1
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Börner M, Fuhrmann D, Klose J, Krautscheid H, Kersting B. Ethereal Hydroperoxides: Powerful Reagents for S-Oxygenation of Bridging Thiophenolate Functions. Inorg Chem 2021; 60:13517-13527. [PMID: 34415154 DOI: 10.1021/acs.inorgchem.1c01854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
S-Oxygenation of thiophenolate bridges by ethereal hydroperoxides was studied. [NiII2LS(PhCO2)]+ (1), where LS = macrocyclic aminethiolate supporting ligand, is S-oxygenated readily in a mixed methanol/acetonitrile solution with ether/dioxygen at room temperature in the presence of daylight. The reactions were found to depend strongly on the choice of the ether. Uptake of two O atoms occurs in dioxane to give a mixed thiolate/sulfinate complex [NiII2LSO2(PhCO2)]+ (2) containing the rare five-membered Ni(μ1,1-S)(μ1,2-OS)Ni core. In tetrahydrofuran, four O atoms are taken up by 1 to generate the bis(sulfinate) species [NiII2LSO4(PhCO2)]+ (3). A mono-S-oxygenated sulfenate intermediate can be detected by electrospray ionization mass spectrometry. The oxygenation reactions proceed in high yields without complex disintegration and invariably provide μ1,2-bridging sulfinates as established by spectroscopy (IR and UV/vis), X-ray crystallography, and accompanying density functional theory calculations. The oxygenation of the S atoms has a strong impact on the electronic structures of the nickel complexes. The monosulfinate complex 2 has an S = 2 ground state resulting from moderate ferromagnetic exchange coupling interactions (J = +15.7 cm-1; H = -2JS1S2), while an antiferromagnetic exchange interaction in 3 shows the presence of a ground state with spin S = 0 (J = -0.56 cm-1).
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Affiliation(s)
- Martin Börner
- Institut für Anorganische Chemie, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany.,Leibniz-Institut für Oberflächenmodifizierung, Abteilung Funktionale Oberflächen, Permoserstrasse 15, D-04318 Leipzig, Germany
| | - Daniel Fuhrmann
- Institut für Anorganische Chemie, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany
| | - Jennifer Klose
- Institut für Anorganische Chemie, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany
| | - Harald Krautscheid
- Institut für Anorganische Chemie, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany
| | - Berthold Kersting
- Institut für Anorganische Chemie, Universität Leipzig, Johannisallee 29, 04103 Leipzig, Germany
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2
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Domergue J, Guinard P, Douillard M, Pécaut J, Proux O, Lebrun C, Le Goff A, Maldivi P, Delangle P, Duboc C. A Bioinspired Ni II Superoxide Dismutase Catalyst Designed on an ATCUN-like Binding Motif. Inorg Chem 2021; 60:12772-12780. [PMID: 34416109 DOI: 10.1021/acs.inorgchem.1c00899] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nickel superoxide dismutase (NiSOD) is an enzyme that protects cells against O2·-. While the structure of its active site is known, the mechanism of the catalytic cycle is still not elucidated. Its active site displays a square planar NiII center with two thiolates, the terminal amine and an amidate. We report here a bioinspired NiII complex built on an ATCUN-like binding motif modulated with one cysteine, which demonstrates catalytic SOD activity in water (kcat = 8.4(2) × 105 M-1 s-1 at pH = 8.1). Its reactivity with O2·- was also studied in acetonitrile allowing trapping two different short-lived species that were characterized by electron paramagnetic resonance or spectroelectrochemistry and a combination of density functional theory (DFT) and time-dependent DFT calculations. Based on these observations, we propose that O2·- interacts first with the complex outer sphere through a H-bond with the peptide scaffold in a [NiIIO2·-] species. This first species could then evolve into a NiIII hydroperoxo inner sphere species through a reaction driven by protonation that is thermodynamically highly favored according to DFT calculations.
