Wolfgang Lubitz

Max Planck Institute for Chemical Energy Conversion, Mülheim-on-Ruhr, North Rhine-Westphalia, Germany

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Publications (433)2078.17 Total impact

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    ABSTRACT: Das aktive Zentrum von Hydrogenasen inspiriert die Entwicklung molekularer Katalysatoren zur Wasserstoffumsetzung. Ein direkter Vergleich zwischen diesen Katalysatoren und dem Enzym war jedoch bisher nicht möglich, weil verschiedene Techniken zur Bewertung der Katalysatoreigenschaften verwendet wurden. Dies macht es schwierig zu beurteilen, inwieweit die synthetisierten Katalysatoren in ihrer Leistung an das Enzym heranreichen. Hier vergleichen wir die katalytischen Eigenschaften von Ni[(PCy2NGly2)2]+2 mit denen der [NiFe]-Hydrogenase aus Desulfovibrio vulgaris. Beide wurden auf funktionalisierten Elektroden unter identischen Bedingungen immobilisiert. Das Enzym zeigt bei pH 7 eine höhere Aktivität, geringere Überspannung und eine bessere Stabilität, während bei niedrigem pH-Wert der molekulare Katalysator das Enzym in jeder Hinsicht übertrifft. Dieser erste direkte Vergleich gibt Auskunft über die Vor- und Nachteile der beiden Systeme und Hinweise auf eine mögliche Verwendung bioinspirierter Komplexe in Brennstoffzellen.
    Angewandte Chemie 07/2015; DOI:10.1002/ange.201502364
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    ABSTRACT: The active site of hydrogenases has been a source of inspiration for the development of molecular catalysts. However, direct comparisons between molecular catalysts and enzymes have not been possible because different techniques are used to evaluate both types of catalysts, minimizing our ability to determine how far we have come in mimicking the enzymatic performance. The catalytic properties of the [Ni(P(Cy) 2 N(Gly) 2 )2 ](2+) complex with the [NiFe]-hydrogenase from Desulfovibrio vulgaris immobilized on a functionalized electrode were compared under identical conditions. At pH 7, the enzyme shows higher activity and lower overpotential with better stability, while at low pH, the molecular catalyst outperforms the enzyme in all respects. This is the first direct comparison of enzymes and molecular complexes, enabling a unique understanding of the benefits and detriments of both systems, and advancing our understanding of the utilization of these bio-inspired complexes in fuel cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Angewandte Chemie International Edition 07/2015; DOI:10.1002/anie.201502364 · 11.26 Impact Factor
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    ABSTRACT: Diamagnetic iron chloro compounds [(P(Ph)2N(Ph)2)FeCp*Cl] [1Cl] and [(P(Cy)2N(Ph)2)FeCp*Cl] [2Cl] and the corresponding hydrido complexes [(P(Ph2)N(Ph2))FeCp*H] [1H] and [(P(Cy)2N(Ph)2)FeCp*H] [2H] have been synthesized and characterized by NMR spectroscopy, electrochemical studies, electronic absorption, and (57)Fe Mössbauer spectroscopy (P(Ph)2N(Ph)2 = 1,3,5,7-tetraphenyl-1,5-diphospha-3,7-diazacyclooctane, P(Cy2)N(Ph2) = 1,5-dicyclohexyl-3,7-diphenyl-1,5-diphospha-3,7-diazacyclooctane, Cp* = pentamethylcyclopentadienyl). Molecular structures of [2Cl], [1H], and [2H], derived from single-crystal X-ray diffraction, revealed that these compounds have a typical piano-stool geometry. The results show that the electronic properties of the hydrido complexes are strongly influenced by the substituents at the phosphorus donor atoms of the P(R)2N(Ph)2 ligand, whereas those of the chloro complexes are less affected. These results illustrate that the hydride is a strong-field ligand, as compared to chloride, and thus leads to a significant degree of covalent character of the iron hydride bonds. This is important in the context of possible catalytic intermediates of iron hydrido species, as proposed for the catalytic cycle of [FeFe] hydrogenases and other synthetic catalysts. Both hydrido compounds [1H] and [2H] show enhanced catalytic currents in cyclic voltammetry upon addition of the strong acid trifluoromethanesulfonimide [NHTf2] (pKa(MeCN) = 1.0). In contrast to the related complex [(P(tBu)N(Bn))2FeCp(C6F5)H], which was reported by Liu et al. (Nat. Chem. 2013, 5, 228-233) to be an electrocatalyst for hydrogen splitting, the here presented hydride complexes [1H] and [2H] show the tendency for electrocatalytic hydrogen production. Hence, the catalytic direction of this class of monoiron compounds can be reversed by specific ligand modifications.
