1
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Takeda H, Shimba K, Horitani M, Kimura T, Nomura T, Kubo M, Shiro Y, Tosha T. Trapping of a Mononitrosyl Nonheme Intermediate of Nitric Oxide Reductase by Cryo-Photolysis of Caged Nitric Oxide. J Phys Chem B 2023; 127:846-854. [PMID: 36602896 DOI: 10.1021/acs.jpcb.2c05852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Characterization of short-lived reaction intermediates is essential for elucidating the mechanism of the reaction catalyzed by metalloenzymes. Here, we demonstrated that the photolysis of a caged compound under cryogenic temperature followed by thermal annealing is an invaluable technique for trapping of short-lived reaction intermediates of metalloenzymes through the study of membrane-integrated nitric oxide reductase (NOR) that catalyzes reductive coupling of two NO molecules to N2O at its heme/nonheme FeB binuclear center. Although NO produced by the photolysis of caged NO did not react with NOR under cryogenic temperature, annealing to ∼160 K allowed NO to diffuse and react with NOR, which was evident from the appearance of EPR signals assignable to the S = 3/2 state. This indicates that the nonheme FeB-NO species can be trapped as the intermediate. Time-resolved IR spectroscopy with the use of the photolysis of caged NO as a reaction trigger showed that the intermediate formed at 10 μs gave the NO stretching frequency at 1683 cm-1 typical of nonheme Fe-NO, confirming that the combination of the cryo-photolysis of caged NO and annealing enabled us to trap the reaction intermediate. Thus, the cryo-photolysis of the caged compound has great potential for the characterization of short-lived reaction intermediates.
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Affiliation(s)
- Hanae Takeda
- Graduate School of Life Science, University of Hyogo, Ako, Hyogo 678-1297, Japan.,RIKEN SPring-8 center, Sayo, Hyogo 679-5148, Japan
| | - Kanji Shimba
- Graduate School of Life Science, University of Hyogo, Ako, Hyogo 678-1297, Japan.,RIKEN SPring-8 center, Sayo, Hyogo 679-5148, Japan
| | - Masaki Horitani
- Department of Applied Biochemistry & Food Science, Saga University, Saga 840-8502, Japan.,The United Graduate School of Agricultural Science, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan
| | - Tetsunari Kimura
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe 657-8501, Japan
| | - Takashi Nomura
- Graduate School of Life Science, University of Hyogo, Ako, Hyogo 678-1297, Japan
| | - Minoru Kubo
- Graduate School of Life Science, University of Hyogo, Ako, Hyogo 678-1297, Japan
| | - Yoshitsugu Shiro
- Graduate School of Life Science, University of Hyogo, Ako, Hyogo 678-1297, Japan
| | - Takehiko Tosha
- Graduate School of Life Science, University of Hyogo, Ako, Hyogo 678-1297, Japan.,RIKEN SPring-8 center, Sayo, Hyogo 679-5148, Japan
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2
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Awakawa T, Mori T, Ushimaru R, Abe I. Structure-based engineering of α-ketoglutarate dependent oxygenases in fungal meroterpenoid biosynthesis. Nat Prod Rep 2023; 40:46-61. [PMID: 35642933 DOI: 10.1039/d2np00014h] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Non-heme iron- and α-ketoglutarate-dependent oxygenases (αKG OXs) are key enzymes that play a major role in diversifying the structure of fungal meroterpenoids. They activate a specific C-H bond of the substrate to first generate radical species, which is usually followed by oxygen rebound to produce cannonical hydroxylated products. However, in some cases remarkable chemistry induces dramatic structural changes in the molecular scaffolds, depending on the stereoelectronic characters of the substrate/intermediates and the resulting conformational changes/movements of the active site of the enzyme. Their molecular bases have been extensively investigated by crystallographic structural analyses and structure-based mutagenesis, which revealed intimate structural details of the enzyme reactions. This information facilitates the manipulation of the enzyme reactions to create unnatural, novel molecules for drug discovery. This review summarizes recent progress in the structure-based engineering of αKG OX enzymes, involved in the biosynthesis of polyketide-derived fungal meroterpenoids. The literature published from 2016 through February 2022 is reviewed.
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Affiliation(s)
- Takayoshi Awakawa
- Graduate School of Pharmaceutical Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan. .,Collaborative Research Institute for Innovative Microbiology, the University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takahiro Mori
- Graduate School of Pharmaceutical Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan. .,Collaborative Research Institute for Innovative Microbiology, the University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.,PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Richiro Ushimaru
- Graduate School of Pharmaceutical Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan. .,Collaborative Research Institute for Innovative Microbiology, the University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.,ACT-X, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Ikuro Abe
- Graduate School of Pharmaceutical Sciences, the University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan. .,Collaborative Research Institute for Innovative Microbiology, the University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan
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3
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Rabe P, Walla CC, Goodyear NK, Welsh J, Southwart R, Clifton I, Linyard JDS, Tumber A, Claridge TDW, Myers WK, Schofield CJ. Spectroscopic studies reveal details of substrate-induced conformational changes distant from the active site in isopenicillin N synthase. J Biol Chem 2022; 298:102249. [PMID: 35835215 PMCID: PMC9403350 DOI: 10.1016/j.jbc.2022.102249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 07/06/2022] [Accepted: 07/07/2022] [Indexed: 11/06/2022] Open
Abstract
Isopenicillin N synthase (IPNS) catalyzes formation of the β-lactam and thiazolidine rings of isopenicillin N from its linear tripeptide l-δ-(α-aminoadipoyl)-l-cysteinyl-d-valine (ACV) substrate in an iron- and dioxygen (O2)-dependent four-electron oxidation without precedent in current synthetic chemistry. Recent X-ray free-electron laser studies including time-resolved serial femtosecond crystallography show that binding of O2 to the IPNS–Fe(II)–ACV complex induces unexpected conformational changes in α-helices on the surface of IPNS, in particular in α3 and α10. However, how substrate binding leads to conformational changes away from the active site is unknown. Here, using detailed 19F NMR and electron paramagnetic resonance experiments with labeled IPNS variants, we investigated motions in α3 and α10 induced by binding of ferrous iron, ACV, and the O2 analog nitric oxide, using the less mobile α6 for comparison. 19F NMR studies were carried out on singly and doubly labeled α3, α6, and α10 variants at different temperatures. In addition, double electron–electron resonance electron paramagnetic resonance analysis was carried out on doubly spin-labeled variants. The combined spectroscopic and crystallographic results reveal that substantial conformational changes in regions of IPNS including α3 and α10 are induced by binding of ACV and nitric oxide. Since IPNS is a member of the structural superfamily of 2-oxoglutarate-dependent oxygenases and related enzymes, related conformational changes may be of general importance in nonheme oxygenase catalysis.
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Affiliation(s)
- Patrick Rabe
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom.
| | - Carla C Walla
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Noelle K Goodyear
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Jordan Welsh
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom; Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, UK
| | - Rebecca Southwart
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Ian Clifton
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - James D S Linyard
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Anthony Tumber
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - Tim D W Claridge
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom
| | - William K Myers
- Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, UK.
| | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, United Kingdom.
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4
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Li X, Awakawa T, Mori T, Ling M, Hu D, Wu B, Abe I. Heterodimeric Non-heme Iron Enzymes in Fungal Meroterpenoid Biosynthesis. J Am Chem Soc 2021; 143:21425-21432. [PMID: 34881885 DOI: 10.1021/jacs.1c11548] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Talaromyolides (1-6) are a group of unusual 6/6/6/6/6/6 hexacyclic meroterpenoids with (3R)-6-hydroxymellein and 4,5-seco-drimane substructures, isolated from the marine fungus Talaromyces purpureogenus. We have identified the biosynthetic gene cluster tlxA-J by heterologous expression in Aspergillus, in vitro enzyme assays, and CRISPR-Cas9-based gene inactivation. Remarkably, the heterodimer of non-heme iron (NHI) enzymes, TlxJ-TlxI, catalyzes three steps of oxidation including a key reaction, hydroxylation at C-5 and C-9 of 12, the intermediate with 3-ketohydroxydrimane scaffold, to facilitate a retro-aldol reaction, leading to the construction of the 4,5-secodrimane skeleton and characteristic ketal scaffold of 1-6. The products of TlxJ-TlxI, 1 and 4, were further hydroxylated at C-4'β by another NHI heterodimer, TlxA-TlxC, and acetylated by TlxB to yield the final products, 3 and 6. The X-ray structural analysis coupled with site-directed mutagenesis provided insights into the heterodimer TlxJ-TlxI formation and its catalysis. This is the first report to show that two NHI proteins form a heterodimer for catalysis and utilizes a novel methodology to create functional oxygenase structures in secondary metabolite biosynthesis.
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Affiliation(s)
- Xinyang Li
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Takayoshi Awakawa
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Takahiro Mori
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan.,PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Meiqi Ling
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Dan Hu
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, Guangzhou 510632, China
| | - Bin Wu
- Ocean College, Zhejiang University, Hangzhou 310058, China
| | - Ikuro Abe
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan.,Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
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5
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McCracken J, Casey TM, Hausinger RP. 1H-HYSCORE Reveals Structural Details at the Fe(II) Active Site of Taurine:2-Oxoglutarate Dioxygenase. APPLIED MAGNETIC RESONANCE 2021; 52:971-994. [PMID: 35250178 PMCID: PMC8896577 DOI: 10.1007/s00723-020-01288-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 09/23/2020] [Accepted: 10/15/2020] [Indexed: 06/14/2023]
Abstract
Proton Hyperfine Sublevel Correlation (1H-HYSCORE) experiments have been used to probe the ligation structure of the Fe(II) active site of taurine:2-oxoglutarate dioxygenase (TauD), a non-heme Fe(II) hydroxylase. To facilitate Electron Paramagnetic Resonance (EPR) experiments, Fe(II) derivatives of the enzyme were studied using nitric oxide as a substitute for molecular oxygen. The addition of NO to the enzyme yields an S = 3/2 {FeNO}7 paramagnetic center characterized by nearly axial EPR spectra with g⊥ = 4 and g|| = 2. Using results from (i) an X-ray crystallographic study of TauD crystallized under anaerobic conditions in the presence of both cosubstrate 2-oxoglutarate and substrate taurine, (ii) a published theoretical description of the {FeNO}7 derivative of this form of the enzyme, and (iii) previous 2H-Electron Spin Echo Envelope Modulation (ESEEM) studies, we were able to assign the proton cross peaks detected in orientation-selected 1H-HYSCORE spectra. Discrete contributions from the protons of two coordinated histidine ligands were resolved. If substrate taurine is absent from the complex, orientation-selective HYSCORE spectra show cross peaks that are less resolved and when combined with information obtained from continuous wave EPR, support an alternate binding scheme for 2-oxoglutarate. HYSCORE studies of TauD in the absence of 2-oxoglutarate show additional 1H cross peaks that can be assigned to two distinct bound water molecules. In addition, 1H and 14N cross peaks that arise from the coordinated histidine side chains show a change in NO coordination for this species. For all of the TauD species, 1H hyperfine couplings and their orientations are sensitive to the detailed electronic structure of the {FeNO}7 center.
