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Oya R, Ota K, Fuki M, Kobori Y, Higashi M, Nagao K, Ohmiya H. Biomimetic design of an α-ketoacylphosphonium-based light-activated oxygenation auxiliary. Chem Sci 2023; 14:10488-10493. [PMID: 37799983 PMCID: PMC10548508 DOI: 10.1039/d3sc03572g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 09/04/2023] [Indexed: 10/07/2023] Open
Abstract
The biomimetic design of a transition metal complex based on the iron(iv)-oxo porphyrin π-cation radical species in cytochrome P450 enzymes has been studied extensively. Herein, we translate the functions of this iron(iv)-oxo porphyrin π-cation radical species to an α-ketoacyl phosphonium species comprised of non-metal atoms and utilize it as a light-activated oxygenation auxiliary for ortho-selective oxygenation of anilines. Visible light irradiation converts the α-ketoacyl phosphonium species to the excited state, which acts as a transiently generated oxidant. The intramolecular nature of the process ensures high regioselectivity and chemoselectivity. The auxiliary is easily removable. A one-pot protocol is also described.
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Affiliation(s)
- Ryoto Oya
- Division of Pharmaceutical Sciences, Graduate School of Medical Sciences, Kanazawa University Kakuma-Machi Kanazawa 920-1192 Japan
| | - Kenji Ota
- Institute for Chemical Research, Kyoto University Gokasho, Uji Kyoto 611-0011 Japan
| | - Masaaki Fuki
- Molecular Photoscience Research Center, Department of Chemistry, Graduate School of Science, Kobe University Kobe 657-8501 Japan
| | - Yasuhiro Kobori
- Molecular Photoscience Research Center, Department of Chemistry, Graduate School of Science, Kobe University Kobe 657-8501 Japan
| | - Masahiro Higashi
- Department of Molecular Engineering, Graduate School of Engineering, Kyoto University Kyoto 615-8510 Japan
| | - Kazunori Nagao
- Institute for Chemical Research, Kyoto University Gokasho, Uji Kyoto 611-0011 Japan
| | - Hirohisa Ohmiya
- Institute for Chemical Research, Kyoto University Gokasho, Uji Kyoto 611-0011 Japan
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Rogers MS, Gordon AM, Rappe TM, Goodpaster JD, Lipscomb JD. Contrasting Mechanisms of Aromatic and Aryl-Methyl Substituent Hydroxylation by the Rieske Monooxygenase Salicylate 5-Hydroxylase. Biochemistry 2023; 62:507-523. [PMID: 36583545 PMCID: PMC9854337 DOI: 10.1021/acs.biochem.2c00610] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The hydroxylase component (S5HH) of salicylate-5-hydroxylase catalyzes C5 ring hydroxylation of salicylate but switches to methyl hydroxylation when a C5 methyl substituent is present. The use of 18O2 reveals that both aromatic and aryl-methyl hydroxylations result from monooxygenase chemistry. The functional unit of S5HH comprises a nonheme Fe(II) site located 12 Å across a subunit boundary from a one-electron reduced Rieske-type iron-sulfur cluster. Past studies determined that substrates bind near the Fe(II), followed by O2 binding to the iron to initiate catalysis. Stopped-flow-single-turnover reactions (STOs) demonstrated that the Rieske cluster transfers an electron to the iron site during catalysis. It is shown here that fluorine ring substituents decrease the rate constant for Rieske electron transfer, implying a prior reaction of an Fe(III)-superoxo intermediate with a substrate. We propose that the iron becomes fully oxidized in the resulting Fe(III)-peroxo-substrate-radical intermediate, allowing Rieske electron transfer to occur. STO using 5-CD3-salicylate-d8 occurs with an inverse kinetic isotope effect (KIE). In contrast, STO of a 1:1 mixture of unlabeled and 5-CD3-salicylate-d8 yields a normal product isotope effect. It is proposed that aromatic and aryl-methyl hydroxylation reactions both begin with the Fe(III)-superoxo reaction with a ring carbon, yielding the inverse KIE due to sp2 → sp3 carbon hybridization. After Rieske electron transfer, the resulting Fe(III)-peroxo-salicylate intermediate can continue to aromatic hydroxylation, whereas the equivalent aryl-methyl intermediate formation must be reversible to allow the substrate exchange necessary to yield a normal product isotope effect. The resulting Fe(III)-(hydro)peroxo intermediate may be reactive or evolve through a high-valent iron intermediate to complete the aryl-methyl hydroxylation.
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Affiliation(s)
- Melanie S. Rogers
- Department of Biochemistry, Molecular Biology, and Biophysics and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Adrian M. Gordon
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Todd M. Rappe
- Minnesota NMR Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Jason D. Goodpaster
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - John D. Lipscomb
- Department of Biochemistry, Molecular Biology, and Biophysics and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
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Su Q, Schittich AR, Jensen MM, Ng H, Smets BF. Role of Ammonia Oxidation in Organic Micropollutant Transformation during Wastewater Treatment: Insights from Molecular, Cellular, and Community Level Observations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:2173-2188. [PMID: 33543927 DOI: 10.1021/acs.est.0c06466] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Organic micropollutants (OMPs) are a threat to aquatic environments, and wastewater treatment plants may act as a source or a barrier of OMPs entering the environment. Understanding the fate of OMPs in wastewater treatment processes is needed to establish efficient OMP removal strategies. Enhanced OMP biotransformation has been documented during biological nitrogen removal and has been attributed to the cometabolic activity of ammonia-oxidizing bacteria (AOB) and, specifically, to the ammonia monooxygenase (AMO) enzyme. Yet, the exact mechanisms of OMP biotransformation are often unknown. This critical review aims to fundamentally and quantitatively evaluate the role of ammonia oxidation in OMP biotransformation during wastewater treatment processes. OMPs can be transformed by AOB via direct and indirect enzymatic reactions: AMO directly transforms OMPs primarily via hydroxylation, while biologically produced reactive nitrogen species (hydroxylamine (NH2OH), nitrite (NO2-), and nitric oxide (NO)) can chemically transform OMPs through nitration, hydroxylation, and deamination and can contribute significantly to the observed OMP transformations. OMPs containing alkyl, aliphatic hydroxyl, ether, and sulfide functional groups as well as substituted aromatic rings and aromatic primary amines can be biotransformed by AMO, while OMPs containing alkyl groups, phenols, secondary amines, and aromatic primary amines can undergo abiotic transformations mediated by reactive nitrogen species. Higher OMP biotransformation efficiencies and rates are obtained in AOB-dominant microbial communities, especially in autotrophic reactors performing nitrification or nitritation, than in non-AOB-dominant microbial communities. The biotransformations of OMPs in wastewater treatment systems can often be linked to ammonium (NH4+) removal following two central lines of evidence: (i) Similar transformation products (i.e., hydroxylated, nitrated, and desaminated TPs) are detected in wastewater treatment systems as in AOB pure cultures. (ii) Consistency in OMP biotransformation (rbio, μmol/g VSS/d) to NH4+ removal (rNH4+, mol/g VSS/d) rate ratios (rbio/rNH4+) is observed for individual OMPs across different systems with similar rNH4+ and AOB abundances. In this review, we conclude that AOB are the main drivers of OMP biotransformation during wastewater treatment processes. The importance of biologically driven abiotic OMP transformation is quantitatively assessed, and functional groups susceptible to transformations by AMO and reactive nitrogen species are systematically classified. This critical review will improve the prediction of OMP transformation and facilitate the design of efficient OMP removal strategies during wastewater treatment.
