1
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Tabaru K, Obora Y. Synergic Palladium Catalysis for Aerobic Oxidative Coupling. European J Org Chem 2022. [DOI: 10.1002/ejoc.202200618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Kazuki Tabaru
- Kansai University: Kansai Daigaku Department of Chemistry and Materials Engineering 3-3-35 Yamate-cho 564-8680 Suita JAPAN
| | - Yasushi Obora
- Kansai University: Kansai Daigaku Department of Chemistry and Materials Engineering 3-3-35 Yamate-cho 564-8680 Suita JAPAN
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2
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Chowdhury R. Eosin-Y/Cu(OAc) 2-catalyzed aerobic oxidative coupling reactions of glycine esters in the dark. Org Biomol Chem 2022; 20:5387-5392. [PMID: 35748811 DOI: 10.1039/d2ob00678b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Catalytic aerobic oxidative coupling reactions of glycine esters with β-keto acids, indoles, naphthols, and pyrrole have been realized at ambient temperature via the manipulation of the ground state reactivity of eosin-Y in the presence of Cu(OAc)2 in the dark. This method delivers structurally diverse unnatural amino acid derivatives under mild reaction conditions. UV-vis absorption spectroscopy, cyclic voltammetry, X-ray photoelectron spectroscopy, high-resolution mass spectrometry, and control experiments were performed to formulate a plausible mechanistic pathway. The step economy, broad substrate scope, use of air as a green oxidant, and operationally simple set-up make this protocol highly appealing for both academic and industrial applications.
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Affiliation(s)
- Raghunath Chowdhury
- Bio-Organic Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India. .,Homi Bhabha National Institute, Anushaktingar, Mumbai-94, India
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3
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Shoji M, Murakawa T, Nakanishi S, Boero M, Shigeta Y, Hayashi H, Okajima T. Molecular mechanism of a large conformational change of the quinone cofactor in the semiquinone intermediate of bacterial copper amine oxidase. Chem Sci 2022; 13:10923-10938. [PMID: 36320691 PMCID: PMC9491219 DOI: 10.1039/d2sc01356h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 08/16/2022] [Indexed: 11/21/2022] Open
Abstract
Copper amine oxidase from Arthrobacter globiformis (AGAO) catalyses the oxidative deamination of primary amines via a large conformational change of a topaquinone (TPQ) cofactor during the semiquinone formation step. This conformational change of TPQ occurs in the presence of strong hydrogen bonds and neighboring bulky amino acids, especially the conserved Asn381, which restricts TPQ conformational changes over the catalytic cycle. Whether such a semiquinone intermediate is catalytically active or inert has been a matter of debate in copper amine oxidases. Here, we show that the reaction rate of the Asn381Ala mutant decreases 160-fold, and the X-ray crystal structures of the mutant reveals a TPQ-flipped conformation in both the oxidized and reduced states, preceding semiquinone formation. Our hybrid quantum mechanics/molecular mechanics (QM/MM) simulations show that the TPQ conformational change is realized through the sequential steps of the TPQ ring-rotation and slide. We determine that the bulky side chain of Asn381 hinders the undesired TPQ ring-rotation in the oxidized form, favoring the TPQ ring-rotation in reduced TPQ by a further stabilization leading to the TPQ semiquinone form. The acquired conformational flexibility of TPQ semiquinone promotes a high reactivity of Cu(i) to O2, suggesting that the semiquinone form is catalytically active for the subsequent oxidative half-reaction in AGAO. The ingenious molecular mechanism exerted by TPQ to achieve the “state-specific” reaction sheds new light on a drastic environmental transformation around the catalytic center. The large conformational change of topaquinone in bacterial copper amine oxidase occurs through the TPQ ring rotation and slide, which are essential to stabilize the semiquinone form.![]()
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Affiliation(s)
- Mitsuo Shoji
- Center for Computational Sciences, University of Tsukuba 1-1-1 Tennodai Tsukuba 305-8577 Ibaraki Japan
- JST-PRESTO 4-1-8 Honcho Kawaguchi 332-0012 Saitama Japan
| | - Takeshi Murakawa
- Department of Biochemistry, Osaka Medical and Pharmaceutical University 2-7 Daigakumachi Takatsuki 569-8686 Osaka Japan
| | - Shota Nakanishi
- Institute of Scientific and Industrial Research, Osaka University 8-1 Mihogaoka Ibaraki 567-0047 Osaka Japan
| | - Mauro Boero
- University of Strasbourg, Institut de Physique et Chimie des Matériaux de Strasbourg, CNRS, UMR 7504 23 rue du Loess F-67034 France
| | - Yasuteru Shigeta
- Center for Computational Sciences, University of Tsukuba 1-1-1 Tennodai Tsukuba 305-8577 Ibaraki Japan
| | - Hideyuki Hayashi
- Department of Chemistry, Osaka Medical and Pharmaceutical University 2-7 Daigakumachi Takatsuki 569-8686 Osaka Japan
| | - Toshihide Okajima
- Institute of Scientific and Industrial Research, Osaka University 8-1 Mihogaoka Ibaraki 567-0047 Osaka Japan
- Department of Chemistry, Osaka Medical and Pharmaceutical University 2-7 Daigakumachi Takatsuki 569-8686 Osaka Japan
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4
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Yuan Z, Liao J, Jiang H, Cao P, Li Y. Aldehyde catalysis - from simple aldehydes to artificial enzymes. RSC Adv 2020; 10:35433-35448. [PMID: 35515689 PMCID: PMC9056934 DOI: 10.1039/d0ra06651f] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Accepted: 09/16/2020] [Indexed: 12/22/2022] Open
Abstract
Chemists have been learning and mimicking enzymatic catalysis in various aspects of organic synthesis. One of the major goals is to develop versatile catalysts that inherit the high catalytic efficiency of enzymatic processes, while being effective for a broad scope of substrates. In this field, the study of aldehyde catalysts has achieved significant progress. This review summarizes the application of aldehydes as sustainable and effective catalysts in different reactions. The fields, in which the aldehydes successfully mimic enzymatic systems, include light energy absorption/transfer, intramolecularity introduction through tether formation, metal binding for activation/orientation and substrate activation via aldimine formation. Enantioselective aldehyde catalysis has been achieved with the development of chiral aldehyde catalysts. Direct simplification of aldehyde-dependent enzymes has also been investigated for the synthesis of noncanonical chiral amino acids. Further development in aldehyde catalysis is expected, which might also promote exploration in fields related to prebiotic chemistry, early enzyme evolution, etc.
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Affiliation(s)
- Zeqin Yuan
- College of Chemistry and Materials Science, Sichuan Normal University Chengdu 610068 China
| | - Jun Liao
- College of Chemistry and Materials Science, Sichuan Normal University Chengdu 610068 China
| | - Hao Jiang
- Undisclosed Pharmaceutical Company Copenhagen Denmark
| | - Peng Cao
- College of Chemistry and Materials Science, Sichuan Normal University Chengdu 610068 China
| | - Yang Li
- College of Chemistry and Materials Science, Sichuan Normal University Chengdu 610068 China
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5
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Abstract
Lytic polysaccharide monooxygenases (LPMOs) are a recently discovered class of monocopper enzymes broadly distributed across the tree of life. Recent reports indicate that LPMOs can use H2O2 as an oxidant and thus carry out a novel type of peroxygenase reaction involving unprecedented copper chemistry. Here, we present a combined computational and experimental analysis of the H2O2-mediated reaction mechanism. In silico studies, based on a model of the enzyme in complex with a crystalline substrate, suggest that a network of hydrogen bonds, involving both the enzyme and the substrate, brings H2O2 into a strained reactive conformation and guides a derived hydroxyl radical toward formation of a copper-oxyl intermediate. The initial cleavage of H2O2 and subsequent hydrogen atom abstraction from chitin by the copper-oxyl intermediate are the main energy barriers. Stopped-flow fluorimetry experiments demonstrated that the priming reduction of LPMO-Cu(II) to LPMO-Cu(I) is a fast process compared to the reoxidation reactions. Using conditions resulting in single oxidative events, we found that reoxidation of LPMO-Cu(I) is 2,000-fold faster with H2O2 than with O2, the latter being several orders of magnitude slower than rates reported for other monooxygenases. The presence of substrate accelerated reoxidation by H2O2, whereas reoxidation by O2 became slower, supporting the peroxygenase paradigm. These insights into the peroxygenase nature of LPMOs will aid in the development and application of enzymatic and synthetic copper catalysts and contribute to a further understanding of the roles of LPMOs in nature, varying from biomass conversion to chitinolytic pathogenesis-defense mechanisms.