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Affiliation(s)
- John McCracken
- Department of Chemistry, Michigan State University, East Lansing, MI 48824
| | - Thomas M. Casey
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106
| | - Robert P. Hausinger
- Departments of Biochemistry and Molecular Biology, and Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824
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6
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Rabe P, Kamps JJAG, Sutherlin KD, Linyard JDS, Aller P, Pham CC, Makita H, Clifton I, McDonough MA, Leissing TM, Shutin D, Lang PA, Butryn A, Brem J, Gul S, Fuller FD, Kim IS, Cheah MH, Fransson T, Bhowmick A, Young ID, O'Riordan L, Brewster AS, Pettinati I, Doyle M, Joti Y, Owada S, Tono K, Batyuk A, Hunter MS, Alonso-Mori R, Bergmann U, Owen RL, Sauter NK, Claridge TDW, Robinson CV, Yachandra VK, Yano J, Kern JF, Orville AM, Schofield CJ. X-ray free-electron laser studies reveal correlated motion during isopenicillin N synthase catalysis. SCIENCE ADVANCES 2021; 7:eabh0250. [PMID: 34417180 PMCID: PMC8378823 DOI: 10.1126/sciadv.abh0250] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Accepted: 06/29/2021] [Indexed: 05/23/2023]
Abstract
Isopenicillin N synthase (IPNS) catalyzes the unique reaction of l-δ-(α-aminoadipoyl)-l-cysteinyl-d-valine (ACV) with dioxygen giving isopenicillin N (IPN), the precursor of all natural penicillins and cephalosporins. X-ray free-electron laser studies including time-resolved crystallography and emission spectroscopy reveal how reaction of IPNS:Fe(II):ACV with dioxygen to yield an Fe(III) superoxide causes differences in active site volume and unexpected conformational changes that propagate to structurally remote regions. Combined with solution studies, the results reveal the importance of protein dynamics in regulating intermediate conformations during conversion of ACV to IPN. The results have implications for catalysis by multiple IPNS-related oxygenases, including those involved in the human hypoxic response, and highlight the power of serial femtosecond crystallography to provide insight into long-range enzyme dynamics during reactions presently impossible for nonprotein catalysts.
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Affiliation(s)
- Patrick Rabe
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Jos J A G Kamps
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK
| | - Kyle D Sutherlin
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - James D S Linyard
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Pierre Aller
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK
| | - Cindy C Pham
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Hiroki Makita
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Ian Clifton
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Michael A McDonough
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Thomas M Leissing
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Denis Shutin
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Pauline A Lang
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Agata Butryn
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK
| | - Jürgen Brem
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Sheraz Gul
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Franklin D Fuller
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - In-Sik Kim
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Mun Hon Cheah
- Department of Chemistry - Ångström, Molecular Biomimetics, Uppsala University, SE 751 20 Uppsala, Sweden
| | - Thomas Fransson
- Interdisciplinary Center for Scientific Computing, University of Heidelberg, 69120 Heidelberg, Germany
| | - Asmit Bhowmick
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Iris D Young
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, 600 16th Street, San Francisco, CA 94158, USA
| | - Lee O'Riordan
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Aaron S Brewster
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Ilaria Pettinati
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Margaret Doyle
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Yasumasa Joti
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Shigeki Owada
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Kensuke Tono
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148, Japan
| | - Alexander Batyuk
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Mark S Hunter
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Roberto Alonso-Mori
- Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Uwe Bergmann
- Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, WI 53706, USA
| | - Robin L Owen
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - Nicholas K Sauter
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Timothy D W Claridge
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Carol V Robinson
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Vittal K Yachandra
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA
| | - Jan F Kern
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720, USA.
| | - Allen M Orville
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK.
- Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK
| | - Christopher J Schofield
- Chemistry Research Laboratory, Department of Chemistry and the Ineos Oxford Institute for Antimicrobial Research, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK.
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7
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Wang Y, Davis I, Chan Y, Naik SG, Griffith WP, Liu A. Characterization of the nonheme iron center of cysteamine dioxygenase and its interaction with substrates. J Biol Chem 2020; 295:11789-11802. [PMID: 32601061 DOI: 10.1074/jbc.ra120.013915] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 06/25/2020] [Indexed: 12/15/2022] Open
Abstract
Cysteamine dioxygenase (ADO) has been reported to exhibit two distinct biological functions with a nonheme iron center. It catalyzes oxidation of both cysteamine in sulfur metabolism and N-terminal cysteine-containing proteins or peptides, such as regulator of G protein signaling 5 (RGS5). It thereby preserves oxygen homeostasis in a variety of physiological processes. However, little is known about its catalytic center and how it interacts with these two types of primary substrates in addition to O2 Here, using electron paramagnetic resonance (EPR), Mössbauer, and UV-visible spectroscopies, we explored the binding mode of cysteamine and RGS5 to human and mouse ADO proteins in their physiologically relevant ferrous form. This characterization revealed that in the presence of nitric oxide as a spin probe and oxygen surrogate, both the small molecule and the peptide substrates coordinate the iron center with their free thiols in a monodentate binding mode, in sharp contrast to binding behaviors observed in other thiol dioxygenases. We observed a substrate-bound B-type dinitrosyl iron center complex in ADO, suggesting the possibility of dioxygen binding to the iron ion in a side-on mode. Moreover, we observed substrate-mediated reduction of the iron center from ferric to the ferrous oxidation state. Subsequent MS analysis indicated corresponding disulfide formation of the substrates, suggesting that the presence of the substrate could reactivate ADO to defend against oxidative stress. The findings of this work contribute to the understanding of the substrate interaction in ADO and fill a gap in our knowledge of the substrate specificity of thiol dioxygenases.
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Affiliation(s)
- Yifan Wang
- Department of Chemistry, University of Texas at San Antonio, Texas, USA
| | - Ian Davis
- Department of Chemistry, University of Texas at San Antonio, Texas, USA.,Department of Chemistry, Georgia State University, Atlanta, Georgia, USA
| | - Yan Chan
- Department of Chemistry, Georgia State University, Atlanta, Georgia, USA
| | - Sunil G Naik
- Department of Chemistry, University of Texas at San Antonio, Texas, USA
| | | | - Aimin Liu
- Department of Chemistry, University of Texas at San Antonio, Texas, USA .,Department of Chemistry, Georgia State University, Atlanta, Georgia, USA
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8
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Sardar S, Weitz A, Hendrich MP, Pierce BS. Outer-Sphere Tyrosine 159 within the 3-Mercaptopropionic Acid Dioxygenase S-H-Y Motif Gates Substrate-Coordination Denticity at the Non-Heme Iron Active Site. Biochemistry 2019; 58:5135-5150. [PMID: 31750652 PMCID: PMC10071547 DOI: 10.1021/acs.biochem.9b00674] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thiol dioxygenases are non-heme mononuclear iron enzymes that catalyze the O2-dependent oxidation of free thiols (-SH) to produce the corresponding sulfinic acid (-SO2-). Regardless of the phylogenic domain, the active site for this enzyme class is typically comprised of two major features: (1) a mononuclear ferrous iron coordinated by three protein-derived histidines and (2) a conserved sequence of outer Fe-coordination-sphere amino acids (Ser-His-Tyr) spatially adjacent to the iron site (∼3 Å). Here, we utilize a promiscuous 3-mercaptopropionic acid dioxygenase cloned from Azotobacter vinelandii (Av MDO) to explore the function of the conserved S-H-Y motif. This enzyme exhibits activity with 3-mercaptopropionic acid (3mpa), l-cysteine (cys), as well as several other thiol-bearing substrates, thus making it an ideal system to study the influence of residues within the highly conserved S-H-Y motif (H157 and Y159) on substrate specificity and reactivity. The pKa values for these residues were determined by pH-dependent steady-state kinetics, and their assignments verified by comparison to H157N and Y159F variants. Complementary electron paramagnetic resonance and Mössbauer studies demonstrate a network of hydrogen bonds connecting H157-Y159 and Fe-bound ligands within the enzymatic Fe site. Crucially, these experiments suggest that the hydroxyl group of Y159 hydrogen bonds to Fe-bound NO and, by extension, Fe-bound oxygen during native catalysis. This interaction alters both the NO binding affinity and rhombicity of the 3mpa-bound iron-nitrosyl site. In addition, Fe coordination of cys is switched from thiolate only to bidentate (thiolate/amine) for the Y159F variant, indicating that perturbations within the S-H-Y proton relay network also influence cys Fe binding denticity.
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Affiliation(s)
- Sinjinee Sardar
- Department of Chemistry and Biochemistry , The University of Texas at Arlington , 700 Planetarium Place , Arlington , Texas 76019 , United States
| | - Andrew Weitz
- Department of Chemistry , Carnegie Mellon University , 4400 Fifth Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Michael P Hendrich
- Department of Chemistry , Carnegie Mellon University , 4400 Fifth Avenue , Pittsburgh , Pennsylvania 15213 , United States
| | - Brad S Pierce
- Department of Chemistry and Biochemistry , University of Alabama , 250 Hackberry Lane , Tuscaloosa , Alabama 35487 , United States
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9
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Abstract
The organosulfur metabolite dimethylsulfoniopropionate (DMSP) and its enzymatic breakdown product dimethyl sulfide (DMS) have important implications in the global sulfur cycle and in marine microbial food webs. Enormous amounts of DMSP are produced in marine environments where microbial communities import and catabolize it via either the demethylation or the cleavage pathways. The enzymes that cleave DMSP are termed "DMSP lyases" and generate acrylate or hydroxypropionate, and ~107tons of DMS annually. An important environmental factor affecting DMS generation by the DMSP lyases is the availability of metal ions as these enzymes use various cofactors for catalysis. This chapter summarizes advances on bacterial DMSP catabolism, with an emphasis on various biochemical methods employed for the isolation and characterization of bacterial DMSP lyases. Strategies are presented for the purification of DMSP lyases expressed in bacterial cells. Specific conditions for the efficient isolation of apoproteins in Escherichia coli are detailed. DMSP cleavage is effectively inferred, utilizing the described HPLC-based acrylate detection assay. Finally, substrate and metal binding interactions are examined using fluorescence and UV-visible assays. Together, these methods are rapid and well suited for the biochemical and structural characterization of DMSP lyases and in the assessment of uncharacterized DMSP catabolic enzymes, and new metalloenzymes in general.