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Affiliation(s)
- Qingxian Su
- National University of Singapore Environmental Research Institute, 5A Engineering Drive 1, 117411 Singapore, Singapore
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - Anna-Ricarda Schittich
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - Marlene Mark Jensen
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
| | - Howyong Ng
- National University of Singapore Environmental Research Institute, 5A Engineering Drive 1, 117411 Singapore, Singapore
- Centre for Water Research, Department of Civil & Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, 117576 Singapore, Singapore
| | - Barth F Smets
- Department of Environmental Engineering, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark
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Qiao Z, Hu S, Wu Y, Sun R, Liu X, Chan J. Changes in the fluorescence intensity, degradability, and aromaticity of organic carbon in ammonium and phenanthrene-polluted aquatic ecosystems. RSC Adv 2021; 11:1066-1076. [PMID: 35423689 PMCID: PMC8693519 DOI: 10.1039/d0ra08655j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2020] [Accepted: 11/27/2020] [Indexed: 11/21/2022] Open
Abstract
Mixed cultures were established by a sediment to investigate the changes in organic carbon (C) in a combined ammonium and phenanthrene biotransformation process in aquatic ecosystems. The microorganisms in the sediment demonstrated significant ammonium-N and phenanthrene biotransformation capacity with removal efficiencies of 99.96% and 99.99%, respectively. The changes in the organic C characteristics were evaluated by the fluorescence intensity, degradability (humification index (HIX) and UV absorbance at 254 nm (A254)), aromaticity (specific UV absorbance at 254 nm (SUVA254) and fluorescence index (FI)). Compared with C2 (the second control), the lower values of fluorescence intensity (after the 15th d), HIX (after the 8th d), A254 (after the 11th d), and SUVA254 (after the 8th d) and the higher FI value (after the 8th d) in ammonium and phenanthrene-fed mixed cultures (N_PHE) suggest that aromatic structures and some condensed molecules were easier to break down in N_PHE. Similar results were obtained from Fourier transformation infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H NMR) spectra. Changes in organic C characteristics may be due to two key organisms Massilia and Azohydromonas. The biodiversity also suggested that the selective pressure of ammonium and phenanthrene is the decisive factor for changes in organic C characteristics. This study will shed light on theoretical insights into the interaction of N and aromatic compounds in aquatic ecosystems. Mixed cultures were established by a sediment to investigate the changes in organic carbon (C) in a combined ammonium and phenanthrene biotransformation process in aquatic ecosystems.![]()
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Affiliation(s)
- Zixia Qiao
- Department of Applied Chemistry
- Northwestern Polytechnical University
- Xi'an 710129
- China
| | - Sihai Hu
- Department of Applied Chemistry
- Northwestern Polytechnical University
- Xi'an 710129
- China
| | - Yaoguo Wu
- Department of Applied Chemistry
- Northwestern Polytechnical University
- Xi'an 710129
- China
| | - Ran Sun
- Department of Applied Chemistry
- Northwestern Polytechnical University
- Xi'an 710129
- China
| | - Xiaoyan Liu
- Department of Applied Chemistry
- Northwestern Polytechnical University
- Xi'an 710129
- China
| | - Jiangwei Chan
- Department of Applied Chemistry
- Northwestern Polytechnical University
- Xi'an 710129
- China
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Wright CL, Schatteman A, Crombie AT, Murrell JC, Lehtovirta-Morley LE. Inhibition of Ammonia Monooxygenase from Ammonia-Oxidizing Archaea by Linear and Aromatic Alkynes. Appl Environ Microbiol 2020; 86:e02388-19. [PMID: 32086308 PMCID: PMC7170481 DOI: 10.1128/aem.02388-19] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 02/15/2020] [Indexed: 01/20/2023] Open
Abstract
Ammonia monooxygenase (AMO) is a key nitrogen-transforming enzyme belonging to the same copper-dependent membrane monooxygenase family (CuMMO) as the particulate methane monooxygenase (pMMO). The AMO from ammonia-oxidizing archaea (AOA) is very divergent from both the AMO of ammonia-oxidizing bacteria (AOB) and the pMMO from methanotrophs, and little is known about the structure or substrate range of the archaeal AMO. This study compares inhibition by C2 to C8 linear 1-alkynes of AMO from two phylogenetically distinct strains of AOA, "Candidatus Nitrosocosmicus franklandus" C13 and "Candidatus Nitrosotalea sinensis" Nd2, with AMO from Nitrosomonas europaea and pMMO from Methylococcus capsulatus (Bath). An increased sensitivity of the archaeal AMO to short-chain-length alkynes (≤C5) appeared to be conserved across AOA lineages. Similarities in C2 to C8 alkyne inhibition profiles between AMO from AOA and pMMO from M. capsulatus suggested that the archaeal AMO has a narrower substrate range than N. europaea AMO. Inhibition of AMO from "Ca Nitrosocosmicus franklandus" and N. europaea by the aromatic alkyne phenylacetylene was also investigated. Kinetic data revealed that the mechanisms by which phenylacetylene inhibits "Ca Nitrosocosmicus franklandus" and N. europaea are different, indicating differences in the AMO active site between AOA and AOB. Phenylacetylene was found to be a specific and irreversible inhibitor of AMO from "Ca Nitrosocosmicus franklandus," and it does not compete with NH3 for binding at the active site.IMPORTANCE Archaeal and bacterial ammonia oxidizers (AOA and AOB, respectively) initiate nitrification by oxidizing ammonia to hydroxylamine, a reaction catalyzed by ammonia monooxygenase (AMO). AMO enzyme is difficult to purify in its active form, and its structure and biochemistry remain largely unexplored. The bacterial AMO and the closely related particulate methane monooxygenase (pMMO) have a broad range of hydrocarbon cooxidation substrates. This study provides insights into the AMO of previously unstudied archaeal genera, by comparing the response of the archaeal AMO, a bacterial AMO, and pMMO to inhibition by linear 1-alkynes and the aromatic alkyne, phenylacetylene. Reduced sensitivity to inhibition by larger alkynes suggests that the archaeal AMO has a narrower hydrocarbon substrate range than the bacterial AMO, as previously reported for other genera of AOA. Phenylacetylene inhibited the archaeal and bacterial AMOs at different thresholds and by different mechanisms of inhibition, highlighting structural differences between the two forms of monooxygenase.