    Inorganic Chemistry 07/2015; 54(14). DOI:10.1021/acs.inorgchem.5b00911 · 4.79 Impact Factor
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    ABSTRACT: The preparation and spectroscopic characterization of a fully active [FeFe] hydrogenase with a selectively 57Fe-labeled binuclear subsite is described. The precursor [57Fe2(adt)(CN)2(CO)4]2- was synthesized from the 57Fe metal, S8, CO, [Et4N]CN, NH4Cl, and OCH2. (Et4N)2[57Fe2(adt)(CN)2(CO)4] was then used for the maturation of the [FeFe] hydrogenase HydA1 from Chlamydomonas reinhardtii, to yield the enzyme selectively labeled at the [2Fe]H subcluster. Complementary 57Fe enrichment of the [4Fe-4S]H cluster was realized by reconstitution with 57FeCl3 and Na2S. The Hox-CO state of [257Fe]H and [457Fe-4S]H HydA1 was characterized by Mössbauer, HYSCORE, ENDOR, and nuclear resonance vibrational spectroscopy.
    Journal of the American Chemical Society 06/2015; 137(28). DOI:10.1021/jacs.5b03270 · 11.44 Impact Factor
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    ABSTRACT: Die Integration empfindlicher Katalysatoren in Redoxpolymere ist eine Möglichkeit, diese vor desaktivierenden Molekülen wie O2 zu schützen. [FeFe]-Hydrogenasen sind Enzyme, die die Oxidation sowie Produktion von H2 katalysieren. Da sie aber durch O2 irreversibel desaktiviert werden, war die Verwendung dieser Enzyme unter aeroben Bedingungen bisher unmöglich. Die Integration solcher Hydrogenasen in mit Viologenderivaten modifizierten Hydrogelfilmen ermöglicht auch in Gegenwart von O2 katalytische Ströme für die H2-Oxidation und demonstriert damit einen Schutzmechanismus unabhängig von Reaktivierungsprozessen. Im Hydrogel werden die Elektronen aus der durch die Hydrogenase katalysierten H2-Oxidation zur Hydrogel-Elektrolyt-Grenzfläche transportiert, um dort die schädlichen O2-Moleküle abzufangen, bevor sie die Hydrogenase desaktivieren können. Wir illustrieren mögliche Anwendungen dieses Schutzmechanismus für eine Biobrennstoffzelle bei gemischter H2/O2-Zufuhr.