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10
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Truong PT, Broering EP, Dzul SP, Chakraborty I, Stemmler TL, Harrop TC. Simultaneous nitrosylation and N-nitrosation of a Ni-thiolate model complex of Ni-containing SOD. Chem Sci 2018; 9:8567-8574. [PMID: 30568781 PMCID: PMC6253683 DOI: 10.1039/c8sc03321h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Accepted: 09/17/2018] [Indexed: 11/21/2022] Open
Abstract
Nitric oxide (NO) is used as a substrate analogue/spectroscopic probe of metal sites that bind and activate oxygen and its derivatives. To assess the interaction of superoxide with the Ni center in Ni-containing superoxide dismutase (NiSOD), we studied the reaction of NO+ and NO with the model complex, Et4N[Ni(nmp)(SPh-o-NH2-p-CF3)] (1; nmp2- = dianion of N-(2-mercaptoethyl)picolinamide; -SPh-o-NH2-p-CF3 = 2-amino-4-(trifluoromethyl)benzenethiolate) and its oxidized analogue 1ox , respectively. The ultimate products of these reactions are the disulfide of -SPh-o-NH2-p-CF3 and the S,S-bridged tetrameric complex [Ni4(nmp)4], a result of S-based redox activity. However, introduction of NO to 1 affords the green dimeric {NiNO}10 complex (Et4N)2[{Ni(κ2-SPh-o-NNO-p-CF3)(NO)}2] (2) via NO-induced loss of nmp2- as the disulfide and N-nitrosation of the aromatic thiolate. Complex 2 was characterized by X-ray crystallography and several spectroscopies. These measurements are in-line with other tetrahedral complexes in the {NiNO}10 classification. In contrast to the established stability of this metal-nitrosyl class, the Ni-NO bond of 2 is labile and release of NO from this unit was quantified by trapping the NO with a CoII-porphyrin (70-80% yield). In the process, the Ni ends up coordinated by two o-nitrosaminobenzenethiolato ligands to result in the structurally characterized trans-(Et4N)2[Ni(SPh-o-NNO-p-CF3)2] (3), likely by a disproportionation mechanism. The isolation and characterization of 2 and 3 suggest that: (i) the strongly donating thiolates dominate the electronic structure of Ni-nitrosyls that result in less covalent Ni-NO bonds, and (ii) superoxide undergoes disproportionation via an outer-sphere mechanism in NiSOD as complexes in the {NiNO}9/8 state have yet to be isolated.
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Affiliation(s)
- Phan T Truong
- Department of Chemistry , Center for Metalloenzyme Studies , The University of Georgia , Athens , Georgia 30602 , USA .
| | - Ellen P Broering
- Department of Chemistry , Center for Metalloenzyme Studies , The University of Georgia , Athens , Georgia 30602 , USA .
| | - Stephen P Dzul
- Departments of Pharmaceutical Sciences, Biochemistry, and Molecular Biology , Wayne State University , Detroit , Michigan 48201 , USA
| | - Indranil Chakraborty
- Department of Chemistry and Biochemistry , Florida International University , Miami , Florida 33199 , USA
| | - Timothy L Stemmler
- Departments of Pharmaceutical Sciences, Biochemistry, and Molecular Biology , Wayne State University , Detroit , Michigan 48201 , USA
| | - Todd C Harrop
- Department of Chemistry , Center for Metalloenzyme Studies , The University of Georgia , Athens , Georgia 30602 , USA .
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11
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Goudarzi S, Babicz JT, Kabil O, Banerjee R, Solomon EI. Spectroscopic and Electronic Structure Study of ETHE1: Elucidating the Factors Influencing Sulfur Oxidation and Oxygenation in Mononuclear Nonheme Iron Enzymes. J Am Chem Soc 2018; 140:14887-14902. [PMID: 30362717 DOI: 10.1021/jacs.8b09022] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
ETHE1 is a member of a growing subclass of nonheme Fe enzymes that catalyzes transformations of sulfur-containing substrates without a cofactor. ETHE1 dioxygenates glutathione persulfide (GSSH) to glutathione (GSH) and sulfite in a reaction which is similar to that of cysteine dioxygenase (CDO), but with monodentate (vs bidentate) substrate coordination and a 2-His/1-Asp (vs 3-His) ligand set. In this study, we demonstrate that GSS- binds directly to the iron active site, causing coordination unsaturation to prime the site for O2 activation. Nitrosyl complexes without and with GSSH were generated and spectroscopically characterized as unreactive analogues for the invoked ferric superoxide intermediate. New spectral features from persulfide binding to the FeIII include the appearance of a low-energy FeIII ligand field transition, an energy shift of a NO- to FeIII CT transition, and two new GSS- to FeIII CT transitions. Time-dependent density functional theory calculations were used to simulate the experimental spectra to determine the persulfide orientation. Correlation of these spectral features with those of monodentate cysteine binding in isopenicillin N synthase (IPNS) shows that the persulfide is a poorer donor but still results in an equivalent frontier molecular orbital for reactivity. The ETHE1 persulfide dioxygenation reaction coordinate was calculated, and while the initial steps are similar to the reaction coordinate of CDO, an additional hydrolysis step is required in ETHE1 to break the S-S bond. Unlike ETHE1 and CDO, which both oxygenate sulfur, IPNS oxidizes sulfur through an initial H atom abstraction. Thus, factors that determine oxygenase vs oxidase reactivity were evaluated. In general, sulfur oxygenation is thermodynamically favored and has a lower barrier for reactivity. However, in IPNS, second-sphere residues in the active site pocket constrain the substrate, raising the barrier for sulfur oxygenation relative to oxidation via H atom abstraction.
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Affiliation(s)
- Serra Goudarzi
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Jeffrey T Babicz
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States
| | - Omer Kabil
- Department of Biological Chemistry , University of Michigan Medical School , Ann Arbor , Michigan 48109 , United States
| | - Ruma Banerjee
- Department of Biological Chemistry , University of Michigan Medical School , Ann Arbor , Michigan 48109 , United States
| | - Edward I Solomon
- Department of Chemistry , Stanford University , Stanford , California 94305 , United States.,SLAC National Accelerator Laboratory , Menlo Park , California 94025 , United States
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12
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Rabe P, Kamps JJAG, Schofield CJ, Lohans CT. Roles of 2-oxoglutarate oxygenases and isopenicillin N synthase in β-lactam biosynthesis. Nat Prod Rep 2018; 35:735-756. [PMID: 29808887 PMCID: PMC6097109 DOI: 10.1039/c8np00002f] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Indexed: 01/01/2023]
Abstract
Covering: up to 2017 2-Oxoglutarate (2OG) dependent oxygenases and the homologous oxidase isopenicillin N synthase (IPNS) play crucial roles in the biosynthesis of β-lactam ring containing natural products. IPNS catalyses formation of the bicyclic penicillin nucleus from a tripeptide. 2OG oxygenases catalyse reactions that diversify the chemistry of β-lactams formed by both IPNS and non-oxidative enzymes. Reactions catalysed by the 2OG oxygenases of β-lactam biosynthesis not only involve their typical hydroxylation reactions, but also desaturation, epimerisation, rearrangement, and ring-forming reactions. Some of the enzymes involved in β-lactam biosynthesis exhibit remarkable substrate and product selectivities. We review the roles of 2OG oxygenases and IPNS in β-lactam biosynthesis, highlighting opportunities for application of knowledge of their roles, structures, and mechanisms.
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Affiliation(s)
- Patrick Rabe
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Jos J A G Kamps
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Christopher J Schofield
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
| | - Christopher T Lohans
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK.
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13
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Kal S, Que L. Dioxygen activation by nonheme iron enzymes with the 2-His-1-carboxylate facial triad that generate high-valent oxoiron oxidants. J Biol Inorg Chem 2017; 22:339-365. [PMID: 28074299 DOI: 10.1007/s00775-016-1431-2] [Citation(s) in RCA: 159] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 12/13/2016] [Indexed: 11/24/2022]
Abstract
The 2-His-1-carboxylate facial triad is a widely used scaffold to bind the iron center in mononuclear nonheme iron enzymes for activating dioxygen in a variety of oxidative transformations of metabolic significance. Since the 1990s, over a hundred different iron enzymes have been identified to use this platform. This structural motif consists of two histidines and the side chain carboxylate of an aspartate or a glutamate arranged in a facial array that binds iron(II) at the active site. This triad occupies one face of an iron-centered octahedron and makes the opposite face available for the coordination of O2 and, in many cases, substrate, allowing the tailoring of the iron-dioxygen chemistry to carry out a plethora of diverse reactions. Activated dioxygen-derived species involved in the enzyme mechanisms include iron(III)-superoxo, iron(III)-peroxo, and high-valent iron(IV)-oxo intermediates. In this article, we highlight the major crystallographic, spectroscopic, and mechanistic advances of the past 20 years that have significantly enhanced our understanding of the mechanisms of O2 activation and the key roles played by iron-based oxidants.
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Affiliation(s)
- Subhasree Kal
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Lawrence Que
- Department of Chemistry, Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, MN, 55455, USA.
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14
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Proshlyakov DA, McCracken J, Hausinger RP. Spectroscopic analyses of 2-oxoglutarate-dependent oxygenases: TauD as a case study. J Biol Inorg Chem 2016; 22:367-379. [PMID: 27812832 DOI: 10.1007/s00775-016-1406-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/25/2016] [Indexed: 11/28/2022]
Abstract
A wide range of spectroscopic approaches have been used to interrogate the mononuclear iron metallocenter in 2-oxoglutarate (2OG)-dependent oxygenases. The results from these spectroscopic studies have provided valuable insights into the structural changes at the active site during substrate binding and catalysis, thus providing critical information that complements investigations of these enzymes by X-ray crystallography, biochemical, and computational approaches. This mini-review highlights taurine hydroxylase (taurine:2OG dioxygenase, TauD) as a case study to illustrate the wealth of knowledge that can be generated by applying a diverse array of spectroscopic investigations to a single enzyme. In particular, electronic absorption, circular dichroism, magnetic circular dichroism, conventional and pulse electron paramagnetic, Mössbauer, X-ray absorption, and resonance Raman methods have been exploited to uncover the properties of the metal site in TauD.
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Affiliation(s)
- Denis A Proshlyakov
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - John McCracken
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Robert P Hausinger
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA. .,Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA.
