Assembly and structural characterization of binuclear µ-oxo-di-µ-acetato bridged complexes of manganese(<scp>III</scp>). Analogues of the di-iron(<scp>III</scp>) centre in hemerythrin

Wieghardt, Karl; Bossek, Ursula; Ventur, D.; Weiß, Johannes

doi:10.1039/c39850000347

Cited by 150 publications

(130 citation statements)

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“…The global coordination number for this vector (Nisotropic) was 0.41 2 0.02, or two Mn -Mn interactions at this distance. This is consistent with the presence of one mono-p-oxo and mono-or di-carboxylato bridged moiety per tetramer Wieghardt et al, 1983Wieghardt et al, , 1985Sheats et al, 1987). Inclusion of a second shell of Mn-Ca decreased the fit error by a factor of 2 to 3, depending on the data set, but the results were not conkistent enough to confirm the requirement for this shell.…”

Section: Peak 1 1supporting

confidence: 64%

X-ray absorption spectroscopy and EPR studies of oriented spinach thylakoid preparations

Andrews

1995

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In this study, oriented Photosystem 11 (PS n) particles from spinach chloroplasts are studied with electron paramagnetic resonance (EPR) and x-ray absorption spectroscopy VAS) to determine more details of the structure of the oxygen evolving complex (OEC).The nature of halide binding to Mn is also studied with C1 K-edge and Mn EXAFS (extended x-ray absorption fine structure) of Mn-C1 model compounds, and with Mn EXAFS of oriented PS 1T in which Br has replaced C1.In chapter 2, oriented PS 11 particles from spinach were studied with EPR spectroscopy. The mosaic spread for these samples was determined by comparison of the oxidized cytochrome b559 (cyt b559+) signal measured at angles of 0" to 360" between the EPR magnetic field and sample membrane normal with simulations of oriented cyt b559+.The tyrosine YD+ signal was measured for these oriented samples at 0" and 90°, and a linear relationship was found between the dichroism found in the tyrosine YD+ signal and the mosaic spread.In chapters 3 and 4, Mn XAS was performed on oriented PS 11 membrane particles isolated from spinach. These studies were on control samples (chapter 3) and on samples treated with ammonia (chapter 4), a water analog which can yield insight into the binding of water by the OEC. Structural features of the tetranuclear Mn cluster and the orientation of the cluster with respect to the lipid bilayer were determined in the S2 state of the Kok cycle 1 for control samples, and on the annealed S2 state for the ammonia-treated samples.Variation of the sample orientation with respect to the x-ray e-vector yields highly dichroic In chapter 5, the binding of halide to Mn was studied using C1 K-edge XAS and Mn EXAFS on Mn-CI model compounds, and Mn EXAFS on oriented Br-treated PS IL From the C1 K-edges of model compounds, direct ligation of C1 to Mn could be confirmed with the presence of a pre-edge feature: 'a forbidden 1s to 3d transition which is seen due to mixing of Mn 3d orbitals with C13p orbitals. Bridging and terminal C1 bonds to Mn could be distinguish& EXAFS of Mn-C1 model compounds revealed that Mn-C1 interactions, especially bridging interactions, make an important contribution to the EXAFS. EXAFS of oriented Br-treated PS 11 showed differences from EXAFS of control CI-treated PS II that were on the same order as the variation from sample to sample. Fits to Br-treated and Cl control samples were also inconclusive. Thus, it is not possible to 9 establish or rule out direct ligation of C1 to Mn in the OEC with these studies.2

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Section: Peak 1 1supporting

confidence: 64%

X-ray absorption spectroscopy and EPR studies of oriented spinach thylakoid preparations

Andrews

1995

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“…Iron and manganese are exchangeable in calf thymus ribonucleotide reductase in vitro [29]. Structurally related Me(1II) (p-0x0)-(p-carboxylato)2Me(III) complexes have been synthesized with both metals to model metalloprotein centers [31,321. The light absorption between 400nm and 700nm of our new manganese enzyme (Fig.…”

Section: Discussionmentioning

confidence: 99%

Ribonucleotide reductase of Brevibacterium ammoniagenes is a manganese enzyme

Willing

Follmann

Auling

1988

European Journal of Biochemistry

175

135

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Ribonucleotide reduction and not DNA replication is the site for the specific manganese requirement of DNA synthesis and cell growth in the coryneform bacterium Brevibacterium ammoniagenes. To characterize the metal effect we have isolated and purified ribonucleoside-diphosphate reductase from overproducing bacteria that were first deprived of and then reactivated by manganese ions. Purification on columns of Sephacryl S400, DEAEcellulose and hydroxyapatite provided an apparently homogeneous enzyme consisting of two protein subunits. These were characterized by affinity chromatography on 2',5'-ADP-Sepharose as nucleotide-binding protein B1 ( M , =z 80000) and catalytic protein B2 (Mr = 100000, composed of two M , = 50000 polypeptides), which were both necessary for activity.In vitro the purified enzyme does not require added metal ions except for an unspecific, twofold activity increase observed in the presence of Mg2+ and other divalent cations. Enzyme activity is inhibited by hydroxyurea (Z, o = 2.5 mM). The electronic spectrum with maxima around 455 nm and 485 nm closely resembles that of manganese(II1)-containing pseudocatalase and of 0x0-bridged binuclear Mn(ll1) model complexes. Denaturation of the enzyme in trichloroacetic acid liberated an equimolar amount of Mn(1l) which was detected by EPR spectroscopy. It was not possible to remove and reintroduce metal ions without loss of enzyme activity.Manganese-deficient cell cultures were also grown in the presence of 54MnC12. Ribonucleotide reductase activity and radioactivity cochromatographed in several systems. Non-denaturing polyacrylamide gel electrophoresis showed that protein subunit B2 was specifically 54Mn-labeled.All these properties suggest that the ribonucleotide reductase of B. ammoniagenes is a manganese-containing analog of the non-heme-iron-containing reductases of Escherichia coli and eukaryotes.

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“…However, neither of these scenarios would predict that the first-shell Fourier peak would be more intense in the Mn 2 (III,III) complex than the Mn 2 (III,IV) complex. In fact, a similar mono-µ-oxo Mn 2 (III,III) complex with tacn (triazacyclononane) terminal ligands has been synthesized by Wieghardt et al 304 and it was shown by DeRose et al 72 to have a significantly reduced amplitude of the first-and second-shell Fourier peaks relative to the S 1 state of PS II. Because single crystals have been obtained of all three of these complexes from…”

Section: Exafsmentioning

confidence: 99%

XANES, EXAFS and Kbeta spectroscopic studies of the oxygen-evolving complex in Photosystem II

Robblee

2000

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Assembly and structural characterization of binuclear µ-oxo-di-µ-acetato bridged complexes of manganese(III). Analogues of the di-iron(III) centre in hemerythrin

Cited by 150 publications

References 0 publications

X-ray absorption spectroscopy and EPR studies of oriented spinach thylakoid preparations

X-ray absorption spectroscopy and EPR studies of oriented spinach thylakoid preparations

Ribonucleotide reductase of Brevibacterium ammoniagenes is a manganese enzyme

XANES, EXAFS and Kbeta spectroscopic studies of the oxygen-evolving complex in Photosystem II

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