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6
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Synthesis, characterization and antimicrobial properties of mononuclear copper(II) compounds of N,N′-di(quinolin-8-yl)cyclohexane-1,2-diamine. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2019.119020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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7
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Adelson CN, Johnston EM, Hilmer KM, Watts H, Dey SG, Brown DE, Broderick JB, Shepard EM, Dooley DM, Solomon EI. Characterization of the Preprocessed Copper Site Equilibrium in Amine Oxidase and Assignment of the Reactive Copper Site in Topaquinone Biogenesis. J Am Chem Soc 2019; 141:8877-8890. [PMID: 31060358 DOI: 10.1021/jacs.9b01922] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Copper-dependent amine oxidases produce their redox active cofactor, 2,4,5-trihydroxyphenylalanine quinone (TPQ), via the CuII-catalyzed oxygenation of an active site tyrosine. This study addresses possible mechanisms for this biogenesis process by presenting the geometric and electronic structure characterization of the CuII-bound, prebiogenesis (preprocessed) active site of the enzyme Arthrobacter globiformis amine oxidase (AGAO). CuII-loading into the preprocessed AGAO active site is slow ( kobs = 0.13 h-1), and is preceded by CuII binding in a separate kinetically favored site that is distinct from the active site. Preprocessed active site CuII is in a thermal equilibrium between two species, an entropically favored form with tyrosine protonated and unbound from the CuII site, and an enthalpically favored form with tyrosine bound deprotonated to the CuII active site. It is shown that the CuII-tyrosinate bound form is directly active in biogenesis. The electronic structure determined for the reactive form of the preprocessed CuII active site is inconsistent with a biogenesis pathway that proceeds through a CuI-tyrosyl radical intermediate, but consistent with a pathway that overcomes the spin forbidden reaction of 3O2 with the bound singlet substrate via a three-electron concerted charge-transfer mechanism.
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Affiliation(s)
- Charles N Adelson
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Esther M Johnston
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Kimberly M Hilmer
- Department of Chemistry and Biochemistry , Montana State University , Bozeman , Montana 59717 , United States
| | - Hope Watts
- Department of Chemistry and Biochemistry , Montana State University , Bozeman , Montana 59717 , United States
| | - Somdatta Ghosh Dey
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Doreen E Brown
- Department of Chemistry and Biochemistry , Montana State University , Bozeman , Montana 59717 , United States
| | - Joan B Broderick
- Department of Chemistry and Biochemistry , Montana State University , Bozeman , Montana 59717 , United States
| | - Eric M Shepard
- Department of Chemistry and Biochemistry , Montana State University , Bozeman , Montana 59717 , 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
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8
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Copper amine oxidases catalyze the oxidative deamination and hydrolysis of cyclic imines. Nat Commun 2019; 10:413. [PMID: 30679427 PMCID: PMC6345859 DOI: 10.1038/s41467-018-08280-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 12/28/2018] [Indexed: 01/26/2023] Open
Abstract
Although cyclic imines are present in various bioactive secondary metabolites, their degradative metabolism remains unknown. Here, we report that copper amine oxidases, which are important in metabolism of primary amines, catalyze a cyclic imine cleavage reaction. We isolate a microorganism (Arthrobacter sp. C-4A) which metabolizes a β-carboline alkaloid, harmaline. The harmaline-metabolizing enzyme (HarA) purified from strain C-4A is found to be copper amine oxidase and catalyze a ring-opening reaction of cyclic imine within harmaline, besides oxidative deamination of amines. Growth experiments on strain C-4A and Western blot analysis indicate that the HarA expression is induced by harmaline. We propose a reaction mechanism of the cyclic imine cleavage by HarA containing a post-translationally-synthesized cofactor, topaquinone. Together with the above results, the finding of the same activity of copper amine oxidase from E. coli suggests that, in many living organisms, these enzymes may play crucial roles in metabolism of ubiquitous cyclic imines.
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9
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Abeyawardhane DL, Fernández RD, Heitger DR, Crozier MK, Wolver JC, Lucas HR. Copper Induced Radical Dimerization of α-Synuclein Requires Histidine. J Am Chem Soc 2018; 140:17086-17094. [DOI: 10.1021/jacs.8b08947] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
| | - Ricardo D. Fernández
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Denver R. Heitger
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Madeleine K. Crozier
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Julia C. Wolver
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
| | - Heather R. Lucas
- Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284, United States
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10
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Lei WL, Feng KW, Wang T, Wu LZ, Liu Q. Eosin Y- and Copper-Catalyzed Dark Reaction To Construct Ene-γ-Lactams. Org Lett 2018; 20:7220-7224. [DOI: 10.1021/acs.orglett.8b03147] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Wen-Long Lei
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P. R. China
| | - Kai-Wen Feng
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P. R. China
| | - Tao Wang
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P. R. China
| | - Li-Zhu Wu
- Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry & University of Chinese Academy of Sciences, the Chinese Academy of Sciences, Beijing 100190, P. R. China
| | - Qiang Liu
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, P. R. China
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11
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Mills SA, Gazica KE, Tierney DL. Co(II) is not oxidized during turnover in the copper amine oxidase from Hansenula polymorpha. J Biol Inorg Chem 2018; 24:31-37. [PMID: 30353442 DOI: 10.1007/s00775-018-1624-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 10/08/2018] [Indexed: 11/28/2022]
Abstract
Co(II) substitution into the copper amine oxidases (CAOs) has been an effective tool for evaluating the mechanism of oxygen reduction in these enzymes. However, formation of hydrogen peroxide during turnover raises questions about the relevant oxidation state of the cobalt in these enzymes and, therefore, the interpretation of the activity of the metal-substituted enzyme with respect to its mechanism of action. In this study, Co(II) was incorporated into the CAO from Hansenula polymorpha (HPAO). The effect of hydrogen peroxide on the catalytic activity of cobalt-substituted HPAO was evaluated. Hydrogen peroxide, either generated during turnover or added exogenously, caused a decrease in the activity of the enzyme but did not oxidize Co(II) to Co(III). These results are in strong contrast with results from the CAO from Arthrobacter globiformis (AGAO), where hydrogen peroxide causes an increase in the activity of the enzyme as the Co(II) is oxidized to Co(III). The results of this study with HPAO support previous reports that have shown that this enzyme acts by transferring an electron directly from the reduced TPQ cofactor to dioxygen rather than passing the electron through the bound metal ion. Furthermore, these results provide additional evidence to support the idea that different CAOs use different mechanisms for catalysis.
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Affiliation(s)
- Stephen A Mills
- Department of Chemistry, Xavier University, 3800 Victory Parkway, Cincinnati, OH, 45207, USA.
| | - Kiera E Gazica
- Department of Chemistry, Xavier University, 3800 Victory Parkway, Cincinnati, OH, 45207, USA
| | - David L Tierney
- Department of Chemistry and Biochemistry, Miami University, 651 E. High St, Oxford, OH, 45056, USA
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12
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Brikis CJ, Zarei A, Chiu GZ, Deyman KL, Liu J, Trobacher CP, Hoover GJ, Subedi S, DeEll JR, Bozzo GG, Shelp BJ. Targeted quantitative profiling of metabolites and gene transcripts associated with 4-aminobutyrate (GABA) in apple fruit stored under multiple abiotic stresses. HORTICULTURE RESEARCH 2018; 5:61. [PMID: 30510768 PMCID: PMC6269452 DOI: 10.1038/s41438-018-0069-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 05/02/2023]
Abstract
4-Aminobutyrate accumulates in plants under abiotic stress. Here, targeted quantitative profiling of metabolites and transcripts was conducted to monitor glutamate- and polyamine-derived 4-aminobutyrate production and its subsequent catabolism to succinate or 4-hydroxybutyrate in apple (Malus x domestica Borkh.) fruit stored at 0 °C with 2.5 kPa O2 and 0.03 or 5 kPa CO2 for 16 weeks. Low-temperature-induced protein hydrolysis appeared to be responsible for the enhanced availability of amino acids during early storage, and the resulting higher glutamate level stimulated 4-aminobutyrate levels more than polyamines. Elevated CO2 increased the levels of polyamines, as well as succinate and 4-hydroxybutyrate, during early storage, and 4-aminobutyrate and 4-hydroxybutyrate over the longer term. Expression of all of the genes likely involved in 4-aminobutyrate metabolism from glutamate/polyamines to succinate/4-hydroxybutyrate was induced in a co-ordinated manner. CO2-regulated expression of apple GLUTAMATE DECARBOXYLASE 2, AMINE OXIDASE 1, ALDEHYDE DEHYDROGENASE 10A8 and POLYAMINE OXIDASE 2 was evident with longer term storage. Evidence suggested that respiratory activities were restricted by the elevated CO2/O2 environment, and that decreasing NAD+ availability and increasing NADPH and NADPH/NADP+, respectively, played key roles in the regulation of succinate and 4-hydroxybutyate accumulation. Together, these findings suggest that both transcriptional and biochemical mechanisms are associated with 4-aminobutyrate and 4-hydroxybutyrate metabolism in apple fruit stored under multiple abiotic stresses.
