1
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Blomberg MRA. Activation of O 2 and NO in heme-copper oxidases - mechanistic insights from computational modelling. Chem Soc Rev 2021; 49:7301-7330. [PMID: 33006348 DOI: 10.1039/d0cs00877j] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Heme-copper oxidases are transmembrane enzymes involved in aerobic and anaerobic respiration. The largest subgroup contains the cytochrome c oxidases (CcO), which reduce molecular oxygen to water. A significant part of the free energy released in this exergonic process is conserved as an electrochemical gradient across the membrane, via two processes, electrogenic chemistry and proton pumping. A deviant subgroup is the cytochrome c dependent NO reductases (cNOR), which reduce nitric oxide to nitrous oxide and water. This is also an exergonic reaction, but in this case none of the released free energy is conserved. Computational studies applying hybrid density functional theory to cluster models of the bimetallic active sites in the heme-copper oxidases are reviewed. To obtain a reliable description of the reaction mechanisms, energy profiles of the entire catalytic cycles, including the reduction steps have to be constructed. This requires a careful combination of computational results with certain experimental data. Computational studies have elucidated mechanistic details of the chemical parts of the reactions, involving cleavage and formation of covalent bonds, which have not been obtainable from pure experimental investigations. Important insights regarding the mechanisms of energy conservation have also been gained. The computational studies show that the reduction potentials of the active site cofactors in the CcOs are large enough to afford electrogenic chemistry and proton pumping, i.e. efficient energy conservation. These results solve a conflict between different types of experimental data. A mechanism for the proton pumping, involving a specific and crucial role for the active site tyrosine, conserved in all CcOs, is suggested. For the cNORs, the calculations show that the low reduction potentials of the active site cofactors are optimized for fast elimination of the toxic NO molecules. At the same time, the low reduction potentials lead to endergonic reduction steps with high barriers. To prevent even higher barriers, which would lead to a too slow reaction, when the electrochemical gradient across the membrane is present, the chemistry must occur in a non-electrogenic manner. This explains why there is no energy conservation in cNOR.
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Affiliation(s)
- Margareta R A Blomberg
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden.
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2
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DiPrimio DJ, Holland PL. Repurposing metalloproteins as mimics of natural metalloenzymes for small-molecule activation. J Inorg Biochem 2021; 219:111430. [PMID: 33873051 DOI: 10.1016/j.jinorgbio.2021.111430] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2020] [Revised: 03/11/2021] [Accepted: 03/15/2021] [Indexed: 12/12/2022]
Abstract
Artificial metalloenzymes (ArMs) consist of an unnatural metal or cofactor embedded in a protein scaffold, and are an excellent platform for applying the concepts of protein engineering to catalysis. In this Focused Review, we describe the application of ArMs as simple, tunable artificial models of the active sites of complex natural metalloenzymes for small-molecule activation. In this sense, ArMs expand the strategies of synthetic model chemistry to protein-based supporting ligands with potential for participation from the second coordination sphere. We focus specifically on ArMs that are structural, spectroscopic, and functional models of enzymes for activation of small molecules like CO, CO2, O2, N2, and NO, as well as production/consumption of H2. These ArMs give insight into the identities and roles of metalloenzyme structural features within and near the cofactor. We give examples of ArM work relevant to hydrogenases, acetyl-coenzyme A synthase, superoxide dismutase, heme oxygenases, nitric oxide reductase, methyl-coenzyme M reductase, copper-O2 enzymes, and nitrogenases.
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Affiliation(s)
- Daniel J DiPrimio
- Department of Chemistry, Yale University, New Haven, CT, 06520, United States
| | - Patrick L Holland
- Department of Chemistry, Yale University, New Haven, CT, 06520, United States.
