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Zhang W, Pan JK, Yu YF, Zhang XJ, Wang JH, Chen WX, Zhuang GL. Correlation of the spin state and catalytic property of M-N 4 single-atom catalysts in oxygen reduction reactions. Phys Chem Chem Phys 2023; 25:11673-11683. [PMID: 37051874 DOI: 10.1039/d3cp00010a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Abstract
The rational design of high-performance catalysts for oxygen reduction reactions (ORRs) is of great importance for large-scale applications in the field of proton-exchange membrane fuel cells and the green synthesis of H2O2. The effect of spin states of paramagnetic metal ions on the selectivity of ORRs is significant for single-atom catalysts (SACs). In this work, via spin-polarization density functional theory (DFT) calculations, we systematically investigated the popular paramagnetic metal-nitrogen graphene (M-N4-C, M = Mn, Fe, and Co) SACs to mainly focus on the correlation of spin states and catalytic performance (e.g. activity and selectivity). Both thermodynamically and kinetically, it was found that Co-N4-C (S = 1/2) has excellent 2e- oxygen reduction performance (hydrogen peroxide production) with an ultralow overpotential of 0.03 V, and the hydrogenation of OOH* is the rate-determining step (RDS) with an energy barrier of 1.20 eV. The 4e- ORR tends to occur along the OOH dissociation pathway (O* + OH*) on Co-N4-C (S = 3/2), in which OOH* decomposition is the RDS with an energy barrier of 1.01 eV. It is proved that the spin magnetic moment is the key factor to regulate the ORR property via multi-angle electronic analysis. The spin states of catalysts play a crucial role in the activity and selectivity of ORRs mainly by manipulating the bond strength between OOH and catalysts. This will provide new insights for the rational design of ORR catalysts with magnetic metals.
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Affiliation(s)
- Wei Zhang
- Institute of Industrial Catalysis, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, P. R. China.
| | - Jin-Kong Pan
- Institute of Industrial Catalysis, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, P. R. China.
- Wanbangde Pharmaceutical Group Co., Ltd., China
| | - Yi-Fan Yu
- Institute of Industrial Catalysis, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, P. R. China.
| | - Xian-Jie Zhang
- Institute of Industrial Catalysis, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, P. R. China.
| | - Jia-Hao Wang
- Institute of Industrial Catalysis, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, P. R. China.
| | - Wen-Xian Chen
- Institute of Industrial Catalysis, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, P. R. China.
| | - Gui-Lin Zhuang
- Institute of Industrial Catalysis, State Key Laboratory Breeding Base of Green-Chemical Synthesis Technology, College of Chemical Engineering, Zhejiang University of Technology, Hangzhou 310032, P. R. China.
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2
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Ortega P, Zanchet A, Sanz-Sanz C, Gómez-Carrasco S, González-Sánchez L, Jambrina PG. DpgC-Catalyzed Peroxidation of 3,5-Dihydroxyphenylacetyl-CoA (DPA-CoA): Insights into the Spin-Forbidden Transition and Charge Transfer Mechanisms*. Chemistry 2020; 27:1700-1712. [PMID: 32975323 DOI: 10.1002/chem.202002993] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Indexed: 11/06/2022]
Abstract
Despite being a very strong oxidizing agent, most organic molecules are not oxidized in the presence of O2 at room temperature because O2 is a diradical whereas most organic molecules are closed-shell. Oxidation then requires a change in the spin state of the system, which is forbidden according to non-relativistic quantum theory. To overcome this limitation, oxygenases usually rely on metal or redox cofactors to catalyze the incorporation of, at least, one oxygen atom into an organic substrate. However, some oxygenases do not require any cofactor, and the detailed mechanism followed by these enzymes remains elusive. To fill this gap, here the mechanism for the enzymatic cofactor-independent oxidation of 3,5-dihydroxyphenylacetyl-CoA (DPA-CoA) is studied by combining multireference calculations on a model system with QM/MM calculations. Our results reveal that intersystem crossing takes place without requiring the previous protonation of molecular oxygen. The characterization of the electronic states reveals that electron transfer is concomitant with the triplet-singlet transition. The enzyme plays a passive role in promoting the intersystem crossing, although spontaneous reorganization of the water wire connecting the active site with the bulk presets the substrate for subsequent chemical transformations. The results show that the stabilization of the singlet radical-pair between dioxygen and enolate is enough to promote spin-forbidden reaction without the need for neither metal cofactors nor basic residues in the active site.