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Affiliation(s)
- Jérémy Domergue
- Universite Grenoble Alpes, CNRS, DCM, Grenoble 38000, France.,Universite Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble 38000, France
| | - Pawel Guinard
- Universite Grenoble Alpes, CNRS, DCM, Grenoble 38000, France.,Universite Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble 38000, France
| | - Magali Douillard
- Universite Grenoble Alpes, CNRS, DCM, Grenoble 38000, France.,Universite Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble 38000, France
| | - Jacques Pécaut
- Universite Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble 38000, France
| | - Olivier Proux
- Universite Grenoble Alpes, CNRS, OSUG, Grenoble 38000, France
| | - Colette Lebrun
- Universite Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble 38000, France
| | - Alan Le Goff
- Universite Grenoble Alpes, CNRS, DCM, Grenoble 38000, France
| | - Pascale Maldivi
- Universite Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble 38000, France
| | - Pascale Delangle
- Universite Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, Grenoble 38000, France
| | - Carole Duboc
- Universite Grenoble Alpes, CNRS, DCM, Grenoble 38000, France
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3
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Domergue J, Pécaut J, Proux O, Lebrun C, Gateau C, Le Goff A, Maldivi P, Duboc C, Delangle P. Mononuclear Ni(II) Complexes with a S3O Coordination Sphere Based on a Tripodal Cysteine-Rich Ligand: pH Tuning of the Superoxide Dismutase Activity. Inorg Chem 2019; 58:12775-12785. [PMID: 31545024 DOI: 10.1021/acs.inorgchem.9b01686] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The superoxide dismutase (SOD) activity of mononuclear NiII complexes, whose structures are inspired by the NiSOD, has been investigated. They have been designed with a sulfur-rich pseudopeptide ligand, derived from nitrilotriacetic acid (NTA), where the three acid functions are grafted with cysteines (L3S). Two mononuclear complexes, which exist in pH-dependent proportions, have been fully characterized by a combination of spectroscopic techniques including 1H NMR, UV-vis, circular dichroism, and X-ray absorption spectroscopy, together with theoretical calculations. They display similar square-planar S3O coordination, with the three thiolates of the three cysteine moieties from L3S coordinated to the NiII ion, together with either a water molecule at physiological pH, as [NiL3S(OH2)]-, or a hydroxo ion in more basic conditions, as [NiL3S(OH)]2-. The 1H NMR study has revealed that contrary to the hydroxo ligand, the bound water molecule is labile. The cyclic voltammogram of both complexes displays an irreversible one-electron oxidation process assigned to the NiII/NiIII redox system with Epa = 0.48 and 0.31 V versus SCE for NiL3S(OH2) and NiL3S(OH), respectively. The SOD activity of both complexes has been tested. On the basis of the xanthine oxidase assay, an IC50 of about 1 μM has been measured at pH 7.4, where NiL3S(OH2) is mainly present (93% of the NiII species), while the IC50 is larger than 100 μM at pH 9.6, where NiL3S(OH) is the major species (92% of the NiII species). Interestingly, only NiL3S(OH2) displays SOD activity, suggesting that the presence of a labile ligand is required. The SOD activity has been also evaluated under catalytic conditions at pH 7.75, where the ratio between NiL3S(OH2)/ NiL3S(OH) is about (86:14), and a rate constant, kcat = 1.8 × 105 M-1 s-1, has been measured. NiL3S(OH2) is thus the first low-molecular weight, synthetic, bioinspired Ni complex that displays catalytic SOD activity in water at physiological pH, although it does not contain any N-donor ligand in its first coordination sphere, as in the NiSOD. Overall, the data show that a key structural feature is the presence of a labile ligand in the coordination sphere of the NiII ion.