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3
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Reed CJ, Lam QN, Mirts EN, Lu Y. Molecular understanding of heteronuclear active sites in heme-copper oxidases, nitric oxide reductases, and sulfite reductases through biomimetic modelling. Chem Soc Rev 2021; 50:2486-2539. [PMID: 33475096 PMCID: PMC7920998 DOI: 10.1039/d0cs01297a] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Heme-copper oxidases (HCO), nitric oxide reductases (NOR), and sulfite reductases (SiR) catalyze the multi-electron and multi-proton reductions of O2, NO, and SO32-, respectively. Each of these reactions is important to drive cellular energy production through respiratory metabolism and HCO, NOR, and SiR evolved to contain heteronuclear active sites containing heme/copper, heme/nonheme iron, and heme-[4Fe-4S] centers, respectively. The complexity of the structures and reactions of these native enzymes, along with their large sizes and/or membrane associations, make it challenging to fully understand the crucial structural features responsible for the catalytic properties of these active sites. In this review, we summarize progress that has been made to better understand these heteronuclear metalloenzymes at the molecular level though study of the native enzymes along with insights gained from biomimetic models comprising either small molecules or proteins. Further understanding the reaction selectivity of these enzymes is discussed through comparisons of their similar heteronuclear active sites, and we offer outlook for further investigations.
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Affiliation(s)
- Christopher J Reed
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urban, IL 61801, USA.
| | - Quan N Lam
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urban, IL 61801, USA
| | - Evan N Mirts
- Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urban, IL 61801, USA. and Department of Biochemistry, University of Illinois at Urbana-Champaign, Urban, IL 61801, USA and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA and Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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4
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Phu PN, Gutierrez CE, Kundu S, Sokaras D, Kroll T, Warren TH, Stieber SCE. Quantification of Ni-N-O Bond Angles and NO Activation by X-ray Emission Spectroscopy. Inorg Chem 2021; 60:736-744. [PMID: 33373520 DOI: 10.1021/acs.inorgchem.0c02724] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of β-diketiminate Ni-NO complexes with a range of NO binding modes and oxidation states were studied by X-ray emission spectroscopy (XES). The results demonstrate that XES can directly probe and distinguish end-on vs side-on NO coordination modes as well as one-electron NO reduction. Density functional theory (DFT) calculations show that the transition from the NO 2s2s σ* orbital has higher intensity for end-on NO coordination than for side-on NO coordination, whereas the 2s2s σ orbital has lower intensity. XES calculations in which the Ni-N-O bond angle was fixed over the range from 80° to 176° suggest that differences in NO coordination angles of ∼10° could be experimentally distinguished. Calculations of Cu nitrite reductase (NiR) demonstrate the utility of XES for characterizing NO intermediates in metalloenzymes. This work shows the capability of XES to distinguish NO coordination modes and oxidation states at Ni and highlights applications in quantifying small molecule activation in enzymes.
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Affiliation(s)
- Phan N Phu
- Department of Chemistry & Biochemistry, California State Polytechnic University, Pomona, California 91768, United States
| | - Carlos E Gutierrez
- Department of Chemistry & Biochemistry, California State Polytechnic University, Pomona, California 91768, United States
| | - Subrata Kundu
- Department of Chemistry, Georgetown University, Box 571227, Washington, D.C. 20057, United States.,School of Chemistry, Indian Institute of Science Education and Research Thiruvananthapuram, Kerala 695551, India
| | - Dimosthenis Sokaras
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Thomas Kroll
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
| | - Timothy H Warren
- Department of Chemistry, Georgetown University, Box 571227, Washington, D.C. 20057, United States
| | - S Chantal E Stieber
- Department of Chemistry & Biochemistry, California State Polytechnic University, Pomona, California 91768, United States
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5
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Arrangement of a NO ligand and the neighboring sulfur-containing species on a dinuclear ruthenium complex by ligand substitution and linkage isomerism of a dimethyl sulfoxide ligand. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2019.02.036] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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6