    Angewandte Chemie 06/2015; DOI:10.1002/ange.201502776
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    ABSTRACT: The integration of sensitive catalysts in redox matrices opens up the possibility for their protection from deactivating molecules such as O2 . [FeFe]-hydrogenases are enzymes catalyzing H2 oxidation/production which are irreversibly deactivated by O2 . Therefore, their use under aerobic conditions has never been achieved. Integration of such hydrogenases in viologen-modified hydrogel films allows the enzyme to maintain catalytic current for H2 oxidation in the presence of O2 , demonstrating a protection mechanism independent of reactivation processes. Within the hydrogel, electrons from the hydrogenase-catalyzed H2 oxidation are shuttled to the hydrogel-solution interface for O2 reduction. Hence, the harmful O2 molecules do not reach the hydrogenase. We illustrate the potential applications of this protection concept with a biofuel cell under H2 /O2 mixed feed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Angewandte Chemie International Edition 06/2015; DOI:10.1002/anie.201502776 · 11.26 Impact Factor
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    ABSTRACT: The two resting forms of the active site of [NiFe] hydrogenase, Ni-A and Ni-B, have significantly different activation kinetics, but reveal nearly identical spectroscopic features which suggest the two states exhibit subtle structural differences. Previous studies have indicated that the states differ by the identity of the bridging ligand between Ni and Fe; proposals include OH-, OOH-, H2O, O2-, accompanied by modified cysteine residues. In this study, we use single crystal ENDOR spectroscopy and quantum chemical calculations within the framework of density functional theory (DFT) to calculate vibrational frequencies, 1H and 17O hyperfine coupling constants and g values with the aim to compare these data to experimental results obtained by crystallography, FTIR and EPR/ENDOR spectroscopy. We find that the Ni-A and Ni-B states are constitutional isomers that differ in their fine structural details. Calculated vibrational frequencies for the cyano and carbonyl ligands and 1H and 17O hyperfine coupling constants indicate that the bridging ligand in both Ni-A and Ni-B is indeed an OH- ligand. The difference in the isotropic hyperfine coupling constants of the β-CH2 protons of Cys-549 is sensitive to the orientation of Cys-549; a difference of 0.5 MHz is observed experimentally for Ni-A and 1.9 MHz for Ni-B, which results from a rotation of 7 degrees about the Cα-Cβ-Sγ-Ni dihedral angle. Likewise, the difference of the intermediate g value is correlated with a rotation of Cys-546 of about 10 degrees.
    Physical Chemistry Chemical Physics 05/2015; 17(24). DOI:10.1039/C5CP01322D · 4.20 Impact Factor
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    ABSTRACT: The regulatory hydrogenase (RH) from Ralstonia eutropha H16 acts as a sensor for the detection of environmental H2 and regulates gene expression related to hydrogenase-mediated cellular metabolism. In marked contrast to prototypical energy-converting [NiFe] hydrogenases, the RH is apparently insensitive to inhibition by O2 and CO. While the physiological function of regulatory hydrogenases is well established, little is known about the redox cycling of the [NiFe] center and the nature of the iron–sulfur (FeS) clusters acting as electron relay. The absence of any FeS cluster signals in EPR had been attributed to their particular nature, whereas the observation of essentially only two active site redox states, namely Ni-SI and Ni-C, invoked a different operant mechanism. In the present work, we employ a combination of Mössbauer, FTIR and EPR spectroscopic techniques to study the RH, and the results are consistent with the presence of three [4Fe–4S] centers in the small subunit. In the as-isolated, oxidized RH all FeS clusters reside in the EPR-silent 2+ state. Incubation with H2 leads to reduction of two of the [4Fe–4S] clusters, whereas only strongly reducing agents lead to reduction of the third cluster, which is ascribed to be the [4Fe–4S] center in ‘proximal’ position to the [NiFe] center. In the two different active site redox states, the low-spin FeII exhibits distinct Mössbauer features attributed to changes in the electronic and geometric structure of the catalytic center. The results are discussed with regard to the spectral characteristics and physiological function of H2-sensing regulatory hydrogenases.
    Chemical Science 05/2015; 6(8):4495-4507. DOI:10.1039/C5SC01560J · 9.21 Impact Factor
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    ABSTRACT: The transfer of photosynthetic electrons by the ferredoxin PetF to the [FeFe] hydrogenase HydA1 in the microalga Chlamydomonas reinhardtii is a key step in hydrogen production. Electron delivery requires a specific interaction between PetF and HydA1. However, due to the transient nature of the corresponding electron-transfer complex, an X-ray-structure remains elusive. Therefore, we performed protein-protein docking based on new experimental data from solution NMR spectroscopy on native and Gallium-substituted PetF that provides valuable information about residues crucial for complex formation and electron transfer. The derived complex model may help pinpoint residue substitution targets for improved hydrogen production. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    ChemBioChem 05/2015; DOI:10.1002/cbic.201500130 · 3.06 Impact Factor
  • Nicholas Cox · Dimitrios A Pantazis · Frank Neese · Wolfgang Lubitz
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    ABSTRACT: In the context of a global artificial photosynthesis (GAP) project, we review our current work on nature's water splitting catalyst. In a recent report (Cox et al. 2014 Science 345, 804-808 (doi:10.1126/science.1254910)), we showed that the catalyst-a Mn4O5Ca cofactor-converts into an 'activated' form immediately prior to the O-O bond formation step. This activated state, which represents an all Mn(IV) complex, is similar to the structure observed by X-ray crystallography but requires the coordination of an additional water molecule. Such a structure locates two oxygens, both derived from water, in close proximity, which probably come together to form the product O2 molecule. We speculate that formation of the activated catalyst state requires inherent structural flexibility. These features represent new design criteria for the development of biomimetic and bioinspired model systems for water splitting catalysts using first-row transition metals with the aim of delivering globally deployable artificial photosynthesis technologies.
