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The purpose of this research is to analyse the phenotypic impacts and physio-chemical features of SNCA mutations using computational methods. Research tools and techniques: Methods from 2Struc, SWISSPDB, and RCSB PDB were utilised to assess physio-chemical characteristics. Findings: By analysing the main structures, the secondary structure is able to deduce the sequence of the protein and the nucleic acids. The aforementioned techniques allow us to deduce the structure of new proteins, The three-state composition, statistics, and structural summary analysis (including X-ray crystallography and nuclear magnetic resonance) are all part of the package. In conclusion, future predictions are based on the varvarious parameters that are part of the prediction framework. [ABSTRACT FROM AUTHOR]

The rapid development of artificial intelligence in predicting the three-dimensional structure of proteins has broken down several important problems that have been faced by experimental structural biologics for decades. Structural biology has assisted in the discovery and development of many new drugs based on structural design. X-ray crystallography and Cryo-EM which have been the gold standard for determining the structure have many challenges in the cost of obtaining large quantities of pure protein samples, the emergence of AI has helped these problems. However, the current artificial intelligence technology actually still requires a database submitted by an experimental biologist for further machine learning material. In the future, stronger collaboration between AI and experimental structural biology is needed in the development of AI for structural biology. This collaboration bridge will provide many advances in the structure-based drug design and become an interesting technique that needs to be understood for integrative structural biology. [ABSTRACT FROM AUTHOR]

In this work, multilayer carbon nanotubes reinforced with Al7075 were employed to homogenise the material. Powder metallurgy and AL7075 were used to create the nanocomposite, which had polyhedral carbon nanotube reinforcement of 0.8, 1.7, and 3.3 percent by weight. Using a hydraulic press, the samples were squeezed and sintered. Furthermore, the sintered samples were dissolved by heating them to 780 degrees Celsius, then chilling and ageing them to determine whether it enhanced their qualities. The sintered joint's micro-strength has increased from 5 hV to 50 hV, representing a 66.66 percent increase in hardness, while the tensile strength has gone from 85 MPa to 145 MPa, representing a 68 percent increase in strength. Heat-treated sintered composites' microhardness rose from 45 HV to 92 HV. Heat-treated sintered composites' hardness and tensile strength rose by 18% and 25%, respectively. Porosity increases with an increasing proportion of sintered and sintered heat-treated composites reinforced, but density decreases with an increasing percentage of sintered and sintered heat-treated composites reinforced. The picture was examined using an electron scanning microscope and X-ray crystallography, which indicated the presence of polyhedral carbon nanotubes uniformly dispersed with the Al7075 matrix. According to photographs acquired with an electron transmission microscope, the entangled and continuous clusters of nanotubes increased the compounds' resistance. [ABSTRACT FROM AUTHOR]

With the ever increasing demand of the construction materials due to unstoppable growth in the field of construction, there exists the need to go for substitutes of the natural resources. The resources that are apt fall in the line with sustainability and that enhances the properties of ultimate material. It has been observed that with the rapid growth in all directions there is a tremendous growth in the production of by products which are treated as waste and causes serious problems to the ecological system. With this perspective the stone crushers by product "prey dirt " and the menace to the society "waste low density polyethylene" has been the considered as the study material for studying the characterization properties. The microstructure characteristics of the materials which are treated as wastes will help to understand the compatibility with the concrete in terms of strength and durability. The constituents of the conventional concrete and the byproducts have been tested for x-ray crystallography and in order to test the longevity the controlled and modified concrete has been tested for rapid chloride penetration test. The dust has been taken in varying percentage from 0 to 100 % whereas the ldpe varies from 0 to 8 % as a modifier in concrete. It has been observed t from particle sizing that, the leanness of the prey dirt produced enhanced pore formation governing to impenetrable model. The petro graphical observation also showed absorbency of concrete specimen with natural sand mixes was on higher side which initiated cracking of matrix whereas with the inclusion of prey dirt and ldpe enhanced the pore structure model and the resistance improved to 20%. The research notifies that the long term conduct of concrete is governed by the formation of fine cleavages due to application of stress applied at initial stage which affects longevity and becomes vulnerable due to passage of water. [ABSTRACT FROM AUTHOR]