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Affiliation(s)
- Carolyne J. Brikis
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario N1G 2W1 Canada
| | - Adel Zarei
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario N1G 2W1 Canada
| | - Greta Z. Chiu
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario N1G 2W1 Canada
| | - Kristen L. Deyman
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario N1G 2W1 Canada
| | - Jingyun Liu
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario N1G 2W1 Canada
| | | | - Gordon J. Hoover
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario N1G 2W1 Canada
| | - Sanjeena Subedi
- Department of Mathematical Sciences, Binghamton University, Binghamton, NY 13902 USA
| | - Jennifer R. DeEll
- Ontario Ministry of Agriculture, Food and Rural Affairs, Box 587, 1283 Blueline Rd. at Highway 3, Simcoe, Ontario N3Y 4N5 Canada
| | - Gale G. Bozzo
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario N1G 2W1 Canada
| | - Barry J. Shelp
- Department of Plant Agriculture, University of Guelph, Guelph, Ontario N1G 2W1 Canada
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13
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Muthuramalingam S, Subramaniyan S, Khamrang T, Velusamy M, Mayilmurugan R. Copper(II)-Bioinspired Models for Copper Amine Oxidases: Oxidative Half-Reaction in Water. ChemistrySelect 2017. [DOI: 10.1002/slct.201601786] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sethuraman Muthuramalingam
- Bioinorganic Chemistry Laboratory/Physical Chemistry; School of Chemistry; Madurai Kamaraj University; Madurai 625 021, Tamil Nadu India
| | - Shanmugam Subramaniyan
- Bioinorganic Chemistry Laboratory/Physical Chemistry; School of Chemistry; Madurai Kamaraj University; Madurai 625 021, Tamil Nadu India
| | - Themmila Khamrang
- Department of Chemistry; North Eastern Hill Universuty; Shillong- 793022 India
| | - Marappan Velusamy
- Department of Chemistry; North Eastern Hill Universuty; Shillong- 793022 India
| | - Ramasamy Mayilmurugan
- Bioinorganic Chemistry Laboratory/Physical Chemistry; School of Chemistry; Madurai Kamaraj University; Madurai 625 021, Tamil Nadu India
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14
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Sehanobish E, Campillo-Brocal JC, Williamson HR, Sanchez-Amat A, Davidson VL. Interaction of GoxA with Its Modifying Enzyme and Its Subunit Assembly Are Dependent on the Extent of Cysteine Tryptophylquinone Biosynthesis. Biochemistry 2016; 55:2305-8. [PMID: 27064961 DOI: 10.1021/acs.biochem.6b00274] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
GoxA is a glycine oxidase bearing a protein-derived cysteine tryptophylquinone (CTQ) cofactor that is formed by posttranslational modifications catalyzed by a flavoprotein, GoxB. Two forms of GoxA were isolated: an active form with mature CTQ and an inactive precursor protein that lacked CTQ. The active GoxA was present as a homodimer with no detectable affinity for GoxB, whereas the precursor was isolated as a monomer in a tight complex with one GoxB. Thus, the interaction of GoxA with GoxB and subunit assembly of mature GoxA are each dependent on the extent of CTQ biosynthesis.
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Affiliation(s)
- Esha Sehanobish
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida , Orlando, Florida 32827, United States
| | | | - Heather R Williamson
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida , Orlando, Florida 32827, United States
| | - Antonio Sanchez-Amat
- Department of Genetics and Microbiology, University of Murcia , Murcia 30100, Spain
| | - Victor L Davidson
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida , Orlando, Florida 32827, United States
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15
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Murakawa T, Hamaguchi A, Nakanishi S, Kataoka M, Nakai T, Kawano Y, Yamaguchi H, Hayashi H, Tanizawa K, Okajima T. Probing the Catalytic Mechanism of Copper Amine Oxidase from Arthrobacter globiformis with Halide Ions. J Biol Chem 2015; 290:23094-109. [PMID: 26269595 DOI: 10.1074/jbc.m115.662726] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Indexed: 11/06/2022] Open
Abstract
The catalytic reaction of copper amine oxidase proceeds through a ping-pong mechanism comprising two half-reactions. In the initial half-reaction, the substrate amine reduces the Tyr-derived cofactor, topa quinone (TPQ), to an aminoresorcinol form (TPQamr) that is in equilibrium with a semiquinone radical (TPQsq) via an intramolecular electron transfer to the active-site copper. We have analyzed this reductive half-reaction in crystals of the copper amine oxidase from Arthrobacter globiformis. Anerobic soaking of the crystals with an amine substrate shifted the equilibrium toward TPQsq in an "on-copper" conformation, in which the 4-OH group ligated axially to the copper center, which was probably reduced to Cu(I). When the crystals were soaked with substrate in the presence of halide ions, which act as uncompetitive and noncompetitive inhibitors with respect to the amine substrate and dioxygen, respectively, the equilibrium in the crystals shifted toward the "off-copper" conformation of TPQamr. The halide ion was bound to the axial position of the copper center, thereby preventing TPQamr from adopting the on-copper conformation. Furthermore, transient kinetic analyses in the presence of viscogen (glycerol) revealed that only the rate constant in the step of TPQamr/TPQsq interconversion is markedly affected by the viscogen, which probably perturbs the conformational change. These findings unequivocally demonstrate that TPQ undergoes large conformational changes during the reductive half-reaction.
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Affiliation(s)
- Takeshi Murakawa
- From the Department of Biochemistry, Osaka Medical College, Takatsuki, Osaka 569-8686, Japan
| | - Akio Hamaguchi
- the Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Shota Nakanishi
- the Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Misumi Kataoka
- the School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan, the Advanced Photon Technology Division, RIKEN SPring-8 Center, Sayo-gun, Hyogo 679-5148, Japan
| | - Tadashi Nakai
- the Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - Yoshiaki Kawano
- the Advanced Photon Technology Division, RIKEN SPring-8 Center, Sayo-gun, Hyogo 679-5148, Japan
| | - Hiroshi Yamaguchi
- the School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo 669-1337, Japan, the Advanced Photon Technology Division, RIKEN SPring-8 Center, Sayo-gun, Hyogo 679-5148, Japan
| | - Hideyuki Hayashi
- the Department of Chemistry, Osaka Medical College, Takatsuki, Osaka 569-8686, Japan, and
| | - Katsuyuki Tanizawa
- the Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan, the Center of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, 783 71 Olomouc, Czech Republic
| | - Toshihide Okajima
- the Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan, the Department of Chemistry, Osaka Medical College, Takatsuki, Osaka 569-8686, Japan, and
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16
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Shepard EM, Dooley DM. Inhibition and oxygen activation in copper amine oxidases. Acc Chem Res 2015; 48:1218-26. [PMID: 25897668 DOI: 10.1021/ar500460z] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Copper-containing amine oxidases (CuAOs) use both copper and 2,4,5-trihydroxyphenylalanine quinone (TPQ) to catalyze the oxidative deamination of primary amines. The CuAO active site is highly conserved and comprised of TPQ and a mononuclear type II copper center that exhibits five-coordinate, distorted square pyramidal coordination geometry with histidine ligands and equatorially and axially bound water in the oxidized, resting state. The active site is buried within the protein, and CuAOs from various sources display remarkable diversity with respect to the composition of the active site channel and cofactor accessibility. Structural and mechanistic factors that influence substrate preference and inhibitor sensitivity and selectivity have been defined. This Account summarizes the strategies used to design selective CuAO inhibitors based on active site channel characteristics, leading to either enhanced steric fits or the trapping of reactive electrophilic products. These findings provide a framework to support the future development of candidate molecules aimed at minimizing the negative side effects associated with drugs containing amine functionalities. This is vital given the existence of human diamine oxidase and vascular adhesion protein-1, which have distinct amine substrate preferences and are associated with different metabolic processes. Inhibition of these enzymes by antifungal or antiprotozoal agents, as well as classic monoamine oxidase (MAO) inhibitors, may contribute to the adverse side effects associated with drug treatment. These observations provide a rationale for the limited clinical value associated with certain amine-containing pharmaceuticals and emphasize the need for more selective AO inhibitors. This Account also discusses the novel roles of copper and TPQ in the chemistry of O2 activation and substrate oxidation. Reduced CuAOs exist in a redox equilibrium between the Cu(II)-TPQAMQ (aminoquinol) and Cu(I)-TPQSQ (semiquinone). Elucidating the roles of Cu(I), TPQSQ, and TPQAMQ in O2 activation, for example, distinguishing inner-sphere versus outer-sphere electron transfer mechanisms, has been actively investigated since the discovery of TPQSQ in 1991 and has only recently been clarified. Kinetics and spectroscopic studies encompassing metal substitution, stopped-flow and temperature-jump relaxation methods, and oxygen kinetic isotope experiments have provided strong support for an inner-sphere electron transfer step from Cu(I) to O2. Data for two enzymes support a mechanism wherein O2 prebinds to a three-coordinate Cu(I) site, yielding a [Cu(II)(η(1)-O2(-1))](+) intermediate, with H2O2 generated from ensuing rate-determining proton coupled electron transfer from TPQSQ. While kinetics data from the cobalt-substituted yeast enzyme indicated that O2 is reduced through an outer-sphere process involving TPQAMQ, new findings with a bacterial CuAO demonstrate that both the Cu(II) and Co(II) forms of the enzyme operate via parallel mechanisms involving metal-superoxide intermediates. Structural observations of a coordinated TPQSQ-Cu(I) complex in two CuAOs supports previous indications that Cu(II)/(I) ligand substitution chemistry may be mechanistically relevant. Substantial evidence indicates that rapid and reversible inner-sphere reduction of O2 at a three-coordinate Cu(I) site occurs, but the existence of a coordinated semiquinone in some AOs suggests that, in these enzymes, an outer-sphere reaction between O2 and TPQSQ may also be possible, since this is expected to be energetically favorable compared with outer-sphere electron transfer from TPQAMQ to O2.
