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Artero V.,CNRS Chemistry and Biology of Metals Laboratory | Saveant J.-M.,University Paris Diderot
Energy and Environmental Science | Year: 2014

Molecular electrocatalysts for H2 evolution are usually studied under various conditions (solvent and proton sources) that prevent direct comparison of their performances. We provide here a rational method for such a benchmark based on (i) the recent analysis of the current-potential response for two-electron-two-step mechanisms and (ii) the derivation of catalytic Tafel plots reflecting the interdependency of turnover frequency and overpotential based on the intrinsic properties of the catalyst, independent of contingent factors such as cell characteristics. Such a methodology is exemplified on a series of molecular catalysts among the most efficient in the recent literature. © 2014 the Partner Organisations.

Tran P.D.,CNRS Chemistry and Biology of Metals Laboratory | Artero V.,CNRS Chemistry and Biology of Metals Laboratory | Fontecave M.,CNRS Chemistry and Biology of Metals Laboratory | Fontecave M.,Collège de France
Energy and Environmental Science | Year: 2010

Photoelectrocatalytic cells for water splitting should combine one or two photosensitive units with a water oxidation catalyst at the anode and a hydrogen evolution catalyst at the cathode. In this perspective article, we first show how a chemist can take the naturally occurring multi-electron catalysts for these two electro- and photochemical reactions, photosystem II and hydrogenases, as a source of inspiration for the design of original, efficient and robust molecular catalysts. The focus of this article is given to the immobilisation of these natural or bio-inspired catalysts onto conducting surfaces and the design of electrode and photoelectrode materials for hydrogen evolution/uptake and water oxidation. © 2010 The Royal Society of Chemistry.

Simmons T.R.,CNRS Chemistry and Biology of Metals Laboratory | Berggren G.,CNRS Chemistry and Biology of Metals Laboratory | Berggren G.,University of Stockholm | Bacchi M.,CNRS Chemistry and Biology of Metals Laboratory | And 3 more authors.
Coordination Chemistry Reviews | Year: 2014

Over the last 15 years, a plethora of research has provided major insights into the structure and function of hydrogenase enzymes. This has led to the important development of chemical models that mimic the inorganic enzymatic co-factors, which in turn has further contributed to the understanding of the specific molecular features of these natural systems that facilitate such large and robust enzyme activities. More recently, efforts have been made to generate guest-host models and artificial hydrogenases, through the incorporation of transition metal-catalysts (guests) into various hosts. This adds a new layer of complexity to hydrogenase-like catalytic systems that allows for better tuning of their activity through manipulation of both the first (the guest) and the second (the host) coordination spheres. Herein we review the aforementioned advances achieved during the last 15 years, in the field of inorganic biomimetic hydrogenase chemistry. After a brief presentation of the enzymes themselves, as well as the early bioinspired catalysts, we review the more recent systems constructed as models for the hydrogenase enzymes, with a specific focus on the various strategies employed for incorporating of synthetic models into supramolecular frameworks and polypeptidic/protein scaffolds, and critically discuss the advantages of such an elaborate approach, with regard to the catalytic performances. © 2014 Elsevier B.V.

Simmons T.R.,CNRS Chemistry and Biology of Metals Laboratory | Artero V.,CNRS Chemistry and Biology of Metals Laboratory
Angewandte Chemie - International Edition | Year: 2013

One metal or two? Recent results in the design of hydrogenase mimics have resulted in NiFe- and Fe-based complexes (see picture) that split molecular H2 into electrons and protons. Although these compounds are still far from technological application they improve our understanding of how nature exploits abundant metals to achieve complex reactions. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Artero V.,CNRS Chemistry and Biology of Metals Laboratory | Fontecave M.,Collège de France
Chemical Society Reviews | Year: 2013

