1
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Reactions of a Dioxidomolybdenum(VI) Complex with Thionation Reagents—Formation of Mo(IV) Species with Sulfur Donors. Molecules 2022; 27:molecules27217154. [PMID: 36363980 PMCID: PMC9655758 DOI: 10.3390/molecules27217154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 10/18/2022] [Accepted: 10/21/2022] [Indexed: 11/05/2022] Open
Abstract
Molecular molybdenum complexes with sulfur donor ligands are generally studied as soluble model compounds for molybdenum enzymes essential for life. The dioxidomolybdenum(VI) complex with tetradentate aminobisphenolate ligand undergoes a reaction with thionation reagent P2S5 or its organic derivative, Lawesson’s reagent, to yield stable Mo(IV) aminobisphenolate complexes, where pristine oxido ligands have been replaced by bidentate sulfur donors tetrasulfide, S42− or (4-methoxyphenyl)phosphonotrithioate residue derived from Lawesson’s reagent. This is in contrast to the behaviour of analogous dioxidotungsten(VI) complex, which, under similar conditions, yields W(VI) S2 systems. The overall cis,trans,cis geometry of the parent dioxidomolybdenum(VI) aminobisphenolate is retained, namely, the neutral nitrogen donors are in cis positions, phenolate oxygens are trans to each other and sulfur donors are cis. Although formally Mo(IV), thus d2 system, the studied complexes have diamagnetic singlet electron configurations as a result of the axially compressed octahedral structures.
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2
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Dille SA, Colston KJ, Ratvasky SC, Pu J, Basu P. Interligand communication in a metal mediated LL'CT system - a case study. RSC Adv 2021; 11:24381-24386. [PMID: 34354823 PMCID: PMC8285364 DOI: 10.1039/d1ra04716g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 07/06/2021] [Indexed: 11/22/2022] Open
Abstract
A series of oxo-Mo(iv) complexes, [MoO(Dt2−)(Dt0)] (where Dt2− = benzene-1,2-dithiol (bdt), toluene-3,4-dithiol (tdt), quinoxaline-2,3-dithiol (qdt), or 3,6-dichloro-benzene-1,2-dithiol (bdtCl2); Dt0 = N,N′-dimethylpiperazine-2,3-dithione (Me2Dt0) or N,N′-diisopropylpiperazine-2,3-dithione (iPr2Dt0)), possessing a fully oxidized and a fully reduced dithiolene ligand have been synthesized and characterized. The assigned oxidation states of coordinated dithiolene ligands are supported with spectral and crystallographic data. The molecular structure of [MoO(tdt)(iPr2Dt0)] (6) demonstrates a large ligand fold angle of 62.6° along the S⋯S vector of the Dt0 ligand. The electronic structure of this system is probed by density functional theory (DFT) calculations. The HOMO is largely localized on the Dt2− ligand while virtual orbitals are mostly Mo and Dt0 in character. Modeling the electronic spectrum of 6 with time dependent (TD) DFT calculations attributes the intense low energy transition at ∼18 000 cm−1 to a ligand-to-ligand charge transfer (LL′CT). The electron density difference map (EDDM) for the low energy transition depicts the electron rich Dt2− ligand donating charge density to the redox-active orbitals of the electron deficient Dt0 ligand. Electronic communication between dithiolene ligands is facilitated by a Mo-monooxo center and distortion about its primary coordination sphere. The interligand communication between non-innocent dithiolene ligands of different oxidation states has been described in a Mo system. The fully reduced ene-dithiolate (Dt2−) acts as a donor moiety to the oxidized dithione (Dt0) in an LL′CT process.![]()
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Affiliation(s)
- Sara A Dille
- Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis Indianapolis IN 46202 USA
| | - Kyle J Colston
- Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis Indianapolis IN 46202 USA
| | - Stephen C Ratvasky
- Department of Chemistry and Biochemistry, Duquesne University Pittsburgh PA 15282 USA
| | - Jingzhi Pu
- Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis Indianapolis IN 46202 USA
| | - Partha Basu
- Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis Indianapolis IN 46202 USA
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3
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Rusmore TA, Behlen MJ, John A, Glatzhofer DT, Nicholas KM. Oxidative kinetic resolution of P-chiral phosphines catalyzed by chiral (salen)dioxomolybdenum complexes. MOLECULAR CATALYSIS 2021. [DOI: 10.1016/j.mcat.2021.111776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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4