This article reports synthesis, characterization and magnetic properties of nanocrystalline CoCr2O4 embedded in amorphous silica host, synthesized via conventional sol-gel method. Powder diffraction X-ray crystallography (PXRD) spectrum confirms the creation of single phase nanostructured CoCr2O4. Transmission Electron Microscopy (TEM) images reveal the formation of spherical shaped particles with a distribution in size which is fitted suitably with log- normal distribution function, resulting the average particle size to be ∼10 nm. Thermal variations of field-cooled (FC) and zero field-cooled (ZFC) magnetizations reveal broadened maxium both in FC and ZFC modes - pointing towards creation of super spin-glass (SSG) like phase in lower temperature. Exchange bias (EB) effect is observed for the sample with systematic dependence of exchange bias field (HE) and coercivity (HC) with variation in cooling field (Hcool). Magnetic relaxation mechanism indicates slow dynamics both in ZFC and FC modes, similar to SSGs. Formation of SSG phase at low temperature and unveiling EB effect is noteworthy in nanocrystalline CoCr2O4, a potential multiferroic. [ABSTRACT FROM AUTHOR]

Neutron and X-ray crystallography are complementary to each other. While X-ray scattering is directly proportional to the number of electrons of an atom, neutrons interact with the atomic nuclei themselves. Neutron crystallography therefore provides an excellent alternative in determining the positions of hydrogens in a biological molecule. In particular, since highly polarized hydrogen atoms (H+) do not have electrons, they cannot be observed by X-rays. Neutron crystallography has its own limitations, mainly due to inherent low flux of neutrons sources, and as a consequence, the need for much larger crystals and for different data collection and analysis strategies. These technical challenges can however be overcome to yield crucial structural insights about protonation states in enzyme catalysis, ligand recognition, as well as the presence of unusual hydrogen bonds in proteins. [ABSTRACT FROM AUTHOR]

The overlap of biology and neutron scattering remains a relatively narrow domain of research. This is partly due to the a priori maladjustment between real space problems and methods based on spatial and temporal correlations. In addition, some major assets of neutron scattering, such as isotopic substitution, can be tricky with biological molecules. More generally, a mutual lack of knowledge of the two concerned communities precluded potential rich interactions in early times. However, the situation changed to the point that, today, biology represents a substantial part of the research activity at neutron facilities. The purpose of this introduction is not to present one more overview of the subject of "neutron scattering" (excellent comprehensive articles are easily accessible to the interested readers [1–4]), but rather to facilitate the reading of the present book by introducing a few neutron scattering notions that may be useful for the community of biologists eventually less familiar with this technique. [ABSTRACT FROM AUTHOR]

The X-ray diffraction analysis of bis(O-amyldithiocarbonato)bis(3,5-dimethylpyridine)nickel(II) which is one of the adducts of O-alkyldithiocarbonate is performed. The complex is found to crystallize in the Monoclinic space group P21/c with unit cell parameters a = 9.1674(2) Å, b = 18.2553(4) Å, c = 9.2999(2) Å and β = 103.472(2)°. Crystal structure was solved by direct method and refined by full matrix least squares procedures to a final R-value of 0.0420 for 2278 observed reflections. [ABSTRACT FROM AUTHOR]

In the present paper the chalcone belonging to D-π-A type push-pull system has been synthesized and the single crystals were grown by controlled solution evaporation technique. The grown single crystals were subjected to NMR, FTIR and powder X-ray diffraction technique to confirm the compound. The linear optical cut-off was found to be at 442 nm. The SHG efficiency was determined in powder form and was found to be 1.57 times that of KDP. The titled chalcone was found to be stable up to 106 °C. The DFT calculations revealed that the intermolecular interaction assisted molecular alignment play a crucial role in SHG. The un-optimal alignment of the molecules in the crystal structure resulted in decreased intermolecular charge transfer in the crystal. The structure-property relation is presented based on the experimental and DFT calculations. [ABSTRACT FROM AUTHOR]

The preparations of [Ni(SC6H3Me-2,6)(triphos)]BPh4 and [Ni(SC6H4R-2)(triphos)]BPh4 (R = Me, MeO or Cl) are described. The complexes have been characterised by ¹H and 31P{¹H} NMR spectroscopies, UV-visible spectroscopy and X-ray crystallography. Whilst [Ni(SC6H3Me-2,6)(triphos)]BPh4 and [Ni(SC6H4R-2)(triphos)]BPh4 (R = Me, MeO) contain a 4-coordinate square planar Ni, ligated by a thiolate S and three phosphorus atoms of triphos, [Ni(SC6H4Cl-2)(triphos)]BPh4 is a distorted square-based pyramid due to the 2-Cl substituent being weakly bound in the apical position. The protonation of all the complexes have been studied in MeCN in situ using 31P{¹H} NMR spectroscopy. The protonation of these complexes with lutH+ (lut = 2,6-dimethylpyridine) indicate simple protonation of the thiolate S. However, protonation by picH+ (pic = 4-methylpyridine) indicate that both protonation and displacement of the thiolate occurs. [ABSTRACT FROM AUTHOR]