    Interface focus: a theme supplement of Journal of the Royal Society interface 04/2015; 5(3):20150009-20150009. DOI:10.1098/rsfs.2015.0009 · 3.12 Impact Factor
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    ABSTRACT: The use of synthetic inorganic complexes as supported catalysts is a key route in energy production and in industrial synthesis. However, their intrinsic oxygen sensitivity is sometimes an issue. Some of us have recently demonstrated that hydrogenases, the fragile but very efficient biological catalysts of H2 oxidation, can be protected from O2 damage upon integration into a film of a specifically designed redox polymer. Catalytic oxidation of H2 produces electrons which reduce oxygen near the film/solution interface, thus providing a self-activated protection from oxygen [Plumeré et al., Nature Chemistry, 6, 822-827 (2014)]. Here, we rationalize this protection mechanism by examining the time-dependent distribution of species in the hydrogenase / polymer film, using measured or estimated values of all relevant parameters and the numerical and analytical solutions of a realistic reaction-diffusion scheme. Our investigation sets the stage for optimizing the design of hydrogenase-polymer films, and for expanding this strategy to other fragile catalysts.
    Journal of the American Chemical Society 04/2015; 137(16). DOI:10.1021/jacs.5b01194 · 11.44 Impact Factor
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    ABSTRACT: Nitrite is an important metabolite in the physiological pathways of NO and other nitrogen oxides in both enzymatic and non-enzymatic reactions. The ferric heme b protein nitrophorin 4 (NP4) is capable of catalyzing nitrite disproportionation at neutral pH, producing NO. Here we attempt to resolve its disproportionation mechanism. Isothermal titration calorimetry of a gallium(III) derivative of NP4 demonstrates that the heme iron coordinates the first substrate nitrite. Contrary to previous low temperature EPR measurements, which assigned the NP4-nitrite complex electronic configuration solely to a low-spin (S =1/2) species, electronic absorption, resonance Raman and (1)H-NMR spectroscopy presented here demonstrate that the NP4-NO2(-) cofactor exists in a high-spin/low-spin equilibrium of 7:3 which is in fast exchange in solution. Spin state interchange is taken as evidence for dynamic NO2(-) coordination, with the high-spin configuration (S = 5/2) representing the reactive species. Subsequent kinetic measurements reveal that the dismutation reaction proceeds in two discrete steps and identify an {FeNO}(7) intermediate species. The first reaction step, generating the {FeNO}(7) intermediate, represents an oxygen atom transfer from the iron bound nitrite to a second nitrite molecule in the protein pocket. In the second step this intermediate reduces a third nitrite substrate yielding two NO molecules. A nearby aspartic acid residue side-chain transiently stores protons required for the reaction, which is crucial for NPs' function as nitrite dismutase.