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Affiliation(s)
- Chloë L Wright
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Arne Schatteman
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Andrew T Crombie
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - J Colin Murrell
- School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom
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6
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Adam SM, Wijeratne GB, Rogler PJ, Diaz DE, Quist DA, Liu JJ, Karlin KD. Synthetic Fe/Cu Complexes: Toward Understanding Heme-Copper Oxidase Structure and Function. Chem Rev 2018; 118:10840-11022. [PMID: 30372042 PMCID: PMC6360144 DOI: 10.1021/acs.chemrev.8b00074] [Citation(s) in RCA: 132] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Heme-copper oxidases (HCOs) are terminal enzymes on the mitochondrial or bacterial respiratory electron transport chain, which utilize a unique heterobinuclear active site to catalyze the 4H+/4e- reduction of dioxygen to water. This process involves a proton-coupled electron transfer (PCET) from a tyrosine (phenolic) residue and additional redox events coupled to transmembrane proton pumping and ATP synthesis. Given that HCOs are large, complex, membrane-bound enzymes, bioinspired synthetic model chemistry is a promising approach to better understand heme-Cu-mediated dioxygen reduction, including the details of proton and electron movements. This review encompasses important aspects of heme-O2 and copper-O2 (bio)chemistries as they relate to the design and interpretation of small molecule model systems and provides perspectives from fundamental coordination chemistry, which can be applied to the understanding of HCO activity. We focus on recent advancements from studies of heme-Cu models, evaluating experimental and computational results, which highlight important fundamental structure-function relationships. Finally, we provide an outlook for future potential contributions from synthetic inorganic chemistry and discuss their implications with relevance to biological O2-reduction.
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Affiliation(s)
- Suzanne M. Adam
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Gayan B. Wijeratne
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Patrick J. Rogler
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Daniel E. Diaz
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - David A. Quist
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Jeffrey J. Liu
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kenneth D. Karlin
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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7
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Asaka M, Fujii H. Participation of Electron Transfer Process in Rate-Limiting Step of Aromatic Hydroxylation Reactions by Compound I Models of Heme Enzymes. J Am Chem Soc 2016; 138:8048-51. [PMID: 27327623 DOI: 10.1021/jacs.6b03223] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Hydroxylation reactions of aromatic rings are key reactions in various biological and chemical processes. In spite of their significance, no consensus mechanism has been established. Here we performed Marcus plot analysis for aromatic hydroxylation reactions with oxoiron(IV) porphyrin π-cation radical complexes (compound I). Although many recent studies support the mechanism involving direct electrophilic attack of compound I, the slopes of the Marcus plots indicate a significant contribution of an electron transfer process in the rate-limiting step, leading us to propose a new reaction mechanism in which the electron transfer process between an aromatic compound and compound I is in equilibrium in a solvent cage and coupled with the subsequent bond formation process.
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Affiliation(s)
- Maaya Asaka
- Department of Chemistry, Graduate School of Humanities and Sciences, Nara Women's University , Kitauoyanishi, Nara 630-8506, Japan
| | - Hiroshi Fujii
- Department of Chemistry, Graduate School of Humanities and Sciences, Nara Women's University , Kitauoyanishi, Nara 630-8506, Japan
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Fernandez-Fontaina E, Gomes IB, Aga DS, Omil F, Lema JM, Carballa M. Biotransformation of pharmaceuticals under nitrification, nitratation and heterotrophic conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 541:1439-1447. [PMID: 26479917 DOI: 10.1016/j.scitotenv.2015.10.010] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 10/02/2015] [Accepted: 10/03/2015] [Indexed: 06/05/2023]
Abstract
The effect of nitrification, nitratation and heterotrophic conditions on the biotransformation of several pharmaceuticals in a highly enriched nitrifying activated sludge was evaluated in this study by selective activation of ammonia oxidizing bacteria (AOB), nitrite oxidizing bacteria (NOB) and heterotrophic bacteria. Nitrifiers displayed a noticeable capacity to process ibuprofen due to hydroxylation by ammonia monooxygenase (AMO) to produce 2-hydroxy-ibuprofen. Naproxen was also biotransformed under nitrifying conditions. On the other hand, heterotrophic bacteria present in the nitrifying activated sludge (NAS) biotransformed sulfamethoxazole. In contrast, both nitrifying and heterotrophic activities were ineffective against diclofenac, diazepam, carbamazepine and trimethoprim. Similar biotransformation rates of erythromycin, roxithromycin and fluoxetine were observed under all conditions tested. Overall, results from this study give more evidence on the role of the different microbial communities present in activated sludge reactors on the biological removal of pharmaceuticals.