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Mirts EN, Bhagi-Damodaran A, Lu Y. Understanding and Modulating Metalloenzymes with Unnatural Amino Acids, Non-Native Metal Ions, and Non-Native Metallocofactors. Acc Chem Res 2019; 52:935-944. [PMID: 30912643 DOI: 10.1021/acs.accounts.9b00011] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Metalloproteins set the gold standard for performing important functions, including catalyzing demanding reactions under mild conditions. Designing artificial metalloenzymes (ArMs) to catalyze abiological reactions has been a major endeavor for many years, but most ArM activities are far below those of native enzymes, making them unsuitable for most pratical applications. A critical step to advance the field is to fundamentally understand what it takes to not only confer but also fine-tune ArM activities so they match those of native enzymes. Indeed, only once we can freely modulate ArM activity to rival (or surpass!) natural enzymes can the potential of ArMs be fully realized. A key to unlocking ArM potential is the observation that one metal primary coordination sphere can display a range of functions and levels of activity, leading to the realization that secondary coordination sphere (SCS) interactions are critically important. However, SCS interactions are numerous, long-range, and weak, making them very difficult to reproduce in ArMs. Furthermore, natural enzymes are tied to a small set of biologically available functional moieties from canonical amino acids and physiologically available metal ions and metallocofactors, severely limiting the chemical space available to probe and tune ArMs. In this Account, we summarize the use of unnatural amino acids (UAAs) and non-native metal ions and metallocofactors by our group and our collaborators to probe and modulate ArM functions. We incorporated isostructural UAAs in a type 1 copper (T1Cu) protein azurin to provide conclusive evidence that axial ligand hydrophobicity is a major determinant of T1Cu redunction potential ( E°'). Closely related work from other groups are also discussed. We also probed the role of protein backbone interactions that cannot be altered by standard mutagenesis by replacing the peptide bond with an ester linkage. We used insight gained from these studies to tune the E°' of azurin across the entire physiological range, the broadest range ever achieved in a single metalloprotein. Introducing UAA analogues of Tyr into ArM models of heme-copper oxidase (HCO) revealed a linear relationship between p Ka, E°', and activity. We also substituted non-native hemes and non-native metal ions for their native equivalents in these models to resolve several issues that were intractable in native HCOs and the closely related nitric oxide reductases, such as their roles in modulating substrate affinity, electron transfer rate, and activity. We incorporated abiological cofactors such as ferrocene and Mn(salen) into azurin and myoglobin, respectively, to stabilize these inorganic and organometallic compounds in water, confer abiological functions, tune their E°' and activity through SCS interactions, and show that the approach to metallocofactor anchoring and orientation can tune enantioselectivity and alter function. Replacing Cu in azurin with non-native Fe or Ni can impart novel activities, such as superoxide reduction and C-C bond formation. While progress was made, we have identified only a small fraction of the interactions that can be generally applied to ArMs to fine-tune their functions. Because SCS interactions are subtle and heavily interconnected, it has been difficult to characterize their effects quantitatively. It is vital to develop spectroscopic and computational techniques to detect and quantify their effects in both resting states and catalytic intermediates.
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Affiliation(s)
- Evan N. Mirts
- Department of Chemistry and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Ambika Bhagi-Damodaran
- Department of Chemistry and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Yi Lu
- Department of Chemistry and Center for Biophysics and Quantitative Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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7
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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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8
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9
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Li F, Meyer RL, Carpenter SH, VanGelder LE, Nichols AW, Machan CW, Neidig ML, Matson EM. Nitric oxide activation facilitated by cooperative multimetallic electron transfer within an iron-functionalized polyoxovanadate-alkoxide cluster. Chem Sci 2018; 9:6379-6389. [PMID: 30310566 PMCID: PMC6115649 DOI: 10.1039/c8sc00987b] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 06/30/2018] [Indexed: 01/06/2023] Open
Abstract
Cooperative multimetallic electron transfer to accommodate substrate binding.
A series of NO-bound, iron-functionalized polyoxovanadate–alkoxide (FePOV–alkoxide) clusters have been synthesized, providing insight into the role of multimetallic constructs in the coordination and activation of a substrate. Upon exposure of the heterometallic cluster to NO, the vanadium-oxide metalloligand is oxidized by a single electron, shuttling the reducing equivalent to the {FeNO} subunit to form a {FeNO}7 species. Four NO-bound clusters with electronic distributions ranging from [VV3VIV2]{FeNO}7 to [VIV5]{FeNO}7 have been synthesized, and characterized via1H NMR, infrared, and electronic absorption spectroscopies. The ability of the FePOV–alkoxide cluster to store reducing equivalents in the metalloligand for substrate coordination and activation highlights the ultility of the metal-oxide scaffold as a redox reservoir.