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Affiliation(s)
- Pablo Ortega
- Departamento de Química Física, University of Salamanca, Salamanca, 37008, Spain
| | - Alexandre Zanchet
- Departamento de Química Física, University of Salamanca, Salamanca, 37008, Spain.,Instituto de Física Fundamental (CSIC), Madrid, 28006, Spain
| | - Cristina Sanz-Sanz
- Departamento de Química Física Aplicada, University Autónoma de Madrid, Madrid, 28049, Spain
| | | | | | - Pablo G Jambrina
- Departamento de Química Física, University of Salamanca, Salamanca, 37008, Spain
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3
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Engineering glucose oxidase for bioelectrochemical applications. Bioelectrochemistry 2019; 128:218-240. [DOI: 10.1016/j.bioelechem.2019.04.015] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 04/16/2019] [Accepted: 04/16/2019] [Indexed: 01/18/2023]
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4
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Minaev B. How cofactor-free oxygenases can overcome spin prohibition in substrates oxygenation by dioxygen. Chem Phys 2019. [DOI: 10.1016/j.chemphys.2019.01.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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5
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Kannappan B, Cummins PL, Gready JE. Mechanism of Oxygenase-Pathway Reactions Catalyzed by Rubisco from Large-Scale Kohn-Sham Density Functional Calculations. J Phys Chem B 2019; 123:2833-2843. [PMID: 30845802 DOI: 10.1021/acs.jpcb.9b00518] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ribulose 1,5-bisphosphate carboxylase-oxygenase (Rubisco) is the primary carbon-fixing enzyme in photosynthesis, fixing CO2 to a 5-carbon sugar, RuBP, in a series of five reactions. However, it also catalyzes an oxygenase reaction by O2 addition to the same enolized RuBP substrate in an analogous reaction series in the same active site, producing a waste product and loss of photosynthetic efficiency. Starting from RuBP, the reactions are enolization to the enediolate form, addition of CO2 or O2 to form the carboxy or peroxo adduct, hydration to form a gemdiolate, scission of the C2-C3 bond of the original RuBP, and stereospecific or nonstereospecific protonation to form two molecules of the 3-carbon PGA product, or one molecule of PGA, one of 2-carbon PG (waste product), and one water molecule. Reducing the loss of efficiency from the oxygenase reaction is an attractive means to increase crop productivity. However, lack of understanding of key aspects of the catalytic mechanisms for both the carboxylase and oxygenase reactions, particularly those involving proton exchanges and roles of water molecules, has stymied efforts at re-engineering Rubisco to reduce losses from the oxygenation reaction. As the stable form of molecular oxygen is the triplet biradical state (3O2), its reaction with near-universal singlet-state molecules is formally spin forbidden. Although in oxygenase enzymes, 3O2 activation is usually achieved by one-electron transfers using transition-metal ions or organic cofactors, recently, cofactor-less oxygenases in which the substrate itself is the source of the electron for 3O2 activation have been identified, but in all such cases an aromatic ring stabilizes the substrate's negative charge. Here we present the first large-scale Kohn-Sham density functional theory study of the reaction mechanism of the Rubisco oxygenase pathway. First, we show that the enediolate substrate complexed to Mg2+ and its ligands extends the region for charge delocalization and stabilization of its negative charge to allow formation of a caged biradical enediolate-O2 complex. Thus, Rubisco is a unique type of oxygenase without precedent in the literature. Second, for the O2 addition to proceed to the singlet peroxo-adduct intermediate, the system must undergo an intersystem