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Dey K, Maiti RK, Bhar JK. Oxocation complexes, Part X. Oxomolybdenum(V) and dioxomolybdenum(VI) complexes with tri- and tetra-dentate Schiff bases. TRANSIT METAL CHEM 2013. [DOI: 10.1007/bf00623654] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Kanoongo N, Singh R, Tandon JP. Synthetic and structural aspects of hepta-coordinated semicarbazato complexes of oxotungsten(VI). TRANSIT METAL CHEM 2013. [DOI: 10.1007/bf01023904] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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3
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Ngan NK, Lo KM, Wong CSR. Synthesis, structure studies and electrochemistry of molybdenum(VI) Schiff base complexes in the presence of different donor solvent molecules. Polyhedron 2011. [DOI: 10.1016/j.poly.2011.08.038] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Gupta S, Pal S, Barik AK, Roy S, Hazra A, Mandal TN, Butcher RJ, Kar SK. Molybdenum(VI) complexes of a few pyrimidine derived ligands and the study of metal mediated CN bond cleavage resulting in ligand transformation during complex formation. Polyhedron 2009. [DOI: 10.1016/j.poly.2008.12.057] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Andreesen JR, Makdessi K. Tungsten, the surprisingly positively acting heavy metal element for prokaryotes. Ann N Y Acad Sci 2007; 1125:215-29. [PMID: 18096847 DOI: 10.1196/annals.1419.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The history and changing function of tungsten as the heaviest element in biological systems is given. It starts from an inhibitory element/anion, especially for the iron molybdenum-cofactor (FeMoCo)-containing enzyme nitrogenase involved in dinitrogen fixation, as well as for the many "metal binding pterin" (MPT)-, also known as tricyclic pyranopterin- containing classic molybdoenzymes, such as the sulfite oxidase and the xanthine dehydrogenase family of enzymes. They are generally involved in the transformation of a variety of carbon-, nitrogen- and sulfur-containing compounds. But tungstate can serve as a potential positively acting element for some enzymes of the dimethyl sulfoxide (DMSO) reductase family, especially for CO(2)-reducing formate dehydrogenases (FDHs), formylmethanofuran dehydrogenases and acetylene hydratase (catalyzing only an addition of water, but no redox reaction). Tungsten even becomes an essential element for nearly all enzymes of the aldehyde oxidoreductase (AOR) family. Due to the close chemical and physical similarities between molybdate and tungstate, the latter was thought to be only unselectively cotransported or cometabolized with other tetrahedral anions, such as molybdate and also sulfate. However, it has now become clear that it can also be very selectively transported compared to molybdate into some prokaryotic cells by two very selective ABC-type of transporters that contain a binding protein TupA or WtpA. Both proteins exhibit an extremely high affinity for tungstate (K(D) < 1 nM) and can even discriminate between tungstate and molybdate. By that process, tungsten finally becomes selectively incorporated into the few enzymes noted above.
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Affiliation(s)
- Jan R Andreesen
- Institute of Biology/Microbiology, Martin-Luther-University Halle-Wittenberg, Halle, Germany.
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Zhang ZX, Li Y, Li KC, Song WD, Li QS, Xiong HP, Xu JQ, Pan LY. Synthesis, crystal structure and third-order nonlinear optical properties of heterometallic cluster [WM2S4(Pph3)3]·DMF (M2=1.25Ag+0.75Cu). J Mol Struct 2006. [DOI: 10.1016/j.molstruc.2006.01.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Hettmann T, Anemüller S, Borcherding H, Mathé L, Steinrücke P, Diekmann S. Pseudomonas stutzeri soluble nitrate reductase alphabeta-subunit is a soluble enzyme with a similar electronic structure at the active site as the inner membrane-bound alphabetagamma holoenzyme. FEBS Lett 2003; 534:143-50. [PMID: 12527376 DOI: 10.1016/s0014-5793(02)03837-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
A two-subunit (alphabeta) form of dissimilatory nitrate reductase from Pseudomonas stutzeri strain ZoBell was separated from the membrane-residing gamma-subunit by a heat solubilization step. Here we present an optimized purification protocol leading to a soluble alphabeta form with high specific activity (70 U/mg). The soluble form has the stoichiometry alpha(1)beta(1) consisting of the 130 kDa alpha-subunit and the 58 kDa beta-subunit. We did not observe any proteolytic cleavage in the course of the heat solubilization. The enzyme is competively inhibited by azide, but not by chlorate. It exhibits a K(M) value of 3.2 mM for nitrate. We compare the enzymatic and electron paramagnetic resonance (EPR) spectroscopic properties of the alphabeta form with the alphabetagamma holoenzyme which resides in the membrane and can be prepared by detergent extraction. The nearly identical EPR spectra for the Mo(V) signal of both enzyme preparations show that the active site is unaffected by the heat step. The factors influencing the binding of the alpha- and beta-subunit to the gamma-subunit are discussed.