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Affiliation(s)
- F Li
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA .
| | - R L Meyer
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA .
| | - S H Carpenter
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA .
| | - L E VanGelder
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA .
| | - A W Nichols
- Department of Chemistry , University of Virginia , Charlottesville , Virginia 22904-4319 , USA
| | - C W Machan
- Department of Chemistry , University of Virginia , Charlottesville , Virginia 22904-4319 , USA
| | - M L Neidig
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA .
| | - E M Matson
- Department of Chemistry , University of Rochester , Rochester , New York 14627 , USA .
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10
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Arikawa Y, Hiura J, Tsuchii C, Kodama M, Matsumoto N, Umakoshi K. A synthetic NO reduction cycle on a bis(pyrazolato)-bridged dinuclear ruthenium complex including photo-induced transformation. Dalton Trans 2018; 47:7399-7401. [PMID: 29770405 DOI: 10.1039/c8dt01208c] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A synthetic NO reduction cycle (2NO + 2H+ + 2e- → N2O + H2O) on a dinuclear platform {(TpRu)2(μ-pz)2} (Tp = HB(pyrazol-1-yl)3) was achieved, where an unusual N-N coupling complex was included. Moreover, an interesting photo-induced conversion of the N-N coupling complex to an oxido-bridged complex was revealed.
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Affiliation(s)
- Yasuhiro Arikawa
- Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University, Bunkyo-machi 1-14, Nagasaki 852-8521, Japan.
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11
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Abucayon EG, Khade RL, Powell DR, Zhang Y, Richter-Addo GB. Lewis Acid Activation of the Ferrous Heme-NO Fragment toward the N-N Coupling Reaction with NO To Generate N 2O. J Am Chem Soc 2018; 140:4204-4207. [PMID: 29502400 DOI: 10.1021/jacs.7b13681] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Bacterial NO reductase (bacNOR) enzymes utilize a heme/non-heme active site to couple two NO molecules to N2O. We show that BF3 coordination to the nitrosyl O-atom in (OEP)Fe(NO) activates it toward N-N bond formation with NO to generate N2O. 15N-isotopic labeling reveals a reversible nitrosyl exchange reaction and follow-up N-O bond cleavage in the N2O formation step. Other Lewis acids (B(C6F5)3 and K+) also promote the NO coupling reaction with (OEP)Fe(NO). These results, complemented by DFT calculations, provide experimental support for the cis: b3 pathway in bacNOR.
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Affiliation(s)
- Erwin G Abucayon
- Department of Chemistry and Biochemistry , University of Oklahoma , Norman , Oklahoma 73019 , United States
| | - Rahul L Khade
- Department of Chemistry and Chemical Biology , Stevens Institute of Technology , Castle Point on Hudson , Hoboken , New Jersey 07030 , United States
| | - Douglas R Powell
- Department of Chemistry and Biochemistry , University of Oklahoma , Norman , Oklahoma 73019 , United States
| | - Yong Zhang
- Department of Chemistry and Chemical Biology , Stevens Institute of Technology , Castle Point on Hudson , Hoboken , New Jersey 07030 , United States
| | - George B Richter-Addo
- Department of Chemistry and Biochemistry , University of Oklahoma , Norman , Oklahoma 73019 , United States
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12
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Arikawa Y, Otsubo Y, Fujino H, Horiuchi S, Sakuda E, Umakoshi K. Nitrite Reduction Cycle on a Dinuclear Ruthenium Complex Producing Ammonia. J Am Chem Soc 2018; 140:842-847. [PMID: 29257867 DOI: 10.1021/jacs.7b12020] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The fundamental biogeochemical cycle of nitrogen includes cytochrome c nitrite reductase, which catalyzes the reduction of nitrite ions to ammonium with eight protons and six electrons (NO2- + 8H+ + 6e- → NH4+ + 2H2O). This reaction has motivated researchers to explore the reduction of nitrite. Although a number of electrochemical reductions of NO2- have been reported, the synthetic nitrite reduction reaction remains limited. To the best of our knowledge, formation of ammonia has not been reported. We report a three-step nitrite reduction cycle on a dinuclear ruthenium platform {(TpRu)2(μ-pz)} (Tp = HB(pyrazol-1-yl)3), producing ammonia. The cycle comprises conversion of a nitrito ligand to a NO ligand using 2H+ and e-, subsequent reduction of the NO ligand to a nitrido and a H2O ligand by consumption of 2H+ and 5e-, and recovery of the parent nitrito ligand. Moreover, release of ammonia was detected.