crossing. We found that the presence of protonated LYS334 is required to stabilize this intermediate and that both factors (strongly stabilized anion and protonated LYS334) facilitate a barrier-less activation of 3O2. This finding supports our recent proposal that deoxygenation, that is, reversal of gas binding, is possible. Third, as neither CO2 nor O2 binds to the enzyme, our findings support the proposal from our recent carboxylase study that the observed KC or KO (Michaelis-Menten constants) in the steady-state kinetics reflect the respective adducts, carboxy or peroxo. Fourth, after computing hydration pathways with water addition both syn and anti to C3, we found, in contrast to the results of our carboxylation study indicating anti addition, that in the oxygenation reaction only syn-hydration is capable of producing a stable gemdiolate that facilitates the rate-limiting C2-C3 bond scission to final products. Fifth, we propose that an excess proton we previously found was required in the carboxylation reaction for activating the C2-C3 bond scission is utilized in the oxygenation reaction for the required elimination of a water molecule. In summary, despite its oxygenase handicap, Rubisco's success in directing 75% of its substrate through the carboxylation pathway can be considered impressively effective. Although native C3 Rubiscos are in a fix with unwanted activity of 3O2 hampering its primary carboxylase function, mechanistic differences presented here with findings in our recent carboxylase study for both the gas-addition and subsequent reactions provide some clues as to how creative Rubisco re-engineering may offer a solution to reducing the oxygenase activity.
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Affiliation(s)
- Babu Kannappan
- John Curtin School of Medical Research , The Australian National University , Canberra ACT 0200 , Australia
| | - Peter L Cummins
- John Curtin School of Medical Research , The Australian National University , Canberra ACT 0200 , Australia
| | - Jill E Gready
- John Curtin School of Medical Research , The Australian National University , Canberra ACT 0200 , Australia
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6
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Spin-orbit coupling effects in O(2) activation by cofactor-independent 2,4-dioxygenase. UKRAINIAN BIOCHEMICAL JOURNAL 2019. [DOI: 10.15407/ubj91.01.038] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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7
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Tremey E, Stines-Chaumeil C, Gounel S, Mano N. Designing an O2
-Insensitive Glucose Oxidase for Improved Electrochemical Applications. ChemElectroChem 2017. [DOI: 10.1002/celc.201700646] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Emilie Tremey
- CNRS, CRPP - UPR 8641; 115 Avenue du Docteur Schweitzer 33600 Pessac France
- Univ Bordeaux; 146 rue Léo Saignat 33076 Bordeaux Cedex France
| | - Claire Stines-Chaumeil
- CNRS, CRPP - UPR 8641; 115 Avenue du Docteur Schweitzer 33600 Pessac France
- Univ Bordeaux; 146 rue Léo Saignat 33076 Bordeaux Cedex France
| | - Sébastien Gounel
- CNRS, CRPP - UPR 8641; 115 Avenue du Docteur Schweitzer 33600 Pessac France
- Univ Bordeaux; 146 rue Léo Saignat 33076 Bordeaux Cedex France
| | - Nicolas Mano
- CNRS, CRPP - UPR 8641; 115 Avenue du Docteur Schweitzer 33600 Pessac France
- Univ Bordeaux; 146 rue Léo Saignat 33076 Bordeaux Cedex France
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8
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Liu H, Shi D, Sun J, Zhu Z. Excited-states and spectroscopic properties of superoxide anion: a theoretical study including spin–orbit coupling. Mol Phys 2016. [DOI: 10.1080/00268976.2016.1221157] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Hui Liu
- College of Physics and Material Science, Henan Normal University, Xinxiang, China
