Die [Mn2IV(μ‐O)(μ‐PhBO2)2]2+‐Einheit: ein neues Strukturmodell für manganhaltige Metalloproteine

Bossek, Ursula; Hummel, Helga; Weyhermüller, Thomas; Wieghardt, Karl; Russell, Stephen W.; Wolf, Lodewijk van der; Kolb, U.

doi:10.1002/ange.19961081334

Cited by 26 publications

(14 citation statements)

References 19 publications

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“…77,78 It is, however, interesting that all Mn II Mn III model compounds exhibit only one -oxo bridge, but two carboxylate bridges. 26,31,46,47 Recently, a mutant (Y42F) from MnCAT of L. plantarum has been investigated by X-ray diffraction. 16 Albeit Tyr42 is at a distance of about 4Å from Mn in the wild type, this mutation interrupts a network of hydrogen bonds, leading to an 'open' form of the oxidized Mn III Mn III cluster, where one of the two -oxo bridges in the wild type is now bound to only one Mn.…”

Section: Discussion Of Results With Respect To Catalase Structure Andmentioning

confidence: 99%

High-field EPR investigations of MnIIIMnIV and MnIIMnIII states of dimanganese catalase and related model systems

Teutloff

Schäfer

Sinnecker³

et al. 2005

Magn. Reson. Chem.

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Multi-frequency EPR experiments at 9, 34 and 94 GHz are reported on the antiferromagnetically coupled mixed valence Mn(II)Mn(III) complex of manganese catalase and on several dinuclear manganese model systems. They are compared with similar experiments obtained earlier for the Mn(III)Mn(IV) states. It is demonstrated how accurate information on the G- and 55Mn hyperfine tensors can be derived from this approach. Furthermore, the effect of oxidation state, planarity of the manganese-oxygen core and the type of ligands bridging the manganese ions on the magnetic resonance parameters and the related electronic structure is investigated. 'Broken-symmetry' density functional calculations on two Mn(III)Mn(IV) complexes, including the superoxidized state of the catalase, are presented. The agreement between calculated and experimental EPR parameters and complex geometries is remarkably good. Implications of these results for the structure and function of the dimanganese catalase are discussed.

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Section: Discussion Of Results With Respect To Catalase Structure Andmentioning

confidence: 99%

High-field EPR investigations of MnIIIMnIV and MnIIMnIII states of dimanganese catalase and related model systems

Teutloff

Schäfer

Sinnecker³

et al. 2005

Magn. Reson. Chem.

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“…Group 9 and 10 boronate complexes are transient species in Suzuki–Miyaura coupling reactions, and the structural features of the other boronate metal complexes reveal a tendency for aryl boronates to bridge transition metals in a fashion similar to that of their close carbon analogues, carboxylates. The compounds formed when aryl boronates are used as ligands are stable enough to offer promise as magnetic materials15a–c, 16 and as catalysts for the epoxidation of alkenes 15d…”

Section: Methodsmentioning

confidence: 99%

Tailoring the Catalytic Performance of Sol–Gel‐Encapsulated Tetra‐n‐propylammonium Perruthenate (TPAP) in Aerobic Oxidation of Alcohols

Ciriminna

Pagliaro

2003

Chemistry A European J

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Sol-gel nanohybrid silica particles organically modified and doped with the ruthenium species tetra-n-propylammonium perruthenate (TPAP) are highly efficient catalysts for the selective oxidation of alcohols to carbonyl groups with O(2) at low pressure in toluene. The materials are easily prepared by a one-step sol-gel process, and their catalytic performance can be optimised by tailoring the conditions of their synthesis by hydrolytic co-polycondensation of tetramethoxysilane (TMOS) and alkyltrimethoxysilanes R-Si(OMe)(3) in the presence of TPAP. Eventually, heterogeneous catalysts considerably more active than the unsupported perruthenate were obtained, while also being leach-proof and recyclable. The correlation between the materials' activity, surface polarity and textural properties suggests valuable information on the chemical behaviour of sol-gel catalytic materials in oxidation catalysis; this is of interest in view of the importance of efficient solid catalysts for the selective oxidation of alcohols with O(2).

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“…The one-electron oxidation of manganese has been found to be accompanied by an up-shift of the X-ray edge by 2-4 eV ( [28,32,34,67,68,69,72]; see also Figs. 7 and 9).…”

Section: Empirical Approaches To Determine Oxidation Statesmentioning

confidence: 96%

“…7A immediately reveals: (1) An increase in the formal oxidation state is related to a shift of the X-ray edge position to higher energies, and (2) the shape of the spectra in the edge region differs clearly between all the compounds shown. Correlations between the formal manganese oxidation state and edge positions have been confirmed for extended sets of model compounds [28,32,67,68,69]. XANES analysis has been used for numerous metalloenzymes to obtain insights into the metal-oxidation state and its coordination geometry.…”

Section: Xanes Of Mn Oxides and The Psii-mn Complexmentioning

confidence: 99%

X-ray absorption spectroscopy to analyze nuclear geometry and electronic structure of biological metal centers?potential and questions examined with special focus on the tetra-nuclear manganese complex of oxygenic photosynthesis

Dau

Liebisch

Haumann

2003

Analytical and Bioanalytical Chemistry

321

458

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X-ray absorption spectroscopy (XAS) has become a prominent tool for the element-specific analysis of transition metals at the catalytic center of metalloenzymes. In the present study the information content of X-ray spectra with respect to the nuclear geometry and, in particular, to the electronic structure of the protein-bound metal ions is explored using the manganese complex of photosystem II (PSIII) as a model system. The EXAFS range carries direct information on the number and distances of ligands as well as on the chemical type of the ligand donor function. For first-sphere ligands and second-sphere metals (in multinuclear complexes), the determination of precise distances is mostly straightforward, whereas the determination of coordination numbers clearly requires more effort. The EXAFS section starts with an exemplifying discussion of a PSII spectrum data set with focus on the coordination number problem. Subsequently, the method of linear dichroism EXAFS spectroscopy is introduced and it is shown how the EXAFS data leads to an atomic resolution model for the tetra-manganese complex of PSII. In the XANES section the following aspects are considered: (1) Alternative approaches are evaluated for determination of the metal-oxidation state by comparison with a series of model compounds. (2) The interpretation of XANES spectra in terms of molecular orbitals (MOs) is approached by comparative multiple-scattering calculations and MO calculations. (3) The underlying reasons for the oxidation-state dependence of the XANES spectra are explored. Furthermore, the potential of modern XANES theory is demonstrated by presenting first simulations of the dichroism in the XANES spectra of the PSII manganese complex.

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Die [Mn₂^IV(μ‐O)(μ‐PhBO₂)₂]²⁺‐Einheit: ein neues Strukturmodell für manganhaltige Metalloproteine

Cited by 26 publications

References 19 publications

High-field EPR investigations of MnIIIMnIV and MnIIMnIII states of dimanganese catalase and related model systems

High-field EPR investigations of MnIIIMnIV and MnIIMnIII states of dimanganese catalase and related model systems

Tailoring the Catalytic Performance of Sol–Gel‐Encapsulated Tetra‐n‐propylammonium Perruthenate (TPAP) in Aerobic Oxidation of Alcohols

X-ray absorption spectroscopy to analyze nuclear geometry and electronic structure of biological metal centers?potential and questions examined with special focus on the tetra-nuclear manganese complex of oxygenic photosynthesis

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