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Affiliation(s)
- E Fernandez-Fontaina
- Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
| | - I B Gomes
- Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - D S Aga
- Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, NY 14260, United States
| | - F Omil
- Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - J M Lema
- Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
| | - M Carballa
- Department of Chemical Engineering, Institute of Technology, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain
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Banerjee S, Goyal S, Mazumdar S. Role of substituents on the reactivity and product selectivity in reactions of naphthalene derivatives catalyzed by the orphan thermostable cytochrome P450, CYP175A1. Bioorg Chem 2015; 62:94-105. [DOI: 10.1016/j.bioorg.2015.08.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Revised: 08/13/2015] [Accepted: 08/17/2015] [Indexed: 11/28/2022]
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10
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Wang X, Zhang T, Yang Q, Jiang S, Li B. Synthesis and Characterization of Bio-Inspired Diiron Complexes and Their Catalytic Activity for Direct Hydroxylation of Aromatic Compounds. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201402918] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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11
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Romero-Silva MJ, Méndez V, Agulló L, Seeger M. Genomic and functional analyses of the gentisate and protocatechuate ring-cleavage pathways and related 3-hydroxybenzoate and 4-hydroxybenzoate peripheral pathways in Burkholderia xenovorans LB400. PLoS One 2013; 8:e56038. [PMID: 23418504 PMCID: PMC3572157 DOI: 10.1371/journal.pone.0056038] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2012] [Accepted: 01/04/2013] [Indexed: 11/24/2022] Open
Abstract
In this study, the gentisate and protocatechuate pathways in Burkholderia xenovorans LB400 were analyzed by genomic and functional approaches, and their role in 3-hydroxybenzoate (3-HBA) and 4-hydroxybenzoate (4-HBA) degradation was proposed. The LB400 genome possesses two identical mhbRTDHI gene clusters encoding the gentisate pathway and one mhbM gene encoding a 3-HBA 6-hydroxylase that converts 3-HBA into gentisate. The pca genes encoding the protocatechuate pathway and the pobA gene encoding the 4-HBA 3-monooxygenase that oxidizes 4-HBA into protocatechuate are arranged in gene clusters and single genes mainly at the minor chromosome, but also at the major chromosome and the megaplasmid. Strain LB400 was able to grow on gentisate, protocatechuate, 3-HBA and 4-HBA. Transcriptional analyses showed that the mhbD gene encoding the gentisate 1,2-dioxygenase was expressed during growth on 3-HBA, 4-HBA and gentisate, whereas the pcaG gene encoding the protocatechuate 3,4-dioxygenase was expressed only during growth on 4-HBA and protocatechuate. The mhbM gene encoding the 3-HBA 6-hydroxylase was transcribed in strain LB400 during growth on HBAs, gentisate, protocatechuate and glucose. The pobA gene encoding the 4-HBA 3-monooxygenase was expressed during growth on HBAs and glucose. 3-HBA- and 4-HBA-grown LB400 cells showed gentisate 1,2-dioxygenase activity, whereas protocatechuate 3,4-dioxygenase activity was observed only in 4-HBA-grown cells. The mhbR gene encoding a MarR-type transcriptional regulator that probably regulates the expression of the MhbT transporter, and the pcaQ and pcaR genes encoding LysR-type transcriptional regulators that regulate pcaHG and pcaIJBDC genes, respectively, were transcribed during growth on both HBAs, gentisate, protocatechuate and glucose, suggesting a basal constitutive expression. The results indicate active gentisate, protocatechuate, 3-HBA and 4-HBA catabolic pathways in B. xenovorans LB400 and suggest that 3-HBA is channeled exclusively through the gentisate route, whereas 4-HBA is funneled into the protocatechuate central pathway and potentially into the gentisate pathway.
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Affiliation(s)
- María José Romero-Silva
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química and Center for Nanotechnology and Systems Biology, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Valentina Méndez
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química and Center for Nanotechnology and Systems Biology, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Loreine Agulló
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química and Center for Nanotechnology and Systems Biology, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Michael Seeger
- Laboratorio de Microbiología Molecular y Biotecnología Ambiental, Departamento de Química and Center for Nanotechnology and Systems Biology, Universidad Técnica Federico Santa María, Valparaíso, Chile
- * E-mail:
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Henne KR, Tran TB, VandenBrink BM, Rock DA, Aidasani DK, Subramanian R, Mason AK, Stresser DM, Teffera Y, Wong SG, Johnson MG, Chen X, Tonn GR, Wong BK. Sequential Metabolism of AMG 487, a Novel CXCR3 Antagonist, Results in Formation of Quinone Reactive Metabolites That Covalently Modify CYP3A4 Cys239 and Cause Time-Dependent Inhibition of the Enzyme. Drug Metab Dispos 2012; 40:1429-40. [DOI: 10.1124/dmd.112.045708] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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13
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Li JL, Zhang X, Huang XR. Mechanism of benzenehydroxylation by high-valent bare FeivO2+: explicit electronic structure analysis. Phys Chem Chem Phys 2012; 14:246-56. [DOI: 10.1039/c1cp22187f] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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14
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Hong H, Caceres-Cortes J, Su H, Huang X, Roongta V, Bonacorsi S, Hong Y, Tian Y, Iyer RA, Humphreys WG, Christopher LJ. Mechanistic Studies on a P450-Mediated Rearrangement of BMS-690514: Conversion of a Pyrrolotriazine to a Hydroxypyridotriazine. Chem Res Toxicol 2010; 24:125-34. [DOI: 10.1021/tx100337s] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Haizheng Hong
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
| | - Janet Caceres-Cortes
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
| | - Hong Su
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
| | - Xiaohua Huang
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
| | - Vikram Roongta
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
| | - Samuel Bonacorsi
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
| | - Yang Hong
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
| | - Yuan Tian
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
| | - Ramaswamy A. Iyer
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
| | - W. Griffith Humphreys
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
| | - Lisa J. Christopher
- Departments of Pharmaceutical Candidate Optimization and Radiochemistry, Bristol-Myers Squibb Research, Princeton, New Jersey 08543, United States
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15
