Model for the active sites of oxo-transfer molybdoenzymes: reactivity, kinetics, and catalysis

Berg, Jeremy M.; Holm, R. H.

doi:10.1021/ja00290a030

Cited by 140 publications

(84 citation statements)

References 8 publications

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“…The spectral features of the latter enzyme and the DMSO reductase are quite similar; the molar absorption coefficients of the absorption bands are less than 5000 M-1 cm-1 in both enzymes. The broad absorption bands in the oxidized form of Received 14 August 1990/10 December 1990; accepted 17 December 1990 DMSO reductase most probably represent the interaction of the molybdenum centre with sulphur and oxo ligands [15]. These bands are attributable to the Mo(VI) form of the enzyme, since they were bleached upon reduction with dithionite.…”

Section: Discussionmentioning

confidence: 99%

Purification and properties of dimethyl sulphoxide reductase from Rhodobacter capsulatus. A periplasmic molybdoenzyme

McEwan

Ferguson

Jackson

1991

Biochemical Journal

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Dimethyl sulphoxide reductase was purified from the photosynthetic bacterium Rhodobacter capsulatus. The enzyme is composed of a single polypeptide of Mr 82000 and contains a pterin-type molybdenum cofactor as the only detectable prosthetic group. The oxidized molybdenum cofactor of dimethyl sulphoxide reductase is a weak chromophore and exhibits broad absorption bands in the u.v.-visible-absorption spectral region. A distinct spectrum was generated upon addition of dithionite. INTRODUCTIONDimethyl sulphoxide (DMSO) and trimethylamine N-oxide (TMAO) are used by a variety of bacteria as electron acceptors in anaerobic respiration [1]. The reduction of TMAO and DMSO by the photosynthetic bacterium Rhodobacter capsulatus is catalysed by a water-soluble enzyme located in the periplasmic space [2][3][4]. In the present paper we report the purification and characterization of DMSO reductase from R. capsulatus. The enzyme is shown to contain a molybdenum cofactor of the pterin type found in all molybdoenzymes other than nitrogenase. The novel properties of DMSO reductase have also provided a rare opportunity to describe the properties of the u.v.-visibleabsorption spectrum of the molybdenum cofactor in an intact

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Section: Discussionmentioning

confidence: 99%

Purification and properties of dimethyl sulphoxide reductase from Rhodobacter capsulatus. A periplasmic molybdoenzyme

McEwan

Ferguson

Jackson

1991

Biochemical Journal

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“…[14] Bio-inspired dioxomolybdenum(VI) complexes have been prepared in great variety in recent years. [15] Close structural models represent dithiolene-based ligands, [16][17][18][19][20][21] but several oxomolybdenum complexes of non-dithiolene ligands, including pyridine dithiolates, [22,23] tris(pyrazolyl)borate lig-A C H T U N G T R E N N U N G ands, [24] 3,5-tert-butyl-pyrazolate ligands, [25,26] b-ketiminates, [27,28] and bis(phenolate) ligands, [29][30][31][32] were also investigated. Furthermore, biomimetic models have been developed in order to investigate the influence of the spectator oxo effect on the OAT reaction.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insight into the Reactivity of Oxotransferases by Novel Asymmetric Dioxomolybdenum(VI) Model Complexes