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Affiliation(s)
- Jérémy Domergue
- Univ. Grenoble Alpes, CNRS, DCM , 38000 Grenoble , France.,Univ. Grenoble Alpes, CEA, CNRS, IRIG, SYMMES , 38000 Grenoble , France
| | - Jacques Pécaut
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SYMMES , 38000 Grenoble , France
| | - Olivier Proux
- Univ. Grenoble Alpes, CNRS, OSUG , 38000 Grenoble , France
| | - Colette Lebrun
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SYMMES , 38000 Grenoble , France
| | - Christelle Gateau
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SYMMES , 38000 Grenoble , France
| | - Alan Le Goff
- Univ. Grenoble Alpes, CNRS, DCM , 38000 Grenoble , France
| | - Pascale Maldivi
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SYMMES , 38000 Grenoble , France
| | - Carole Duboc
- Univ. Grenoble Alpes, CNRS, DCM , 38000 Grenoble , France
| | - Pascale Delangle
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SYMMES , 38000 Grenoble , France
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4
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Merlini ML, Britovsek GJP, Swart M, Belanzoni P. Understanding the Catalase-Like Activity of a Bioinspired Manganese(II) Complex with a Pentadentate NSNSN Ligand Framework. A Computational Insight into the Mechanism. ACS Catal 2018. [DOI: 10.1021/acscatal.7b03559] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Maria Letizia Merlini
- Laboratoire de Chimie et Biochimie Computationnelles, Institut des Sciences et Ingénierie Chimiques, École Polytechnique Fédérale de Lausanne (EPFL), Av. F.-A. Forel 2, CH-1015 Lausanne, Switzerland
| | - George J. P. Britovsek
- Department of Chemistry, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Marcel Swart
- Institut de Química Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Facultat de Ciències, 17003 Girona, Spain
- Institució Catalana de Recerca i Estudis Avançats ICREA, Pg. Lluís Companys 23, 08010 Barcelona, Spain
| | - Paola Belanzoni
- Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
- Istituto di Scienze e Tecnologie Molecolari del CNR CNR-ISTM, c/o Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, via Elce di Sotto 8, 06123 Perugia, Italy
- Consortium for Computational Molecular and Materials Sciences (CMS)2, via Elce di Sotto 8, 06123 Perugia, Italy
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5
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Truong PT, Gale EM, Dzul SP, Stemmler TL, Harrop TC. Steric Enforcement about One Thiolate Donor Leads to New Oxidation Chemistry in a NiSOD Model Complex. Inorg Chem 2017; 56:7761-7780. [PMID: 28459242 DOI: 10.1021/acs.inorgchem.7b00485] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ni-containing superoxide dismutase (NiSOD) represents an unusual member of the SOD family due to the presence of oxygen-sensitive Ni-SCys bonds at its active site. Reported in this account is the synthesis and properties of the NiII complex of the N3S2 ligand [N3S2Me2]3- ([N3S2Me2]3- = deprotonated form of 2-((2-mercapto-2-methylpropyl)(pyridin-2-ylmethyl)amino)-N-(2-mercaptoethyl)acetamide), namely Na[Ni(N3S2Me2)] (2), as a NiSOD model that features sterically robust gem-(CH3)2 groups on the thiolate α-C positioned trans to the carboxamide. The crystal structure of 2, coupled with spectroscopic measurements from 1H NMR, X-ray absorption, IR, UV-vis, and mass spectrometry (MS), reveal a planar NiII (S = 0) ion coordinated by only the N2S2 basal donors of the N3S2 ligand. While the structure and spectroscopic properties of 2 resemble those of NiSODred and other models, the asymmetric S ligands open up new reaction paths upon chemical oxidation. One unusual oxidation product is the planar NiII-N3S complex [Ni(Lox)] (5; Lox = 2-(5,5-dimethyl-2-(pyridin-2-yl)thiazolidin-3-yl)-N-(2-mercaptoethyl)acetamide), where two-electron oxidation takes place at the substituted thiolate and py-CH2 carbon to generate a thiazolidine heterocycle. Electrochemical measurements of 2 reveal irreversible events wholly consistent with thiolate redox, which were identified by comparison to the ZnII complex Na[Zn(N3S2Me2)] (3). Although no reaction is observed between 2 and azide, reaction of 2 with superoxide produces multiple products on the basis of UV-vis and MS data, one of which is 5. Density functional theory (DFT) computations suggest that the HOMO in 2 is π* with primary contributions from Ni-dπ/S-pπ orbitals. These contributions can be modulated and biased toward Ni when electron-withdrawing groups are placed on the thiolate α-C. Analysis of the oxidized five-coordinate species 2ox* by DFT reveal a singly occupied spin-up (α) MO that is largely thiolate based, which supports the proposed NiIII-thiolate/NiII-thiyl radical intermediates that ultimately yield 5 and other products.