- College of Physics and Electronic Engineering, Xinyang Normal University, Xinyang, China,
| | - Deheng Shi
- College of Physics and Material Science, Henan Normal University, Xinxiang, China
| | - Jingfeng Sun
- College of Physics and Material Science, Henan Normal University, Xinxiang, China
| | - Zunlue Zhu
- College of Physics and Material Science, Henan Normal University, Xinxiang, China
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9
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Hernández-Ortega A, Quesne MG, Bui S, Heyes DJ, Steiner RA, Scrutton NS, de Visser SP. Catalytic Mechanism of Cofactor-Free Dioxygenases and How They Circumvent Spin-Forbidden Oxygenation of Their Substrates. J Am Chem Soc 2015; 137:7474-87. [DOI: 10.1021/jacs.5b03836] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Aitor Hernández-Ortega
- Manchester
Institute of Biotechnology and Faculty of Life Sciences, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Matthew G. Quesne
- Manchester
Institute of Biotechnology and School of Chemical Engineering and
Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Soi Bui
- Randall
Division of Cell and Molecular Biophysics, King’s College London, London SE1 1UL, United Kingdom
| | - Derren J. Heyes
- Manchester
Institute of Biotechnology and Faculty of Life Sciences, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Roberto A. Steiner
- Randall
Division of Cell and Molecular Biophysics, King’s College London, London SE1 1UL, United Kingdom
| | - Nigel S. Scrutton
- Manchester
Institute of Biotechnology and Faculty of Life Sciences, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Sam P. de Visser
- Manchester
Institute of Biotechnology and School of Chemical Engineering and
Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
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10
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Mayhall NJ, Horn PR, Sundstrom EJ, Head-Gordon M. Spin–flip non-orthogonal configuration interaction: a variational and almost black-box method for describing strongly correlated molecules. Phys Chem Chem Phys 2014; 16:22694-705. [DOI: 10.1039/c4cp02818j] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Wongnate T, Surawatanawong P, Visitsatthawong S, Sucharitakul J, Scrutton NS, Chaiyen P. Proton-Coupled Electron Transfer and Adduct Configuration Are Important for C4a-Hydroperoxyflavin Formation and Stabilization in a Flavoenzyme. J Am Chem Soc 2013; 136:241-53. [DOI: 10.1021/ja4088055] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Thanyaporn Wongnate
- Department
of Biochemistry and Center of Excellence in Protein Structure and
Function, Faculty of Science, Mahidol University, Bangkok, 10400 Thailand
| | - Panida Surawatanawong
- Department
of Chemistry and Center of Excellence for Innovation in Chemistry, Mahidol University, Bangkok 10400 Thailand
| | - Surawit Visitsatthawong
- Department
of Chemistry and Center of Excellence for Innovation in Chemistry, Mahidol University, Bangkok 10400 Thailand
| | - Jeerus Sucharitakul
- Department
of Biochemistry, Faculty of Dentistry, Chulalongkorn University, Henri-Dunant
Road, Patumwan, Bangkok, 10300 Thailand
| | - Nigel S. Scrutton
- Manchester
Institute of Biotechnology and Faculty of Life Sciences, The University of Manchester, Manchester M1 7DN United Kingdom
| | - Pimchai Chaiyen
- Department
of Biochemistry and Center of Excellence in Protein Structure and
Function, Faculty of Science, Mahidol University, Bangkok, 10400 Thailand
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12
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Saen-Oon S, Lucas MF, Guallar V. Electron transfer in proteins: theory, applications and future perspectives. Phys Chem Chem Phys 2013; 15:15271-85. [DOI: 10.1039/c3cp50484k] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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13