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De Gusseme B, Pycke B, Hennebel T, Marcoen A, Vlaeminck SE, Noppe H, Boon N, Verstraete W. Biological removal of 17alpha-ethinylestradiol by a nitrifier enrichment culture in a membrane bioreactor. WATER RESEARCH 2009; 43:2493-2503. [PMID: 19324389 DOI: 10.1016/j.watres.2009.02.028] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2008] [Revised: 02/18/2009] [Accepted: 02/19/2009] [Indexed: 05/27/2023]
Abstract
Increasing concern about the fate of 17alpha-ethinylestradiol (EE2) in the environment stimulates the search for alternative methods for wastewater treatment plant (WWTP) effluent polishing. The aim of this study was to establish an innovative and effective biological removal technique for EE2 by means of a nitrifier enrichment culture (NEC) applied in a membrane bioreactor (MBR). In batch incubation tests, the microbial consortium was able to remove EE2 from both a synthetic minimal medium and WWTP effluent. A maximum EE2 removal rate of 9.0 microg EE2 g(-1)biomass-VSS h(-1) was achieved (>94% removal efficiency). Incubation of the heterotrophic bacteria isolated from the NEC did not result in a significant EE2 removal, indicating the importance of nitrification as driving force in the mechanism. Application of the NEC in a MBR to treat a synthetic influent with an EE2 concentration of 83 ng EE2 L(-1) resulted in a removal efficiency of 99% (loading rates up to 208 ng EE2 L(-1)d(-1); membrane flux rate: 6.9 L m(-2) h(-1)). Simultaneously, complete nitrification was achieved at an optimal ammonium influent concentration of 1.0 mg NH(4)(+)-N L(-1). This minimal NH(4)(+)-N input is very advantageous for effluent polishing since the concomitant effluent nitrate concentrations will be low as well and it offers opportunities for the nitrifying MBR as a promising add-on technology for WWTP effluent polishing.
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Affiliation(s)
- Bart De Gusseme
- Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Gent, Belgium
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16
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Abstract
Ammonia oxidizing bacteria extract energy for growth from the oxidation of ammonia to nitrite. Ammonia monooxygenase, which initiates ammonia oxidation, remains enigmatic given the lack of purified preparations. Genetic and biochemical studies support a model for the enzyme consisting of three subunits and metal centers of copper and iron. Knowledge of hydroxylamine oxidoreductase, which oxidizes hydroxylamine formed by ammonia monooxygenase to nitrite, is informed by a crystal structure and detailed spectroscopic and catalytic studies. Other inorganic nitrogen compounds, including NO, N2O, NO2, and N2 can be consumed and/or produced by ammonia-oxidizing bacteria. NO and N2O can be produced as byproducts of hydroxylamine oxidation or through nitrite reduction. NO2 can serve as an alternative oxidant in place of O2 in some ammonia-oxidizing strains. Our knowledge of the diversity of inorganic N metabolism by ammonia-oxidizing bacteria continues to grow. Nonetheless, many questions remain regarding the enzymes and genes involved in these processes and the role of these pathways in ammonia oxidizers.
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Affiliation(s)
- Daniel J Arp
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.
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17
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Boyd DR, Sharma ND, Harrison JS, Malone JF, McRoberts WC, Hamilton JTG, Harper DB. Enzyme-catalysed synthesis and reactions of benzene oxide/oxepine derivatives of methyl benzoates. Org Biomol Chem 2008; 6:1251-9. [DOI: 10.1039/b718375e] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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18
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Kang MJ, Song WJ, Han AR, Choi YS, Jang HG, Nam W. Mechanistic Insight into the Aromatic Hydroxylation by High-Valent Iron(IV)-oxo Porphyrin π-Cation Radical Complexes. J Org Chem 2007; 72:6301-4. [PMID: 17622172 DOI: 10.1021/jo070557y] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mechanistic studies of the aromatic hydroxylation by high-valent iron(IV)-oxo porphyrin pi-cation radicals revealed that the aromatic oxidation involves an initial electrophilic attack on the pi-system of the aromatic ring to produce a tetrahedral radical or cationic sigma-complex. The mechanism was proposed on the basis of experimental results such as a large negative Hammett rho value and an inverse kinetic isotope effect. By carrying out isotope labeling studies, the oxygen in oxygenated products was found to derive from the iron-oxo porphyrin intermediates.
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Affiliation(s)
- Min-Jung Kang
- Department of Chemistry, Division of Nano Sciences, and Center for Biomimetic Systems, Ewha Womans University, Seoul 120-750, Korea
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19
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de Visser SP, Oh K, Han AR, Nam W. Combined experimental and theoretical study on aromatic hydroxylation by mononuclear nonheme iron(IV)-oxo complexes. Inorg Chem 2007; 46:4632-41. [PMID: 17444641 DOI: 10.1021/ic700462h] [Citation(s) in RCA: 155] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The hydroxylation of aromatic compounds by mononuclear nonheme iron(IV)-oxo complexes, [FeIV(Bn-tpen)(O)]2+ (Bn-tpen=N-benzyl-N,N',N'-tris(2-pyridylmethyl)ethane-1,2-diamine) and [FeIV(N4Py)(O)]2+ (N4Py=N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine), has been investigated by a combined experimental and theoretical approach. In the experimental work, we have performed kinetic studies of the oxidation of anthracene with nonheme iron(IV)-oxo complexes generated in situ, thereby determining kinetic and thermodynamic parameters, a Hammett rho value, and a kinetic isotope effect (KIE) value. A large negative Hammett rho value of -3.9 and an inverse KIE value of 0.9 indicate that the iron-oxo group attacks the aromatic ring via an electrophilic pathway. By carrying out isotope labeling experiments, the oxygen in oxygenated products was found to derive from the nonheme iron(IV)-oxo species. In the theoretical work, we have conducted density functional theory (DFT) calculations on the hydroxylation of benzene by [FeIV(N4Py)(O)]2+. The calculations show that the reaction proceeds via two-state reactivity patterns on competing triplet and quintet spin states via an initial rate determining electrophilic substitution step. In analogy to heme iron(IV)-oxo catalysts, the ligand is noninnocent and actively participates in the reaction mechanism by reshuttling a proton from the ipso position to the oxo group. Calculated kinetic isotope effects of C6H6 versus C6D6 confirm an inverse isotope effect for the electrophilic substitution pathway. Based on the experimental and theoretical results, we have concluded that the aromatic ring oxidation by mononuclear nonheme iron(IV)-oxo complexes does not occur via a hydrogen atom abstraction mechanism but involves an initial electrophilic attack on the pi-system of the aromatic ring to produce a tetrahedral radical or cationic sigma-complex.