Catalysis is a key enabling technology for solar fuel generation. A number of catalytic systems, either molecular/homogeneous or solid/heterogeneous, have been developed during the last few decades for both the reductive and oxidative multi-electron reactions required for fuel production from water or CO 2 as renewable raw materials. While allowing for a fine tuning of the catalytic properties through ligand design, molecular approaches are frequently criticized because of the inherent fragility of the resulting catalysts, when exposed to extreme redox potentials. In a number of cases, it has been clearly established that the true catalytic species is heterogeneous in nature, arising from the transformation of the initial molecular species, which should rather be considered as a pre-catalyst. Whether such a situation is general or not is a matter of debate in the community. In this review, covering water oxidation and reduction catalysts, involving noble and non-noble metal ions, we limit our discussion to the cases in which this issue has been directly and properly addressed as well as those requiring more confirmation. The methodologies proposed for discriminating homogeneous and heterogeneous catalysis are inspired in part by those previously discussed by Finke in the case of homogeneous hydrogenation reaction in organometallic chemistry [J. A. Widegren and R. G. Finke, J. Mol. Catal. A, 2003, 198, 317-341]. © 2013 The Royal Society of Chemistry.

Seneque O.,CNRS Chemistry and Biology of Metals Laboratory | Latour J.-M.,CNRS Chemistry and Biology of Metals Laboratory
Journal of the American Chemical Society | Year: 2010

Zinc fingers are ubiquitous small protein domains which have a Zn(Cys) 4-x(His) x site. They possess great diversity in their structure and amino acid composition. Using a family of six peptides, it was possible to assess the influence of hydrophobic amino acids on the metal-peptide affinities and on the rates of metal association and dissociation. A model of a treble-clef zinc finger, a model of the zinc finger site of a redox-switch protein, and four variants of the classical ββα zinc finger were used. They differ in their coordination set, their sequence length, and their hydrophobic amino acid content. The speciation, metal binding constants, and structure of these peptides have been investigated as a function of pH. The zinc binding constants of peptides, which adopt a well-defined structure, were found to be around 10 15 at pH 7.0. The rates of zinc exchange between EDTA and the peptides were also assessed. We evidenced that the packing of hydrophobic amino acids into a well-defined hydrophobic core can have a drastic influence on both the binding constant and the kinetics of metal exchange. Notably, well-packed hydrophobic amino acids can increase the stability constant by 4 orders of magnitude. The half-life of zinc exchange was also seen to vary significantly depending on the sequence of the zinc finger. The possible causes for this behavior are discussed. This work will help in understanding the dynamics of zinc exchange in zinc-containing proteins. © 2010 American Chemical Society.

Artero V.,CNRS Chemistry and Biology of Metals Laboratory | Chavarot-Kerlidou M.,CNRS Chemistry and Biology of Metals Laboratory | Fontecave M.,CNRS Chemistry and Biology of Metals Laboratory | Fontecave M.,Collège de France
Angewandte Chemie - International Edition | Year: 2011

The future of energy supply depends on innovative breakthroughs regarding the design of cheap, sustainable, and efficient systems for the conversion and storage of renewable energy sources, such as solar energy. The production of hydrogen, a fuel with remarkable properties, through sunlight-driven water splitting appears to be a promising and appealing solution. While the active sites of enzymes involved in the overall water-splitting process in natural systems, namely hydrogenases and photosystem II, use iron, nickel, and manganese ions, cobalt has emerged in the past five years as the most versatile non-noble metal for the development of synthetic H 2- and O 2- evolving catalysts. Such catalysts can be further coupled with photosensitizers to generate photocatalytic systems for light-induced hydrogen evolution from water. It's cobalt's turn: Splitting water with light appears to be a promising solution for the renewable production of a fuel such as hydrogen. Recent developments on cobalt-based catalysts for H 2 or O 2 evolution are discussed, along with how they can be coupled with photosensitizers, to generate light-driven systems, or immobilized onto conducting materials to form electrodes or photoelectrodes for integration in a photoelectrochemical cell. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Taking the opportunity of the 20th anniversary of the word "proteomics", this young adult age is a good time to remember how proteomics came from enormous progress in protein separation and protein microanalysis techniques, and from the conjugation of these advances into a high performance and streamlined working setup. However, in the history of the almost three decades that encompass the first attempts to perform large scale analysis of proteins to the current high throughput proteomics that we can enjoy now, it is also interesting to underline and to recall how difficult the first decade was. Indeed when the word was cast, the battle was already won. This recollection is mostly devoted to the almost forgotten period where proteomics was being conceived and put to birth, as this collective scientific work will never appear when searched through the keyword "proteomics". Biological significance: The significance of this manuscript is to recall and review the two decades that separated the first attempts of performing large scale analysis of proteins from the solid technical corpus that existed when the word "proteomics" was coined twenty years ago. This recollection is made within the scientific historical context of this decade, which also saw the blossoming of DNA cloning and sequencing.This article is part of a Special Issue entitled: 20 years of Proteomics in memory of Viatliano Pallini. Guest Editors: Luca Bini , Juan J. Calvete, Natacha Turck, Denis Hochstrasser and Jean-Charles Sanchez. © 2014 Elsevier B.V.

