CNRS Chemistry, Biology and Innovation Laboratory

Paris, France

CNRS Chemistry, Biology and Innovation Laboratory

Paris, France
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Obexer R.,ETH Zurich | Godina A.,ETH Zurich | Godina A.,CNRS Chemistry, Biology and Innovation Laboratory | Garrabou X.,ETH Zurich | And 4 more authors.
Nature Chemistry | Year: 2017

Designing catalysts that achieve the rates and selectivities of natural enzymes is a long-standing goal in protein chemistry. Here, we show that an ultrahigh-throughput droplet-based microfluidic screening platform can be used to improve a previously optimized artificial aldolase by an additional factor of 30 to give a >10 9 rate enhancement that rivals the efficiency of class I aldolases. The resulting enzyme catalyses a reversible aldol reaction with high stereoselectivity and tolerates a broad range of substrates. Biochemical and structural studies show that catalysis depends on a Lys-Tyr-Asn-Tyr tetrad that emerged adjacent to a computationally designed hydrophobic pocket during directed evolution. This constellation of residues is poised to activate the substrate by Schiff base formation, promote mechanistically important proton transfers and stabilize multiple transition states along a complex reaction coordinate. The emergence of such a sophisticated catalytic centre shows that there is nothing magical about the catalytic activities or mechanisms of naturally occurring enzymes, or the evolutionary process that gave rise to them. © 2016 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.


Yeates J.A.M.,Portland State University | Yeates J.A.M.,CNRS Chemistry, Biology and Innovation Laboratory | Nghe P.,CNRS Chemistry, Biology and Innovation Laboratory | Lehman N.,Portland State University
RNA | Year: 2017

An RNA-directed recombination reaction can result in a network of interacting RNA species. It is now becoming increasingly apparent that such networks could have been an important feature of the RNA world during the nascent evolution of life on the Earth. However, the means by which such small RNA networks assimilate other available genotypes in the environment to grow and evolve into the more complex networks that are thought to have existed in the prebiotic milieu are not known. Here, we used the ability of fragments of the Azoarcus group I intron ribozyme to covalently self-assemble via genotype-selfish and genotype-cooperative interactions into full-length ribozymes to investigate the dynamics of small (three- and four-membered) networks. We focused on the influence of a three-membered core network on the incorporation of additional nodes, and on the degree and direction of connectivity as single new nodes are added to this core. We confirmed experimentally the predictions that additional links to a core should enhance overall network growth rates, but that the directionality of the link (a "giver" or a "receiver") impacts the growth of the core itself. Additionally, we used a simple mathematical model based on the first-order effects of lower-level interactions to predict the growth of more complex networks, and find that such a model can, to a first approximation, predict the ordinal rankings of nodes once a steady-state distribution has been reached. © 2017 Yeates et al.


Botet R.,University Paris - Sud | Cabane B.,CNRS Chemistry, Biology and Innovation Laboratory | Goehring L.,Max Planck Institute for Dynamics and Self-Organization | Li J.,Max Planck Institute for Dynamics and Self-Organization | Artzner F.,Rennes Institute of Physics
Faraday Discussions | Year: 2016

A modified version of the Gibbs-ensemble Monte-Carlo method reveals how polydisperse charged colloidal particles can build complex colloidal crystals. It provides general rules that are applicable to this fractionated crystallization that stems from size segregation. It explains the spontaneous formation of complex crystals with very large unit-cells in suspensions of nanoparticles with a broad size distribution. © The Royal Society of Chemistry 2016.


Demoulin D.,CNRS Chemistry, Biology and Innovation Laboratory | Carlier M.-F.,French National Center for Scientific Research | Bibette J.,CNRS Chemistry, Biology and Innovation Laboratory | Baudry J.,CNRS Chemistry, Biology and Innovation Laboratory
Proceedings of the National Academy of Sciences of the United States of America | Year: 2014

The actin cytoskeleton has the unique capability of producing pushing forces at the leading edge of motile cells without the implication of molecular motors. This phenomenon has been extensively studied theoretically, and molecular models, including the widely known Brownian ratchet, have been proposed. However, supporting experimental work is lacking, due in part to hardly accessible molecular length scales. We designed an experiment to directly probe the mechanism of force generation in a setup where a population of actin filaments grows against a load applied by magnetic microparticles. The filaments, arranged in stiff bundles by fascin, are constrained to point toward the applied load. In this protrusion-like geometry, we are able to directly measure the velocity of filament elongation and its dependence on force. Using numerical simulations, we provide evidence that our experimental data are consistent with a Brownian ratchet-based model. We further demonstrate the existence of a force regime far below stalling where the mechanical power transduced by the ratcheting filaments to the load is maximal. The actin machinery in migrating cells may tune the number of filaments at the leading edge to work in this force regime. © 2014 National Academy of Sciences. All rights reserved.