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15
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Peck SC, van der Donk WA. Go it alone: four-electron oxidations by mononuclear non-heme iron enzymes. J Biol Inorg Chem 2016; 22:381-394. [PMID: 27783267 DOI: 10.1007/s00775-016-1399-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Accepted: 10/11/2016] [Indexed: 10/20/2022]
Abstract
This review discusses the current mechanistic understanding of a group of mononuclear non-heme iron-dependent enzymes that catalyze four-electron oxidation of their organic substrates without the use of any cofactors or cosubstrates. One set of enzymes acts on α-ketoacid-containing substrates, coupling decarboxylation to oxygen activation. This group includes 4-hydroxyphenylpyruvate dioxygenase, 4-hydroxymandelate synthase, and CloR involved in clorobiocin biosynthesis. A second set of enzymes acts on substrates containing a thiol group that coordinates to the iron. This group is comprised of isopenicillin N synthase, thiol dioxygenases, and enzymes involved in the biosynthesis of ergothioneine and ovothiol. The final group of enzymes includes HEPD and MPnS that both carry out the oxidative cleavage of the carbon-carbon bond of 2-hydroxyethylphosphonate but generate different products. Commonalities amongst many of these enzymes are discussed and include the initial substrate oxidation by a ferric-superoxo-intermediate and a second oxidation by a ferryl species.
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Affiliation(s)
- Spencer C Peck
- Department of Chemistry and Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA.,Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL, 61801, USA
| | - Wilfred A van der Donk
- Department of Chemistry and Howard Hughes Medical Institute, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, IL, 61801, USA. .,Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL, 61801, USA.
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16
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Meier KK, Rogers MS, Kovaleva EG, Lipscomb JD, Bominaar EL, Münck E. Enzyme Substrate Complex of the H200C Variant of Homoprotocatechuate 2,3-Dioxygenase: Mössbauer and Computational Studies. Inorg Chem 2016; 55:5862-70. [PMID: 27275865 PMCID: PMC4924929 DOI: 10.1021/acs.inorgchem.6b00148] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The extradiol, aromatic ring-cleaving enzyme homoprotocatechuate 2,3-dioxygenase (HPCD) catalyzes a complex chain of reactions that involve second sphere residues of the active site. The importance of the second-sphere residue His200 was demonstrated in studies of HPCD variants, such as His200Cys (H200C), which revealed significant retardations of certain steps in the catalytic process as a result of the substitution, allowing novel reaction cycle intermediates to be trapped for spectroscopic characterization. As the H200C variant largely retains the wild-type active site structure and produces the correct ring-cleaved product, this variant presents a valuable target for mechanistic HPCD studies. Here, the high-spin Fe(II) states of resting H200C and the H200C-homoprotocatechuate enzyme-substrate (ES) complex have been characterized with Mössbauer spectroscopy to assess the electronic structures of the active site in these states. The analysis reveals a high-spin Fe(II) center in a low symmetry environment that is reflected in the values of the zero-field splitting (ZFS) (D ≈ - 8 cm(-1), E/D ≈ 1/3 in ES), as well as the relative orientations of the principal axes of the (57)Fe magnetic hyperfine (A) and electric field gradient (EFG) tensors relative to the ZFS tensor axes. A spin Hamiltonian analysis of the spectra for the ES complex indicates that the magnetization axis of the integer-spin S = 2 Fe(II) system is nearly parallel to the symmetry axis, z, of the doubly occupied dxy ground orbital deduced from the EFG and A-values, an observation, which cannot be rationalized by DFT assisted crystal-field theory. In contrast, ORCA/CASSCF calculations for the ZFS tensor in combination with DFT calculations for the EFG- and A-tensors describe the experimental data remarkably well.
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Affiliation(s)
- Katlyn K. Meier
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Melanie S. Rogers
- Department of Biochemistry, Molecular Biology and Biophysics and Center for Metals in Biocatalysis, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Elena G. Kovaleva
- Stanford Synchrotron Radiation Lightsource, 2575 Sand Hill Road, Menlo Park, California 94025, 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
| | - Emile L. Bominaar
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Eckard Münck
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
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17
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Brummett AE, Schnicker NJ, Crider A, Todd JD, Dey M. Biochemical, Kinetic, and Spectroscopic Characterization of Ruegeria pomeroyi DddW--A Mononuclear Iron-Dependent DMSP Lyase. PLoS One 2015; 10:e0127288. [PMID: 25993446 PMCID: PMC4437653 DOI: 10.1371/journal.pone.0127288] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 04/13/2015] [Indexed: 11/19/2022] Open
Abstract
The osmolyte dimethylsulfoniopropionate (DMSP) is a key nutrient in marine environments and its catabolism by bacteria through enzymes known as DMSP lyases generates dimethylsulfide (DMS), a gas of importance in climate regulation, the sulfur cycle, and signaling to higher organisms. Despite the environmental significance of DMSP lyases, little is known about how they function at the mechanistic level. In this study we biochemically characterize DddW, a DMSP lyase from the model roseobacter Ruegeria pomeroyi DSS-3. DddW is a 16.9 kDa enzyme that contains a C-terminal cupin domain and liberates acrylate, a proton, and DMS from the DMSP substrate. Our studies show that as-purified DddW is a metalloenzyme, like the DddQ and DddP DMSP lyases, but contains an iron cofactor. The metal cofactor is essential for DddW DMSP lyase activity since addition of the metal chelator EDTA abolishes its enzymatic activity, as do substitution mutations of key metal-binding residues in the cupin motif (His81, His83, Glu87, and His121). Measurements of metal binding affinity and catalytic activity indicate that Fe(II) is most likely the preferred catalytic metal ion with a nanomolar binding affinity. Stoichiometry studies suggest DddW requires one Fe(II) per monomer. Electronic absorption and electron paramagnetic resonance (EPR) studies show an interaction between NO and Fe(II)-DddW, with NO binding to the EPR silent Fe(II) site giving rise to an EPR active species (g = 4.29, 3.95, 2.00). The change in the rhombicity of the EPR signal is observed in the presence of DMSP, indicating that substrate binds to the iron site without displacing bound NO. This work provides insight into the mechanism of DMSP cleavage catalyzed by DddW.
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Affiliation(s)
- Adam E. Brummett
- Department of Chemistry, University of Iowa, Iowa City, Iowa, United States of America
| | - Nicholas J. Schnicker
- Department of Chemistry, University of Iowa, Iowa City, Iowa, United States of America
| | - Alexander Crider
- Department of Chemistry, University of Iowa, Iowa City, Iowa, United States of America
| | - Jonathan D. Todd
- School of Biological Sciences, University of East Anglia, Norwich Research Park, United Kingdom
| | - Mishtu Dey
- Department of Chemistry, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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18
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Pettinati I, Brem J, McDonough MA, Schofield CJ. Crystal structure of human persulfide dioxygenase: structural basis of ethylmalonic encephalopathy. Hum Mol Genet 2015; 24:2458-69. [PMID: 25596185 PMCID: PMC4383860 DOI: 10.1093/hmg/ddv007] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/13/2015] [Indexed: 01/08/2023] Open
Abstract
The ethylmalonic encephalopathy protein 1 (ETHE1) catalyses the oxygen-dependent oxidation of glutathione persulfide (GSSH) to give persulfite and glutathione. Mutations to the hETHE1 gene compromise sulfide metabolism leading to the genetic disease ethylmalonic encephalopathy. hETHE1 is a mono-iron binding member of the metallo-β-lactamase (MBL) fold superfamily. We report crystallographic analysis of hETHE1 in complex with iron to 2.6 Å resolution. hETHE1 contains an αββα MBL-fold, which supports metal-binding by the side chains of an aspartate and two histidine residues; three water molecules complete octahedral coordination of the iron. The iron binding hETHE1 enzyme is related to the ‘classical’ di-zinc binding MBL hydrolases involved in antibiotic resistance, but has distinctive features. The histidine and aspartate residues involved in iron-binding in ETHE1, occupy similar positions to those observed across both the zinc 1 and zinc 2 binding sites in classical MBLs. The active site of hETHE1 is very similar to an ETHE1-like enzyme from Arabidopsis thaliana (60% sequence identity). A channel leading to the active site is sufficiently large to accommodate a GSSH substrate. Some of the observed hETHE1 clinical mutations cluster in the active site region. The structure will serve as a basis for detailed functional and mechanistic studies on ETHE1 and will be useful in the development of selective MBL inhibitors.
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Affiliation(s)
- Ilaria Pettinati
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Jürgen Brem
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
| | - Michael A McDonough
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, UK
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19
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Park J, McCormick SP, Cockrell AL, Chakrabarti M, Lindahl PA. High-spin ferric ions in Saccharomyces cerevisiae vacuoles are reduced to the ferrous state during adenine-precursor detoxification. Biochemistry 2014; 53:3940-51. [PMID: 24919141 PMCID: PMC4072367 DOI: 10.1021/bi500148y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The majority of Fe in Fe-replete yeast cells is located in vacuoles. These acidic organelles store Fe for use under Fe-deficient conditions and they sequester it from other parts of the cell to avoid Fe-associated toxicity. Vacuolar Fe is predominantly in the form of one or more magnetically isolated nonheme high-spin (NHHS) Fe(III) complexes with polyphosphate-related ligands. Some Fe(III) oxyhydroxide nanoparticles may also be present in these organelles, perhaps in equilibrium with the NHHS Fe(III). Little is known regarding the chemical properties of vacuolar Fe. When grown on adenine-deficient medium (A↓), ADE2Δ strains of yeast such as W303 produce a toxic intermediate in the adenine biosynthetic pathway. This intermediate is conjugated with glutathione and shuttled into the vacuole for detoxification. The iron content of A↓ W303 cells was determined by Mössbauer and EPR spectroscopies. As they transitioned from exponential growth to stationary state, A↓ cells (supplemented with 40 μM Fe(III) citrate) accumulated two major NHHS Fe(II) species as the vacuolar NHHS Fe(III) species declined. This is evidence that vacuoles in A↓ cells are more reducing than those in adenine-sufficient cells. A↓ cells suffered less oxidative stress despite the abundance of NHHS Fe(II) complexes; such species typically promote Fenton chemistry. Most Fe in cells grown for 5 days with extra yeast-nitrogen-base, amino acids and bases in minimal medium was HS Fe(III) with insignificant amounts of nanoparticles. The vacuoles of these cells might be more acidic than normal and can accommodate high concentrations of HS Fe(III) species. Glucose levels and rapamycin (affecting the TOR system) affected cellular Fe content. This study illustrates the sensitivity of cellular Fe to changes in metabolism, redox state and pH. Such effects broaden our understanding of how Fe and overall cellular metabolism are integrated.
