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Gif-sur-Yvette, France

Perez J.,Synchrotron Soleil | Koutsioubas A.,Julich Research Center
Acta Crystallographica Section D: Biological Crystallography | Year: 2015

The application of small-angle X-ray scattering (SAXS) to structural investigations of transmembrane proteins in detergent solution has been hampered by two main inherent hurdles. On the one hand, the formation of a detergent corona around the hydrophobic region of the protein strongly modifies the scattering curve of the protein. On the other hand, free micelles of detergent without a precisely known concentration coexist with the protein-detergent complex in solution, therefore adding an uncontrolled signal. To gain robust structural information on such systems from SAXS data, in previous work, advantage was taken of the online combination of size-exclusion chromatography (SEC) and SAXS, and the detergent corona around aquaporin-0, a membrane protein of known structure, could be modelled. A precise geometrical model of the corona, shaped as an elliptical torus, was determined. Here, in order to better understand the correlations between the corona model parameters and to discuss the uniqueness of the model, this work was revisited by analyzing systematic SAXS simulations over a wide range of parameters of the torus. © 2015. Source

Perez J.,Synchrotron Soleil | Nishino Y.,Hokkaido University
Current Opinion in Structural Biology | Year: 2012

Small-angle X-ray scattering (SAXS) of macromolecular systems in solution has become an obvious complement to high resolution structural studies. Using SAXS, structural hypotheses can be directly tested against experimental data in solution. Conformational changes or complex formation can be monitored, and help understanding structure-function relationships. Additionally, the reliability of the data has been much strengthened by on-line purification approaches. Moreover, when coherent X-rays are used for sample illumination, SAXS patterns become speckled and can provide electron-density maps directly by computational phase-retrieval methods. Furthermore, X-ray free-electron laser with femtosecond pulse duration will enable us to take time-frozen images of biomolecules in solution free from radiation damage. In this paper, recent experimental and methodological advances in both classical and coherent SAXS are reviewed. © 2012 Elsevier Ltd. Source

Rueff J.-P.,Synchrotron Soleil | Rueff J.-P.,University Pierre and Marie Curie | Shukla A.,University Pierre and Marie Curie
Reviews of Modern Physics | Year: 2010

Investigating electronic structure and excitations under extreme conditions gives access to a rich variety of phenomena. High pressure typically induces behavior such as magnetic collapse and the insulator-metal transition in 3d transition-metal compounds, valence fluctuations or Kondo-like characteristics in f -electron systems, and coordination and bonding changes in molecular solids and glasses. This article reviews research concerning electronic excitations in materials under extreme conditions using inelastic x-ray scattering (IXS). IXS is a spectroscopic probe of choice for this study because of its chemical and orbital selectivity and the richness of information it provides. Being an all-photon technique, IXS has a penetration depth compatible with high-pressure requirements. Electronic transitions under pressure in 3d transition-metal compounds and f -electron systems, most of them strongly correlated, are reviewed. Implications for geophysics are mentioned. Since the incident x-ray energy can easily be tuned to absorption edges, resonant IXS, often employed, is discussed at length. Finally studies involving local structure changes and electronic transitions under pressure in materials containing light elements are reviewed. © 2010 The American Physical Society. Source

Miller L.M.,Brookhaven National Laboratory | Dumas P.,Synchrotron Soleil
Current Opinion in Structural Biology | Year: 2010

Current efforts in structural biology aim to integrate structural information within the context of cellular organization and function. X-rays and infrared radiation stand at opposite ends of the electromagnetic spectrum and act as complementary probes for achieving this goal. Intense and bright beams are produced by synchrotron radiation, and are efficiently used in the wavelength domain extending from hard X-rays to the far-infrared (or THz) regime. While X-ray crystallography provides exquisite details on atomic structure, Fourier transform infrared microspectroscopy (FTIRM) is emerging as a spectroscopic probe and imaging tool for correlating molecular structure to biochemical dynamics and function. In this manuscript, the role of synchrotron FTIRM in bridging the gap towards 'functional biology' is discussed based upon recent achievements, with a critical assessment of the contributions to biological and biomedical research. © 2010. Source

Agency: Cordis | Branch: H2020 | Program: RIA | Phase: INFRAIA-1-2014-2015 | Award Amount: 10.00M | Year: 2015

Structural biology provides insight into the molecular architecture of cells up to atomic resolution, revealing the biological mechanisms that are fundamental to life. It is thus key to many innovations in chemistry, biotechnology and medicine such as engineered enzymes, new potent drugs, innovative vaccines and novel biomaterials. iNEXT (infrastructure for NMR, EM and X-rays for Translational research) will provide high-end structural biology instrumentation and expertise, facilitating expert and non-expert European users to translate their fundamental research into biomedical and biotechnological applications. iNEXT brings together leading European structural biology facilities under one interdisciplinary organizational umbrella and includes synchrotron sites for X-rays, NMR centers with ultra-high field instruments, and, for the first time, advanced electron microscopy and light imaging facilities. Together with key partners in biological and biomedical institutions, partners focusing on training and dissemination activities, and ESFRI projects (Instruct, Euro-BioImaging, EU-OPENSCREEN and future neutron-provider ESS), iNEXT forms an inclusive European network of world class. iNEXT joint research projects (fragment screening for drug development, membrane protein structure, and multimodal cellular imaging) and networking, training and transnational access activities will be important for SMEs, established industries and academics alike. In particular, iNEXT will provide novel access modes to attract new and non-expert users, which are often hindered from engaging in structural biology projects through lack of instrumentation and expertise: a Structural Audit procedure, whereby a sample is assessed for its suitability for structural studies; Enhanced Project Support, allowing users to get expert help in an iNEXT facility; and High-End Data Collection, enabling experienced users to take full benefit of the iNEXT state-of-the-art equipment.

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