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Affiliation(s)
- Yasuhiro Arikawa
- Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University , Bunkyo-machi 1-14, Nagasaki 852-8521, Japan
| | - Yuji Otsubo
- Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University , Bunkyo-machi 1-14, Nagasaki 852-8521, Japan
| | - Hiroki Fujino
- Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University , Bunkyo-machi 1-14, Nagasaki 852-8521, Japan
| | - Shinnosuke Horiuchi
- Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University , Bunkyo-machi 1-14, Nagasaki 852-8521, Japan
| | - Eri Sakuda
- Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University , Bunkyo-machi 1-14, Nagasaki 852-8521, Japan
| | - Keisuke Umakoshi
- Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University , Bunkyo-machi 1-14, Nagasaki 852-8521, Japan
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13
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Scheidt WR, Li J, Sage JT. What Can Be Learned from Nuclear Resonance Vibrational Spectroscopy: Vibrational Dynamics and Hemes. Chem Rev 2017; 117:12532-12563. [PMID: 28921972 PMCID: PMC5639469 DOI: 10.1021/acs.chemrev.7b00295] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
![]()
Nuclear resonance
vibrational spectroscopy (NRVS; also known as
nuclear inelastic scattering, NIS) is a synchrotron-based method that
reveals the full spectrum of vibrational dynamics for Mössbauer
nuclei. Another major advantage, in addition to its completeness (no
arbitrary optical selection rules), is the unique selectivity of NRVS.
The basics of this recently developed technique are first introduced
with descriptions of the experimental requirements and data analysis
including the details of mode assignments. We discuss the use of NRVS
to probe 57Fe at the center of heme and heme protein derivatives
yielding the vibrational density of states for the iron. The application
to derivatives with diatomic ligands (O2, NO, CO, CN–) shows the strong capabilities of identifying mode
character. The availability of the complete vibrational spectrum of
iron allows the identification of modes not available by other techniques.
This permits the correlation of frequency with other physical properties.
A significant example is the correlation we find between the Fe–Im
stretch in six-coordinate Fe(XO) hemes and the trans Fe–N(Im)
bond distance, not possible previously. NRVS also provides uniquely
quantitative insight into the dynamics of the iron. For example, it
provides a model-independent means of characterizing the strength
of iron coordination. Prediction of the temperature-dependent mean-squared
displacement from NRVS measurements yields a vibrational “baseline”
for Fe dynamics that can be compared with results from techniques
that probe longer time scales to yield quantitative insights into
additional dynamical processes.