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Affiliation(s)
- Jinkyu Park
- Department of Chemistry, Texas A&M University , College Station, Texas 77843-3255, United States
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20
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Li J, Banerjee A, Pawlak PL, Brennessel WW, Chavez FA. Highest Recorded N–O Stretching Frequency for 6-Coordinate {Fe-NO}7 Complexes: An Iron Nitrosyl Model for His3 Active Sites. Inorg Chem 2014; 53:5414-6. [DOI: 10.1021/ic500558j] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Jia Li
- Department of Chemistry, Oakland University, Rochester, Michigan 48309-4477, United States
| | - Atanu Banerjee
- Department of Chemistry, Oakland University, Rochester, Michigan 48309-4477, United States
| | - Piotr L. Pawlak
- Department of Chemistry, Oakland University, Rochester, Michigan 48309-4477, United States
| | - William W. Brennessel
- Department of Chemistry, University of Rochester, Rochester, New York 14627-0216, United States
| | - Ferman A. Chavez
- Department of Chemistry, Oakland University, Rochester, Michigan 48309-4477, United States
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Clifton IJ, Ge W, Adlington RM, Baldwin JE, Rutledge PJ. The crystal structure of an isopenicillin N synthase complex with an ethereal substrate analogue reveals water in the oxygen binding site. FEBS Lett 2013; 587:2705-9. [DOI: 10.1016/j.febslet.2013.07.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 07/04/2013] [Accepted: 07/04/2013] [Indexed: 10/26/2022]
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22
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Paradkar A, Jensen S, Mosher R. Comparative Genetics and Molecular Biology of ß-Lactam Biosynthesis. ACTA ACUST UNITED AC 2013. [DOI: 10.1201/b14856-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/04/2023]
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23
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Daruzzaman A, Clifton IJ, Adlington RM, Baldwin JE, Rutledge PJ. The Interaction of Isopenicillin N Synthase with Homologated Substrate Analogues δ-(L-α-Aminoadipoyl)-L-homocysteinyl-D-Xaa Characterised by Protein Crystallography. Chembiochem 2013; 14:599-606. [DOI: 10.1002/cbic.201200728] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Indexed: 11/11/2022]
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24
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Daruzzaman A, Clifton IJ, Adlington RM, Baldwin JE, Rutledge PJ. The crystal structure of isopenicillin N synthase with a dipeptide substrate analogue. Arch Biochem Biophys 2013; 530:48-53. [DOI: 10.1016/j.abb.2012.12.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 12/07/2012] [Accepted: 12/09/2012] [Indexed: 11/29/2022]
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25
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Hamed RB, Gomez-Castellanos JR, Henry L, Ducho C, McDonough MA, Schofield CJ. The enzymes of β-lactam biosynthesis. Nat Prod Rep 2013; 30:21-107. [DOI: 10.1039/c2np20065a] [Citation(s) in RCA: 146] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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26
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Lundberg M, Borowski T. Oxoferryl species in mononuclear non-heme iron enzymes: Biosynthesis, properties and reactivity from a theoretical perspective. Coord Chem Rev 2013. [DOI: 10.1016/j.ccr.2012.03.047] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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27
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Abstract
The toxic free radical NO (nitric oxide) has diverse biological roles in eukaryotes and bacteria, being involved in signalling, vasodilation, blood clotting and immunity, and as an intermediate in microbial denitrification. The predominant biological mechanism of detecting NO is through the formation of iron nitrosyl complexes, although this is a deleterious process for other iron-containing enzymes. We have previously applied techniques such as UV–visible and EPR spectroscopy to the analysis of protein Fe–NO complex formation in order to study how NO controls the activity of the bacterial transcriptional regulators NorR and NsrR. These studies have analysed NO-dependent biological activity both in vitro and in vivo using diverse biochemical, molecular and spectroscopic methods. Recently, we have applied ultrafast 2D-IR (two-dimensional IR) spectroscopy to the analysis of NO–protein interactions using Mb (myoglobin) and Cc (cytochrome c) as model haem proteins. The ultrafast fluctuations of Cc and Mb show marked differences, indicating altered flexibility of the haem pockets. We have extended this analysis to bacterial catalase enzymes that are known to play a role in the nitrosative stress response by detoxifying peroxynitrite. The first 2D-IR analysis of haem nitrosylation and perspectives for the future are discussed.
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Bjørnstad L, Zoppellaro G, Tomter A, Falnes P, Andersson K. Spectroscopic and magnetic studies of wild-type and mutant forms of the Fe(II)- and 2-oxoglutarate-dependent decarboxylase ALKBH4. Biochem J 2011; 434:391-8. [PMID: 21166655 PMCID: PMC3048578 DOI: 10.1042/bj20101667] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Revised: 12/14/2010] [Accepted: 12/20/2010] [Indexed: 11/24/2022]
Abstract
The Fe(II)/2OG (2-oxoglutarate)-dependent dioxygenase superfamily comprises proteins that couple substrate oxidation to decarboxylation of 2OG to succinate. A member of this class of mononuclear non-haem Fe proteins is the Escherichia coli DNA/RNA repair enzyme AlkB. In the present work, we describe the magnetic and optical properties of the yet uncharacterized human ALKBH4 (AlkB homologue). Through EPR and UV-visible spectroscopy studies, we address the Fe-binding environment of the proposed catalytic centre of wild-type ALKBH4 and an Fe(II)-binding mutant. We could observe a novel unusual Fe(III) high-spin EPR-active species in the presence of sulfide with a g(max) of 8.2. The Fe(II) site was probed with NO. An intact histidine-carboxylate site is necessary for productive Fe binding. We also report the presence of a unique cysteine-rich motif conserved in the N-terminus of ALKBH4 orthologues, and investigate its possible Fe-binding ability. Furthermore, we show that recombinant ALKBH4 mediates decarboxylation of 2OG in absence of primary substrate. This activity is dependent on Fe as well as on residues predicted to be involved in Fe(II) co-ordination. The present results demonstrate that ALKBH4 represents an active Fe(II)/2OG-dependent decarboxylase and suggest that the cysteine cluster is involved in processes other than Fe co-ordination.
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Key Words
- alkb
- alkb homologue (alkbh4)
- epr
- non-haem fe
- uv–visible spectroscopy
- alkbh, alkb homologue
- fto, fat mass and obesity-associated protein
- gst, glutathione transferase
- icp-aep, inductively coupled plasma atomic emission spectroscopy
- ipns, isopenicillin n synthase
- iptg, isopropyl β-d-thiogalactopyranoside
- mv•+, methyl viologen radical cation
- 2og, 2-oxoglutarate
- pah, phenylalanine hydroxylase
- 4,5-pcd, protocatechuate 4,5-dioxygenase
- taud, taurine dioxygenase
- uv–vis, uv–visible
- zfs, zero-field splitting
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Affiliation(s)
- Linn G. Bjørnstad
- Department of Molecular Biosciences, University of Oslo, P.O. Box 1041, Blindern, NO-0316 Oslo, Norway
| | - Giorgio Zoppellaro
- Department of Molecular Biosciences, University of Oslo, P.O. Box 1041, Blindern, NO-0316 Oslo, Norway
| | - Ane B. Tomter
- Department of Molecular Biosciences, University of Oslo, P.O. Box 1041, Blindern, NO-0316 Oslo, Norway
| | - Pål Ø. Falnes
- Department of Molecular Biosciences, University of Oslo, P.O. Box 1041, Blindern, NO-0316 Oslo, Norway
| | - K. Kristoffer Andersson
- Department of Molecular Biosciences, University of Oslo, P.O. Box 1041, Blindern, NO-0316 Oslo, Norway
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Villar-Acevedo G, Nam E, Fitch S, Benedict J, Freudenthal J, Kaminsky W, Kovacs JA. Influence of thiolate ligands on reductive N-O bond activation. Probing the O2(-) binding site of a biomimetic superoxide reductase analogue and examining the proton-dependent reduction of nitrite. J Am Chem Soc 2011; 133:1419-27. [PMID: 21207999 PMCID: PMC3178331 DOI: 10.1021/ja107551u] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nitric oxide (NO) is frequently used to probe the substrate-binding site of "spectroscopically silent" non-heme Fe(2+) sites of metalloenzymes, such as superoxide reductase (SOR). Herein we use NO to probe the superoxide binding site of our thiolate-ligated biomimetic SOR model [Fe(II)(S(Me(2))N(4)(tren))](+) (1). Like NO-bound trans-cysteinate-ligated SOR (SOR-NO), the rhombic S = 3/2 EPR signal of NO-bound cis-thiolate-ligated [Fe(S(Me(2))N(4)(tren)(NO)](+) (2; g = 4.44, 3.54, 1.97), the isotopically sensitive ν(NO)(ν((15)NO)) stretching frequency (1685(1640) cm(-1)), and the 0.05 Å decrease in Fe-S bond length are shown to be consistent with the oxidative addition of NO to Fe(II) to afford an Fe(III)-NO(-) {FeNO}(7) species containing high-spin (S = 5/2) Fe(III) antiferromagnetically coupled to NO(-) (S = 1). The cis versus trans positioning of the thiolate does not appear to influence these properties. Although it has yet to be crystallographically characterized, SOR-NO is presumed to possess a bent Fe-NO similar to that of 2 (Fe-N-O = 151.7(4)°). The N-O bond is shown to be more activated in 2 relative to N- and O-ligated {FeNO}(7) complexes, and this is attributed to the electron-donating properties of the thiolate ligand. Hydrogen-bonding to the cysteinate sulfur attenuates N-O bond activation in SOR, as shown by its higher ν(NO) frequency (1721 cm(-1)). In contrast, the ν(O-O) frequency of the SOR peroxo intermediate and its analogues is not affected by H-bonds to the cysteinate sulfur or other factors influencing the Fe-SR bond strength; these only influence the ν(Fe-O) frequency. Reactions between 1 and NO(2)(-) are shown to result in the proton-dependent heterolytic cleavage of an N-O bond. The mechanism of this reaction is proposed to involve both Fe(II)-NO(2)(-) and {FeNO}(6) intermediates similar to those implicated in the mechanism of NiR-promoted NO(2)(-) reduction.
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Affiliation(s)
| | - Elaine Nam
- Department of Chemistry, University of Washington, Seattle, WA 98195
| | - Sarah Fitch
- Department of Chemistry, University of Washington, Seattle, WA 98195
| | | | | | | | - Julie A. Kovacs
- Department of Chemistry, University of Washington, Seattle, WA 98195
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30
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Sun N, Liu LV, Dey A, Villar-Acevedo G, Kovacs JA, Darensbourg MY, Hodgson KO, Hedman B, Solomon EI. S K-edge X-ray absorption spectroscopy and density functional theory studies of high and low spin {FeNO}7 thiolate complexes: exchange stabilization of electron delocalization in {FeNO}7 and {FeO2}8. Inorg Chem 2011; 50:427-36. [PMID: 21158471 PMCID: PMC3130116 DOI: 10.1021/ic1006378] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
S K-edge X-ray absorption spectroscopy (XAS) is a direct experimental probe of metal ion electronic structure as the pre-edge energy reflects its oxidation state, and the energy splitting pattern of the pre-edge transitions reflects its spin state. The combination of sulfur K-edge XAS and density functional theory (DFT) calculations indicates that the electronic structures of {FeNO}(7) (S = 3/2) (S(Me2)N4(tren)Fe(NO), complex I) and {FeNO}(7) (S = 1/2) ((bme-daco)Fe(NO), complex II) are Fe(III)(S = 5/2)-NO(-)(S = 1) and Fe(III)(S = 3/2)-NO(-)(S = 1), respectively. When an axial ligand is computationally added to complex II, the electronic structure becomes Fe(II)(S = 0)-NO•(S = 1/2). These studies demonstrate how the ligand field of the Fe center defines its spin state and thus changes the electron exchange, an important factor in determining the electron distribution over {FeNO}(7) and {FeO2}(8) sites.