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Affiliation(s)
- Sam P de Visser
- Department of Chemistry, Division of Nano Sciences, and Center for Biomimetic Systems, Ewha Womans University, Seoul 120-750, Korea.
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20
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Zepeda A, Texier AC, Razo-Flores E, Gomez J. Kinetic and metabolic study of benzene, toluene and m-xylene in nitrifying batch cultures. WATER RESEARCH 2006; 40:1643-9. [PMID: 16603220 DOI: 10.1016/j.watres.2006.02.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2005] [Revised: 01/11/2006] [Accepted: 02/03/2006] [Indexed: 05/08/2023]
Abstract
The effect of benzene, toluene, and m-xylene (BTX) compounds on the nitrifying activity of a sludge produced in steady-state nitrification was evaluated in batch cultures. Benzene and m-xylene at 10 mg C/L decreased ammonium consumption efficiency by 57% and 26%, respectively, whereas toluene did not affect the ammonium oxidation process. The consumed NH4+-N was totally oxidized to NO3- -N. There was no significant effect at 5 mg C/L of each aromatic compound. BTX (5-20mg C/L) induced a significant decrease in the values for specific rates of NH4+ -N consumption (76-99%) and NO3- -N production (45-98%). At 10 mg C/L of BTX compounds, the inhibition order on nitrate production was: benzene > m-xylene > toluene while at 20 mg C/L, the sequence changed to m-xylene > toluene > benzene for both nitrification inhibition and BTX compounds persistence. At 5 mg C/L of BTX compounds, there was no toxic effect on the sludge whereas from 10 to 50 mgC/L, bacteria did not totally recover their nitrifying activity. At a concentration of 5 mg C/L, toluene was first oxidized to benzyl alcohol, which was later oxidized to butyrate while m-xylene was oxidized to acetate and butyrate.
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Affiliation(s)
- A Zepeda
- Universidad Autónoma Metropolitana-Iztapalapa, Div. CBS, Departamento de Biotecnología. Av. San Rafael Atlixco 186, Col. Vicentina, C.P. 09340, México
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21
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Lucchese B, Humphreys KJ, Lee DH, Incarvito CD, Sommer RD, Rheingold AL, Karlin KD. Mono-, Bi-, and Trinuclear CuII-Cl Containing Products Based on the Tris(2-pyridylmethyl)amine Chelate Derived from Copper(I) Complex Dechlorination Reactions of Chloroform. Inorg Chem 2004; 43:5987-98. [PMID: 15360248 DOI: 10.1021/ic0497477] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The ligand TMPA (tris(2-pyridylmethyl)amine) and its copper complexes have played a prominent role in recent (bio)inorganic chemistry studies; the copper(I) complex [CuI(TMPA)(CH3CN)]+ possesses an extensive dioxygen reactivity, and it is also known to effect the reductive dechlorination of substrates such as dichloromethane and benzyl and allyl chlorides. In this report, we describe a set of new analogues of TMPA, ligand 6TMPAOH, binucleating Iso-DO, and trinucleating SYMM. Copper(I) complexes with these ligands and a previously described binucleating ligand DO react with chloroform, resulting in reductive dechlorination and production of [CuIIx(L)Clx]x+ (x = 1, 2, or 3). X-ray crystal structures of [CuII(6TMPAOH)Cl]PF6, [CuII2(Iso-DO)Cl2](PF6)2, [CuII2(DO)Cl2](PF6)2, and [Cu3(SYMM)Cl3](PF6)3 are presented, and the compounds are also characterized by UV-vis and EPR spectroscopies as well as cyclic voltammetry. The steric influence of a pyridyl 6-substituent (in the complexes with 6TMPAOH, Iso-DO, and SYMM) on the solid state and solution structures and redox potentials are compared and contrasted to those chlorocopper(II) complexes with a pyridyl 5'-substituent (in [CuII2(DO)Cl2](PF6)2 and in [CuII(TMPA)Cl]+). Some insights into the reductive dechlorination process have been obtained by using 2H NMR spectroscopy in following the reaction of [Cu2(Iso-DO)(CH3CN)2](PF6)2 with CDCl3, in the presence or absence of a radical trap, 2,4-di-tert-butylphenol.
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Affiliation(s)
- Baldo Lucchese
- Department of Chemistry, The Johns Hopkins University, 3400 N. Charles Street, Baltimore, Maryland 21218, USA
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22
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Meunier B, de Visser SP, Shaik S. Mechanism of Oxidation Reactions Catalyzed by Cytochrome P450 Enzymes. Chem Rev 2004; 104:3947-80. [PMID: 15352783 DOI: 10.1021/cr020443g] [Citation(s) in RCA: 1711] [Impact Index Per Article: 85.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Bernard Meunier
- Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse Cedex 4, France.