    Journal of the American Chemical Society 03/2015; 137(12). DOI:10.1021/ja512938u · 11.44 Impact Factor
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    ABSTRACT: The symmetry of the arrangement of objects has fascinated philosophers, artists and scientists for a long time, and still does. Symmetries often exist in Nature, but is also created artificially, for instance by chemical synthesis of novel molecules and materials. The one-sided, non-orientable Möbius band topology is a paradigm of such a symmetry-based fascination. In the early 1960’s, in synthetic organic chemistry the interest in molecules with Möbius symmetry was greatly stimulated by a short paper by Edgar Heilbronner. He predicted that sufficiently large [n]annulenes with a closed-shell electron configuration of 4n π-electrons should allow for sufficient π-overlap stabilization to be synthesizable by twisting them with a 180◦ phase change into the Möbius symmetry of their hydrocarbon skeleton. In 2007, the group of Lechosław Latos-Grażyński succeeded in synthesizing the compound di-p-benzi[28]hexa-phyrin(, compound 1, which can dynamically switch between Hückel and Möbius conjugation depending, in a complex manner, on the polarity and temperature of the surrounding solvent. This discovery of “topology switching” between the two-sided (Hückel) and one-sided (Möbius) molecular state with closed-shell electronic configuration was based primarily on the results of NMR spectroscopy and DFT calculations. The present EPR and ENDOR work on the radical cation state of compound 1 is the first study of a ground-state open-shell system which exhibits a Hückel-Möbius topology switch that is controlled by temperature, like in the case of the closed-shell precursor. The unpaired electron interacting with magnetic nuclei in the molecule is used as a sensitive probe for the electronic structure and its symmetry properties. For a Hückel conformer with its higher symmetry, we expect – and observe – fewer ENDOR lines than for a Möbius conformer. The ENDOR results are supplemented by and in accordance with theoretical calculations based on density functional theory at the ORCA level.
    Physical Chemistry Chemical Physics 02/2015; 17(9). DOI:10.1039/C4CP05745G · 4.20 Impact Factor
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    ABSTRACT: [FeFe]-hydrogenases are to date the only enzymes for which it has been demonstrated that the native inorganic binuclear cofactor of the active site Fe2(adt)(CO)3(CN)2 (adt = azadithiolate = [S-CH2-NH-CH2-S](2-)) can be synthesized on the laboratory bench and subsequently inserted into the unmaturated enzyme to yield fully functional holo-enzyme (Berggren, G. et al. (2013) Nature 499, 66?70, Esselborn, J. et al. (2013) Nat Chem Biol 9, 607?610). In the current study, we exploit this procedure to introduce non-native cofactors into the enzyme. Mimics of the binuclear sub-cluster with a modified bridging dithiolate ligand (thiodithiolate, N-methylazadithiolate, dimethyl-azadithiolate) and three variants containing only one CN(-) ligand were inserted into the active site of the enzyme. We investigate the activity of these variants for hydrogen oxidation as well as proton reduction and their structural accommodation within the active site was analyzed using Fourier transform infrared spectroscopy. Interestingly, the mono-cyanide variant with the azadithiolate bridge showed ?50% of the native Enzyme activity. This would suggest that the CN(-) ligands are not essential for catalytic activity but rather serve to anchor the binuclear subsite inside the protein pocket through hydrogen bonding. The inserted artificial cofactors with a propanedithiolate and an N-methylazadithiolate bridge as well as their mono-cyanide variants also showed residual activity. However, these activities were less than 1% of the native enzyme. Our findings indicate that even small changes in the dithiolate bridge of the binuclear sub-site lead to a rather strong decrease of the catalytic activity. We conclude that both the Br?nsted base function and the conformational flexibility of the native azadithiolate amine moiety are essential for the high catalytic activity of the native enzyme.
    Biochemistry 01/2015; 54(7). DOI:10.1021/bi501391d · 3.01 Impact Factor
  • Hideaki Ogata · Koji Nishikawa · Wolfgang Lubitz
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    ABSTRACT: The enzyme hydrogenase reversibly converts dihydrogen to protons and electrons at a metal catalyst. The location of the abundant hydrogens is of key importance for understanding structure and function of the protein. However, in protein X-ray crystallography the detection of hydrogen atoms is one of the major problems, since they display only weak contributions to diffraction and the quality of the single crystals is often insufficient to obtain sub-ångström resolution. Here we report the crystal structure of a standard [NiFe] hydrogenase (∼91.3 kDa molecular mass) at 0.89 Å resolution. The strictly anoxically isolated hydrogenase has been obtained in a specific spectroscopic state, the active reduced Ni-R (subform Ni-R1) state. The high resolution, proper refinement strategy and careful modelling allow the positioning of a large part of the hydrogen atoms in the structure. This has led to the direct detection of the products of the heterolytic splitting of dihydrogen into a hydride (H(-)) bridging the Ni and Fe and a proton (H(+)) attached to the sulphur of a cysteine ligand. The Ni-H(-) and Fe-H(-) bond lengths are 1.58 Å and 1.78Å, respectively. Furthermore, we can assign the Fe-CO and Fe-CN(-) ligands at the active site, and can obtain the hydrogen-bond networks and the preferred proton transfer pathway in the hydrogenase. Our results demonstrate the precise comprehensive information available from ultra-high-resolution structures of proteins as an alternative to neutron diffraction and other methods such as NMR structural analysis.