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Affiliation(s)
- W Robert Scheidt
- Department of Chemistry and Biochemistry, University of Notre Dame , Notre Dame, Indiana 46556 United States
| | - Jianfeng Li
- College of Materials Science and Optoelectronic Technology, University of Chinese Academy of Sciences , YanQi Lake, HuaiRou District, Beijing 101408, China
| | - J Timothy Sage
- Department of Physics and Center for Interdisciplinary Research on Complex Systems, Northeastern University , 120 Forsyth Street, Boston, Massachusetts 02115, United States
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14
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Reed JH, Shi Y, Zhu Q, Chakraborty S, Mirts EN, Petrik ID, Bhagi-Damodaran A, Ross M, Moënne-Loccoz P, Zhang Y, Lu Y. Manganese and Cobalt in the Nonheme-Metal-Binding Site of a Biosynthetic Model of Heme-Copper Oxidase Superfamily Confer Oxidase Activity through Redox-Inactive Mechanism. J Am Chem Soc 2017; 139:12209-12218. [PMID: 28768416 PMCID: PMC5673108 DOI: 10.1021/jacs.7b05800] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The presence of a nonheme metal, such as copper and iron, in the heme-copper oxidase (HCO) superfamily is critical to the enzymatic activity of reducing O2 to H2O, but the exact mechanism the nonheme metal ion uses to confer and fine-tune the activity remains to be understood. We herein report that manganese and cobalt can bind to the same nonheme site and confer HCO activity in a heme-nonheme biosynthetic model in myoglobin. While the initial rates of O2 reduction by the Mn, Fe, and Co derivatives are similar, the percentages of reactive oxygen species (ROS) formation are 7%, 4%, and 1% and the total turnovers are 5.1 ± 1.1, 13.4 ± 0.7, and 82.5 ± 2.5, respectively. These results correlate with the trends of nonheme-metal-binding dissociation constants (35, 22, and 9 μM) closely, suggesting that tighter metal binding can prevent ROS release from the active site, lessen damage to the protein, and produce higher total turnover numbers. Detailed spectroscopic, electrochemical, and computational studies found no evidence of redox cycling of manganese or cobalt in the enzymatic reactions and suggest that structural and electronic effects related to the presence of different nonheme metals lead to the observed differences in reactivity. This study of the roles of nonheme metal ions beyond the Cu and Fe found in native enzymes has provided deeper insights into nature's choice of metal ion and reaction mechanism and allows for finer control of the enzymatic activity, which is a basis for the design of efficient catalysts for the oxygen reduction reaction in fuel cells.
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Affiliation(s)
- Julian H. Reed
- Department of Biochemistry, University of Illinois at
Urbana-Champaign, Urbana, IL, 61801, USA
| | - Yelu Shi
- Department of Biomedical Engineering, Chemistry, and Biological
Sciences, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - Qianhong Zhu
- Division of Environmental & Biomolecular Systems, Institute
of Environmental Health, Oregon Health & Science University, Portland, OR,
97239, USA
| | - Saumen Chakraborty
- Department of Chemistry & Biochemistry, University of
Mississippi, Oxford, Mississippi, 38677, USA
| | - Evan N. Mirts
- Center for Biophysics and Quantitative Biology, University of
Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Igor D. Petrik
- Department of Chemistry, University of Illinois at Urbana-Champaign,
Urbana, IL, 61801, USA
| | - Ambika Bhagi-Damodaran
- Department of Pharmaceutical Chemistry, University of California,
San Francisco, San Francisco, CA, 94143, USA
| | - Matthew Ross
- Department of Chemistry, Northwestern University, Evanston, IL,
60208, USA
| | - Pierre Moënne-Loccoz
- Division of Environmental & Biomolecular Systems, Institute
of Environmental Health, Oregon Health & Science University, Portland, OR,
97239, USA
| | - Yong Zhang
- Department of Biomedical Engineering, Chemistry, and Biological
Sciences, Stevens Institute of Technology, Hoboken, NJ, 07030, USA
| | - Yi Lu
- Department of Biochemistry, University of Illinois at
Urbana-Champaign, Urbana, IL, 61801, USA
- Center for Biophysics and Quantitative Biology, University of
Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Chemistry, University of Illinois at Urbana-Champaign,
Urbana, IL, 61801, USA
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15