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Affiliation(s)
- Phan T Truong
- Department of Chemistry and Center for Metalloenzyme Studies, The University of Georgia , 140 Cedar Street, Athens, Georgia 30602, United States
| | - Eric M Gale
- Department of Chemistry and Center for Metalloenzyme Studies, The University of Georgia , 140 Cedar Street, Athens, Georgia 30602, United States
| | - Stephen P Dzul
- Departments of Pharmaceutical Sciences, Biochemistry and Molecular Biology, Wayne State University , Detroit, Michigan 48201, United States
| | - Timothy L Stemmler
- Departments of Pharmaceutical Sciences, Biochemistry and Molecular Biology, Wayne State University , Detroit, Michigan 48201, United States
| | - Todd C Harrop
- Department of Chemistry and Center for Metalloenzyme Studies, The University of Georgia , 140 Cedar Street, Athens, Georgia 30602, United States
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6
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Steiner RA, Dzul SP, Stemmler TL, Harrop TC. Synthesis and Speciation-Dependent Properties of a Multimetallic Model Complex of NiSOD That Exhibits Unique Hydrogen-Bonding. Inorg Chem 2017; 56:2849-2862. [PMID: 28212040 DOI: 10.1021/acs.inorgchem.6b02997] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The complex Na3[{NiII(nmp)}3S3BTAalk)] (1) (nmp2- = deprotonated form of N-(2-mercaptoethyl)picolinamide; H3S3BTAalk = N1,N3,N5-tris(2-mercaptoethyl)benzene-1,3,5-tricarboxamide, where H = dissociable protons), supported by the thiolate-benzenetricarboxamide scaffold (S3BTAalk), has been synthesized as a trimetallic model of nickel-containing superoxide dismutase (NiSOD). X-ray absorption spectroscopy (XAS) and 1H NMR measurements on 1 indicate that the NiII centers are square-planar with N2S2 coordination, and Ni-N and Ni-S distances of 1.95 and 2.16 Å, respectively. Additional evidence from IR indicates the presence of H-bonds in 1 from the approximately -200 cm-1 shift in νNH from free ligand. The presence of H-bonds allows for speciation that is temperature-, concentration-, and solvent-dependent. In unbuffered water and at low temperature, a dimeric complex (1A; λ = 410 nm) that aggregates through intermolecular NH···O═C bonds of BTA units is observed. Dissolution of 1 in pH 7.4 buffer or in unbuffered water at temperatures above 50 °C results in monomeric complex (1M; λ = 367 nm) linked through intramolecular NH···S bonds. DFT computations indicate a low energy barrier between 1A and 1M with nearly identical frontier MOs and Ni-ligand metrics. Notably, 1A and 1M exhibit remarkable stability in protic solvents such as MeOH and H2O, in stark contrast to monometallic [NiII(nmp)(SR)]- complexes. The reactivity of 1 with excess O2, H2O2, and O2•- is species-dependent. IR and UV-vis reveal that 1A in MeOH reacts with excess O2 to yield an S-bound sulfinate, but does not react with O2•-. In contrast, 1M is stable to O2 in pH 7.4 buffer, but reacts with O2•- to yield a putative [NiII(nmp)(O2)]- complex from release of the BTA-thiolate based on EPR.