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Affiliation(s)
- Eric M. Shepard
- Department
of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - David M. Dooley
- Office
of the President, University of Rhode Island, Kingston, Rhode Island 02881, United States
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Kakuda S, Rolle C, Ohkubo K, Siegler MA, Karlin KD, Fukuzumi S. Lewis acid-induced change from four- to two-electron reduction of dioxygen catalyzed by copper complexes using scandium triflate. J Am Chem Soc 2015; 137:3330-7. [PMID: 25659416 PMCID: PMC4630010 DOI: 10.1021/ja512584r] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mononuclear copper complexes, [(tmpa)Cu(II)(CH3CN)](ClO4)2 (1, tmpa = tris(2-pyridylmethyl)amine) and [(BzQ)Cu(II)(H2O)2](ClO4)2 (2, BzQ = bis(2-quinolinylmethyl)benzylamine)], act as efficient catalysts for the selective two-electron reduction of O2 by ferrocene derivatives in the presence of scandium triflate (Sc(OTf)3) in acetone, whereas 1 catalyzes the four-electron reduction of O2 by the same reductant in the presence of Brønsted acids such as triflic acid. Following formation of the peroxo-bridged dicopper(II) complex [(tmpa)Cu(II)(O2)Cu(II)(tmpa)](2+), the two-electron reduced product of O2 with Sc(3+) is observed to be scandium peroxide ([Sc(III)(O2(2-))](+)). In the presence of 3 equiv of hexamethylphosphoric triamide (HMPA), [Sc(III)(O2(2-))](+) was oxidized by [Fe(bpy)3](3+) (bpy = 2,2-bipyridine) to the known superoxide species [(HMPA)3Sc(III)(O2(•-))](2+) as detected by EPR spectroscopy. A kinetic study revealed that the rate-determining step of the catalytic cycle for the two-electron reduction of O2 with 1 is electron transfer from Fc* to 1 to give a cuprous complex which is highly reactive toward O2, whereas the rate-determining step with 2 is changed to the reaction of the cuprous complex with O2 following electron transfer from ferrocene derivatives to 2. The explanation for the change in catalytic O2-reaction stoichiometry from four-electron with Brønsted acids to two-electron reduction in the presence of Sc(3+) and also for the change in the rate-determining step is clarified based on a kinetics interrogation of the overall catalytic cycle as well as each step of the catalytic cycle with study of the observed effects of Sc(3+) on copper-oxygen intermediates.
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Affiliation(s)
- Saya Kakuda
- Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, ALCA (JST), Osaka University, Suita, Osaka 565-0871, Japan
| | - Clarence Rolle
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Kei Ohkubo
- Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, ALCA (JST), Osaka University, Suita, Osaka 565-0871, Japan
| | - Maxime A. Siegler
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Shunichi Fukuzumi
- Department of Material and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, ALCA (JST), Osaka University, Suita, Osaka 565-0871, Japan
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18
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Abstract
In order to address how diverse metalloprotein active sites, in particular those containing iron and copper, guide O₂binding and activation processes to perform diverse functions, studies of synthetic models of the active sites have been performed. These studies have led to deep, fundamental chemical insights into how O₂coordinates to mono- and multinuclear Fe and Cu centers and is reduced to superoxo, peroxo, hydroperoxo, and, after O-O bond scission, oxo species relevant to proposed intermediates in catalysis. Recent advances in understanding the various factors that influence the course of O₂activation by Fe and Cu complexes are surveyed, with an emphasis on evaluating the structure, bonding, and reactivity of intermediates involved. The discussion is guided by an overarching mechanistic paradigm, with differences in detail due to the involvement of disparate metal ions, nuclearities, geometries, and supporting ligands providing a rich tapestry of reaction pathways by which O₂is activated at Fe and Cu sites.
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19
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Klinman JP, Bonnot F. Intrigues and intricacies of the biosynthetic pathways for the enzymatic quinocofactors: PQQ, TTQ, CTQ, TPQ, and LTQ. Chem Rev 2014; 114:4343-65. [PMID: 24350630 PMCID: PMC3999297 DOI: 10.1021/cr400475g] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Judith P. Klinman
- Department of Chemistry University of California, Berkeley, California 94720, U.S.A. Supported by the National Institutes of Health (GM025765) to J.P.K
- Department of Molecular and Cell Biology University of California, Berkeley, California 94720, U.S.A. Supported by the National Institutes of Health (GM025765) to J.P.K
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, U.S.A. Supported by the National Institutes of Health (GM025765) to J.P.K
| | - Florence Bonnot
- Department of Chemistry University of California, Berkeley, California 94720, U.S.A. Supported by the National Institutes of Health (GM025765) to J.P.K
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, California 94720, U.S.A. Supported by the National Institutes of Health (GM025765) to J.P.K
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20
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Sehanobish E, Shin S, Sanchez-Amat A, Davidson VL. Steady-state kinetic mechanism of LodA, a novel cysteine tryptophylquinone-dependent oxidase. FEBS Lett 2014; 588:752-6. [PMID: 24462691 DOI: 10.1016/j.febslet.2014.01.021] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/02/2014] [Accepted: 01/05/2014] [Indexed: 11/19/2022]
Abstract
LodA is a novel lysine-ε-oxidase which possesses a cysteine tryptophylquinone cofactor. It is the first tryptophylquinone enzyme known to function as an oxidase. A steady-state kinetic analysis shows that LodA obeys a ping-pong kinetic mechanism with values of kcat of 0.22±0.04 s(-1), Klysine of 3.2±0.5 μM and KO2 of 37.2±6.1 μM. The kcat exhibited a pH optimum at 7.5 while kcat/Klysine peaked at 7.0 and remained constant to pH 8.5. Alternative electron acceptors could not effectively substitute for O2 in the reaction. A mechanism for the reductive half reaction of LodA is proposed that is consistent with the ping-pong kinetics.
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Affiliation(s)
- Esha Sehanobish
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, United States
| | - Sooim Shin
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, United States
| | - Antonio Sanchez-Amat
- Department of Genetics and Microbiology, University of Murcia, Murcia 30100, Spain
| | - Victor L Davidson
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, FL 32827, United States.
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Murakawa T, Hayashi H, Sunami T, Kurihara K, Tamada T, Kuroki R, Suzuki M, Tanizawa K, Okajima T. High-resolution crystal structure of copper amine oxidase fromArthrobacter globiformis: assignment of bound diatomic molecules as O2. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2013; 69:2483-94. [DOI: 10.1107/s0907444913023196] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 08/18/2013] [Indexed: 11/10/2022]
Abstract
The crystal structure of a copper amine oxidase fromArthrobacter globiformiswas determined at 1.08 Å resolution with the use of low-molecular-weight polyethylene glycol (LMW PEG; average molecular weight ∼200) as a cryoprotectant. The final crystallographicRfactor andRfreewere 13.0 and 15.0%, respectively. Several molecules of LMW PEG were found to occupy cavities in the protein interior, including the active site, which resulted in a marked reduction in the overallBfactor and consequently led to a subatomic resolution structure for a relatively large protein with a monomer molecular weight of ∼70 000. About 40% of the presumed H atoms were observed as clear electron densities in theFo−Fcdifference map. Multiple minor conformers were also identified for many residues. Anisotropic displacement fluctuations were evaluated in the active site, which contains a post-translationally derived quinone cofactor and a Cu atom. Furthermore, diatomic molecules, most likely to be molecular oxygen, are bound to the protein, one of which is located in a region that had previously been proposed as an entry route for the dioxygen substrate from the central cavity of the dimer interface to the active site.