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Chacón Villalba ME, Franca CA, Güida JA. Photo release of nitrous oxide from the hyponitrite ion studied by infrared spectroscopy. Evidence for the generation of a cobalt-N 2O complex. Experimental and DFT calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 176:189-196. [PMID: 28107725 DOI: 10.1016/j.saa.2017.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 12/27/2016] [Accepted: 01/02/2017] [Indexed: 06/06/2023]
Abstract
The solid state photolysis of sodium, silver and thallium hyponitrite (M2N2O2, M=Na, Ag, Tl) salts and a binuclear complex of cobalt bridged by hyponitrite ([Co(NH3)5-N(O)-NO-Co(NH3)5]4+) were studied by irradiation with visible and UV light in the electronic absorption region. The UV-visible spectra for free hyponitrite ion and binuclear complex of cobalt were interpreted in terms of Density Functional Theory calculations in order to explain photolysis behavior. The photolysis of each compound depends selectively on the irradiation wavelength. Irradiation with 340-460nm light and with the 488nm laser line generates photolysis only in silver and thallium hyponitrite salts, while 253.7nm light photolyzed all the studied compounds. Infrared spectroscopy was used to follow the photolysis process and to identify the generated products. Remarkably, gaseous N2O was detected after photolysis in the infrared spectra of sodium, silver, and thallium hyponitrite KBr pellets. The spectra for [Co(NH3)5-N(O)-NO-Co(NH3)5]4+ suggest that one cobalt ion remains bonded to N2O from which the generation of a [(NH3)5CoNNO]+3 complex is inferred. Density Functional Theory (DFT) based calculations confirm the stability of this last complex and provide the theoretical data which are used in the interpretation of the electronic spectra of the hyponitrite ion and the cobalt binuclear complex and thus in the elucidation of their photolysis behavior. Carbonate ion is also detected after photolysis in all studied compounds, presumably due to the reaction of atmospheric CO2 with the microcrystal surface reaction products. Kinetic measurements for the photolysis of the binuclear complex suggest a first order law for the intensity decay of the hyponitrite IR bands and for the intensity increase in the N2O generation. Predicted and experimental data are in very good agreement.
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Affiliation(s)
- M Elizabeth Chacón Villalba
- CEQUINOR, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CONICET (CCT La Plata), Boulevard 120 N° 1465, 1900 La Plata, Argentina; Comisión de Investigaciones Científicas CICPBA, Provincia de Buenos Aires, Argentina
| | - Carlos A Franca
- CEQUINOR, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CONICET (CCT La Plata), Boulevard 120 N° 1465, 1900 La Plata, Argentina
| | - Jorge A Güida
- CEQUINOR, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CONICET (CCT La Plata), Boulevard 120 N° 1465, 1900 La Plata, Argentina; Departamento de Ciencias Básicas, Universidad Nacional de Luján, Luján, Argentina; Departamento de Ciencias Básicas, Facultad de Ingeniería, Universidad Nacional de La Plata, La Plata, Argentina.
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16
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Bhagi-Damodaran A, Michael MA, Zhu Q, Reed J, Sandoval BA, Mirts EN, Chakraborty S, Moënne-Loccoz P, Zhang Y, Lu Y. Why copper is preferred over iron for oxygen activation and reduction in haem-copper oxidases. Nat Chem 2017; 9:257-263. [PMID: 28221360 PMCID: PMC5321616 DOI: 10.1038/nchem.2643] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 09/09/2016] [Indexed: 01/13/2023]
Abstract
Haem-copper oxidase (HCO) catalyses the natural reduction of oxygen to water using a haem-copper centre. Despite decades of research on HCOs, the role of non-haem metal and the reason for nature's choice of copper over other metals such as iron remains unclear. Here, we use a biosynthetic model of HCO in myoglobin that selectively binds different non-haem metals to demonstrate 30-fold and 11-fold enhancements in the oxidase activity of Cu- and Fe-bound HCO mimics, respectively, as compared with Zn-bound mimics. Detailed electrochemical, kinetic and vibrational spectroscopic studies, in tandem with theoretical density functional theory calculations, demonstrate that the non-haem metal not only donates electrons to oxygen but also activates it for efficient O-O bond cleavage. Furthermore, the higher redox potential of copper and the enhanced weakening of the O-O bond from the higher electron density in the d orbital of copper are central to its higher oxidase activity over iron. This work resolves a long-standing question in bioenergetics, and renders a chemical-biological basis for the design of future oxygen-reduction catalysts.