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Affiliation(s)
- Ramsey A Steiner
- Department of Chemistry and Center for Metalloenzyme Studies, The University of Georgia , 140 Cedar St, Athens, Georgia 30602, United States
| | - Stephen P Dzul
- Departments of Pharmaceutical Sciences, and Biochemistry and Molecular Biology, Wayne State University , Detroit, Michigan 48201, United States
| | - Timothy L Stemmler
- Departments of Pharmaceutical Sciences, and Biochemistry and Molecular Biology, Wayne State University , Detroit, Michigan 48201, United States
| | - Todd C Harrop
- Department of Chemistry and Center for Metalloenzyme Studies, The University of Georgia , 140 Cedar St, Athens, Georgia 30602, United States
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7
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Shearer J, Peck KL, Schmitt JC, Neupane KP. Cysteinate protonation and water hydrogen bonding at the active-site of a nickel superoxide dismutase metallopeptide-based mimic: implications for the mechanism of superoxide reduction. J Am Chem Soc 2014; 136:16009-22. [PMID: 25322331 DOI: 10.1021/ja5079514] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nickel-containing superoxide dismutase (NiSOD) is a mononuclear cysteinate-ligated nickel metalloenzyme that catalyzes the disproportionation of superoxide into dioxygen and hydrogen peroxide by cycling between Ni(II) and Ni(III) oxidation states. All of the ligating residues to nickel are found within the first six residues from the N-terminus, which has prompted several research groups to generate NiSOD metallopeptide-based mimics derived from the first several residues of the NiSOD sequence. To assess the viability of using these metallopeptide-based mimics (NiSOD maquettes) to probe the mechanism of SOD catalysis facilitated by NiSOD, we computationally explored the initial step of the O2(-) reduction mechanism catalyzed by the NiSOD maquette {Ni(II)(SOD(m1))} (SOD(m1) = HCDLP CGVYD PA). Herein we use spectroscopic (S K-edge X-ray absorption spectroscopy, electronic absorption spectroscopy, and circular dichroism spectroscopy) and computational techniques to derive the detailed active-site structure of {Ni(II)(SOD(m1))}. These studies suggest that the {Ni(II)(SOD(m1))} active-site possesses a Ni(II)-S(H(+))-Cys(6) moiety and at least one associated water molecule contained in a hydrogen-bonding interaction to the coordinated Cys(2) and Cys(6) sulfur atoms. A computationally derived mechanism for O2(-) reduction using the formulated active-site structure of {Ni(II)(SOD(m1))} suggests that O2(-) reduction takes place through an apparent initial outersphere hydrogen atom transfer (HAT) from the Ni(II)-S(H(+))-Cys(6) moiety to the O2(-) molecule. It is proposed that the water molecule aids in driving the reaction forward by lowering the Ni(II)-S(H(+))-Cys(6) pK(a). Such a mechanism is not possible in NiSOD itself for structural reasons. These results therefore strongly suggest that maquettes derived from the primary sequence of NiSOD are mechanistically distinct from NiSOD itself despite the similarities in the structure and physical properties of the metalloenzyme vs the NiSOD metallopeptide-based models.
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Affiliation(s)
- Jason Shearer
- Department of Chemistry, University of Nevada, Reno , Reno, Nevada 89557, United States
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8
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Nguyen VH, Chew HQ, Su B, Yip JHK. Synthesis and Spectroscopy of Anionic Cyclometalated Iridium(III)-Dithiolate and -Sulfinates—Effect of Sulfur Dioxygenation on Electronic Structure and Luminescence. Inorg Chem 2014; 53:9739-50. [DOI: 10.1021/ic501278n] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Van Ha Nguyen
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Hui Qi Chew
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - Bochao Su
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
| | - John H. K. Yip
- Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543
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9