Mayilmurugan

Harum

Volpe

et al. 2010

Chemistry A European J

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The asymmetric molybdenum(VI) dioxo complexes of the bis(phenolate) ligands 1,4-bis(2-hydroxybenzyl)-1,4-diazepane, 1,4-bis(2-hydroxy-4-methylbenzyl)-1,4-diazepane, 1,4-bis(2-hydroxy-3,5-dimethylbenzyl)-1,4-diazepane, 1,4-bis(2-hydroxy-3,5-di-tert-butylbenzyl)-1,4-diazepane, 1,4-bis(2-hydroxy-4-flurobenzyl)-1,4-diazepane, and 1,4-bis(2-hydroxy-4-chlorobenzyl)-1,4-diazepane (H(2)(L1)-H(2)(L6), respectively) have been isolated and studied as functional models for molybdenum oxotransferase enzymes. These complexes have been characterized as asymmetric complexes of type [MoO(2)(L)] 1-6 by using NMR spectroscopy, mass spectrometry, elemental analysis, and electrochemical methods. The molecular structures of [MoO(2)(L)] 1-4 have been successfully determined by single-crystal X-ray diffraction analyses, which show them to exhibit a distorted octahedral coordination geometry around molybdenum(VI) in an asymmetrical cis-β configuration. The Mo-O(oxo) bond lengths differ only by ≈0.01 Å. Complexes 1, 2, 5, and 6 exhibit two successive Mo(VI)/Mo(V) (E(1/2), -1.141 to -1.848 V) and Mo(V)/Mo(IV) (E(1/2), -1.531 to -2.114 V) redox processes. However, only the Mo(VI)/Mo(V) redox couple was observed for 3 and 4, suggesting that the subsequent reduction of the molybdenum(V) species is difficult. Complexes 1, 2, 5, and 6 elicit efficient catalytic oxygen-atom transfer (OAT) from dimethylsulfoxide (DMSO) to PMe(3) at 65 °C at a significantly faster rate than the symmetric molybdenum(VI) complexes of the analogous linear bis(phenolate) ligands known so far to exhibit OAT reactions at a higher temperature (130 °C). However, complexes 3 and 4 fail to perform the OAT reaction from DMSO to PMe(3) at 65 °C. DFT/B3LYP calculations on the OAT mechanism reveal a strong trans effect.

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“…25 The solution structures of the molybdenum centers of the sulfur compound in a six-fold coordination sphere and the molybdenum of the selenium complex having one free coordination site.…”

Section: Catalytic Reaction Mechanismsmentioning

confidence: 99%

The difference one ligand atom makes – An altered oxygen transfer reaction mechanism caused by an exchange of selenium for sulfur

Andrade

Meyer‐Klaucke

et al. 2010

Polyhedron

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Please cite this article as: C.E.A. Andrade, X. Ma, W. Meyer-Klaucke, C. Schulzke, The difference one ligand atom makes -an altered oxygen transfer reaction mechanism caused by an exchange of selenium for sulfur, Polyhedron (2009Polyhedron ( ), doi: 10.1016Polyhedron ( /j.poly.2009 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ACCEPTED MANUSCRIPTThe difference one ligand atom makes -an altered oxygen transfer reaction mechanism caused by an exchange of selenium for sulfur Carlos Enrique Abad Andrade, [a] Xiaoli Ma, [b] Wolfram Meyer-Klaucke, [ AbstractThe influence of sulfur versus selenium coordination to molybdenum on the oxo transfer reaction mechanisms of functional models for oxidoreductases has been studied. The solution structure of the dimeric molybdenum compound with tridentate bis-anionic ligands containing a thioether function ( -O(CH 2 ) 3 S(CH 2 ) 3 O -) has been determined using EXAFS spectroscopy to be able to compare a feature of its solution structure to that of its selenoether analogue. A significant difference is found for the solution structures of the two compounds. The thioether group remains coordinated in solution, whereas the selenoether does not. The influence of this difference on the catalytic oxo transfer has been investigated in detail by following the catalytic transition of PPh 3 to OPPh 3 with DMSO as oxygen donor with variation of both substrate concentrations.

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Model for the active sites of oxo-transfer molybdoenzymes: reactivity, kinetics, and catalysis

Cited by 140 publications

References 8 publications

Purification and properties of dimethyl sulphoxide reductase from Rhodobacter capsulatus. A periplasmic molybdoenzyme

Purification and properties of dimethyl sulphoxide reductase from Rhodobacter capsulatus. A periplasmic molybdoenzyme

Mechanistic Insight into the Reactivity of Oxotransferases by Novel Asymmetric Dioxomolybdenum(VI) Model Complexes

The difference one ligand atom makes – An altered oxygen transfer reaction mechanism caused by an exchange of selenium for sulfur

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