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Duffus BR, Schrapers P, Schuth N, Mebs S, Dau H, Leimkühler S, Haumann M. Anion Binding and Oxidative Modification at the Molybdenum Cofactor of Formate Dehydrogenase from Rhodobacter capsulatus Studied by X-ray Absorption Spectroscopy. Inorg Chem 2019; 59:214-225. [PMID: 31814403 DOI: 10.1021/acs.inorgchem.9b01613] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Formate dehydrogenase (FDH) enzymes are versatile catalysts for CO2 conversion. The FDH from Rhodobacter capsulatus contains a molybdenum cofactor with the dithiolene functions of two pyranopterin guanine dinucleotide molecules, a conserved cysteine, and a sulfido group bound at Mo(VI). In this study, we focused on metal oxidation state and coordination changes in response to exposure to O2, inhibitory anions, and redox agents using X-ray absorption spectroscopy (XAS) at the Mo K-edge. Differences in the oxidative modification of the bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor relative to samples prepared aerobically without inhibitor, such as variations in the relative numbers of sulfido (Mo═S) and oxo (Mo═O) bonds, were observed in the presence of azide (N3-) or cyanate (OCN-). Azide provided best protection against O2, resulting in a quantitatively sulfurated cofactor with a displaced cysteine ligand and optimized formate oxidation activity. Replacement of the cysteine ligand by a formate (HCO2-) ligand at the molybdenum in active enzyme is compatible with our XAS data. Cyanide (CN-) inactivated the enzyme by replacing the sulfido ligand at Mo(VI) with an oxo ligand. Evidence that the sulfido group may become protonated upon molybdenum reduction was obtained. Our results emphasize the role of coordination flexibility at the molybdenum center during inhibitory and catalytic processes of FDH enzymes.
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Affiliation(s)
- Benjamin R Duffus
- Institut für Biochemie und Biologie, Molekulare Enzymologie , Universität Potsdam , Karl-Liebknecht Strasse 24-25 , 14476 Potsdam , Germany
| | - Peer Schrapers
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Nils Schuth
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Stefan Mebs
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Holger Dau
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Silke Leimkühler
- Institut für Biochemie und Biologie, Molekulare Enzymologie , Universität Potsdam , Karl-Liebknecht Strasse 24-25 , 14476 Potsdam , Germany
| | - Michael Haumann
- Institut für Experimentalphysik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
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5
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Fogeron T, Retailleau P, Chamoreau L, Li Y, Fontecave M. Pyranopterin Related Dithiolene Molybdenum Complexes as Homogeneous Catalysts for CO
2
Photoreduction. Angew Chem Int Ed Engl 2018; 57:17033-17037. [DOI: 10.1002/anie.201809084] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 10/19/2018] [Indexed: 01/14/2023]
Affiliation(s)
- Thibault Fogeron
- Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS Collège de France, Université Paris Sorbonne 11 Place Marcelin Berthelot 75231 Paris Cedex 05 France
| | - Pascal Retailleau
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301 Université Paris-Saclay 1, av.de la Terrasse 91198 Gif-sur-Yvette France
| | - Lise‐Marie Chamoreau
- Sorbonne Universités Université Paris Sorbonne Institut Parisien de Chimie Moléculaire, UMR 8232 CNRS 4 place Jussieu 75252 Paris Cedex 5 France
| | - Yun Li
- Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS Collège de France, Université Paris Sorbonne 11 Place Marcelin Berthelot 75231 Paris Cedex 05 France
| | - Marc Fontecave
- Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS Collège de France, Université Paris Sorbonne 11 Place Marcelin Berthelot 75231 Paris Cedex 05 France
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6
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Fogeron T, Retailleau P, Chamoreau L, Li Y, Fontecave M. Pyranopterin Related Dithiolene Molybdenum Complexes as Homogeneous Catalysts for CO
2
Photoreduction. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201809084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Thibault Fogeron
- Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS Collège de France, Université Paris Sorbonne 11 Place Marcelin Berthelot 75231 Paris Cedex 05 France
| | - Pascal Retailleau
- Institut de Chimie des Substances Naturelles, CNRS UPR 2301 Université Paris-Saclay 1, av.de la Terrasse 91198 Gif-sur-Yvette France
| | - Lise‐Marie Chamoreau
- Sorbonne Universités Université Paris Sorbonne Institut Parisien de Chimie Moléculaire, UMR 8232 CNRS 4 place Jussieu 75252 Paris Cedex 5 France
| | - Yun Li
- Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS Collège de France, Université Paris Sorbonne 11 Place Marcelin Berthelot 75231 Paris Cedex 05 France
| | - Marc Fontecave
- Laboratoire de Chimie des Processus Biologiques, UMR 8229 CNRS Collège de France, Université Paris Sorbonne 11 Place Marcelin Berthelot 75231 Paris Cedex 05 France
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7
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Reschke S, Mebs S, Sigfridsson-Clauss KGV, Kositzki R, Leimkühler S, Haumann M. Protonation and Sulfido versus Oxo Ligation Changes at the Molybdenum Cofactor in Xanthine Dehydrogenase (XDH) Variants Studied by X-ray Absorption Spectroscopy. Inorg Chem 2017; 56:2165-2176. [DOI: 10.1021/acs.inorgchem.6b02846] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Stefan Reschke
- Institut für
Biochemie und Biologie, Molekulare Enzymologie, Universität Potsdam, 14476 Potsdam, Germany
| | - Stefan Mebs
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | | | - Ramona Kositzki
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Silke Leimkühler
- Institut für
Biochemie und Biologie, Molekulare Enzymologie, Universität Potsdam, 14476 Potsdam, Germany
| | - Michael Haumann
- Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
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8
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Ghosh AC, Samuel PP, Schulzke C. Synthesis, characterization and oxygen atom transfer reactivity of a pair of Mo(iv)O- and Mo(vi)O2-enedithiolate complexes – a look at both ends of the catalytic transformation. Dalton Trans 2017; 46:7523-7533. [DOI: 10.1039/c7dt01470h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A novel pair of mono-oxo and di-oxo bis-dithiolene molybdenum complexes were synthesized, characterized and catalytically investigated as models for a molybdenum dependent oxidoreductase.
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Affiliation(s)
- Ashta C. Ghosh
- Institute of Condensed Matter and Nanosciences
- Molecules
- Solids and Reactivity (IMCN/MOST)
- Université catholique de Louvain
- 1348 Louvain-la-Neuve
| | - Prinson P. Samuel
- Universität Göttingen
- Institut für Anorganische Chemie
- 37077 Göttingen
- Germany
| | - Carola Schulzke
- Institut für Biochemie
- Ernst-Moritz-Arndt-Universitat Greifswald
- 17487 Greifswald
- Germany
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9
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Correia MAS, Otrelo-Cardoso AR, Schwuchow V, Sigfridsson Clauss KGV, Haumann M, Romão MJ, Leimkühler S, Santos-Silva T. The Escherichia coli Periplasmic Aldehyde Oxidoreductase Is an Exceptional Member of the Xanthine Oxidase Family of Molybdoenzymes. ACS Chem Biol 2016; 11:2923-2935. [PMID: 27622978 DOI: 10.1021/acschembio.6b00572] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The xanthine oxidase (XO) family comprises molybdenum-dependent enzymes that usually form homodimers (or dimers of heterodimers/trimers) organized in three domains that harbor two [2Fe-2S] clusters, one FAD, and a Mo cofactor. In this work, we crystallized an unusual member of the family, the periplasmic aldehyde oxidoreductase PaoABC from Escherichia coli. This is the first example of an E. coli protein containing a molybdopterin-cytosine-dinucleotide cofactor and is the only heterotrimer of the XO family so far structurally characterized. The crystal structure revealed the presence of an unexpected [4Fe-4S] cluster, anchored to an additional 40 residues subdomain. According to phylogenetic analysis, proteins containing this cluster are widely spread in many bacteria phyla, putatively through repeated gene transfer events. The active site of PaoABC is highly exposed to the surface with no aromatic residues and an arginine (PaoC-R440) making a direct interaction with PaoC-E692, which acts as a base catalyst. In order to understand the importance of R440, kinetic assays were carried out, and the crystal structure of the PaoC-R440H variant was also determined.