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Shearer J. Insight into the structure and mechanism of nickel-containing superoxide dismutase derived from peptide-based mimics. Acc Chem Res 2014; 47:2332-41. [PMID: 24825124 DOI: 10.1021/ar500060s] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Nickel superoxide dismutase (NiSOD) is a nickel-containing metalloenzyme that catalyzes the disproportionation of superoxide through a ping-pong mechanism that relies on accessing reduced Ni(II) and oxidized Ni(III) oxidation states. NiSOD is the most recently discovered SOD. Unlike the other known SODs (MnSOD, FeSOD, and (CuZn)SOD), which utilize "typical" biological nitrogen and oxygen donors, NiSOD utilizes a rather unexpected ligand set. In the reduced Ni(II) oxidation state, NiSOD utilizes nitrogen ligands derived from the N-terminal amine and an amidate along with two cysteinates sulfur donors. These are unusual biological ligands, especially for an SOD: amine and amidate donors are underrepresented as biological ligands, whereas cysteinates are highly susceptible to oxidative damage. An axial histidine imidazole binds to nickel upon oxidation to Ni(III). This bond is long (2.3-2.6 Å) owing to a tight hydrogen-bonding network. All of the ligating residues to Ni(II) and Ni(III) are found within the first 6 residues from the NiSOD N-terminus. Thus, small nickel-containing metallopeptides derived from the first 6-12 residues of the NiSOD sequence can reproduce many of the properties of NiSOD itself. Using these nickel-containing metallopeptide-based NiSOD mimics, we have shown that the minimal sequence needed for nickel binding and reproduction of the structural, spectroscopic, and functional properties of NiSOD is H2N-HCXXPC. Insight into how NiSOD avoids oxidative damage has also been gained. Using small NiN2S2 complexes and metallopeptide-based mimics, it was shown that the unusual nitrogen donor atoms protect the cysteinates from oxidative damage (both one-electron oxidation and oxygen atom insertion reactions) by fine-tuning the electronic structure of the nickel center. Changing the nitrogen donor set to a bis-amidate or bis-amine nitrogen donor led to catalytically nonviable species owing to nickel-cysteinate bond oxidative damage. Only the amine/amidate nitrogen donor atoms within the NiSOD ligand set produce a catalytically viable species. These metallopeptide-based mimics have also hinted at the detailed mechanism of SOD catalysis by NiSOD. One such aspect is that the axial imidazole likely remains ligated to the Ni center under rapid catalytic conditions (i.e., high superoxide loads). This reduces the degree of structural rearrangement about the nickel center, leading to higher catalytic rates. Metallopeptide-based mimics have also shown that, although an axial ligand to Ni(III) is required for catalysis, the rates are highest when this is a weak interaction, suggesting a reason for the long axial His-Ni(III) bond found in NiSOD. These mimics have also suggested a surprising mechanistic insight: O2(-) reduction via a "H(•)" tunneling event from a R-S(H(+))-Ni(II) moiety to O2(-) is possible. The importance of this mechanism in NiSOD has not been verified.
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Affiliation(s)
- Jason Shearer
- Department
of Chemistry, University of Nevada, Reno, Reno, Nevada 89557, United States
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10
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Nakane D, Wasada-Tsutsui Y, Funahashi Y, Hatanaka T, Ozawa T, Masuda H. A Novel Square-Planar Ni(II) Complex with an Amino—Carboxamido—Dithiolato-Type Ligand as an Active-Site Model of NiSOD. Inorg Chem 2014; 53:6512-23. [DOI: 10.1021/ic402574d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Daisuke Nakane
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan
| | - Yuko Wasada-Tsutsui
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan
| | - Yasuhiro Funahashi
- Department
of Chemistry, Graduate School of Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Tsubasa Hatanaka
- Department
of Chemistry, Graduate School of Science, Osaka University, 1-1
Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Tomohiro Ozawa
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan
| | - Hideki Masuda
- Department
of Frontier Materials, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan
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11
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Shearer J. Dioxygen and superoxide stability of metallopeptide based mimics of nickel containing superoxide dismutase: The influence of amine/amidate vs. bis-amidate ligation. J Inorg Biochem 2013; 129:145-9. [DOI: 10.1016/j.jinorgbio.2013.09.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 08/07/2013] [Accepted: 09/02/2013] [Indexed: 10/26/2022]
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12