Isaac M.,CNRS Chemistry and Biology of Metals Laboratory | Latour J.-M.,CNRS Chemistry and Biology of Metals Laboratory | Seneque O.,CNRS Chemistry and Biology of Metals Laboratory
Chemical Science | Year: 2012

During the past decades it has been established that zinc-bound cysteines in proteins can react with various electrophiles to perform physiological functions such as alkyl transfer reactions or oxidative stress sensing. Electrophiles targeting especially vulnerable structural zinc fingers have also been proposed as therapeutic agents against cancers or HIV. However, the nucleophilic reactivity of zinc fingers remains poorly understood. In this article, we investigate the nucleophilic reaction of zinc finger model peptides with H 2O 2 in order to get deeper insight into the factors governing the reactivity of zinc-bound cysteines of zinc finger sites. We use a set of nine peptides belonging to two different peptide families with (Cys) 4, (Cys) 3(His) and (Cys) 2(His) 2 coordination sets. One family is derived from the consensus peptide of classical ββα zinc fingers and the other one derived from the zinc finger site of the oxidative stress sensor Hsp33 that adopts a loosened zinc ribbon fold. The coordination properties and the structural behaviors of the new members of the latter family were carefully characterized. The rate constants of the reaction of the nine zinc finger models with H 2O 2 were measured at various temperatures to determine the activation parameters. In all cases, the reaction is characterized by a small enthalpy of activation, which shows that the nucleophilic reaction of zinc-bound cysteines is easy, and large unfavorable negative entropy of activation. Neutral Zn(Cys) 2(His) 2 cores are intrinsically less reactive than negatively charged Zn(Cys) 4 and Zn(Cys) 3(His). Interestingly, we observe that the more flexible zinc finger sites are the more reactive. Indeed the entropies of activation are strongly linked to the conformational behavior of the peptide in solution. This work reveals important factors that govern the reactivity of zinc-bound cysteines in these two structural classes of zinc fingers and can be used to identify reactive zinc fingers in proteins. © 2012 The Royal Society of Chemistry.

Delangle P.,Stendhal University | Mintz E.,CNRS Chemistry and Biology of Metals Laboratory
Dalton Transactions | Year: 2012

Wilson's disease is an orphan disease due to copper homeostasis dysfunction. Mutations of the ATP7B gene induces an impaired functioning of a Cu-ATPase, impaired Cu detoxification in the liver and copper overload in the body. Indeed, even though copper is an essential element, which is used as cofactor by many enzymes playing vital roles, it becomes toxic when in excess as it promotes cytotoxic reactions leading to oxidative stress. In this perspective, human copper homeostasis is first described in order to explain the mechanisms promoting copper overload in Wilson's disease. We will see that the liver is the main organ for copper distribution and detoxification in the body. Nowadays this disease is treated life-long by systemic chelation therapy, which is not satisfactory in many cases. Therefore the design of more selective and efficient drugs is of great interest. A strategy to design more specific chelators to treat localized copper accumulation in the liver will then be presented. In particular we will show how bioinorganic chemistry may help in the design of such novel chelators by taking inspiration from the biological copper cell transporters. © 2012 The Royal Society of Chemistry.

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