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23
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24
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Fairley DJ, Boyd DR, Sharma ND, Allen CCR, Morgan P, Larkin MJ. Aerobic metabolism of 4-hydroxybenzoic acid in Archaea via an unusual pathway involving an intramolecular migration (NIH shift). Appl Environ Microbiol 2002; 68:6246-55. [PMID: 12450849 PMCID: PMC134420 DOI: 10.1128/aem.68.12.6246-6255.2002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A novel haloarchaeal strain, Haloarcula sp. strain D1, grew aerobically on 4-hydroxybenzoic acid (4HBA) as a sole carbon and energy source and is the first member of the domain Archaea reported to do so. Unusually, D1 metabolized 4HBA via gentisic acid rather than via protocatechuic acid, hydroquinone, or catechol. Gentisate was detected in 4HBA-grown cultures, and gentisate 1,2-dioxygenase activity was induced in 4HBA-grown cells. Stoichiometric accumulation of gentisate from 4HBA was demonstrated in 4HBA-grown cell suspensions containing 2,2'-dipyridyl (which strongly inhibits gentisate 1,2-dioxygenase). To establish whether initial 1-hydroxylation of 4HBA with concomitant 1,2-carboxyl group migration to yield gentisate occurred, 2,6-dideutero-4HBA was synthesized and used as a substrate. Deuterated gentisate was recovered from cell suspensions and identified as 3-deutero-gentisate, using gas chromatography-mass spectrometry and proton nuclear magnetic resonance spectroscopy. This structural isomer would be expected only if a 1,2-carboxyl group migration had taken place, and it provides compelling evidence that the 4HBA pathway in Haloarcula sp. strain D1 involves a hydroxylation-induced intramolecular migration. To our knowledge, this is the first report of a pathway which involves such a transformation (called an NIH shift) in the domain Archaea.
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Affiliation(s)
- D J Fairley
- Queen's University Environmental Science and Technology Research Centre, The Queen's University of Belfast, Northern Ireland.
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25
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Mutch PJ, Dear GJ, Ismail IM. Formation of a defluorinated metabolite of a quinoxaline antiviral drug catalysed by human cytochrome P450 1A2. J Pharm Pharmacol 2001; 53:403-8. [PMID: 11291757 DOI: 10.1211/0022357011775479] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The in-vitro metabolism of GW420867X ((S)-2-ethyl-7-fluoro-3-oxo-3, 4-dihydro-2H-quinoxaline-1-carboxylic acid isopropyl ester), a quinoxaline drug for the potential treatment of HIV, has been studied with singly expressed human cytochromes P450 (CYP 450). No biotransformation of [14C]GW420867X was evident in the presence of any of the CYP 450 isoforms, with the exception of CYP 450 1A2, where a single metabolite was observed in the HPLC radiochromatograms of enzyme incubations with the test compound. The structure of this metabolite was determined by nuclear magnetic resonance spectroscopy and mass spectrometry, and was shown to correspond to the replacement of the aromatic fluorine of GW420867X with a hydroxyl group. Thus, it appeared that CYP 450 1A2 catalysed the specific defluorination of GW420867X, presumably during formation of an arene oxide intermediate during aromatic hydroxylation.
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Affiliation(s)
- P J Mutch
- Division of Bioanalysis and Drug Metabolism, Glaxo Wellcome Research and Development, Hertfordshire, UK
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26
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Lontoh S, DiSpirito AA, Krema CL, Whittaker MR, Hooper AB, Semrau JD. Differential inhibition in vivo of ammonia monooxygenase, soluble methane monooxygenase and membrane-associated methane monoxygenase by phenylacetylene. Environ Microbiol 2000; 2:485-94. [PMID: 11233157 DOI: 10.1046/j.1462-2920.2000.00130.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Phenylacetylene was investigated as a differential inhibitor of ammonia monooxygenase (AMO), soluble methane monooxygenase (sMMO) and membrane-associated or particulate methane monooxygenase (pMMO) in vivo. At phenylacetylene concentrations > 1 microM, whole-cell AMO activity in Nitrosomonas europaea was completely inhibited. Phenylacetylene concentrations above 100 microM inhibited more than 90% of sMMO activity in Methylococcus capsulatus Bath and Methylosinus trichosporium OB3b. In contrast, activity of pMMO in M. trichosporium OB3b, M. capsulatus Bath, Methylomicrobium album BG8, Methylobacter marinus A45 and Methylomonas strain MN was still measurable at phenylacetylene concentrations up to 1,000 microM. AMO of Nitrosococcus oceanus has more sequence similarity to pMMO than to AMO of N. europaea. Correspondingly, AMO in N. oceanus was also measurable in the presence of 1,000 microM phenylacetylene. Measurement of oxygen uptake indicated that phenylacetylene acted as a specific and mechanistic-based inhibitor of whole-cell sMMO activity; inactivation of sMMO was irreversible, time dependent, first order and required catalytic turnover. Corresponding measurement of oxygen uptake in whole cells of methanotrophs expressing pMMO showed that pMMO activity was inhibited by phenylacetylene, but only if methane was already being oxidized, and then only at much higher concentrations of phenylacetylene and at lower rates compared with sMMO. As phenylacetylene has a high solubility and low volatility, it may prove to be useful for monitoring methanotrophic and nitrifying activity as well as identifying the form of MMO predominantly expressed in situ.