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Affiliation(s)
- Thomas Hettmann
- Department of Molecular Biology, IMB, Beutenbergstr. 11, D-07745 Jena, Germany
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Doherty R, Hubbard CR, Mighell AD, Siedle AR, Stewart J. Synthesis and crystal and molecular structure of [(C7H7)3P]4Cu4W2O2S6, a dimer of bis((tri-p-tolylphosphine)copper)oxotrithiotungsten. Inorg Chem 2002. [DOI: 10.1021/ic50201a010] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Wollmann RG, Hendrickson DN. Reaction of .mu.-oxo-bridged iron(III) complexes with organic acids: a characterization of the products. Inorg Chem 2002. [DOI: 10.1021/ic50182a026] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Gardner JK, Pariyadath N, Corbin JL, Stiefel EI. Molybdenum and rhenium complexes of aromatic aminethiolate ligands. Inorg Chem 2002. [DOI: 10.1021/ic50182a021] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Diekmann S, Weston J, Anders E, Boland W, Schönecker B, Hettmann T, von Langen J, Erhardt S, Mauksch M, Bräuer M, Beckmann C, Rost M, Sperling P, Heinz E. Metal-mediated reactions modeled after nature. J Biotechnol 2002; 90:73-94. [PMID: 12069195 DOI: 10.1016/s1389-0352(01)00067-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
The Collaborative Research Center (CRC) 436 'Metal-Mediated Reactions Modeled after Nature' was founded for the express purpose of analyzing the catalytic principles of metallo-enzymes in order to construct efficient catalysts on a chemical basis. The structure of the active center and neighboring chemical environment in enzymes serves as a focal point for developing reactivity models for the chemical redesign of catalysts. Instead of simply copying enzyme construction, we strive to achieve new chemical intuition based on the results of long-lasting natural evolution. We hope for success, since nature uses a limited set of building blocks, whereas we can apply the full repertoire of chemistry. Key substrates in this approach are small molecules, such as CO2, O2 NO3- and N2. Nature complexes these substrates, activates them and performs chemical transformations--all within the active center of a metalloenzyme. In this article, we report on some aspects and first results of the Collaborative Research Center (CRC) 436, such as nitrate reductase, sphingolipid desaturase, carbonic anhydrase, leucine aminopeptidase and dopamine beta-monooxygenase.
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Affiliation(s)
- Stephan Diekmann
- Collaborative Research Center (SFB), Metal-Mediated Reactions Modeled after Nature, Institut für Organische Chemie und Makromolekulare Chemie, Friedrich-Schiller-Universität, Jena, Germany.
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Dias JM, Than ME, Humm A, Huber R, Bourenkov GP, Bartunik HD, Bursakov S, Calvete J, Caldeira J, Carneiro C, Moura JJ, Moura I, Romão MJ. Crystal structure of the first dissimilatory nitrate reductase at 1.9 A solved by MAD methods. Structure 1999; 7:65-79. [PMID: 10368307 DOI: 10.1016/s0969-2126(99)80010-0] [Citation(s) in RCA: 248] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND The periplasmic nitrate reductase (NAP) from the sulphate reducing bacterium Desulfovibrio desulfuricans ATCC 27774 is induced by growth on nitrate and catalyses the reduction of nitrate to nitrite for respiration. NAP is a molybdenum-containing enzyme with one bis-molybdopterin guanine dinucleotide (MGD) cofactor and one [4Fe-4S] cluster in a single polypeptide chain of 723 amino acid residues. To date, there is no crystal structure of a nitrate reductase. RESULTS The first crystal structure of a dissimilatory (respiratory) nitrate reductase was determined at 1.9 A resolution by multiwavelength anomalous diffraction (MAD) methods. The structure is folded into four domains with an alpha/beta-type topology and all four domains are involved in cofactor binding. The [4Fe-4S] centre is located near the periphery of the molecule, whereas the MGD cofactor extends across the interior of the molecule interacting with residues from all four domains. The molybdenum atom is located at the bottom of a 15 A deep crevice, and is positioned 12 A from the [4Fe-4S] cluster. The structure of NAP reveals the details of the catalytic molybdenum site, which is coordinated to two MGD cofactors, Cys140, and a water/hydroxo ligand. A facile electron-transfer pathway through bonds connects the molybdenum and the [4Fe-4S] cluster. CONCLUSIONS The polypeptide fold of NAP and the arrangement of the cofactors is related to that of Escherichia coli formate dehydrogenase (FDH) and distantly resembles dimethylsulphoxide reductase. The close structural homology of NAP and FDH shows how small changes in the vicinity of the molybdenum catalytic site are sufficient for the substrate specificity.