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Affiliation(s)
- Ning Sun
- Department of Chemistry, Stanford University, Stanford, California 94305
| | - Lei V. Liu
- Department of Chemistry, Stanford University, Stanford, California 94305
| | - Abhishek Dey
- Department of Chemistry, Stanford University, Stanford, California 94305
| | | | - Julie A. Kovacs
- Department of Chemistry, University of Washington, Seattle, Washington 98195
| | | | - Keith O. Hodgson
- Department of Chemistry, Stanford University, Stanford, California 94305
- Stanford Synchrotron Radiation Lightsource, SLAC, Stanford University, Menlo Park, California 94025
| | - Britt Hedman
- Stanford Synchrotron Radiation Lightsource, SLAC, Stanford University, Menlo Park, California 94025
| | - Edward I. Solomon
- Department of Chemistry, Stanford University, Stanford, California 94305
- Stanford Synchrotron Radiation Lightsource, SLAC, Stanford University, Menlo Park, California 94025
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31
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Trapping and spectroscopic characterization of an FeIII-superoxo intermediate from a nonheme mononuclear iron-containing enzyme. Proc Natl Acad Sci U S A 2010; 107:16788-93. [PMID: 20837547 DOI: 10.1073/pnas.1010015107] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Fe(III)-O(2)*(-) intermediates are well known in heme enzymes, but none have been characterized in the nonheme mononuclear Fe(II) enzyme family. Many steps in the O(2) activation and reaction cycle of Fe(II)-containing homoprotocatechuate 2,3-dioxygenase are made detectable by using the alternative substrate 4-nitrocatechol (4NC) and mutation of the active site His200 to Asn (H200N). Here, the first intermediate (Int-1) observed after adding O(2) to the H200N-4NC complex is trapped and characterized using EPR and Mössbauer (MB) spectroscopies. Int-1 is a high-spin (S(1) = 5/2) Fe(III) antiferromagnetically (AF) coupled to an S(2) = 1/2 radical (J ≈ 6 cm(-1) in ). It exhibits parallel-mode EPR signals at g = 8.17 from the S = 2 multiplet, and g = 8.8 and 11.6 from the S = 3 multiplet. These signals are broadened significantly by hyperfine interactions (A((17)O) ≈ 180 MHz). Thus, Int-1 is an AF-coupled species. The experimental observations are supported by density functional theory calculations that show nearly complete transfer of spin density to the bound O(2). Int-1 decays to form a second intermediate (Int-2). MB spectra show that it is also an AF-coupled Fe(III)-radical complex. Int-2 exhibits an EPR signal at g = 8.05 arising from an S = 2 state. The signal is only slightly broadened by (< 3% spin delocalization), suggesting that Int-2 is a peroxo-Fe(III)-4NC semiquinone radical species. Our results demonstrate facile electron transfer between Fe(II), O(2), and the organic ligand, thereby supporting the proposed wild-type enzyme mechanism.
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32
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Hayashi T, Caranto JD, Wampler DA, Kurtz DM, Moënne-Loccoz P. Insights into the nitric oxide reductase mechanism of flavodiiron proteins from a flavin-free enzyme. Biochemistry 2010; 49:7040-9. [PMID: 20669924 PMCID: PMC2923256 DOI: 10.1021/bi100788y] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Flavodiiron proteins (FDPs) catalyze reductive scavenging of dioxygen and nitric oxide in air-sensitive microorganisms. FDPs contain a distinctive non-heme diiron/flavin mononucleotide (FMN) active site. Alternative mechanisms for the nitric oxide reductase (NOR) activity consisting of either protonation of a diiron-bridging hyponitrite or "super-reduction" of a diferrous-dinitrosyl by the proximal FMNH(2) in the rate-determining step have been proposed. To test these alternative mechanisms, we examined a deflavinated FDP (deflavo-FDP) from Thermotoga maritima. The deflavo-FDP retains an intact diiron site but does not exhibit multiturnover NOR or O(2) reductase (O(2)R) activity. Reactions of the reduced (diferrous) deflavo-FDP with nitric oxide were examined by UV-vis absorption, EPR, resonance Raman, and FTIR spectroscopies. Anaerobic addition of nitric oxide up to one NO per diferrous deflavo-FDP results in formation of a diiron-mononitrosyl complex characterized by a broad S = (1)/(2 )EPR signal arising from antiferromagnetic coupling of an S = (3)/(2) {FeNO}(7) with an S = 2 Fe(II). Further addition of NO results in two reaction pathways, one of which produces N(2)O and the diferric site and the other of which produces a stable diiron-dinitrosyl complex. Both NO-treated and as-isolated deflavo-FDPs regain full NOR and O(2)R activities upon simple addition of FMN. The production of N(2)O upon addition of NO to the mononitrosyl deflavo-FDP supports the hyponitrite mechanism, but the concomitant formation of a stable diiron-dinitrosyl complex in the deflavo-FDP is consistent with a super-reduction pathway in the flavinated enzyme. We conclude that a diiron-mononitrosyl complex is an intermediate in the NOR catalytic cycle of FDPs.
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Affiliation(s)
- Takahiro Hayashi
- Department of Science & Engineering, School of Medicine, Oregon Health & Science University, 20,000 NW Walker Road, Beaverton, Oregon 97006, USA
| | - Jonathan D. Caranto
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, USA
| | - David A. Wampler
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, USA
| | - Donald M. Kurtz
- Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas 78249, USA
| | - Pierre Moënne-Loccoz
- Department of Science & Engineering, School of Medicine, Oregon Health & Science University, 20,000 NW Walker Road, Beaverton, Oregon 97006, USA
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33
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Ye S, Price JC, Barr EW, Green MT, Bollinger JM, Krebs C, Neese F. Cryoreduction of the NO-adduct of taurine:alpha-ketoglutarate dioxygenase (TauD) yields an elusive {FeNO}(8) species. J Am Chem Soc 2010; 132:4739-51. [PMID: 20218714 DOI: 10.1021/ja909715g] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The Fe(II)- and alpha-ketoglutarate (alphaKG)-dependent enzymes are a functionally and mechanistically diverse group of mononuclear nonheme-iron enzymes that activate dioxygen to couple the decarboxylation of alphaKG, which yields succinate and CO(2), to the oxidation of an aliphatic C-H bond of their substrates. Their mechanisms have been studied in detail by a combination of kinetic, spectroscopic, and computational methods. Two reaction intermediates have been trapped and characterized for several members of this enzyme family. The first intermediate is the C-H-cleaving Fe(IV)-oxo complex, which exhibits a large deuterium kinetic isotope effect on its decay. The second intermediate is a Fe(II):product complex. Reaction intermediates proposed to occur before the Fe(IV)-oxo intermediate do not accumulate and therefore cannot be characterized experimentally. One of these intermediates is the initial O(2) adduct, which is a {FeO(2)}(8) species in the notation introduced by Enemark and Feltham. Here, we report spectroscopic and computational studies on the stable NO-adduct of taurine:alphaKG dioxygenase (TauD), termed TauD-{FeNO}(7), and its one-electron reduced form, TauD-{FeNO}(8). The latter is isoelectronic with the proposed O(2) adduct and was generated by low-temperature gamma-irradiation of TauD-{FeNO}(7). To our knowledge, TauD-{FeNO}(8) is the first paramagnetic {FeNO}(8) complex. The detailed analysis of experimental and computational results shows that TauD-{FeNO}(8) has a triplet ground state. This has mechanistic implications that are discussed in this Article. Annealing of the triplet {FeNO}(8) species presumably leads to an equally elusive {FeHNO}(8) complex with a quintet ground state.
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Affiliation(s)
- Shengfa Ye
- Institute of Physical and Theoretical Chemistry, Universität Bonn, D-53115 Bonn, Germany
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34
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Schroeder S, Lawrence AD, Biedendieck R, Rose RS, Deery E, Graham RM, McLean KJ, Munro AW, Rigby SEJ, Warren MJ. Demonstration that CobG, the monooxygenase associated with the ring contraction process of the aerobic cobalamin (vitamin B12) biosynthetic pathway, contains an Fe-S center and a mononuclear non-heme iron center. J Biol Chem 2008; 284:4796-805. [PMID: 19068481 DOI: 10.1074/jbc.m807184200] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ring contraction process that occurs during cobalamin (vitamin B(12)) biosynthesis is mediated via the action of two enzymes, CobG and CobJ. The first of these generates a tertiary alcohol at the C-20 position of precorrin-3A by functioning as a monooxygenase, a reaction that also forms a gamma lactone with the acetic acid side chain on ring A. The product, precorrin-3B, is then acted upon by CobJ, which methylates at the C-17 position and promotes ring contraction of the macrocycle by catalyzing a masked pinacol rearrangement. Here, we report the characterization of CobG enzymes from Pseudomonas denitrificans and Brucella melitensis. We show that both contain a [4Fe-4S] center as well as a mononuclear non-heme iron. Although both enzymes are active in vivo, the P. denitrificans enzyme was found to be inactive in vitro. Further analysis of this enzyme revealed that the mononuclear non-heme iron was not reducible, and it was concluded that it is rapidly inactivated once it is released from the bacterial cell. In contrast, the B. melitensis enzyme was found to be fully active in vitro and the mononuclear non-heme iron was reducible by dithionite. The reduced mononuclear non-heme was able to react with the oxygen analogue NO, but only in the presence of the substrate precorrin-3A. The cysteine residues responsible for binding the Fe-S center were identified by site-directed mutagenesis. A mechanism for CobG is presented.