    Nature 01/2015; 520(7548). DOI:10.1038/nature14110 · 42.35 Impact Factor
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    ABSTRACT: Hydrogenases are enzymes that catalyze the oxidation of H2 as well as the reduction of protons to form H2. The active site of [FeFe] hydrogenase is referred to as the "H-cluster" and consists of a "classical" [4Fe-4S] cluster connected via a bridging cysteine thiol group to a unique [2Fe]H sub-cluster, containing CN(-) and CO ligands as well as a bidentate azadithiolate ligand. It has been recently shown that the biomimetic [Fe2(adt)(CO)4(CN)2](2-) (adt(2-) = azadithiolate) complex resembling the diiron sub-cluster can be inserted in vitro into the apo-protein of [FeFe] hydrogenase, which contains only the [4Fe-4S] part of the H-cluster, resulting in a fully active enzyme. This synthetic tool allows convenient incorporation of a variety of diiron mimics, thus generating hydrogenases with artificial active sites. [FeFe] hydrogenase from Chlamydomonas reinhardtii maturated with the biomimetic complex [Fe2(pdt)(CO)4(CN)2](2-) (pdt(2-) = propanedithiolate), in which the bridging adt(2-) ligand is replaced by pdt(2-), can be stabilized in a state strongly resembling the active oxidized (Hox) state of the native protein. This state is EPR active and the signal originates from the mixed valence Fe(I)Fe(II) state of the diiron sub-cluster. Taking advantage of the variant with (15)N and (13)C isotope labeled CN(-) ligands we performed HYSCORE and ENDOR studies on this hybrid protein. The (13)C hyperfine couplings originating from both CN(-) ligands were determined and assigned. Only the (15)N coupling from the CN(-) ligand bound to the terminal iron was observed. Detailed orientation selective ENDOR and HYSCORE experiments at multiple field positions enabled the extraction of accurate data for the relative orientations of the nitrogen and carbon hyperfine tensors. These data are consistent with the crystal structure assuming a g-tensor orientation following the local symmetry of the binuclear sub-cluster.
    Physical Chemistry Chemical Physics 01/2015; 17(7). DOI:10.1039/c4cp05426a · 4.20 Impact Factor
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    ABSTRACT: A central question in biological water splitting concerns the oxidation states of the manganese ions that comprise the oxygen-evolving complex of photosystem II. Understanding the nature and order of oxidation events that occur during the catalytic cycle of five Si states (i = 0–4) is of fundamental importance both for the natural system and for artificial water oxidation catalysts. Despite the widespread adoption of the so-called “high-valent scheme”—where, for example, the Mn oxidation states in the S2 state are assigned as III, IV, IV, IV—the competing “low-valent scheme” that differs by a total of two metal unpaired electrons (i.e. III, III, III, IV in the S2 state) is favored by several recent studies for the biological catalyst. The question of the correct oxidation state assignment is addressed here by a detailed computational comparison of the two schemes using a common structural platform and theoretical approach. Models based on crystallographic constraints were constructed for all conceivable oxidation state assignments in the four (semi)stable S states of the oxygen evolving complex, sampling various protonation levels and patterns to ensure comprehensive coverage. The models are evaluated with respect to their geometric, energetic, electronic, and spectroscopic properties against available experimental EXAFS, XFEL-XRD, EPR, ENDOR and Mn K pre-edge XANES data. New 2.5 K 55Mn ENDOR data of the S2 state are also reported. Our results conclusively show that the entire S state phenomenology can only be accommodated within the high-valent scheme by adopting a single motif and protonation pattern that progresses smoothly from S0 (III, III, III, IV) to S3 (IV, IV, IV, IV), satisfying all experimental constraints and reproducing all observables. By contrast, it was impossible to construct a consistent cycle based on the low-valent scheme for all S states. Instead, the low-valent models developed here may provide new insight into the over-reduced S states and the states involved in the assembly of the catalytically active water oxidizing cluster.