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Affiliation(s)
- J M Dias
- Departamento de Quimica, CQFB, FCT, Universidade Nova de Lisboa, Caparica, Portugal
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Canales F, Gimeno MC, Laguna A. Heterobimetallic Complexes of Gold(I) with the Tetrathiovanadate Anion. Crystal Structure of [VS4(AuPPh3)2{Au(PPh3)2}]. Inorg Chem 1998. [DOI: 10.1021/ic9712939] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fernando Canales
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - M. Concepción Gimeno
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
| | - Antonio Laguna
- Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
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Cindrić M, Matković-Čalogović D, Vrdoljak V, Kamenar B. Molybdenum(V) and molybdenum(IV) complexes with trifluorothioacetylacetone. X-ray structure of [Mo2O3{CF3C(O)CHC(S)CH3}4]. INORG CHEM COMMUN 1998. [DOI: 10.1016/s1387-7003(98)00060-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Ray K, Mandal PC, Mukherjee DC. Electron transfer oxidation kinetics of Na2[Mo2O4EDTA] by S2O82? ion in dilute acid medium. INT J CHEM KINET 1997. [DOI: 10.1002/(sici)1097-4601(1997)29:4<269::aid-kin5>3.0.co;2-s] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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18
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Maurya MR, Antony DC, Gopinathan S, Gopinathan C. Binuclear Dioxomolybdenum(VI) Complexes of Flexibly-Bridged Hexadentate Tetraanionic Schiff’s Bases Derived from Methylene- or Dithio-bis(salicylaldehyde) andS-Methyldithiocarbazate orS-Benzyldithiocarbazate. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1995. [DOI: 10.1246/bcsj.68.554] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Dioxomolybdenum(VI) complexes of new binucleating schiff bases derived from methylene- or dithio-bis(salicyclaldehyde) and various amines. Polyhedron 1993. [DOI: 10.1016/s0277-5387(00)80125-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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20
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Enemark JH, Young CG. Bioinorganic Chemistry of Pterin-Containing Molybdenum and Tungsten Enzymes. ADVANCES IN INORGANIC CHEMISTRY 1993. [DOI: 10.1016/s0898-8838(08)60181-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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21
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Kamenar B, Korpar-Čolig B, Cindrić M, Penavić M, Strukan N. Molybdenum(V) complexes with monothio-β-diketones: thiodipivaloylmethane, thiodibenzoylmethane and benzoylthioacetone. ACTA ACUST UNITED AC 1992. [DOI: 10.1039/dt9920002093] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Gonzalez MC, Féliz MR, San Román E, Capparelli AL. Flash photolysis of aqueous solutions of bis(μ-oxo) bis(oxo-molybdenum(V)). J Photochem Photobiol A Chem 1989. [DOI: 10.1016/1010-6030(89)87091-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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23
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Mártire D, Féliz M, Capparelli A. Ligand deprotonation significance in the formation of the molybdate ion-malic acid complexes. Polyhedron 1988. [DOI: 10.1016/s0277-5387(00)83896-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Djordjevic C, Vuletic N, Sinn E. Synthesis and properties of peroxo α-amino acid complexes of molybdenum(VI). The structures of MoO(O2)2(HAA)(H2O), HAA = glycine, proline. Inorganica Chim Acta 1985. [DOI: 10.1016/s0020-1693(00)83775-5] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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25
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Agh-Atabay N, Ashmawy F, McAuliffe C, Hill W. Synthesis and characterisation of oxotungsten(VI) complexes of phosphines and phosphine oxides. Inorganica Chim Acta 1985. [DOI: 10.1016/s0020-1693(00)86418-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Nath PK, Dash KC. cis-Dioxo(N-salicylidene-2-aminophenolato)(imidazole)-molybdenum(VI) complexes. TRANSIT METAL CHEM 1985. [DOI: 10.1007/bf00621083] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Wieghardt K, Backes-Dahmann G, Herrmann W, Weiss J. Zweikerniger, gemischtvalenter MoVI/V-Komplex; Kristallstruktur von [(C9H21N3)2Mo2VI O5](Br3)2. Angew Chem Int Ed Engl 1984. [DOI: 10.1002/ange.19840961112] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Beltr�n-Porter A, Cervilla A, Caturla F, Vila MJ. Lactate complexes of molybdenum(VI). TRANSIT METAL CHEM 1983. [DOI: 10.1007/bf00618562] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Syamal A, Kumar D. Molybdenum complexes of bioinorganic interest. New dioxomolybdenum(VI) complexes of schiff bases derived from salicylaldehydes and salicylhydrazide. TRANSIT METAL CHEM 1982. [DOI: 10.1007/bf00618197] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Sasaki Y, Kawamura R. Kinetics of the Oxidation ofN-(2-Hydroxyethyl)ethylenediamine-N,N′,N′-triacetate Complex of Di-μ-oxo-bis[oxomolybdenum(V)] with Hexachloroiridate(IV) and μ-Hyperoxo-bis[pentaamminecobalt(III)] Ions in Aqueous Media. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1981. [DOI: 10.1246/bcsj.54.3379] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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M�ller A, Rittner W, Neumann A, Sharma RC. Polychalkogenoanionen der �bergangsmetalle. IV. Neuartige Redoxkondensationsreaktionen von MoO2S22? in H2O und zur Darstellung von Di-?-sulfido-Komplexen von Mov. Z Anorg Allg Chem 1981. [DOI: 10.1002/zaac.19814720107] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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M�ller A, Bhattacharyya RG, Mohan N, Pfefferkorn B. On the preparation of binuclear S, S bridged molybdenum(V) complexes crystal and molecular structure of [Mo2S4(Et2dtc)2]. Z Anorg Allg Chem 1979. [DOI: 10.1002/zaac.19794540118] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Mason J, Cardin C, Dennehy A. The role of sulphide and sulphide oxidation in the copper molybdenum antagonism in rats and guinea pigs. Res Vet Sci 1978. [DOI: 10.1016/s0034-5288(18)33107-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Sykes A. Substitution and redox reactions of molybdenum species in aqueous solution and possible relevance to the function of molybdenum in enzymes. ACTA ACUST UNITED AC 1977. [DOI: 10.1016/0022-5088(77)90062-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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39
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Sasaki Y. Kinetics of the Oxidation of Ethylenediaminetetraacetato and Aqua Complex of Dimeric Molybdenum(V) by the μ-Hyperoxo-bis[pentaamminecobalt(III)] Ion in Aqueous Perchloric Acid Solution. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1977. [DOI: 10.1246/bcsj.50.1939] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Watt G, McDonald J, Newton W. Thermochemical studies of molybdenum dithio-carbamate complexes as models for molybdoenzymes. ACTA ACUST UNITED AC 1977. [DOI: 10.1016/0022-5088(77)90064-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Glowiak T, Rudolf M, Sabat M, Jezowska-Trzebiatowska B. The electronic, crystal and molecular structures of novel dimeric μ-oxo, di-μ-oxo and di-μ-oxo-μ-carboxylato bridged oxodimolybdates(V). ACTA ACUST UNITED AC 1977. [DOI: 10.1016/0022-5088(77)90124-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Cardin CJ, Mason J. Molybdate and tungstate transfer by rat ileum. Competitive inhibition by sulphate. BIOCHIMICA ET BIOPHYSICA ACTA 1976; 455:937-46. [PMID: 999946 DOI: 10.1016/0005-2736(76)90062-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
For both MoO42- and WO42- the maximum rate of uptake by the small intestine of the rat (studied in vitro using the everted sac technique) occurs in the lower ileum. Kinetic constants, derived by a least squares procedure, are compared with those previously obtained for SO42- transport. For both V and Ka, SO42- greater than MoO42- greater than WO42-, with only small differences between sacs IV and V. Mutual inhibition of MoO42- and WO42- transport and inhibition of both by SO42- are competitive processes. This is shown by the generally good agreement between Ka values and derived Ki values and by V values in the presence and absence of the inhibiting species. The three ions SO42-, MoO42- and WO42- are probably transferred across the intestine by a common carrier system. Implications for the sulphate-molybdenum interaction in molybdosis are discussed.
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Burns PS, Harrod JF, Williams RJ, Wright PE. A study of redox reactions of biological importance between Fe(III) complexes and aromatic moieties. Biochim Biophys Acta Gen Subj 1976; 428:261-8. [PMID: 6046 DOI: 10.1016/0304-4165(76)90033-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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