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Affiliation(s)
- Susanne Schroeder
- Protein Science Group, Department of Biosciences, University of Kent, Canterbury, Kent CT27NJ, United Kingdom
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35
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Lundberg M, Kawatsu T, Vreven T, Frisch MJ, Morokuma K. Transition States in a Protein Environment − ONIOM QM:MM Modeling of Isopenicillin N Synthesis. J Chem Theory Comput 2008; 5:222-34. [DOI: 10.1021/ct800457g] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Marcus Lundberg
- Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan, and Gaussian, Inc., 340 Quinnipiac Street, Building 40, Wallingford, Connecticut 06492
| | - Tsutomu Kawatsu
- Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan, and Gaussian, Inc., 340 Quinnipiac Street, Building 40, Wallingford, Connecticut 06492
| | - Thom Vreven
- Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan, and Gaussian, Inc., 340 Quinnipiac Street, Building 40, Wallingford, Connecticut 06492
| | - Michael J. Frisch
- Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan, and Gaussian, Inc., 340 Quinnipiac Street, Building 40, Wallingford, Connecticut 06492
| | - Keiji Morokuma
- Fukui Institute for Fundamental Chemistry, Kyoto University, 34-4 Takano Nishihiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan, and Gaussian, Inc., 340 Quinnipiac Street, Building 40, Wallingford, Connecticut 06492
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36
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Tennyson AG, Dhar S, Lippard SJ. Synthesis and Characterization of {Ni(NO)}10and {Co(NO)2}10Complexes Supported by Thiolate Ligands. J Am Chem Soc 2008; 130:15087-98. [DOI: 10.1021/ja803992y] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Andrew G. Tennyson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Shanta Dhar
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Stephen J. Lippard
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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37
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Kovaleva EG, Lipscomb JD. Versatility of biological non-heme Fe(II) centers in oxygen activation reactions. Nat Chem Biol 2008; 4:186-93. [PMID: 18277980 PMCID: PMC2720164 DOI: 10.1038/nchembio.71] [Citation(s) in RCA: 492] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Oxidase and oxygenase enzymes allow the use of relatively unreactive O2 in biochemical reactions. Many of the mechanistic strategies used in nature for this key reaction are represented within the 2-histidine-1-carboxylate facial triad family of non-heme Fe(II)-containing enzymes. The open face of the metal coordination sphere opposite the three endogenous ligands participates directly in the reaction chemistry. Here, data from several studies are presented showing that reductive O2 activation within this family is initiated by substrate (and in some cases cosubstrate or cofactor) binding, which then allows coordination of O2 to the metal. From this starting point, the O2 activation process and the reactions with substrates diverge broadly. The reactive species formed in these reactions have been proposed to encompass four oxidation states of iron and all forms of reduced O2 as well as several of the reactive oxygen species that derive from O-O bond cleavage.
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Affiliation(s)
- Elena G Kovaleva
- Elena G. Kovaleva and John D. Lipscomb are in the Department of Biochemistry, Molecular Biology and Biophysics and the Center for Metals in Biocatalysis, University of Minnesota, 6-155 Jackson Hall, Minneapolis, Minnesota, 55455 USA
| | - John D Lipscomb
- Elena G. Kovaleva and John D. Lipscomb are in the Department of Biochemistry, Molecular Biology and Biophysics and the Center for Metals in Biocatalysis, University of Minnesota, 6-155 Jackson Hall, Minneapolis, Minnesota, 55455 USA
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38
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Stewart AC, Clifton IJ, Adlington RM, Baldwin JE, Rutledge PJ. A Cyclobutanone Analogue Mimics Penicillin in Binding to Isopenicillin N Synthase. Chembiochem 2007; 8:2003-7. [PMID: 17907118 DOI: 10.1002/cbic.200700176] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A carbocyclic analogue of the beta-lactam antibiotic isopenicillin N (IPN) has been synthesised and cocrystallised with isopenicillin N synthase (IPNS), the central enzyme in the biosynthesis of penicillin antibiotics. The crystal structure of the IPNS-cyclobutanone complex reveals an active site environment similar to that seen in the enzyme-product complex generated by turnover of the natural substrate within the crystalline protein. The IPNS-cyclobutanone structure demonstrates that the product analogue is tethered to the protein by hydrogen bonding and salt bridge interactions with its carboxylate groups, as seen previously for the natural substrate and product. Furthermore, the successful cocrystallisation of this analogue with IPNS provides firm structural evidence for the utility of such cyclobutanone derivatives as hydrolytically stable analogues of bicyclic beta-lactams.
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Affiliation(s)
- Amanda C Stewart
- Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
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Roncaroli F, Videla M, Slep LD, Olabe JA. New features in the redox coordination chemistry of metal nitrosyls {M–NO+; M–NO; M–NO−(HNO)}. Coord Chem Rev 2007. [DOI: 10.1016/j.ccr.2007.04.012] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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40
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Klink A, Elsner B, Strube K, Cramm R. Characterization of the signaling domain of the NO-responsive regulator NorR from Ralstonia eutropha H16 by site-directed mutagenesis. J Bacteriol 2007; 189:2743-9. [PMID: 17277050 PMCID: PMC1855821 DOI: 10.1128/jb.01865-06] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Ralstonia eutropha H16, the nitric oxide (NO)-responsive transcriptional activator NorR controls the expression of a dicistronic operon that encodes a membrane-bound NO reductase, NorB, and a protein of unknown function, NorA. The N-terminal domain (NTD) of NorR is responsible for perception of the signal molecule, nitric oxide. Thirteen out of 29 conserved residues of the NTD were exchanged by site-directed mutagenesis. Replacement of R63, R72, D93, D96, C112, D130, or F137 strongly decreased NorR-dependent promoter activation, while the exchange of Y95 or H110 led to an increase in promoter activity compared to that of the wild type. A purified truncated NorR comprising only the NTD (NorR-NTD) contained one iron atom per molecule and was able to bind NO in the as-isolated state. Based on the iron content of NorR-NTD proteins with single amino acid replacements, residues R72, D93, D96, C112, and D130 are likely candidates for iron ligands. Residues R63, Y95, and H110 appear not to be involved in NO binding but may take part in subsequent steps of the signal transduction mechanism of NorR.
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Affiliation(s)
- Andrea Klink
- Institut für Biologie/Mikrobiologie, Humboldt-Universität zu Berlin, Chausseestrasse 117, 10115 Berlin, Germany
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41
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Daruzzaman A, Clifton IJ, Adlington RM, Baldwin JE, Rutledge PJ. Unexpected Oxidation of a Depsipeptide Substrate Analogue in Crystalline Isopenicillin N Synthase. Chembiochem 2006; 7:351-8. [PMID: 16444759 DOI: 10.1002/cbic.200500282] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Isopenicillin N synthase (IPNS) is a non-heme iron(ii)-dependent oxidase that is central to penicillin biosynthesis. Herein, we report mechanistic studies of the IPNS reaction in the crystalline state, using the substrate analogue delta-(L-alpha-aminoadipoyl)-(3R)-methyl-L-cysteine D-alpha-hydroxyisovaleryl ester (AmCOV) to probe the early stages of the catalytic cycle. The X-ray crystal structure of the anaerobic IPNS:Fe(II):AmCOV complex was solved to 1.40 A resolution, and it reveals several subtle differences in the active site relative to the complex of the enzyme with its natural substrate. The crystalline IPNS:Fe(II):AmCOV complex was then exposed to oxygen gas at high pressure; this brought about reaction to give what appears to be a hydroxymethyl/ene-thiol product. A mechanism for this reaction is proposed. These results offer further insight into the delicate interplay of steric and electronic effects in the IPNS active site and the mechanistic intricacies of this remarkable enzyme.
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Affiliation(s)
- Adam Daruzzaman
- Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
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42
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Bollinger JM, Price JC, Hoffart LM, Barr EW, Krebs C. Mechanism of Taurine: α‐Ketoglutarate Dioxygenase (TauD) from
Escherichia coli. Eur J Inorg Chem 2005. [DOI: 10.1002/ejic.200500476] [Citation(s) in RCA: 162] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- J. Martin Bollinger
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA, Fax: +1‐814‐863‐7024
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
| | - John C. Price
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA, Fax: +1‐814‐863‐7024
| | - Lee M. Hoffart
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA, Fax: +1‐814‐863‐7024
| | - Eric W. Barr
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA, Fax: +1‐814‐863‐7024
| | - Carsten Krebs
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA, Fax: +1‐814‐863‐7024
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA
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43
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Shan X, Que L. Intermediates in the oxygenation of a nonheme diiron(II) complex, including the first evidence for a bound superoxo species. Proc Natl Acad Sci U S A 2005; 102:5340-5. [PMID: 15802473 PMCID: PMC556236 DOI: 10.1073/pnas.0409640102] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The reaction of [Fe(2)(mu-OH)(2)(6-Me(3)-TPA)(2)](2+) (1) [6-Me(3)-TPA, Tris(6-methyl-2-pyridylmethyl)amine] with O(2) in CH(2)Cl(2) at -80 degrees C gives rise to two new intermediates, 2 and 3, before the formation of previously characterized [Fe(2)(O)(O(2))(6-Me(3)-TPA)(2)](2+) (4) that allow the oxygenation reaction to be monitored one electron-transfer step at a time. Raman evidence assigns 2 and 3 as a diiron-superoxo species and a diiron-peroxo species, respectively. Intermediate 2 exhibits its nu(O-O) at 1,310 cm(-1) with a -71-cm(-1) (18)O isotope shift. A doublet peak pattern for the (16)O(18)O isotopomer of 2 in mixed-isotope Raman experiments strongly suggests that the superoxide ligand of 2 is bound end-on. This first example of a nonheme iron-superoxo intermediate exhibits the highest frequency nu(O-O) yet observed for a biomimetic metal-dioxygen adduct. The bound superoxide of 2, unlike the bound peroxide of 4, is readily reduced by 2,4-di-tert-butylphenol via a proton-coupled electron-transfer mechanism, emphasizing that metal-superoxo species may serve as oxidants in oxygen activation mechanisms of metalloenzymes. The discovery of intermediates 2 and 3 allows us to dissect the initial steps of dioxygen binding at a diiron center leading to its activation for substrate oxidation.
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Affiliation(s)
- Xiaopeng Shan
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota, 207 Pleasant Street Southeast, Minneapolis, MN 55455, USA
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Lu S, Libby E, Saleh L, Xing G, Bollinger JM, Moënne-Loccoz P. Characterization of NO adducts of the diiron center in protein R2 of Escherichia coli ribonucleotide reductase and site-directed variants; implications for the O2 activation mechanism. J Biol Inorg Chem 2004; 9:818-27. [PMID: 15311337 DOI: 10.1007/s00775-004-0582-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2004] [Accepted: 07/06/2004] [Indexed: 11/30/2022]
Abstract
The R2 subunit of Escherichia coli ribonucleotide reductase contains a diiron site that reacts with O(2) to produce a tyrosine radical (Y122.). In wild-type R2 (R2-wt), the first observable reaction intermediate is a high-valent [Fe(III)-Fe(IV)] state called compound X, but in related diiron proteins such as methane monooxygenase, Delta(9)-desaturase, and ferritin, peroxodiiron(III) complexes have been characterized. Substitution of iron ligand D84 by E within the active site of R2 allows an intermediate (mu-1,2-peroxo)diiron species to accumulate. To investigate the possible involvement of a bridging peroxo species within the O(2) activation sequence of R2-wt, we have characterized the iron-nitrosyl species that form at the diiron sites in R2-wt, R2-D84E, and R2-W48F/D84E by using vibrational spectroscopy. Previous work has shown that the diiron center in R2-wt binds one NO per iron to form an antiferromagnetically coupled [(FeNO)(7)](2) center. In the wt and variant proteins, we also observe that both irons bind one NO to form a (FeNO)(7) dimer where both Fe-N-O units share a common vibrational signature. In the wt protein, nu(Fe-NO), delta(Fe-N-O), and nu(N-O) bands are observed at 445, 434 and 1742 cm(-1), respectively, while in the variant proteins the nu(Fe-NO) and delta(Fe-N-O) bands are observed approximately 10 cm(-1) higher and the nu(N-O) approximately 10 cm(-1) lower at 1735 cm(-1). These results demonstrate that all three proteins accommodate fully symmetric [(FeNO)(7)](2) species with two identical Fe-N-O units. The formation of equivalent NO adducts in the wt and variant proteins strongly favors the formation of a symmetric bridging peroxo intermediate during the O(2) activation process in R2-wt.