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Affiliation(s)
- S Lontoh
- Department of Civil and Environmental Engineering, The University of Michigan, Ann Arbor 48109-2125, USA
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27
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Hartmann S, Hultschig C, Eisenreich W, Fuchs G, Bacher A, Ghisla S. NIH shift in flavin-dependent monooxygenation: mechanistic studies with 2-aminobenzoyl-CoA monooxygenase/reductase. Proc Natl Acad Sci U S A 1999; 96:7831-6. [PMID: 10393907 PMCID: PMC22147 DOI: 10.1073/pnas.96.14.7831] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The flavoprotein 2-aminobenzoyl-CoA monooxygenase/reductase from the eubacterium Azoarcus evansii catalyzes the dearomatization of 2-aminobenzoyl-CoA. The reaction consists in an O2-dependent monooxygenation at the benzene position 5, which is followed immediately by an NADH-dependent hydrogenation of the intermediate at the same catalytic locus. The reaction was studied by 1H, 2H, and 13C NMR spectroscopy of the products. The main product was characterized as 5-oxo-2-aminocyclohex-1-ene-1-carboxyl-CoA by two-dimensional NMR spectroscopy. Thus, [5-2H]2-aminobenzoyl-CoA was converted into [6-2H]5-oxo-2-aminocyclohex-1-ene-1-carboxyl-CoA, indicating a 5 --> 6 shift of the [5-2H] label. Label from NAD2H was transferred to the 3 position of the cyclic eneamine, whereas label from solvent D2O was incorporated into the 4 and the 6 positions of 5-oxo-2-aminocyclohex-1-ene-1-carboxyl-CoA. The labeling pattern is compatible with the monooxygenation proceeding via what is formally an NIH shift, yielding 5-oxo-2-aminocyclohex-1, 3-diene-1-carboxyl-CoA as a protein-bound intermediate. It is suggested that this shift in flavin-dependent monooxygenation may have general validity.
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Affiliation(s)
- S Hartmann
- Fakultät Biologie, Universität Konstanz, P.O. Box 5560-M644, D-78457 Konstanz, Germany
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28
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Dean AM, Dean FM. Carbocations in the synthesis of prostaglandins by the cyclooxygenase of PGH synthase? A radical departure! Protein Sci 1999; 8:1087-98. [PMID: 10338019 PMCID: PMC2144324 DOI: 10.1110/ps.8.5.1087] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Evidence already available is used to demonstrate that although prostaglandin G/H synthase hydroxylates arachidonic acid through radical intermediates, it effects cyclizations through a carbocation center at C-10. This is produced following migration of H to the initial radical at C-13 and a 1epsilon oxidation. Under orbital symmetry control, the cyclizations can give only the ring size and trans stereochemistry actually observed. After cyclization, the H-shift reverses to take the sequence back into current radical theory for hydroxylation at C-15. Thus 10,10-difluoroarachidonic acid cannot be cyclized, although it can be hydroxylated. Acetylation of Ser516 in the isoform synthase-2 is considered to oppose carbocation formation and/or H-migration and so prevent cyclizations while permitting hydroxylations; the associated inversion of chirality at C-15 can then readily be accommodated without the change in conformation required by other schemes. Suicide inhibition occurs when carbocations form stable bonds upon (thermal) contact with adjacent heteroatoms, etc. Because the cyclooxygenase and peroxidase functions operate simultaneously through the same heme, phenol acts as reducing cosubstrate for the cyclooxygenase, thus enabling it to promote PGG2 production and protect the enzyme from oxidative destruction.
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Affiliation(s)
- A M Dean
- Biological Process Technology Institute and Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul 55108-6106, USA.
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29
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Keener WK, Russell SA, Arp DJ. Kinetic characterization of the inactivation of ammonia monooxygenase in Nitrosomonas europaea by alkyne, aniline and cyclopropane derivatives. BIOCHIMICA ET BIOPHYSICA ACTA 1998; 1388:373-85. [PMID: 9858770 DOI: 10.1016/s0167-4838(98)00188-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The kinetic mechanisms of seven inactivators of ammonia oxidation activity in cells of the nitrifying bacterium, Nitrosomonas europaea were investigated. The effects of the inactivators were specific for ammonia monooxygenase (AMO) which oxidizes ammonia to hydroxylamine. The aniline derivatives, 1,3-phenylenediamine and p-anisidine, were potent inactivators of AMO while other derivatives were ineffective as inactivators. Two cyclopropane derivatives, 1, 2-dimethylcyclopropane and cyclopropyl bromide, were inactivators while cyclopropane was not an inactivator. The mechanisms of three alkynes, 1-hexyne, 3-hexyne, and acetylene, were also examined. For all seven compounds, the inactivation of AMO was irreversible, time-dependent, first-order, and dependent on catalytic turnover. Saturation of the rate of inactivation was indicated for p-anisidine (kinact=2.85 min-1; KI=1.0 mM) and cyclopropyl bromide (kinact=4.4 min-1; KI=97 microM), but not for any of the remaining five inactivators, including acetylene. Ammonia slowed the rate of inactivation for acetylene and cyclopropyl bromide, but enhanced the rate of inactivation for the remaining inactivators. All seven compounds appear to be mechanism-based inactivators of AMO.
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Affiliation(s)
- W K Keener
- Laboratory for Nitrogen Fixation Research, Department of Botany and Plant Pathology, Oregon State University, 2082 Cordley, Corvallis, OR 97331, USA
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30
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Song R, Sorokin A, Bernadou J, Meunier B. Metalloporphyrin-Catalyzed Oxidation of 2-Methylnaphthalene to Vitamin K(3) and 6-Methyl-1,4-naphthoquinone by Potassium Monopersulfate in Aqueous Solution. J Org Chem 1997; 62:673-678. [PMID: 11671463 DOI: 10.1021/jo961421v] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The metalloporphyrin-catalyzed oxidation of 2-methynaphthalene (1) by potassium monopersulfate produced mainly two naphthoquinones: 2-methyl-1,4-naphthoquinone (2) (menadione or vitamin K(3)) and 6-methyl-1,4-naphthoquinone (3). In aqueous solution and at room temperature in the presence of 5 mol % of the water-soluble metalloporphyrins MnTPPS or FeTMPS, 2-methylnaphthalene was quantitatively oxidized to quinones 2 and 3. Based on experiments performed in(18)O-labeled water and according to the "redox tautomerism" mechanism previously described for such catalysts, the oxidation to quinones is proposed to be mainly due to a cytochrome P-450-type oxygenation reaction (oxygen atom transfer), rather than a peroxidase-type oxidation (electron transfer).
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Affiliation(s)
- Rita Song
- Laboratoire de Chimie de Coordination du CNRS, 205 route de Narbonne, 31077 Toulouse cedex 4, France
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31
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Affiliation(s)
- Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305
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