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Liu Y, Mukherjee A, Nahumi N, Ozbil M, Brown D, Angeles-Boza AM, Dooley DM, Prabhakar R, Roth JP. Experimental and Computational Evidence of Metal-O2 Activation and Rate-Limiting Proton-Coupled Electron Transfer in a Copper Amine Oxidase. J Phys Chem B 2012; 117:218-29. [DOI: 10.1021/jp3121484] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Yi Liu
- Department of Chemistry, Johns Hopkins University, 3400 North
Charles Street, Baltimore, Maryland 21218, United States
| | - Arnab Mukherjee
- Department of Chemistry, Johns Hopkins University, 3400 North
Charles Street, Baltimore, Maryland 21218, United States
| | - Nadav Nahumi
- Department of Chemistry, Johns Hopkins University, 3400 North
Charles Street, Baltimore, Maryland 21218, United States
| | - Mehmet Ozbil
- Department of Chemistry, University of Miami, 1301 Memorial Drive,
Coral Gables, Florida 33146, United States
| | - Doreen Brown
- Department of Chemistry
and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Alfredo M. Angeles-Boza
- Department of Chemistry, Johns Hopkins University, 3400 North
Charles Street, Baltimore, Maryland 21218, United States
| | - David M. Dooley
- Department of Chemistry
and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Rajeev Prabhakar
- Department of Chemistry, University of Miami, 1301 Memorial Drive,
Coral Gables, Florida 33146, United States
| | - Justine P. Roth
- Department of Chemistry, Johns Hopkins University, 3400 North
Charles Street, Baltimore, Maryland 21218, United States
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14
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Zapata-Rivera J, Caballol R, Calzado CJ. Comparing the peroxo/superoxo nature of the interaction between molecular O2 and β-diketiminato-copper and nickel complexes. Phys Chem Chem Phys 2011; 13:20241-7. [DOI: 10.1039/c1cp22121c] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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16
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Smith MA, Pirrat P, Pearson AR, Kurtis CRP, Trinh CH, Gaule TG, Knowles PF, Phillips SEV, McPherson MJ. Exploring the roles of the metal ions in Escherichia coli copper amine oxidase. Biochemistry 2010; 49:1268-80. [PMID: 20052994 PMCID: PMC2817917 DOI: 10.1021/bi901738k] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
To investigate the role of the active site copper in Escherichia coli copper amine oxidase (ECAO), we initiated a metal-substitution study. Copper reconstitution of ECAO (Cu-ECAO) restored only approximately 12% wild-type activity as measured by k(cat(amine)). Treatment with EDTA, to remove exogenous divalent metals, increased Cu-ECAO activity but reduced the activity of wild-type ECAO. Subsequent addition of calcium restored wild-type ECAO and further enhanced Cu-ECAO activities. Cobalt-reconstituted ECAO (Co-ECAO) showed lower but significant activity. These initial results are consistent with a direct electron transfer from TPQ to oxygen stabilized by the metal. If a Cu(I)-TPQ semiquinone mechanism operates, then an alternative outer-sphere electron transfer must also exist to account for the catalytic activity of Co-ECAO. The positive effect of calcium on ECAO activity led us to investigate the peripheral calcium binding sites of ECAO. Crystallographic analysis of wild-type ECAO structures, determined in the presence and absence of EDTA, confirmed that calcium is the normal ligand of these peripheral sites. The more solvent exposed calcium can be easily displaced by mono- and divalent cations with no effect on activity, whereas removal of the more buried calcium ion with EDTA resulted in a 60-90% reduction in ECAO activity and the presence of a lag phase, which could be overcome under oxygen saturation or by reoccupying the buried site with various divalent cations. Our studies indicate that binding of metal ions in the peripheral sites, while not essential, is important for maximal enzymatic activity in the mature enzyme.