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22
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Johnson BJ, Yukl ET, Klema VJ, Klinman JP, Wilmot CM. Structural snapshots from the oxidative half-reaction of a copper amine oxidase: implications for O2 activation. J Biol Chem 2013; 288:28409-17. [PMID: 23940035 DOI: 10.1074/jbc.m113.501791] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mechanism of molecular oxygen activation is the subject of controversy in the copper amine oxidase family. At their active sites, copper amine oxidases contain both a mononuclear copper ion and a protein-derived quinone cofactor. Proposals have been made for the activation of molecular oxygen via both a Cu(II)-aminoquinol catalytic intermediate and a Cu(I)-semiquinone intermediate. Using protein crystallographic freeze-trapping methods under low oxygen conditions combined with single-crystal microspectrophotometry, we have determined structures corresponding to the iminoquinone and semiquinone forms of the enzyme. Methylamine reduction at acidic or neutral pH has revealed protonated and deprotonated forms of the iminoquinone that are accompanied by a bound oxygen species that is likely hydrogen peroxide. However, methylamine reduction at pH 8.5 has revealed a copper-ligated cofactor proposed to be the semiquinone form. A copper-ligated orientation, be it the sole identity of the semiquinone or not, blocks the oxygen-binding site, suggesting that accessibility of Cu(I) may be the basis of partitioning O2 activation between the aminoquinol and Cu(I).
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Affiliation(s)
- Bryan J Johnson
- From the Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, Minnesota 55455 and
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23
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Das D, Lee YM, Ohkubo K, Nam W, Karlin KD, Fukuzumi S. Temperature-independent catalytic two-electron reduction of dioxygen by ferrocenes with a copper(II) tris[2-(2-pyridyl)ethyl]amine catalyst in the presence of perchloric acid. J Am Chem Soc 2013; 135:2825-34. [PMID: 23394287 DOI: 10.1021/ja312523u] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Selective two-electron plus two-proton (2e(-)/2H(+)) reduction of O(2) to hydrogen peroxide by ferrocene (Fc) or 1,1'-dimethylferrocene (Me(2)Fc) in the presence of perchloric acid is catalyzed efficiently by a mononuclear copper(II) complex, [Cu(II)(tepa)](2+) (1; tepa = tris[2-(2-pyridyl)ethyl]amine) in acetone. The E(1/2) value for [Cu(II)(tepa)](2+) as measured by cyclic voltammetry is 0.07 V vs Fc/Fc(+) in acetone, being significantly positive, which makes it possible to use relatively weak one-electron reductants such as Fc and Me(2)Fc for the overall two-electron reduction of O(2). Fast electron transfer from Fc or Me(2)Fc to 1 affords the corresponding Cu(I) complex [Cu(I)(tepa)](+) (2), which reacts at low temperature (193 K) with O(2), however only in the presence of HClO(4), to afford the hydroperoxo complex [Cu(II)(tepa)(OOH)](+) (3). A detailed kinetic study on the homogeneous catalytic system reveals the rate-determining step to be the O(2)-binding process in the presence of HClO(4) at lower temperature as well as at room temperature. The O(2)-binding kinetics in the presence of HClO(4) were studied, demonstrating that the rate of formation of the hydroperoxo complex 3 as well as the overall catalytic reaction remained virtually the same with changing temperature. The apparent lack of activation energy for the catalytic two-electron reduction of O(2) is shown to result from the existence of a pre-equilibrium between 2 and O(2) prior to the formation of the hydroperoxo complex 3. No further reduction of [Cu(II)(tepa)(OOH)](+) (3) by Fc or Me(2)Fc occurred, and instead 3 is protonated by HClO(4) to yield H(2)O(2) accompanied by regeneration of 1, thus completing the catalytic cycle for the two-electron reduction of O(2) by Fc or Me(2)Fc.
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Affiliation(s)
- Dipanwita Das
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea
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24
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Samonina-Kosicka J, Kańska M. Mechanistic studies of reactions catalysed by diamine oxidase using isotope effects. ISOTOPES IN ENVIRONMENTAL AND HEALTH STUDIES 2013; 49:357-364. [PMID: 24117430 DOI: 10.1080/10256016.2013.825612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Diamine oxidase (DAO), the enzyme that is responsible for amine biodegradation in animals, plants and humans, catalyses the biotransformation of amines such as histamine (HA), putrescine, 1-phenylethylamine, tyrosine, tryptamine, serotonine and spermine. The kinetic and solvent isotope effects (SIEs) were applied to study the mechanism of the biotransformation using HA and its methylderivatives. The SIE for the biotransformation of HA, N(τ)-methylhistamine and N(π)-methylhistamine was found to be 3.58, 2.22 and 5.70 on Vmax, and 1.58, 1.06 and 1.14 on Vmax/KM, respectively. On the other hand, the kinetic isotope effect for oxidation of stereospecifically deuterium-labelled [(α R)-(2)H]-N(τ)-methylhistamine and [(α R)-(2)H]-N(π)-methylhistamine was 0.69 and 0.62 on Vmax, and 15.06 and 7.50 on Vmax/K(M), respectively. These results demonstrate that DAO catalyses amine biotransformation by stereospecifically cleaving the αC-H bond in the pro-S position. Moreover, the oxidation of amine to aldehyde involves several transition states, including hybridisation change from sp(3) (Schiff base) to sp(2) (imine), then back again to sp(3) to give a final product with hybridisation sp(2) (aldehyde).
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25
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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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26
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The role of protein crystallography in defining the mechanisms of biogenesis and catalysis in copper amine oxidase. Int J Mol Sci 2012; 13:5375-5405. [PMID: 22754303 PMCID: PMC3382800 DOI: 10.3390/ijms13055375] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Revised: 04/22/2012] [Accepted: 04/26/2012] [Indexed: 12/22/2022] Open
Abstract
Copper amine oxidases (CAOs) are a ubiquitous group of enzymes that catalyze the conversion of primary amines to aldehydes coupled to the reduction of O2 to H2O2. These enzymes utilize a wide range of substrates from methylamine to polypeptides. Changes in CAO activity are correlated with a variety of human diseases, including diabetes mellitus, Alzheimer’s disease, and inflammatory disorders. CAOs contain a cofactor, 2,4,5-trihydroxyphenylalanine quinone (TPQ), that is required for catalytic activity and synthesized through the post-translational modification of a tyrosine residue within the CAO polypeptide. TPQ generation is a self-processing event only requiring the addition of oxygen and Cu(II) to the apoCAO. Thus, the CAO active site supports two very different reactions: TPQ synthesis, and the two electron oxidation of primary amines. Crystal structures are available from bacterial through to human sources, and have given insight into substrate preference, stereospecificity, and structural changes during biogenesis and catalysis. In particular both these processes have been studied in crystallo through the addition of native substrates. These latter studies enable intermediates during physiological turnover to be directly visualized, and demonstrate the power of this relatively recent development in protein crystallography.
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Fukuzumi S, Tahsini L, Lee YM, Ohkubo K, Nam W, Karlin KD. Factors that control catalytic two- versus four-electron reduction of dioxygen by copper complexes. J Am Chem Soc 2012; 134:7025-35. [PMID: 22462521 DOI: 10.1021/ja211656g] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The selective two-electron reduction of O(2) by one-electron reductants such as decamethylferrocene (Fc*) and octamethylferrocene (Me(8)Fc) is efficiently catalyzed by a binuclear Cu(II) complex [Cu(II)(2)(LO)(OH)](2+) (D1) {LO is a binucleating ligand with copper-bridging phenolate moiety} in the presence of trifluoroacetic acid (HOTF) in acetone. The protonation of the hydroxide group of [Cu(II)(2)(LO)(OH)](2+) with HOTF to produce [Cu(II)(2)(LO)(OTF)](2+) (D1-OTF) makes it possible for this to be reduced by 2 equiv of Fc* via a two-step electron-transfer sequence. Reactions of the fully reduced complex [Cu(I)(2)(LO)](+) (D3) with O(2) in the presence of HOTF led to the low-temperature detection of the absorption spectra due to the peroxo complex [Cu(II)(2)(LO)(OO)] (D) and the protonated hydroperoxo complex [Cu(II)(2)(LO)(OOH)](2+) (D4). No further Fc* reduction of D4 occurs, and it is instead further protonated by HOTF to yield H(2)O(2) accompanied by regeneration of [Cu(II)(2)(LO)(OTF)](2+) (D1-OTF), thus completing the catalytic cycle for the two-electron reduction of O(2) by Fc*. Kinetic studies on the formation of Fc*(+) under catalytic conditions as well as for separate examination of the electron transfer from Fc* to D1-OTF reveal there are two important reaction pathways operating. One is a rate-determining second reduction of D1-OTF, thus electron transfer from Fc* to a mixed-valent intermediate [Cu(II)Cu(I)(LO)](2+) (D2), which leads to [Cu(I)(2)(LO)](+) that is coupled with O(2) binding to produce [Cu(II)(2)(LO)(OO)](+) (D). The other involves direct reaction of O(2) with the mixed-valent compound D2 followed by rapid Fc* reduction of a putative superoxo-dicopper(II) species thus formed, producing D.