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Affiliation(s)
- Márcia A. S. Correia
- UCIBIO/Requimte,
Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Ana Rita Otrelo-Cardoso
- UCIBIO/Requimte,
Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Viola Schwuchow
- Institut
für Biologie und Biochemie, Universität Potsdam, Am Neuen Palais
10, 14469 Potsdam, Deutschland
| | | | - Michael Haumann
- Freie Universität Berlin, Fachbereich Physik, 14195 Berlin, Germany
| | - Maria João Romão
- UCIBIO/Requimte,
Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Silke Leimkühler
- Institut
für Biologie und Biochemie, Universität Potsdam, Am Neuen Palais
10, 14469 Potsdam, Deutschland
| | - Teresa Santos-Silva
- UCIBIO/Requimte,
Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
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10
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Ghosh AC, Weisz K, Schulzke C. Selective Capture of Ni2+Ions by Naphthalene- and Coumarin-Substituted Dithiolenes. Eur J Inorg Chem 2015. [DOI: 10.1002/ejic.201500847] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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11
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Doonan CJ, Gourlay C, Nielsen DJ, Ng VWL, Smith PD, Evans DJ, George GN, White JM, Young CG. d(1) Oxosulfido-Mo(V) Compounds: First Isolation and Unambiguous Characterization of an Extended Series. Inorg Chem 2015; 54:6386-96. [PMID: 26046577 DOI: 10.1021/acs.inorgchem.5b00708] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reaction of Tp(iPr)Mo(VI)OS(OAr) with cobaltocene in toluene results in the precipitation of brown, microcrystalline oxosulfido-Mo(V) compounds, [CoCp2][Tp(iPr)Mo(V)OS(OAr)] (Cp(-) = η(5)-C5H5(-), Tp(iPr)(-) = hydrotris(3-isopropylpyrazol-1-yl)borate, OAr(-) = phenolate or 2-(s)Bu, 2-(t)Bu, 3-(t)Bu, 4-(s)Bu, 4-Ph, 3,5-(s)Bu2, 2-CO2Me, 2-CO2Et or 2-CO2Ph derivative thereof). The compounds are air- and water-sensitive and display ν(Mo═O) and ν(Mo[Formula: see text]S) IR absorption bands at ca. 890 and 435 cm(-1), respectively, 20-40 cm(-1) lower in energy than the corresponding bands in Tp(iPr)MoOS(OAr). They are electrochemically active and exhibit three reversible cyclovoltammetric waves (E(Mo(VI)/Mo(V)) = -0.40 to -0.66 V, E([CoCp2](+)/CoCp2) = -0.94 V and E(CoCp2/[CoCp2](-)) = -1.88 V vs SCE). Structural characterization of [CoCp2][Tp(iPr)MoOS(OC6H4CO2Et-2)]·2CH2Cl2 revealed a distorted octahedral Mo(V) anion with Mo═O and Mo[Formula: see text]S distances of 1.761(5) and 2.215(2) Å, respectively, longer than corresponding distances in related Tp(iPr)MoOS(OAr) compounds. The observation of strong S(1s) → (S(3p) + Mo(4d)) S K-preedge transitions indicative of a d(1) sulfido-Mo(V) moiety and the presence of short Mo═O (ca. 1.72 Å) and Mo[Formula: see text]S (ca. 2.25 Å) backscattering contributions in the Mo K-edge EXAFS further support the oxosulfido-Mo(V) formulation. The compounds are EPR-active, exhibiting highly anisotropic (Δg 0.124-0.150), rhombic, frozen-glass spectra with g1 close to the value observed for the free electron (ge = 2.0023). Spectroscopic studies are consistent with the presence of a highly covalent Mo[Formula: see text]S π* singly occupied molecular orbital. The compounds are highly reactive, with reactions localized at the terminal sulfido ligand. For example, the compounds react with cyanide and PPh3 to produce thiocyanate and SPPh3, respectively, and various (depending on solvent) oxo-Mo(V) species. Reactions with copper reagents also generally lead to desulfurization and the formation of oxo-Mo(V) or -Mo(IV) complexes.
