(DMF)](2+) (1), a structurally characterized dicopper Robin-Day class I mixed-valent Cu(II)Cu(I) complex, with UN-O(-) as a binucleating ligand and where dimethylformamide (DMF) binds to the Cu(II) ion, leads to a superoxo-dicopper(II) species [Cu(II)2(UN-O(-))(O2(•-))](2+) (2). The formation kinetics provide that kon = 9 × 10(-2) M(-1) s(-1) (-80 °C), ΔH(‡) = 31.1 kJ mol(-1) and ΔS(‡) = -99.4 J K(-1) mol(-1) (from -60 to -90 °C data). Complex 2 can be reversibly reduced to the peroxide species [Cu(II)2(UN-O(-))(O2(2-))](+) (3), using varying outer-sphere ferrocene or ferrocenium redox reagents. A Nernstian analysis could be performed by utilizing a monodiphenylamine substituted ferrocenium salt to oxidize 3, leading to an equilibrium mixture with Ket = 5.3 (-80 °C); a standard reduction potential for the superoxo-peroxo pair is calculated to be E° = +130 mV vs SCE. A literature survey shows that this value falls into the range of biologically relevant redox reagents, e.g., cytochrome c and an organic solvent solubilized ascorbate anion. Using mixed-isotope resonance Raman (rRaman) spectroscopic characterization, accompanied by DFT calculations, it is shown that the superoxo complex consists of a mixture of μ-1,2- (2(1,2)) and μ-1,1- (2(1,1)) isomers, which are in rapid equilibrium. The electron transfer process involves only the μ-1,2-superoxo complex [Cu(II)2(UN-O(-))(μ-1,2-O2(•-))](2+) (2(1,2)) and μ-1,2-peroxo structures [Cu(II)2(UN-O(-))(O2(2-))](+) (3) having a small bond reorganization energy of 0.4 eV (λin). A stopped-flow kinetic study results reveal an outer-sphere electron transfer process with a total reorganization energy (λ) of 1.1 eV between 2(1,2) and 3 calculated in the context of Marcus theory.
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Affiliation(s)
- Rui Cao
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Claudio Saracini
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States.,Department of Chemistry and Nano Science, Ewha Womans University , Seoul 120-750, Korea
| | - Jake W Ginsbach
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | | | - Maxime A Siegler
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Edward I Solomon
- Department of Chemistry, Stanford University , Stanford, California 94305, United States
| | - Shunichi Fukuzumi
- Faculty of Science and Engineering, ALCA, SENTAN, Japan Science and Technology Agency (JST), Meijo University , Nagoya, Aichi 468-0073, Japan.,Department of Chemistry and Nano Science, Ewha Womans University , Seoul 120-750, Korea
| | - Kenneth D Karlin
- Department of Chemistry, Johns Hopkins University , Baltimore, Maryland 21218, United States
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45
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Eberle B, Damjanović M, Enders M, Leingang S, Pfisterer J, Krämer C, Hübner O, Kaifer E, Himmel HJ. Radical Monocationic Guanidino-Functionalized Aromatic Compounds (GFAs) as Bridging Ligands in Dinuclear Metal Acetate Complexes: Synthesis, Electronic Structure, and Magnetic Coupling. Inorg Chem 2016; 55:1683-96. [DOI: 10.1021/acs.inorgchem.5b02614] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Benjamin Eberle
- Ruprecht-Karls-Universität Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Marko Damjanović
- Ruprecht-Karls-Universität Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Markus Enders
- Ruprecht-Karls-Universität Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Simone Leingang
- Ruprecht-Karls-Universität Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Jessica Pfisterer
- Ruprecht-Karls-Universität Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Christoph Krämer
- Ruprecht-Karls-Universität Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Olaf Hübner
- Ruprecht-Karls-Universität Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Elisabeth Kaifer
- Ruprecht-Karls-Universität Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
| | - Hans-Jörg Himmel
- Ruprecht-Karls-Universität Heidelberg, Anorganisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
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46
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Saracini C, Ohkubo K, Suenobu T, Meyer GJ, Karlin KD, Fukuzumi S. Laser-Induced Dynamics of Peroxodicopper(II) Complexes Vary with the Ligand Architecture. One-Photon Two-Electron O2 Ejection and Formation of Mixed-Valent Cu(I)Cu(II)-Superoxide Intermediates. J Am Chem Soc 2015; 137:15865-74. [PMID: 26651492 DOI: 10.1021/jacs.5b10177] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Photoexcitation of end-on trans-μ-1,2-peroxodicopper(II) complex [(tmpa)2Cu(II)2(O2)](2+) (1) (λmax = 525 and 600 nm) and side-on μ-η(2):η(2)-peroxodicopper(II) complexes [(N5)Cu(II)2(O2)](2+) (2) and [(N3)Cu(II)2(O2)](2+) (3) at -80 °C in acetone led to one-photon two-electron peroxide-to-dioxygen oxidation chemistry (O2(2-) + hν → O2 + 2e(-)). Interestingly, light excitation of 2 and 3 (having side-on μ-η(2):η(2)-peroxo ligation) led to release of dioxygen, while photoexcitation of 1 (having an end-on trans-1,2-peroxo geometry) did not, even though spectroscopic studies revealed that both reactions proceeded through previously unknown mixed-valent superoxide species: [Cu(II)(O2(•-))Cu(I)](2+) (λmax = 685-740 nm). For 1, this intermediate underwent further fast intramolecular electron transfer to yield an "O2-caged" dicopper(I) adduct, Cu(I)2-O2, and a barrierless stepwise back electron transfer to regenerate 1 occurred. Femtosecond laser excitation of 2 and 3 under the same conditions still led to [Cu(II)(O2(•-))Cu(I)](2+) intermediates that, instead, underwent O2 release with a quantum yield of 0.14 ± 0.1 for 3. Such remarkable differences in reaction pathways likely result from the well-known ligand-derived stability of 2 and 3 vs 1 indicated by ligand-Cu(II/I) redox potentials; (N5)Cu(I) and (N3)Cu(I) complexes are far more stable than (tmpa)Cu(I) species. The fast Cu(I)2/O2 rebinding kinetics was also measured after photoexcitation of 2 and 3, with the results closely tracking those known for the dicopper proteins hemocyanin and tyrosinase, for which the synthetic dicopper(I) precursors [(N5)Cu(I)2](2+) and [(N3)Cu(I)2](2+) and their dioxygen adducts serve as models. The biological relevance of the present findings is discussed, including the potential impact on the solar water splitting process.