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Affiliation(s)
- Shen Lu
- Department of Environmental & Biomolecular Systems, OGI School of Science & Engineering, Oregon Health & Science University, Beaverton, OR 97006-8921, USA
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Patra AK, Rowland JM, Marlin DS, Bill E, Olmstead MM, Mascharak PK. Iron nitrosyls of a pentadentate ligand containing a single carboxamide group: syntheses, structures, electronic properties, and photolability of NO. Inorg Chem 2004; 42:6812-23. [PMID: 14552634 DOI: 10.1021/ic0301627] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Three iron complexes of a pentadentate ligand N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-carboxamide (PaPy(3)H, H is the dissociable amide proton) have been synthesized. All three species, namely, two nitrosyls [(PaPy(3))Fe(NO)](ClO(4))(2) (2) and [(PaPy(3))Fe(NO)](ClO(4)) (3) and one nitro complex [(PaPy(3))Fe(NO(2))](ClO(4)) (4), have been structurally characterized. These complexes provide the opportunity to compare the structural and spectral properties of a set of isostructural [Fe-NO](6,7) complexes (2 and 3, respectively) and an analogous genuine Fe(III) complex with an "innocent" sixth ligand ([(PaPy(3))Fe(NO(2))](ClO(4)), 4). The most striking difference in the structural features of 2 and 3 is the Fe-N-O angle (Fe-N-O = 173.1(2) degrees in the case of 2 and 141.29(15) degrees in the case of 3). The clean (1)H NMR spectrum of 2 in CD(3)CN reveals its S = 0 ground state and confirms its [Fe-NO](6) configuration. The binding of NO at the non-heme iron center in 2 is completely reversible and the bound NO is photolabile. Mössbauer data, electron paramagnetic resonance signal at g approximately 2.00, and variable temperature magnetic susceptibility measurements indicate the S = (1)/(2) spin state of the [Fe-NO](7) complex 3. Analysis of the spectroscopic data suggests Fe(II)-NO(+) and Fe(II)-NO(*) formulations for 2 and 3, respectively. The bound NO in 3 does not show any photolability. However, in MeCN solution, it reacts rapidly with dioxygen to afford the nitro complex 4, which has also been synthesized independently from [(PaPy(3))Fe(MeCN)](2+) and NO(2)(-). Nucleophilic attack of hydroxide ion to the N atom of the NO ligand in 2 in MeCN in the dark gives rise to 4 in high yield.
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Affiliation(s)
- Apurba K Patra
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
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Clay MD, Cosper CA, Jenney FE, Adams MWW, Johnson MK. Nitric oxide binding at the mononuclear active site of reduced Pyrococcus furiosus superoxide reductase. Proc Natl Acad Sci U S A 2003; 100:3796-801. [PMID: 12655067 PMCID: PMC153001 DOI: 10.1073/pnas.0636858100] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nitric oxide (NO) has been used as a substrate analog to explore the structural and electronic determinants of enzymatic superoxide reduction at the mononuclear iron active site of Pyrococcus furiosus superoxide reductase (SOR) through the use of EPR, resonance Raman, Fourier transform IR, UV-visible absorption, and variable-temperature variable-field magnetic CD spectroscopies. The NO adduct of reduced SOR is shown to have a near-axial S = 32 ground state with ED = 0.06 and D = 12 +/- 2 cm(-1) (where D and E are the axial and rhombic zero-field splitting parameters, respectively) and the UV-visible absorption and magnetic CD spectra are dominated by an out-of-plane NO(-)(pi*)-to-Fe(3+)(dpi) charge-transfer transition, polarized along the zero-field splitting axis. Resonance Raman studies indicate that the NO adduct is six-coordinate with NO ligated in a bent conformation trans to the cysteinyl S, as evidenced by the identification of nu(N-O) at 1,721 cm(-1), nu(Fe-NO) at 475 cm(-1), and nu(Fe-S(Cys), at 291 cm(-1), via (34)S and (15)NO isotope shifts. The electronic and vibrational properties of the S = 32 (FeNO)(7) unit are rationalized in terms of a limiting formulation involving a high-spin (S = 52) Fe(3+) center antiferromagnetically coupled to a (S = 1) NO(-) anion, with a highly covalent Fe(3+)-NO(-) interaction. The results support a catalytic mechanism for SOR, with the first step involving oxidative addition of superoxide to form a ferric-peroxo intermediate, and indicate the important roles that the Fe spin state and the trans cysteinate ligand play in effecting superoxide reduction and peroxide release.
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Affiliation(s)
- Michael D Clay
- Department of Chemistry, University of Georgia, Athens, GA 30602, USA
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47
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Li M, Bonnet D, Bill E, Neese F, Weyhermüller T, Blum N, Sellmann D, Wieghardt K. Tuning the electronic structure of octahedral iron complexes [FeL(X)] (L = 1-alkyl-4,7-bis(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane, X = Cl, CH(3)O, CN, NO). The S = 1/2 <==>3/2 Spin equilibrium of [FeL(Pr)(NO)]. Inorg Chem 2002; 41:3444-56. [PMID: 12079463 DOI: 10.1021/ic011243a] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two new pentadentate, pendent arm macrocyclic ligands of the type 1-alkyl-4,7-bis(4-tert-butyl-2-mercaptobenzyl)-1,4,7-triazacyclononane where alkyl represents an isopropyl, (L(Pr))(2-), or an ethyl group, (L(Et))(2-), have been synthesized. It is shown that they bind strongly to ferric ions generating six-coordinate species of the type [Fe(L(alk))X]. The ground state of these complexes is governed by the nature of the sixth ligand, X: [Fe(III)(L(Et))Cl] (2) possesses an S = 5/2 ground state as do [Fe(III)(L(Et))(OCH(3))] (3) and [Fe(III)(L(Pr))(OCH(3))] (4). In contrast, the cyano complexes [Fe(III)(L(Et))(CN)] (5) and [Fe(III)(L(Pr))(CN)] (6) are low spin ferric species (S = 1/2). The octahedral [FeNO](7) nitrosyl complex [Fe(L(Pr))(NO)] (7) displays spin equilibrium behavior S = 1/2<==>S = (3)/(2) in the solid state. Complexes [Zn(L(Pr))] (1), 4.CH(3)OH, 5.0.5toluene.CH(2)Cl(2), and 7.2.5CH(2)Cl(2) have been structurally characterized by low-temperature (100 K) X-ray crystallography. All iron complexes have been carefully studied by zero- and applied-field Mössbauer spectroscopy. In addition, Sellmann's complexes [Fe(pyS(4))(NO)](0/1+) and [Fe(pyS(4))X] (X = PR(3), CO, SR(2)) have been studied by EPR and Mössbauer spectroscopies and DFT calculations (pyS(4) = 2,6-bis(2-mercaptophenylthiomethyl)pyridine(2-)). It is concluded that the electronic structure of 7 with an S = 1/2 ground state is low spin ferrous (S(Fe) = 0) with a coordinated neutral NO radical (Fe(II)-NO) whereas the S = 3/2 state corresponds to a high spin ferric (S(Fe) = 5/2) antiferromagnetically coupled to an NO(-) anion (S = 1). The S = 1/2<==>S = 3/2 equilibrium is then that of valence tautomers rather than that of a simple high spin<==>low spin crossover.
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Affiliation(s)
- Ming Li
- Max-Planck-Institut für Strahlenchemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
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48
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Chatel S, Chauvin AS, Tuchagues JP, Leduc P, Bill E, Chottard JC, Mansuy D, Artaud I. Structural and spectroscopic characterization of a five-coordinate {Fe(NO)}6 complex derived from an iron complex with carboxamido N and thiolato S donors. Inorganica Chim Acta 2002. [DOI: 10.1016/s0020-1693(02)00818-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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49
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Wanat A, Wolak M, Orzeł Ł, Brindell M, van Eldik R, Stochel G. Laser flash photolysis as tool in the elucidation of the nitric oxide binding mechanism to metallobiomolecules. Coord Chem Rev 2002. [DOI: 10.1016/s0010-8545(02)00091-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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50
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Schneppensieper T, Wanat A, Stochel G, van Eldik R. Mechanistic information on the reversible binding of NO to selected iron(II) chelates from activation parameters. Inorg Chem 2002; 41:2565-73. [PMID: 11978128 DOI: 10.1021/ic011220w] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mechanistic insight on the reversible binding of NO to Fe(II) chelate complexes as potential catalysts for the removal of NO from effluent gas streams has been obtained from the temperature and pressure parameters for the "on" and "off" reactions determined using a combination of flash photolysis and stopped-flow techniques. These parameters are correlated with those for water exchange reactions on the corresponding Fe(II) and Fe(III) chelate complexes, from which mechanistic conclusions are drawn. Small and positive Delta V(++) values are found for NO binding to and release from all the selected complexes, consistent with a dissociative interchange (I(d)) mechanism. The only exception in the series of studied complexes is the binding of NO to [Fe(II)(nta)(H(2)O)(2)](-). The negative volume of activation observed for this reaction supports the operation of an I(a) ligand substitution mechanism. The apparent mechanistic differences can be accounted for in terms of the electronic and structural features of the studied complexes. The results indicate that the aminocarboxylate chelates affect the rate and overall equilibrium constants, as well as the nature of the substitution mechanism by which NO coordinates to the selected complexes. There is, however, no simple correlation between the rate and activation parameters and the selected donor groups or overall charge on the iron(II) complexes.
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Affiliation(s)
- Thorsten Schneppensieper
- Institute for Inorganic Chemistry, University of Erlangen-Nürnberg, Egerlandstrasse 1, 91058 Erlangen, Germany
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