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Affiliation(s)
- Mark A Smith
- Astbury Centre for Structural Molecular Biology and Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
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17
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Shan D, Zhang J, Xue HG, Ding SN, Cosnier S. Colloidal laponite nanoparticles: Extended application in direct electrochemistry of glucose oxidase and reagentless glucose biosensing. Biosens Bioelectron 2010; 25:1427-33. [DOI: 10.1016/j.bios.2009.10.046] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2009] [Revised: 10/23/2009] [Accepted: 10/28/2009] [Indexed: 10/20/2022]
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18
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Mukherjee A, Smirnov VV, Lanci MP, Brown DE, Shepard EM, Dooley DM, Roth JP. Inner-sphere mechanism for molecular oxygen reduction catalyzed by copper amine oxidases. J Am Chem Soc 2008; 130:9459-73. [PMID: 18582059 DOI: 10.1021/ja801378f] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Copper and topaquinone (TPQ) containing amine oxidases utilize O2 for the metabolism of biogenic amines while concomitantly generating H2O2 for use by the cell. The mechanism of O2 reduction has been the subject of long-standing debate due to the obscuring influence of a proton-coupled electron transfer between the tyrosine-derived TPQ and copper, a rapidly established equilibrium precluding assignment of the enzyme in its reactive form. Here, we show that substrate-reduced pea seedling amine oxidase (PSAO) exists predominantly in the Cu(I), TPQ semiquinone state. A new mechanistic proposal for O2 reduction is advanced on the basis of thermodynamic considerations together with kinetic studies (at varying pH, temperature, and viscosity), the identification of steady-state intermediates, and the analysis of competitive oxygen kinetic isotope effects, (18)O KIEs, [kcat/KM((16,16)O2)]/[kcat/KM((16,18)O2)]. The (18)O KIE = 1.0136 +/- 0.0013 at pH 7.2 is independent of temperature from 5 degrees C to 47 degrees C and insignificantly changed to 1.0122 +/- 0.0020 upon raising the pH to 9, thus indicating the absence of kinetic complexity. Using density functional methods, the effect is found to be precisely in the range expected for reversible O2 binding to Cu(I) to afford a superoxide, [Cu(II)(eta(1)-O2)(-I)](+), intermediate. Electron transfer from the TPQ semiquinone follows in the first irreversible step to form a peroxide, Cu(II)(eta(1)-O2)(-II), intermediate driving the reduction of O2. The similar (18)O KIEs reported for copper amine oxidases from other sources raise the possibility that all enzymes react by related inner-sphere mechanisms although additional experiments are needed to test this proposal.
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Affiliation(s)
- Arnab Mukherjee
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, USA
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19
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Santos HA, Ferreira ES, Pereira EJ, Pereira CM, Kontturi K, Silva F. Adsorption–Penetration Studies of Glucose Oxidase into Phospholipid Monolayers at the 1,2-Dichloroethane/Water Interface. Chemphyschem 2007; 8:1540-7. [PMID: 17569093 DOI: 10.1002/cphc.200700137] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The interaction between glucose oxidase (GOx) and phospholipid monolayers is studied at the 1,2-dichloroethane/water interface by electrochemical impedance spectroscopy. Electrochemical experiments show that the presence of GOx induces changes in the capacitance curves at both negative and positive potentials, which are successfully explained by a theoretical model based on the solution of the Poisson-Boltzmann equation. These changes are ascribed to a reduced partition coefficient of GOx and an increase of the permittivity of the lipid hydrocarbon domain. Our results show that the presence of lipid molecules enhances the adsorption of GOx molecules at the liquid/liquid interface. At low lipid concentrations, the adsorption of GOx is probably the first step preceding its penetration into the lipid monolayer. The experimental results indicate that GOx penetrates better and forms more stable monolayers for lipids with longer hydrophobic tails. At high GOx concentrations, the formation of multilayers is observed. The phenomenon described here is strongly dependent on 1) the GOx and lipid concentrations, 2) the nature of the lipid, and 3) the potential drop across the interface.
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Affiliation(s)
- Hélder A Santos
- Laboratory of Physical Chemistry and Electrochemistry, Department of Chemical Technology, Helsinki University of Technology, P.O. Box 6100, Kemistintie 1, 02015 HUT Espoo, Finland.
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20
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Cramer CJ, Tolman WB. Mononuclear Cu-O2 complexes: geometries, spectroscopic properties, electronic structures, and reactivity. Acc Chem Res 2007; 40:601-8. [PMID: 17458929 PMCID: PMC2593863 DOI: 10.1021/ar700008c] [Citation(s) in RCA: 321] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Using interwoven experimental and theoretical methods, detailed studies of several structurally defined 1:1 Cu-O 2 complexes have provided important fundamental chemical information useful for understanding the nature of intermediates involved in aerobic oxidations in synthetic and enzymatic copper-mediated catalysis. In particular, these studies have shed new light on the factors that influence the mode of O 2 coordination (end-on vs side-on) and the electronic structure, which can vary between Cu(II)-superoxo and Cu(III)-peroxo extremes.