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Affiliation(s)
- Claudio Saracini
- Department of Chemistry, The Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Kei Ohkubo
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology Agency (JST) , Suita, Osaka 565-0871, Japan.,Department of Chemistry and Nano Science, Ewha Womans University , Seoul 120-750, Korea
| | - Tomoyoshi Suenobu
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology Agency (JST) , Suita, Osaka 565-0871, Japan
| | - Gerald J Meyer
- Department of Chemistry, The Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Kenneth D Karlin
- Department of Chemistry, The Johns Hopkins University , Baltimore, Maryland 21218, United States
| | - Shunichi Fukuzumi
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, ALCA and SENTAN, Japan Science and Technology Agency (JST) , Suita, Osaka 565-0871, Japan.,Department of Chemistry and Nano Science, Ewha Womans University , Seoul 120-750, Korea.,Faculty of Science and Engineering, Meijo University, ALCA and SENTAN, Japan Science and Technology Agency (JST) , Nagoya, Aichi 468-0073, Japan
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47
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Wild U, Kaifer E, Wadepohl H, Himmel HJ. Combined Oxidation, Deprotonation, and Metal Coordination of a Redox-Active Guanidine Ligand. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500597] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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48
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Oddon F, Chiba Y, Nakazawa J, Ohta T, Ogura T, Hikichi S. Characterization of Mononuclear Non-heme Iron(III)-Superoxo Complex with a Five-Azole Ligand Set. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201502367] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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49
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Oddon F, Chiba Y, Nakazawa J, Ohta T, Ogura T, Hikichi S. Characterization of Mononuclear Non-heme Iron(III)-Superoxo Complex with a Five-Azole Ligand Set. Angew Chem Int Ed Engl 2015; 54:7336-9. [DOI: 10.1002/anie.201502367] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Indexed: 12/25/2022]
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50
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Kim S, Ginsbach JW, Lee JY, Peterson RL, Liu JJ, Siegler MA, Sarjeant AA, Solomon EI, Karlin KD. Amine oxidative N-dealkylation via cupric hydroperoxide Cu-OOH homolytic cleavage followed by site-specific fenton chemistry. J Am Chem Soc 2015; 137:2867-74. [PMID: 25706825 PMCID: PMC4482616 DOI: 10.1021/ja508371q] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Copper(II) hydroperoxide species are significant intermediates in processes such as fuel cells and (bio)chemical oxidations, all involving stepwise reduction of molecular oxygen. We previously reported a Cu(II)-OOH species that performs oxidative N-dealkylation on a dibenzylamino group that is appended to the 6-position of a pyridyl donor of a tripodal tetradentate ligand. To obtain insights into the mechanism of this process, reaction kinetics and products were determined employing ligand substrates with various para-substituent dibenzyl pairs (-H,-H; -H,-Cl; -H,-OMe, and -Cl,-OMe), or with partially or fully deuterated dibenzyl N-(CH2Ph)2 moieties. A series of ligand-copper(II) bis-perchlorate complexes were synthesized, characterized, and the X-ray structures of the -H,-OMe analogue were determined. The corresponding metastable Cu(II)-OOH species were generated by addition of H2O2/base in acetone at -90 °C. These convert (t1/2 ≈ 53 s) to oxidatively N-dealkylated products, producing para-substituted benzaldehydes. Based on the experimental observations and supporting DFT calculations, a reaction mechanism involving dibenzylamine H-atom abstraction or electron-transfer oxidation by the Cu(II)-OOH entity could be ruled out. It is concluded that the chemistry proceeds by rate limiting Cu-O homolytic cleavage of the Cu(II)-(OOH) species, followed by site-specific copper Fenton chemistry. As a process of broad interest in copper as well as iron oxidative (bio)chemistries, a detailed computational analysis was performed, indicating that a Cu(I)OOH species undergoes O-O homolytic cleavage to yield a hydroxyl radical and Cu(II)OH rather than heterolytic cleavage to yield water and a Cu(II)-O(•-) species.
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Affiliation(s)
- Sunghee Kim
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Jake W. Ginsbach
- Department of Chemistry, Stanford University, Stanford, California 94305
| | - Jung Yoon Lee
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Ryan L. Peterson
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Jeffrey J. Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Maxime A. Siegler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Amy A. Sarjeant
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
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