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Affiliation(s)
| | - Matthew A. Michael
- Department of Biomedical Engineering, Chemistry, and
Biological Sciences, Stevens Institute of Technology, Hoboken, NJ, USA
| | - Qianhong Zhu
- Division of Environmental & Biomolecular Systems, Institute
of Environmental Health, Oregon Health & Science University, 3181 SW Sam Jackson Park
Road, Portland, OR, USA
| | - Julian Reed
- Department of Biochemistry, University of Illinois at
Urbana-Champaign, Urbana, IL, USA
| | - Braddock A. Sandoval
- Department of Chemistry, University of Illinois at
Urbana-Champaign, Urbana, IL, USA
| | - Evan N. Mirts
- Center for Biophysics and Quantitative Biology, University
of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Saumen Chakraborty
- Department of Chemistry, University of Illinois at
Urbana-Champaign, Urbana, IL, USA
| | - Pierre Moënne-Loccoz
- Division of Environmental & Biomolecular Systems, Institute
of Environmental Health, Oregon Health & Science University, 3181 SW Sam Jackson Park
Road, Portland, OR, USA
| | - Yong Zhang
- Department of Biomedical Engineering, Chemistry, and
Biological Sciences, Stevens Institute of Technology, Hoboken, NJ, USA
| | - Yi Lu
- Department of Chemistry, University of Illinois at
Urbana-Champaign, Urbana, IL, USA
- Department of Biochemistry, University of Illinois at
Urbana-Champaign, Urbana, IL, USA
- Center for Biophysics and Quantitative Biology, University
of Illinois at Urbana-Champaign, Urbana, IL, USA
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17
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Blomberg MRA. Can Reduction of NO to N2O in Cytochrome c Dependent Nitric Oxide Reductase Proceed through a Trans-Mechanism? Biochemistry 2016; 56:120-131. [DOI: 10.1021/acs.biochem.6b00788] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Margareta R. A. Blomberg
- Department of Organic Chemistry,
Arrhenius Laboratory, Stockholm University, SE-106 91, Stockholm, Sweden
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18
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Bhagi-Damodaran A, Hosseinzadeh P, Mirts E, Reed J, Petrik ID, Lu Y. Design of Heteronuclear Metalloenzymes. Methods Enzymol 2016; 580:501-37. [PMID: 27586347 PMCID: PMC5156654 DOI: 10.1016/bs.mie.2016.05.050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Heteronuclear metalloenzymes catalyze some of the most fundamentally interesting and practically useful reactions in nature. However, the presence of two or more metal ions in close proximity in these enzymes makes them more difficult to prepare and study than homonuclear metalloenzymes. To meet these challenges, heteronuclear metal centers have been designed into small and stable proteins with rigid scaffolds to understand how these heteronuclear centers are constructed and the mechanism of their function. This chapter describes methods for designing heterobinuclear metal centers in a protein scaffold by giving specific examples of a few heme-nonheme bimetallic centers engineered in myoglobin and cytochrome c peroxidase. We provide step-by-step procedures on how to choose the protein scaffold, design a heterobinuclear metal center in the protein scaffold computationally, incorporate metal ions into the protein, and characterize the resulting metalloproteins, both structurally and functionally. Finally, we discuss how an initial design can be further improved by rationally tuning its secondary coordination sphere, electron/proton transfer rates, and the substrate affinity.
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Affiliation(s)
- A Bhagi-Damodaran
- University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - P Hosseinzadeh
- University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - E Mirts
- University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - J Reed
- University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - I D Petrik
- University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Y Lu
- University of Illinois at Urbana-Champaign, Urbana, IL, United States.
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19
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Lehnert N, Peters JC. Preface for Small-Molecule Activation: From Biological Principles to Energy Applications. Part 2: Small Molecules Related to the Global Nitrogen Cycle. Inorg Chem 2015; 54:9229-33. [DOI: 10.1021/acs.inorgchem.5b02124] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Nicolai Lehnert
- Department of Chemistry, The University of Michigan, 930 N. University, Ann Arbor, Michigan 48109, United States
| | - Jonas C. Peters
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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