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Affiliation(s)
- Shunichi Fukuzumi
- Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea.
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28
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Mills SA, Brown DE, Dang K, Sommer D, Bitsimis A, Nguyen J, Dooley DM. Cobalt substitution supports an inner-sphere electron transfer mechanism for oxygen reduction in pea seedling amine oxidase. J Biol Inorg Chem 2012; 17:507-15. [PMID: 22258083 DOI: 10.1007/s00775-011-0872-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Accepted: 12/29/2011] [Indexed: 10/14/2022]
Abstract
Copper amine oxidases (CAOs) are a large family of proteins that use molecular oxygen to oxidize amines to aldehydes with the concomitant production of hydrogen peroxide and ammonia. CAOs utilize two cofactors for this reaction: topaquinone (TPQ) and a Cu(II) ion. Two mechanisms for oxygen reduction have been proposed for these enzymes. In one mechanism (involving inner-sphere electron transfer to O(2)), Cu(II) is reduced by TPQ, forming Cu(I), to which O(2) binds, forming a copper-superoxide complex. In an alternative mechanism (involving outer-sphere electron transfer to O(2)), O(2) is directly reduced by TPQ, without reduction of Cu(II). Substitution of Cu(II) with Co(II) has been used to distinguish between the two mechanisms in several CAOs. Because it is unlikely that Co(II) could be reduced to Co(I) in this environment, an inner-sphere mechanism, as described above, is prevented. We adapted metal replacement methods used for other CAOs to the amine oxidase from pea seedlings (PSAO). Cobalt-substituted PSAO (CoPSAO) displayed nominal catalytic activity: k(cat) is 4.7% of the native k(cat), and K(M) (O(2)) for CoPSAO is substantially (22-fold) higher. The greatly reduced turnover number for CoPSAO suggests that PSAO uses the inner-sphere mechanism, as has been predicted from (18)O isotope effect studies (Mukherjee et al. in J Am Chem Soc 130:9459-9473, 2008), and is catalytically compromised when constrained to operate via outer-sphere electron transfer to O(2). This study, together with previous work, provides strong evidence that CAOs use both proposed mechanisms, but each homolog may prefer one mechanism over the other.
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Affiliation(s)
- Stephen A Mills
- Department of Chemistry and Biochemistry, University of San Diego, 5998 Alcala Park, San Diego, CA 92110, USA.
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29
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Huff GS, Doncheva IS, Brinkley DW, Angeles-Boza AM, Mukherjee A, Cramer CJ, Roth JP. Experimental and Computational Investigations of Oxygen Reactivity in a Heme and Tyrosyl Radical-Containing Fatty Acid α-(Di)oxygenase. Biochemistry 2011; 50:7375-89. [DOI: 10.1021/bi201016h] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Gregory S. Huff
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street
Baltimore, Maryland 21218, United States
| | - Irina S. Doncheva
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street
Baltimore, Maryland 21218, United States
| | - David W. Brinkley
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street
Baltimore, Maryland 21218, United States
| | - Alfredo M. Angeles-Boza
- 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
| | - Christopher J. Cramer
- Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis,
Minnesota 55455, United States
| | - Justine P. Roth
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street
Baltimore, Maryland 21218, United States
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30
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Di Paolo ML, Lunelli M, Fuxreiter M, Rigo A, Simon I, Scarpa M. Active site residue involvement in monoamine or diamine oxidation catalysed by pea seedling amine oxidase. FEBS J 2011; 278:1232-43. [PMID: 21294844 DOI: 10.1111/j.1742-4658.2011.08044.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structures of copper amine oxidases from various sources show good similarity, suggesting similar catalytic mechanisms for all members of this enzyme family. However, the optimal substrates for each member differ, depending on the source of the enzyme and its location. The structural factors underlying substrate selectivity still remain to be discovered. With this in view, we examined the kinetic behaviour of pea seedling amine oxidase with cadaverine and hexylamine, the first bearing two, and the second only one, positively charged amino group. The dependence of K(m) and catalytic constant (k(c)) values on pH, ionic strength and temperature indicates that binding of the monoamine is driven by hydrophobic interactions. Instead, binding of the diamine is strongly facilitated by electrostatic factors, controlled by polar side-chains and two titratable residues present in the active site. The position of the docked substrate is also essential for the participation of titratable amino acid residues in the following catalytic steps. A new mechanistic model explaining the substrate-dependent kinetics of the reaction is discussed.
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RoseFigura JM, Puehringer S, Schwarzenbacher R, Toyama H, Klinman JP. Characterization of a protein-generated O₂ binding pocket in PqqC, a cofactorless oxidase catalyzing the final step in PQQ production. Biochemistry 2011; 50:1556-66. [PMID: 21155540 DOI: 10.1021/bi1015474] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
PQQ is an exogenous, tricyclic, quino-cofactor for a number of bacterial dehydrogenases. The final step of PQQ formation is catalyzed by PqqC, a cofactorless oxidase. This study focuses on the activation of molecular oxygen in an enzyme active site without metal or cofactor and has identified a specific oxygen binding and activating pocket in PqqC. The active site variants H154N, Y175F,S, and R179S were studied with the goal of defining the site of O(2) binding and activation. Using apo-glucose dehydrogenase to assay for PQQ production, none of the mutants in this "O(2) core" are capable of PQQ/PQQH(2) formation. Spectrophotometric assays give insight into the incomplete reactions being catalyzed by these mutants. Active site variants Y175F, H154N, and R179S form a quinoid intermediate (Figure 1) anaerobically. Y175S is capable of proceeding further from quinoid to quinol, whereas Y175F, H154N, and R179S require O(2) to produce the quinol species. None of the mutations precludes substrate/product binding or oxygen binding. Assays for the oxidation of PQQH(2) to PQQ show that these O(2) core mutants are incapable of catalyzing a rate increase over the reaction in buffer, whereas H154N can catalyze the oxidation of PQQH(2) to PQQ in the presence of H(2)O(2) as an electron acceptor. Taken together, these data indicate that none of the targeted mutants can react fully to form quinone even in the presence of bound O(2). The data indicate a successful separation of oxidative chemistry from O(2) binding. The residues H154, Y175, and R179 are proposed to form a core O(2) binding structure that is essential for efficient O(2) activation.