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Affiliation(s)
| | | | | | | | | | | | - Graham N George
- §Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | | | - Charles G Young
- ¶Department of Chemistry and Physics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia
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12
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Schrapers P, Hartmann T, Kositzki R, Dau H, Reschke S, Schulzke C, Leimkühler S, Haumann M. Sulfido and cysteine ligation changes at the molybdenum cofactor during substrate conversion by formate dehydrogenase (FDH) from Rhodobacter capsulatus. Inorg Chem 2015; 54:3260-71. [PMID: 25803130 DOI: 10.1021/ic502880y] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Formate dehydrogenase (FDH) enzymes are attractive catalysts for potential carbon dioxide conversion applications. The FDH from Rhodobacter capsulatus (RcFDH) binds a bis-molybdopterin-guanine-dinucleotide (bis-MGD) cofactor, facilitating reversible formate (HCOO(-)) to CO2 oxidation. We characterized the molecular structure of the active site of wildtype RcFDH and protein variants using X-ray absorption spectroscopy (XAS) at the Mo K-edge. This approach has revealed concomitant binding of a sulfido ligand (Mo=S) and a conserved cysteine residue (S(Cys386)) to Mo(VI) in the active oxidized molybdenum cofactor (Moco), retention of such a coordination motif at Mo(V) in a chemically reduced enzyme, and replacement of only the S(Cys386) ligand by an oxygen of formate upon Mo(IV) formation. The lack of a Mo=S bond in RcFDH expressed in the absence of FdsC implies specific metal sulfuration by this bis-MGD binding chaperone. This process still functioned in the Cys386Ser variant, showing no Mo-S(Cys386) ligand, but retaining a Mo=S bond. The C386S variant and the protein expressed without FdsC were inactive in formate oxidation, supporting that both Mo-ligands are essential for catalysis. Low-pH inhibition of RcFDH was attributed to protonation at the conserved His387, supported by the enhanced activity of the His387Met variant at low pH, whereas inactive cofactor species showed sulfido-to-oxo group exchange at the Mo ion. Our results support that the sulfido and S(Cys386) ligands at Mo and a hydrogen-bonded network including His387 are crucial for positioning, deprotonation, and oxidation of formate during the reaction cycle of RcFDH.
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Affiliation(s)
- Peer Schrapers
- †Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Tobias Hartmann
- ‡Institut für Biochemie und Biologie, Molekulare Enzymologie, Universität Potsdam, 14476 Potsdam, Germany
| | - Ramona Kositzki
- †Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Holger Dau
- †Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Stefan Reschke
- ‡Institut für Biochemie und Biologie, Molekulare Enzymologie, Universität Potsdam, 14476 Potsdam, Germany
| | - Carola Schulzke
- §Institut für Biochemie, Bioanorganische Chemie, Ernst-Moritz-Arndt-Universität Greifswald, 17487 Greifswald, Germany
| | - Silke Leimkühler
- ‡Institut für Biochemie und Biologie, Molekulare Enzymologie, Universität Potsdam, 14476 Potsdam, Germany
| | - Michael Haumann
- †Institut für Experimentalphysik, Freie Universität Berlin, 14195 Berlin, Germany
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13
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Lima FA, Bjornsson R, Weyhermüller T, Chandrasekaran P, Glatzel P, Neese F, DeBeer S. High-resolution molybdenum K-edge X-ray absorption spectroscopy analyzed with time-dependent density functional theory. Phys Chem Chem Phys 2014; 15:20911-20. [PMID: 24197060 DOI: 10.1039/c3cp53133c] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
X-ray absorption spectroscopy (XAS) is a widely used experimental technique capable of selectively probing the local structure around an absorbing atomic species in molecules and materials. When applied to heavy elements, however, the quantitative interpretation can be challenging due to the intrinsic spectral broadening arising from the decrease in the core-hole lifetime. In this work we have used high-energy resolution fluorescence detected XAS (HERFD-XAS) to investigate a series of molybdenum complexes. The sharper spectral features obtained by HERFD-XAS measurements enable a clear assignment of the features present in the pre-edge region. Time-dependent density functional theory (TDDFT) has been previously shown to predict K-pre-edge XAS spectra of first row transition metal compounds with a reasonable degree of accuracy. Here we extend this approach to molybdenum K-edge HERFD-XAS and present the necessary calibration. Modern pure and hybrid functionals are utilized and relativistic effects are accounted for using either the Zeroth Order Regular Approximation (ZORA) or the second order Douglas-Kroll-Hess (DKH2) scalar relativistic approximations. We have found that both the predicted energies and intensities are in excellent agreement with experiment, independent of the functional used. The model chosen to account for relativistic effects also has little impact on the calculated spectra. This study provides an important calibration set for future applications of molybdenum HERFD-XAS to complex catalytic systems.