Najah M.,CNRS Institute of Science and Supramolecular Engineering | Calbrix R.,CNRS Institute of Science and Supramolecular Engineering | Mahendra-Wijaya I.P.,CNRS Institute of Science and Supramolecular Engineering | Beneyton T.,CNRS Chemistry, Biology and Innovation Laboratory | And 3 more authors.
Chemistry and Biology | Year: 2014

Discovery of microorganisms producing enzymes that can efficiently hydrolyze cellulosic biomass is of great importance for biofuel production. To date, however, only a miniscule fraction of natural biodiversity has been tested because of the relatively low throughput of screening systems and their limitation to screening only culturable microorganisms. Here, we describe an ultra-high-throughput droplet-based microfluidic system that allowed the screening of over 100,000 cells in less than 20 min. Uncultured bacteria from a wheat stubble field were screened directly by compartmentalization of single bacteria in 20 pl droplets containing a fluorogenic cellobiohydrolase substrate. Sorting of droplets based on cellobiohydrolase activity resulted in a bacterial population with 17- and 7-fold higher cellobiohydrolase and endogluconase activity, respectively, and very different taxonomic diversity than when selected for growth on medium containing starch and carboxymethylcellulose as carbon source. © 2014 Elsevier Ltd. All rights reserved.


Cahiez G.,CNRS Paris Research Institute of Chemistry | Moyeux A.,CNRS Paris Research Institute of Chemistry | Moyeux A.,University of Paris 13 | Cossy J.,CNRS Chemistry, Biology and Innovation Laboratory
Advanced Synthesis and Catalysis | Year: 2015

Grignard reagents are probably the best organometallics to develop large-scale eco-friendly cross-couplings compatible with the requirements of sustainable development. This account aims to highlight some reactions having an interesting industrial potential and gives the personal point of view of the authors on some attractive fields of research in this area. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Guerinot A.,CNRS Chemistry, Biology and Innovation Laboratory | Cossy J.,CNRS Chemistry, Biology and Innovation Laboratory
Topics in Current Chemistry | Year: 2016

Over the last decades, iron-catalyzed cross-couplings have emerged as an important tool for the formation of C–C bonds. A wide variety of alkenyl, aryl, and alkyl (pseudo)halides have been coupled to organometallic reagents, the most currently used being Grignard reagents. Particular attention has been devoted to the development of iron catalysts for the functionalization of alkyl halides that are generally challenging substrates in classical cross-couplings. The high functional group tolerance of iron-catalyzed cross-couplings has encouraged organic chemists to use them in the synthesis of bioactive compounds. Even if some points remain obscure, numerous studies have been carried out to investigate the mechanism of iron-catalyzed cross-coupling and several hypotheses have been proposed. © 2016, Springer International Publishing Switzerland.


Hostier T.,CNRS Chemistry, Biology and Innovation Laboratory | Ferey V.,CNRS Chemistry, Biology and Innovation Laboratory | Ricci G.,CNRS Chemistry, Biology and Innovation Laboratory | Gomez Pardo D.,CNRS Chemistry, Biology and Innovation Laboratory | Cossy J.,CNRS Chemistry, Biology and Innovation Laboratory
Organic Letters | Year: 2015

A simple, efficient, and practical metal-free C-H sulfenylation of substituted electron-rich arenes has been developed. This method is highly regioselective, and the corresponding aryl sulfides were obtained in moderate to excellent yields from stable and readily accessible N-(alkylthio)- and N-(arylthio)succinimides at room temperature in the presence of TFA. © 2015 American Chemical Society.


Cossy J.,CNRS Chemistry, Biology and Innovation Laboratory | Guerinot A.,CNRS Chemistry, Biology and Innovation Laboratory
Advances in Heterocyclic Chemistry | Year: 2016

Oxygen-containing heterocycles are ubiquitous in biologically active natural products, which can be a great source of inspiration in drug discovery. Due to the importance of this class of compounds, a myriad of synthetic methods has been developed to access oxygen-containing heterocycles, which are based on two main strategies. The first one involves the formation of a C. O bond of the heterocycle while in the second one, a C. C bond is formed. The recent research in this area aims at developing chemo-, regio-, diastereo-, and enantioselective methods involving catalytic processes. © 2016 Elsevier Inc.


Azzouz I.,CNRS Chemistry, Biology and Innovation Laboratory | Essoussi A.,CNRS Chemistry, Biology and Innovation Laboratory | Fleury J.,CNRS Chemistry, Biology and Innovation Laboratory | Haudebourg R.,CNRS Chemistry, Biology and Innovation Laboratory | And 2 more authors.
Journal of Chromatography A | Year: 2015

The preparation conditions of silica monoliths for gas chromatography were investigated. Silica-based monolithic capillary columns based on sol-gel process were tested in the course of high-speed gas chromatographic separations of light hydrocarbons mixture (C1-C4). The impact of modifying the amount of porogen and/or catalyst on the monolith properties were studied. At the best precursor/catalyst/porogen ratio evaluated, a column efficiency of about 6500 theoretical plates per meter was reached with a very good resolution (4.3) for very light compounds (C1-C2). The test mixture was baseline separated on a 70cm column. To our knowledge for the first time a silica-based monolithic capillary column was able to separate light hydrocarbons from methane to n-butane at room temperature with a back pressure in the range of gas chromatography facilities (under 4.1bar). © 2015 Elsevier B.V.

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