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Affiliation(s)
- Jordan M RoseFigura
- Department of Chemistry, University of California, Berkeley, California 94720, United States
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Lucas HR, Meyer GJ, Karlin KD. CO and O2 binding to pseudo-tetradentate ligand-copper(I) complexes with a variable N-donor moiety: kinetic/thermodynamic investigation reveals ligand-induced changes in reaction mechanism. J Am Chem Soc 2011; 132:12927-40. [PMID: 20726586 DOI: 10.1021/ja104107q] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The kinetics, thermodynamics, and coordination dynamics are reported for O(2) and CO 1:1 binding to a series of pseudo-tetradentate ligand-copper(I) complexes ((D)LCu(I)) to give Cu(I)/O(2) and Cu(I)/CO product species. Members of the (D)LCu(I) series possess an identical tridentate core structure where the cuprous ion binds to the bispicolylamine (L) fragment. (D)L also contains a fourth variable N-donor moiety {D = benzyl (Bz); pyridyl (Py); imidazolyl (Im); dimethylamino (NMe(2)); (tert-butylphenyl)pyridyl (TBP); quinolyl (Q)}. The structural characteristics of (D)LCu(I)-CO and (D)LCu(I) are detailed, with X-ray crystal structures reported for (TBP)LCu(I)-CO, (Bz)LCu(I)-CO, and (Q)LCu(I). Infrared studies (solution and solid-state) confirm that (D)LCu(I)-CO possess the same four-coordinate core structure in solution with the variable D moiety "dangling", i.e., not coordinated to the copper(I) ion. Other trends observed for the present series appear to derive from the degree to which the D-group interacts with the cuprous ion center. Electrochemical studies reveal close similarities of behavior for (Im)LCu(I) and (NMe(2))LCu(I) (as well as for (TBP)LCu(I) and (Q)LCu(I)), which relate to the O(2) binding kinetics and thermodynamics. Equilibrium CO binding data (K(CO), ΔH°, ΔS°) were obtained by conducting UV-visible spectrophotometric CO titrations, while CO binding kinetics and thermodynamics (k(CO), ΔH(double dagger), ΔS(double dagger)) were measured through variable-temperature (193-293 K) transient absorbance laser flash photolysis experiments, λ(ex) = 355 nm. Carbon monoxide dissociation rate constants (k(-CO)) and corresponding activation parameters (ΔH(double dagger), ΔS(double dagger)) have also been obtained. CO binding to (D)LCu(I) follows an associative mechanism, with the increased donation from D leading to higher k(CO) values. Unlike observations from previous work, the K(CO) values increased as the k(CO) and k(-CO) values declined; the latter decreased at a faster rate. By using the "flash-and-trap" method (λ(ex) = 355 nm, 188-218 K), the kinetics and thermodynamics (k(O(2)), ΔH(double dagger), ΔS(double dagger)) for O(2) binding to (NMe(2))LCu(I) and (Im)LCu(I) were measured and compared to those for (Py)LCu(I). A surprising change in the O(2) binding mechanism was deduced from the thermodynamic ΔS(double dagger) values observed, associative for (Py)LCu(I) but dissociative for (NMe(2))LCu(I) and (Im)LCu(I); these results are interpreted as arising from a difference in the timing of electron transfer from copper(I) to O(2) as this molecule coordinates and a tetrahydrofuran (THF) solvent molecule dissociates. The change in mechanism was not simply related to alterations in (D)LCu(II/I) geometries or the order in which O(2) and THF coordinate. The equilibrium O(2) binding constant (K(O(2)), ΔH°, ΔS°) and O(2) dissociation rate constants (k(-O(2)), ΔH(double dagger), ΔS(double dagger)) were also determined. Overall the results demonstrate that subtle changes in the coordination environment, as occur over time through evolution in nature or through controlled ligand design in synthetic systems, dictate to a critically detailed level the observed chemistry in terms of reaction kinetics, structure, and reactivity, and thus function. Results reported here are also compared to relevant copper and/or iron biological systems and analogous synthetic ligand-copper systems.
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Affiliation(s)
- Heather R Lucas
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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Largeron M. Amine oxidases of the quinoproteins family: Their implication in the metabolic oxidation of xenobiotics. ANNALES PHARMACEUTIQUES FRANÇAISES 2011; 69:53-61. [DOI: 10.1016/j.pharma.2010.10.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 10/04/2010] [Accepted: 10/13/2010] [Indexed: 12/11/2022]
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Ashley DC, Brinkley DW, Roth JP. Oxygen Isotope Effects as Structural and Mechanistic Probes in Inorganic Oxidation Chemistry. Inorg Chem 2010; 49:3661-75. [DOI: 10.1021/ic901778g] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Daniel C. Ashley
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218
| | - David W. Brinkley
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218
| | - Justine P. Roth
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218
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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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36
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Baron R, McCammon JA, Mattevi A. The oxygen-binding vs. oxygen-consuming paradigm in biocatalysis: structural biology and biomolecular simulation. Curr Opin Struct Biol 2009; 19:672-9. [DOI: 10.1016/j.sbi.2009.10.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2009] [Accepted: 10/07/2009] [Indexed: 11/28/2022]
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Raber ML, Arnett SO, Townsend CA. A conserved tyrosyl-glutamyl catalytic dyad in evolutionarily linked enzymes: carbapenam synthetase and beta-lactam synthetase. Biochemistry 2009; 48:4959-71. [PMID: 19371088 DOI: 10.1021/bi900432n] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Beta-lactam-synthesizing enzymes carbapenam synthetase (CPS) and beta-lactam synthetase (beta-LS) are evolutionarily linked to a common ancestor, asparagine synthetase B (AS-B). These three relatives catalyze substrate acyl-adenylation and nucleophilic acyl substitution by either an external (AS-B) or internal (CPS, beta-LS) nitrogen source. Unlike AS-B, crystal structures of CPS and beta-LS revealed a putative Tyr-Glu dyad (CPS, Y345/E380; beta-LS, Y348/E382) proposed to deprotonate the respective internal nucleophile. CPS and beta-LS site-directed mutagenesis (Y345/8A, Y345/8F, E380/2D, E380/2Q, E380A) resulted in the reduction of their catalytic efficiency, with Y345A, E380A, and E382Q producing undetectable amounts of beta-lactam product. However, [(32)P]PP(i)-ATP exchange assays demonstrated Y345A and E380A undergo the first half-reaction, with the remaining active mutants showing decreased forward commitment to beta-lactam cyclization. pH-rate profiles of CPS and beta-LS supported the importance of a Tyr-Glu dyad in beta-lactam formation and suggested its reverse protonation in beta-LS. The kinetics of CPS double-site mutants reinforced the synergism of Tyr-Glu in catalysis. Furthermore, significant solvent isotope effects on k(cat) ((D)k(cat)) for Y345F (1.9) and Y348F (1.7) maintained the assignment of Y345/8 in proton transfer. A proton inventory on Y348F determined its (D)(k(cat)/K(m)) = 0.2 to arise from multiple reactant-state fractionation factors, presumably from water molecule(s) replacing the missing Tyr hydroxyl. The role of a CPS and beta-LS Tyr-Glu catalytic dyad was solidified by a significant decrease in mutant k(cat) viscosity dependence with respect to the wild-type enzymes. The evolutionary relation and potential for engineered biosynthesis were demonstrated by beta-LS acting as a carbapenam synthetase.
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Affiliation(s)
- Mary L Raber
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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38
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Yu H, Fu Y, Guo Q, Lin Z. DFT Studies on Reactions of Transition Metal Complexes with O2. Organometallics 2009. [DOI: 10.1021/om9002957] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Haizhu Yu
- Department of Chemistry, University of Science and Technology of China, Hefei, People's Republic of China
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China
| | - Yao Fu
- Department of Chemistry, University of Science and Technology of China, Hefei, People's Republic of China
| | - Qingxiang Guo
- Department of Chemistry, University of Science and Technology of China, Hefei, People's Republic of China
| | - Zhenyang Lin
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China
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Balakrishna S, Lomnicki S, McAvey KM, Cole RB, Dellinger B, Cormier SA. Environmentally persistent free radicals amplify ultrafine particle mediated cellular oxidative stress and cytotoxicity. Part Fibre Toxicol 2009; 6:11. [PMID: 19374750 PMCID: PMC2676242 DOI: 10.1186/1743-8977-6-11] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Accepted: 04/17/2009] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND Combustion generated particulate matter is deposited in the respiratory tract and pose a hazard to the lungs through their potential to cause oxidative stress and inflammation. We have previously shown that combustion of fuels and chlorinated hydrocarbons produce semiquinone-type radicals that are stabilized on particle surfaces (i.e. environmentally persistent free radicals; EPFRs). Because the composition and properties of actual combustion-generated particles are complex, heterogeneous in origin, and vary from day-to-day, we have chosen to use surrogate particle systems. In particular, we have chosen to use the radical of 2-monochlorophenol (MCP230) as the EPFR because we have previously shown that it forms a EPFR on Cu(II)O surfaces and catalyzes formation of PCDD/F. To understand the physicochemical properties responsible for the adverse pulmonary effects of combustion by-products, we have exposed human bronchial epithelial cells (BEAS-2B) to MCP230 or the CuO/silica substrate. Our general hypothesis was that the EPFR-containing particle would have greater toxicity than the substrate species. RESULTS Exposure of BEAS-2B cells to our combustion generated particle systems significantly increased reactive oxygen species (ROS) generation and decreased cellular antioxidants resulting in cell death. Resveratrol treatment reversed the decline in cellular glutathione (GSH), glutathione peroxidase (GPx), and superoxide dismutase (SOD) levels for both types of combustion-generated particle systems. CONCLUSION The enhanced cytotoxicity upon exposure to MCP230 correlated with its ability to generate more cellular oxidative stress and concurrently reduce the antioxidant defenses of the epithelial cells (i.e. reduced GSH, SOD activity, and GPx). The EPFRs in MCP230 also seem to be of greater biological concern due to their ability to induce lipid peroxidation. These results are consistent with the oxidizing nature of the CuO/silica ultrafine particles and the reducing nature and prolonged environmental and biological lifetimes of the EPFRs in MCP230.