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Affiliation(s)
- Frederico A Lima
- Max-Planck-Institut für Chemische Energiekonversion, Stiftstrasse 34-36, D- 45470, Mülheim an der Ruhr, Germany.
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14
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Ghosh AC, Reinhardt JK, Kindermann MK, Schulzke C. The ring opening reaction of 1,3-dithiol-2-one systems is fully reversible. Chem Commun (Camb) 2014; 50:10102-4. [DOI: 10.1039/c4cc04414b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The deprotection of a common precursor moiety in dithiolene chemistry was discovered to be fully reversible, which, besides being relevant for researchers working in very different fields with these non-innocent ligand systems, may even have an impact on CO2 housekeeping, as the deprotected ligand acts as an efficient trap.
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Affiliation(s)
- Ashta Chandra Ghosh
- Institut fur Biochemie
- Ernst-Moritz-Arndt-Universitat Greifswald
- 17487 Greifswald, Germany
| | - Jakob Klaus Reinhardt
- Institut fur Biochemie
- Ernst-Moritz-Arndt-Universitat Greifswald
- 17487 Greifswald, Germany
| | - Markus Karl Kindermann
- Institut fur Biochemie
- Ernst-Moritz-Arndt-Universitat Greifswald
- 17487 Greifswald, Germany
| | - Carola Schulzke
- Institut fur Biochemie
- Ernst-Moritz-Arndt-Universitat Greifswald
- 17487 Greifswald, Germany
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15
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Reschke S, Sigfridsson KGV, Kaufmann P, Leidel N, Horn S, Gast K, Schulzke C, Haumann M, Leimkühler S. Identification of a bis-molybdopterin intermediate in molybdenum cofactor biosynthesis in Escherichia coli. J Biol Chem 2013; 288:29736-45. [PMID: 24003231 DOI: 10.1074/jbc.m113.497453] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The molybdenum cofactor is an important cofactor, and its biosynthesis is essential for many organisms, including humans. Its basic form comprises a single molybdopterin (MPT) unit, which binds a molybdenum ion bearing three oxygen ligands via a dithiolene function, thus forming Mo-MPT. In bacteria, this form is modified to form the bis-MPT guanine dinucleotide cofactor with two MPT units coordinated at one molybdenum atom, which additionally contains GMPs bound to the terminal phosphate group of the MPTs (bis-MGD). The MobA protein catalyzes the nucleotide addition to MPT, but the mechanism of the biosynthesis of the bis-MGD cofactor has remained enigmatic. We have established an in vitro system for studying bis-MGD assembly using purified compounds. Quantification of the MPT/molybdenum and molybdenum/phosphorus ratios, time-dependent assays for MPT and MGD detection, and determination of the numbers and lengths of Mo-S and Mo-O bonds by X-ray absorption spectroscopy enabled identification of a novel bis-Mo-MPT intermediate on MobA prior to nucleotide attachment. The addition of Mg-GTP to MobA loaded with bis-Mo-MPT resulted in formation and release of the final bis-MGD product. This cofactor was fully functional and reconstituted the catalytic activity of apo-TMAO reductase (TorA). We propose a reaction sequence for bis-MGD formation, which involves 1) the formation of bis-Mo-MPT, 2) the addition of two GMP units to form bis-MGD on MobA, and 3) the release and transfer of the mature cofactor to the target protein TorA, in a reaction that is supported by the specific chaperone TorD, resulting in an active molybdoenzyme.
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Affiliation(s)
- Stefan Reschke
- From the Institute for Biochemistry and Biology, Department of Molecular Enzymology, and
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Ng VWL, White JM, Young CG. Structural Characterization and Unusual Reactivity of Oxosulfido-Mo(V) Compounds: Implications for the Structure and Electronic Description of the Very Rapid Form of Xanthine Oxidase. J Am Chem Soc 2013; 135:7106-9. [DOI: 10.1021/ja4022057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Victor W. L. Ng
- School
of Chemistry and ‡Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010,
Australia
| | - Jonathan M. White
- School
of Chemistry and ‡Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010,
Australia
| | - Charles G. Young
- School
of Chemistry and ‡Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010,
Australia
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