    Chemical Science 01/2015; 6(3). DOI:10.1039/C4SC03720K · 9.21 Impact Factor
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    ABSTRACT: The structural and dynamical interaction of proteins with their microenvironment in disordered matrices plays a decisive role for their function; EPR spectroscopy is a powerful tool for shading light onto the molecular mechanisms of this protein–matrix interplay. To clarify the molecular mechanisms of disaccharide bioprotection, we studied the structure and dynamics of spin-labeled systems and photosynthetic reaction centers (RCs) in sucrose and trehalose matrices at different hydration levels by means of cw and pulse high-field 95 GHz (W-band) EPR as well as by FTIR. In this minireview, we summarize and discuss EPR and FTIR experiments showing that the anhydrobiotic state of the RC–trehalose system (1) is not the result of matrix-induced changes of the local structure of the charge-separated radical-pair cofactors, \({\text{P}}_{865}^{ \cdot + }\) and \({\text{Q}}_{\text{A}}^{ \cdot - }\) , and (2) is not the result of changes of local dynamics and local hydrogen bonding of QA in its binding pocket. Rather, the extreme impairment of RC dynamics caused by incorporation into the dehydrated trehalose matrix, which also protects it against thermal denaturation, originates in the high rigidity, already at room temperature, of the dry trehalose glass matrix coating the RC protein surface. This surface hydrogen-bonding scaffold shifts the correlation time of thermal conformational fluctuations into the non-biological time domain. Another intriguing aspect of disaccharide bioprotection is the superior efficiency of trehalose versus sucrose matrices in stabilizing the anhydrobiotic state of proteins. To clarify the molecular basis of this specificity, glassy trehalose–water and sucrose–water binary systems, incorporating a nitroxide radical as spin probe, have been studied by high-field W-band EPR spectroscopy at different water contents. Analysis of the EPR spectra revealed a different structural and dynamical organization in the sucrose and trehalose matrix, only the trehalose being homogeneous in terms of residual water and nitroxide distribution.
    Applied Magnetic Resonance 01/2015; 46(4). DOI:10.1007/s00723-014-0633-4 · 1.15 Impact Factor

Publication Stats

9k Citations
2,078.17 Total Impact Points


  • 2006–2015
    • Max Planck Institute for Chemical Energy Conversion
      Mülheim-on-Ruhr, North Rhine-Westphalia, Germany
    • Max Planck Institute for Medical Research
      Heidelburg, Baden-Württemberg, Germany
  • 2003–2015
    • Max Planck Institute for Chemistry
      Mayence, Rheinland-Pfalz, Germany
  • 2007
    • Semenov Institute of Chemical Physics
      Moskva, Moscow, Russia
  • 1991–2007
    • Technische Universität Berlin
      • Department of Chemistry
      Berlín, Berlin, Germany
  • 2005
    • John Innes Centre
      • Department of Biological Chemistry
      Norwich, ENG, United Kingdom
  • 1975–2002
    • Freie Universität Berlin
      • Institute of Experimental Physics
      Berlín, Berlin, Germany
  • 2001
    • VU University Amsterdam
      • Division of Theoretical Chemistry
      Amsterdamo, North Holland, Netherlands
  • 2000
    • Stockholm University
      Tukholma, Stockholm, Sweden
    • Uppsala University
      Uppsala, Uppsala, Sweden
  • 1999
    • University of Amsterdam
      Amsterdamo, North Holland, Netherlands
  • 1996
    • Arizona State University
      • Department of Chemistry and Biochemistry
      Mesa, AZ, United States
  • 1995
    • Max Planck Institute for Biophysical Chemistry
      Göttingen, Lower Saxony, Germany
  • 1985–1995
    • University of California, San Diego
      • Department of Physics
      San Diego, California, United States
  • 1983
    • Goethe-Universität Frankfurt am Main
      • Institut für Anorganische und Analytische Chemie
      Frankfurt, Hesse, Germany
  • 1980
    • University of Jyväskylä
      • Department of Chemistry
      Jyväskylä, Western Finland, Finland