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Affiliation(s)
- Christopher J Cramer
- Department of Chemistry, Supercomputer Institute, and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, Minnesota 55410, USA.
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21
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Shepard EM, Dooley DM. Intramolecular electron transfer rate between active-site copper and TPQ in Arthrobacter globiformis amine oxidase. J Biol Inorg Chem 2006; 11:1039-48. [PMID: 16924556 DOI: 10.1007/s00775-006-0153-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Accepted: 07/18/2006] [Indexed: 10/24/2022]
Abstract
Copper amine oxidases catalyze the oxidative deamination of primary amines operating through a ping-pong bi bi mechanism, divided into reductive and oxidative half-reactions. Considerable debate still exists regarding the role of copper in the oxidative half-reaction, where O2 is reduced to H2O2. Substrate-reduced amine oxidases display an equilibrium between a Cu(II) aminoquinol and a Cu(I) semiquinone, with the magnitude of the equilibrium constant being dependent upon the enzyme source. The initial electron transfer to dioxygen has been proposed to occur from either the reduced Cu(I) center or the reduced aminoquinol cofactor. In order for Cu(I) to be involved, it must be shown that the rate of electron transfer (kET) between the aminoquinol and Cu(II) is sufficiently rapid to place the Cu(I) semiquinone moiety on the mechanistic pathway. To further explore this issue, we measured the intramolecular electron transfer rate for the Cu(II) aminoquinol left arrow over right arrow Cu(I) semiquinone equilibrium in Arthrobacter globiformis amine oxidase (AGAO) by temperature-jump relaxation techniques. The results presented herein establish that kET is greater than the rate of catalysis (kcat) for the preferred amine substrate beta-phenylethylamine at three pH values, thereby permitting the Cu(I) semiquinone to be a viable catalytic intermediate during enzymatic reoxidation in this enzyme. The data show that kET is approximately equivalent at pH 6.2 and 7.2, being 2.5 times kcat for these pH values. At pH 8.2, however, kET decreases, becoming comparable to kcat. Potential reasons for the decreased kET at basic pH are presented. The implications of these results in light of a previously published study measuring reoxidation rates of substrate-reduced AGAO are also addressed.
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Affiliation(s)
- Eric M Shepard
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, USA
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22
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Taylor NE, Cowley AW. Effect of renal medullary H2O2 on salt-induced hypertension and renal injury. Am J Physiol Regul Integr Comp Physiol 2005; 289:R1573-9. [PMID: 16109803 DOI: 10.1152/ajpregu.00525.2005] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dahl salt-sensitive (SS) and consomic, salt-resistant SS-13(BN) rats possess substantial differences in blood pressure salt-sensitivity even with highly similar genetic backgrounds. The present study examined whether increased oxidative stress, particularly H2O2, in the renal medulla of SS rats contributes to these differences. Blood pressure was measured using femoral arterial catheters in three groups of rats: 1) 12-wk-old SS and consomic SS-13(BN) rats fed a 0.4% NaCl diet, 2) SS rats fed a 4% NaCl diet and chronically infused with saline or catalase (6.9 microg x kg(-1) x min(-1)) directly into the renal medulla, and 3) SS-13(BN) fed high salt (4%) and infused with saline or H2O2 (347 nmol x kg(-1) x min(-1)) into the renal medullary interstitium. After chronic blood pressure measurements, renal medullary interstitial H2O2 concentration ([H2O2]) was collected by microdialysis and analyzed with Amplex red. Blood pressure and [H2O2] were both significantly higher in SS (126 +/- 3 mmHg and 145 +/- 17 nM, respectively) vs. SS-13(BN) rats (116 +/- 2 mmHg and 56 +/- 14 nM) fed a 0.4% diet. Renal interstitial catalase infusion significantly decreased [H2O2] (96 +/- 41 vs. 297 +/- 52 nM) and attenuated the hypertension (146 +/- 2 mmHg catalase vs. 163 +/- 4 mmHg saline) in SS rats after 5 days of high salt (4%). H2O2 infused into the renal medulla of consomic SS-13(BN) fed high salt (4%) for 7 days accentuated the salt sensitivity (145 +/- 2 mmHg H2O2 vs. 134 +/- 1 mmHg saline). [H2O2] was also increased in the treated group (83 +/- 1 nM H2O2 vs. 44 +/- 9 nM saline). These data show that medullary production of H2O2 may contribute to salt-induced hypertension in SS rats and that chromosome 13 of the Brown Norway contains gene(s) that protect against renal medullary oxidant stress.