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Widger LR, Jiang Y, Siegler M, Kumar D, Latifi R, de Visser SP, Jameson GN, Goldberg DP. Synthesis and ligand non-innocence of thiolate-ligated (N4S) Iron(II) and nickel(II) bis(imino)pyridine complexes. Inorg Chem 2013; 52:10467-80. [PMID: 23992096 PMCID: PMC3827697 DOI: 10.1021/ic4013558] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The known iron(II) complex [Fe(II)(LN3S)(OTf)] (1) was used as starting material to prepare the new biomimetic (N4S(thiolate)) iron(II) complexes [Fe(II)(LN3S)(py)](OTf) (2) and [Fe(II)(LN3S)(DMAP)](OTf) (3), where LN3S is a tetradentate bis(imino)pyridine (BIP) derivative with a covalently tethered phenylthiolate donor. These complexes were characterized by X-ray crystallography, ultraviolet-visible (UV-vis) spectroscopic analysis, (1)H nuclear magnetic resonance (NMR), and Mössbauer spectroscopy, as well as electrochemistry. A nickel(II) analogue, [Ni(II)(LN3S)](BF4) (5), was also synthesized and characterized by structural and spectroscopic methods. Cyclic voltammetric studies showed 1-3 and 5 undergo a single reduction process with E(1/2) between -0.9 V to -1.2 V versus Fc(+)/Fc. Treatment of 3 with 0.5% Na/Hg amalgam gave the monoreduced complex [Fe(LN3S)(DMAP)](0) (4), which was characterized by X-ray crystallography, UV-vis spectroscopic analysis, electron paramagnetic resonance (EPR) spectroscopy (g = [2.155, 2.057, 2.038]), and Mössbauer (δ = 0.33 mm s(-1); ΔE(Q) = 2.04 mm s(-1)) spectroscopy. Computational methods (DFT) were employed to model complexes 3-5. The combined experimental and computational studies show that 1-3 are 5-coordinate, high-spin (S = 2) Fe(II) complexes, whereas 4 is best described as a 5-coordinate, intermediate-spin (S = 1) Fe(II) complex antiferromagnetically coupled to a ligand radical. This unique electronic configuration leads to an overall doublet spin (S(total) = 1/2) ground state. Complexes 2 and 3 are shown to react with O2 to give S-oxygenated products, as previously reported for 1. In contrast, the monoreduced 4 appears to react with O2 to give a mixture of sulfur oxygenates and iron oxygenates. The nickel(II) complex 5 does not react with O2, and even when the monoreduced nickel complex is produced, it appears to undergo only outer-sphere oxidation with O2.
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Affiliation(s)
- Leland R. Widger
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Yunbo Jiang
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Maxime Siegler
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
| | - Devesh Kumar
- Department of Applied Physics, School for Physical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Rae Bareilly Road, Lucknow (U. P.) 226 025, India
| | - Reza Latifi
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Sam P. de Visser
- Manchester Institute of Biotechnology and School of Chemical Engineering and Analytical Science, The University of Manchester, 131 Princess Street, Manchester M1 7DN, United Kingdom
| | - Guy N.L. Jameson
- Department of Chemistry & MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - David P. Goldberg
- Department of Chemistry, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
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13
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Broering EP, Truong PT, Gale EM, Harrop TC. Synthetic Analogues of Nickel Superoxide Dismutase: A New Role for Nickel in Biology. Biochemistry 2012; 52:4-18. [DOI: 10.1021/bi3014533] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ellen P. Broering
- Department
of Chemistry and Center for Metalloenzyme
Studies, The University of Georgia, 1001
Cedar Street, Athens, Georgia 30602, United States
| | - Phan T. Truong
- Department
of Chemistry and Center for Metalloenzyme
Studies, The University of Georgia, 1001
Cedar Street, Athens, Georgia 30602, United States
| | - Eric M. Gale
- Department
of Chemistry and Center for Metalloenzyme
Studies, The University of Georgia, 1001
Cedar Street, Athens, Georgia 30602, United States
| | - Todd C. Harrop
- Department
of Chemistry and Center for Metalloenzyme
Studies, The University of Georgia, 1001
Cedar Street, Athens, Georgia 30602, United States
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14
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Bolligarla R, Das SK. Sulfur Oxygenation of [Ni(btdt)
2
]
2–
by Aerial Oxidation under Ambient Conditions – Syntheses, Crystal Structures, and Properties of [Bu
4
N]
2
[Ni(btdt)
2
] and [Bu
4
N]
2
[Ni(btdtO
2
)
2
]·H
2
O ({btdt}
2–
= 2,1,3‐Benzenethiadiazole‐5,6‐dithiolate). Eur J Inorg Chem 2012. [DOI: 10.1002/ejic.201101426] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Ramababu Bolligarla
- School of Chemistry, University of Hyderabad, P. O. Central University, Hyderabad 500046, Andhra Pradesh, India, Fax: +91‐40‐2301‐2460
| | - Samar K. Das
- School of Chemistry, University of Hyderabad, P. O. Central University, Hyderabad 500046, Andhra Pradesh, India, Fax: +91‐40‐2301‐2460
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