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Affiliation(s)
- Shrilatha Balakrishna
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
| | - Slawo Lomnicki
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Kevin M McAvey
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana, USA
| | - Richard B Cole
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana, USA
| | - Barry Dellinger
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Stephania A Cormier
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, New Orleans, Louisiana, USA
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Humphreys KJ, Mirica LM, Wang Y, Klinman JP. Galactose oxidase as a model for reactivity at a copper superoxide center. J Am Chem Soc 2009; 131:4657-63. [PMID: 19290629 PMCID: PMC2683747 DOI: 10.1021/ja807963e] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The mononuclear copper enzyme, galactose oxidase, has been investigated under steady-state conditions via O(2)-consumption assays using 1-O-methyl-alpha-D-galactopyranoside as the sugar substrate to produce an aldehyde at the C-6 position. The rate-determining step of the oxidative half-reaction was probed through the measurement of substrate and solvent deuterium and O-18 isotope effects on k(cat)/K(m)(O(2)). The reaction conforms to a ping-pong mechanism with the kinetic parameters for the reductive half, k(cat)/K(m)(S) = 8.3 x 10(3) M(-1) s(-1) at 10 degrees C and pH 7.0, comparing favorably to literature values. The oxidative half-reaction yielded a value of k(cat)/K(m)(O(2)) = 2.5 x 10(6) M(-1) s(-1). A substrate deuterium isotope effect of 32 was measured for the k(cat)/K(m)(S), while a smaller, but significant value of 1.6-1.9 was observed on k(cat)/K(m)(O(2)). O-18 isotope effects of 1.0185 with either protiated or deuterated sugar, together with the absence of any solvent isotope effect, lead to the conclusion that hydrogen atom transfer from reduced cofactor to a Cu(II)-superoxo intermediate is fully rate-determining for k(cat)/K(m)(O(2)). The measured O-18 isotope effects provide corroborative evidence for the reactive superoxo species in the dopamine beta-monooxygenase/peptidylglycine alpha-hydroxylating monooxygenase family, as well as providing a frame of reference for copper-superoxo reactivity. The combination of solvent and substrate deuterium isotope effects rules out solvent deuterium exchange into reduced enzyme as the origin of the relatively small substrate deuterium isotope effect on k(cat)/K(m)(O(2)). These data indicate fundamental differences in the hydrogen transfer step from the carbon of substrate vs the oxygen of reduced cofactor during the reductive and oxidative half-reactions of galactose oxidase.
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Affiliation(s)
- Kristi J. Humphreys
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Liviu M. Mirica
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Yi Wang
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - Judith P. Klinman
- Department of Chemistry, University of California, Berkeley, California 94720, USA
- Departments of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
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41
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Roth JP. Oxygen isotope effects as probes of electron transfer mechanisms and structures of activated O2. Acc Chem Res 2009; 42:399-408. [PMID: 19195996 DOI: 10.1021/ar800169z] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Competitively determined oxygen ((18)O) isotope effects can be powerful probes of chemical and biological transformations involving molecular oxygen as well as superoxide and hydrogen peroxide. They play a complementary role to crystallography and spectroscopy in the study of activated oxygen intermediates by forging a link between electronic/vibrational structure and the bonding that occurs within ground and transition states along the reaction coordinate. Such analyses can be used to assess the plausibility of intermediates and their catalytic relevance in oxidative processes. This Account describes efforts to advance oxygen kinetic isotope effects ((18)O KIEs) and equilibrium isotope effects ((18)O EIEs) as mechanistic probes of reactive, oxygen-derived species. We focus primarily on transition metal mediated oxidations, outlining both advances over the past five years and current limitations of this approach. Computational methods are now being developed to probe transition states and the accompanying kinetic isotope effects. In particular, we describe the importance of using a full-frequency model to accurately predict the magnitudes as well as the temperature dependence of the isotope effects. Earlier studies have used a "cut-off model," which employs only a few isotopic vibrational modes, and such models tend to overestimate (18)O EIEs. Researchers in mechanistic biological inorganic chemistry would like to differentiate "inner-sphere" from "outer-sphere" reactivity of O(2), a designation that describes the extent of the bonding interaction between metal and oxygen in the transition state. Though this problem remains unsolved, we expect that this isotopic approach will help differentiate these processes. For example, comparisons of (18)O KIEs to (18)O EIEs provide benchmarks that allow us to calibrate computationally derived reaction coordinates. Once the physical origins of heavy atom isotope effects are better understood, researchers will be able to apply the competitive isotope fractionation technique to a wide range of pressing problems in small molecule chemistry and biochemistry.
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Affiliation(s)
- Justine P. Roth
- Department of Chemistry, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218
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42
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Lucas HR, Karlin KD. Copper-Carbon Bonds in Mechanistic and Structural Probing of Proteins as well as in Situations where Copper is a Catalytic or Receptor Site. METAL-CARBON BONDS IN ENZYMES AND COFACTORS 2009. [DOI: 10.1039/9781847559333-00295] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
While copper-carbon bonds are well appreciated in organometallic synthetic chemistry, such occurrences are less known in biological settings. By far, the greatest incidence of copper-carbon moieties is in bioinorganic research aimed at probing copper protein active site structure and mechanism; for example, carbon monoxide (CO) binding as a surrogate for O2. Using infrared (IR) spectroscopy, CO coordination to cuprous sites has proven to be an extremely useful tool for determining active site copper ligation (e.g., donor atom number and type). The coupled (hemocyanin, tyrosinase, catechol oxidase) and non-coupled (peptidylglycine α-hydroxylating monooxygenase, dopamine β-monooxygenase) binuclear copper proteins as well as the heme-copper oxidases (HCOs) have been studied extensively via this method. In addition, environmental changes within the vicinity of the active site have been determined based on shifts in the CO stretching frequencies, such as for copper amine oxidases, nitrite reductases and again in the binuclear proteins and HCOs. In many situations, spectroscopic monitoring has provided kinetic and thermodynamic data on CuI-CO formation and CO dissociation from copper(I); recently, processes occurring on a femtosecond timescale have been reported. Copper-cyano moieties have also been useful for obtaining insights into the active site structure and mechanisms of copper-zinc superoxide dismutase, azurin, nitrous oxide reductase, and multi-copper oxidases. Cyanide is a good ligand for both copper(I) and copper(II), therefore multiple physical-spectroscopic techniques can be applied. A more obvious occurrence of a “Cu-C” moiety was recently described for a CO dehydrogenase which contains a novel molybdenum-copper catalytic site. A bacterial copper chaperone (CusF) was recently established to have a novel d-π interaction comprised of copper(I) with the arene containing side-chain of a tryptophan amino acid residue. Meanwhile, good evidence exists that a plant receptor site (ETR1) utilizes copper(I) to sense ethylene, a growth hormone. A copper olfactory receptor has also been suggested. All of the above mentioned occurrences or uses of carbon-containing substrates and/or probes are reviewed and discussed within the framework of copper proteins and other relevant systems.
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Affiliation(s)
- Heather R. Lucas
- Department of Chemistry, The Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA
| | - Kenneth D. Karlin
- Department of Chemistry, The Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA
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Shepard EM, Okonski KM, Dooley DM. Kinetics and spectroscopic evidence that the Cu(I)-semiquinone intermediate reduces molecular oxygen in the oxidative half-reaction of Arthrobacter globiformis amine oxidase. Biochemistry 2009; 47:13907-20. [PMID: 19053231 DOI: 10.1021/bi8011516] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The role of copper during the reoxidation of substrate-reduced amine oxidases by O(2) has not yet been definitively established. Both outer-sphere and inner-sphere pathways for the reduction of O(2) to H(2)O(2) have been proposed. A key step in the inner-sphere mechanism is the reaction of O(2) directly with the Cu(I) center of a Cu(I)-semiquinone intermediate. To thoroughly examine this possibility, we have measured the spectral changes associated with single-turnover reoxidation by O(2) of substrate-reduced Arthrobacter globiformis amine oxidase (AGAO) under a wide range of conditions. We have previously demonstrated that the internal electron-transfer reaction [Cu(II)-TPQ(AMQ) --> Cu(I)-TPQ(SQ)] (where TPQ(AMQ) is the aminoquinol form of reduced TPQ and TPQ(SQ) is the semiquinone form) occurs at a rate that could permit the reaction of O(2) with both species to be observed on the stopped-flow time scale [Shepard, E. M., and Dooley, D. M. (2006) J. Biol. Inorg. Chem. 11, 1039-1048]. The transient absorption spectra observed for the reaction of O(2) with substrate-reduced AGAO provide compelling support for the reaction of the Cu(I)-TPQ(SQ) form. Further, global analysis of the kinetics and the transient absorption spectra are fully consistent with an inner-sphere reaction of the Cu(I)-semiquinone intermediate with O(2) and are inconsistent with an outer-sphere mechanism for the reaction of the reduced enzyme with O(2).
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Affiliation(s)
- Eric M Shepard
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
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