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Affiliation(s)
- Norman E Taylor
- Dept. of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Rd., Milwaukee, WI 53226, USA.
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Leskovac V, Trivić S, Wohlfahrt G, Kandrac J, Pericin D. Glucose oxidase from Aspergillus niger: the mechanism of action with molecular oxygen, quinones, and one-electron acceptors. Int J Biochem Cell Biol 2005; 37:731-50. [PMID: 15694834 DOI: 10.1016/j.biocel.2004.10.014] [Citation(s) in RCA: 168] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Indexed: 11/17/2022]
Abstract
Glucose oxidase from the mold Aspergillus niger (EC 1.1.3.4) oxidizes beta-D-glucose with a wide variety of oxidizing substrates. The substrates were divided into three main groups: molecular oxygen, quinones, and one-electron acceptors. The kinetic and chemical mechanism of action for each group of substrates was examined in turn with a wide variety of kinetic methods and by means of molecular modeling of enzyme-substrate complexes. There are two proposed mechanisms for the reductive half-reaction: hydride abstraction and nucleophilic attack followed by deprotonation. The former mechanism appears plausible; here, beta-D-glucose is oxidized to glucono-delta-lactone by a concerted transfer of a proton from its C1-hydroxyl to a basic group on the enzyme (His516) and a direct hydride transfer from its C1 position to the N5 position in FAD. The oxidative half-reaction proceeds via one- or two-electron transfer mechanisms, depending on the type of the oxidizing substrate. The active site of the enzyme contains, in addition to FAD, three amino acid side chains that are intimately involved in catalysis: His516 with a pK(a)=6.9, and Glu412 with pK(a)=3.4 which is hydrogen bonded to His559, with pK(a)>8. The protonation of each of these residues has a strong influence on all rate constants in the catalytic mechanism.
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Affiliation(s)
- V Leskovac
- Faculty of Technology, Bulevar Cara Lazara 1, 21000 Novi Sad, Yugoslavia.
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Duff AP, Trambaiolo DM, Cohen AE, Ellis PJ, Juda GA, Shepard EM, Langley DB, Dooley DM, Freeman HC, Guss JM. Using Xenon as a Probe for Dioxygen-binding Sites in Copper Amine Oxidases. J Mol Biol 2004; 344:599-607. [PMID: 15533431 DOI: 10.1016/j.jmb.2004.09.075] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Revised: 09/21/2004] [Accepted: 09/24/2004] [Indexed: 11/28/2022]
Abstract
Potential dioxygen-binding sites in three Cu amine oxidases have been investigated by recording X-ray diffraction data at 1.7-2.2A resolution for crystals under a high pressure of xenon gas. Electron-density difference maps and crystallographic refinement provide unequivocal evidence for a number of Xe-binding sites in each enzyme. Only one of these sites is present in all three Cu amine oxidases studied. Structural changes elsewhere in the protein molecules are insignificant. The results illustrate the use of xenon as a probe for cavities, in which a protein may accommodate a dioxygen molecule. The finding of a potential dioxygen-binding cavity close to the active site of Cu amine oxidases may be relevant to the function of the enzymes, since the formation of a transient protein-dioxygen complex is a likely step in the catalytic mechanism. No evidence was found for xenon binding in a region of the molecule that was previously identified in two other Cu amine oxidases as a potential transient dioxygen-binding site.
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Affiliation(s)
- Anthony P Duff
- School of Molecular and Microbial Biosciences, University of Sydney, NSW 2006, Australia
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