We designed and attempted to synthesize bisnitroxides involving a suitable spacer, which are supposed to display switching behavior based on intramolecular covalent-bond formation and cleavage. In this work a biphenyl hinge was applied to bring conformational freedom in a spacer. Nitroxide radical groups are generally introduced by way of organometallic reagents from halogen-metal exchange of organic halides. For the reaction from 2,2’-dibromo-4,4’-di-tert-butylbiphenyl, only one bromine atom was substituted with a tert-butyl nitroxide group. For the reaction from 2,2’,5,5’-tetrabromo-4,4’-di-tert-butylbiphenyl, unexpectedly, two N-tert-butylhydroxylamino groups were introduced at the 5,5’-positions in place of the desired 2,2’-positions. The molecular structure of 2,2’-dibromo-4,4’-di-tert-butyl-5,5’-bis(tert-butylamino)biphenyl-N,N’-dioxyl was characterized by means of X-ray crystallography, and the magnetic study on a SQUID magnetometer revealed that the two spins were present and magnetically isolated in the solid. [ABSTRACT FROM AUTHOR]

New complexes doubly chelated with two paramagnetic ligands, [MII(6bpyNO)2](ClO4)2•xCH3OH [M = Mn (x = 0.53), Ni (x = 1); 6bpyNO = 2,2'-bipyridin-6-yl tert-butyl nitroxide] were prepared. The X-ray crystallographic analysis revealed the isomorphous [M(6bpyNO)2]2+ structure. The magnetic measurements clarified antiferromagnetic 2JMn-rad/kB = -112(2) K and ferromagnetic 2JNi-rad/kB = +384(4) K, based on a symmetrical model H = -2JM-rad(SM•Srad1 +SM•Srad2). The coupling mechanism is explained in terms of the 3d5 and 3d8 spin configurations leading to the dπ-pπ overlap in the Mn complex and the dσ-pπ orthogonal arrangement in the Ni complex along the metal-radical bonds. [ABSTRACT FROM AUTHOR]

Introduction of 2p spins into molecular grids is rare. We prepared 4,6-bis{3-(4,4,5,5-tetramethylimidazolin-1-yloxyl-3-oxido-2-yl)-1H-pyrazol-1-yl}pyrimidine (bis'nitronyl nitroxide') and its bisdeoxygenated derivative (bis'imino nitroxide') as a building block for [2×2] molecular grids. Electron spin resonance spectra were satisfactorily simulated with the corresponding biradical models. The magnetic susceptibility measurements revealed the presence of two radical groups in a molecule. X-Ray crystal structure analysis of the bis'nitronyl nitroxide' derivative clarified the molecular structure constructed as designed. However, the geometries around the single bonds between pyrimidine and pyrazole rings were configured to be transoid (anti) in the crystal. A dichloromethane molecule was incorporated as a guest. [ABSTRACT FROM AUTHOR]

1,1'-Bis(2-bromobenzoylthioureido)ethane was synthesized from the reaction of 2- bromobenzoylisothiocyanate and ethylenediamine in acetonitrile. The compound was characterized by FT-IR, ¹H, and 13C NMR spectroscopy techniques. Furthermor compound was found to crystallized in monoclinic system with space group of P2(1)/c. In each thiourea moiety the thiono group is trans to the benzoyl across their C-N bonds. The crystal structures are stabilized by N-H···S intermolecular hydrogen bonds to form infinite two dimensional network. [ABSTRACT FROM AUTHOR]

Beamline BL44XU at SPring-8 is operated by the Institute for Protein Research of Osaka University. The beamline is designed for X-ray crystallography of large biological macromolecular assemblies. Here we show its detailed performances, results, and the ongoing upgrade plans. [ABSTRACT FROM AUTHOR]

Present works based on the performance of the composite films of Barium Titanate (BaTiO3) with Titanium Dioxide (TiO2) and Poly (methyl methacrylate) (PMMA) prepared by simple solution casting technique. Different wt. % compositions of BaTiO3 have been selected to find out the best optimized condition for further investigations. The structural properties have been carried out at room temperature using X-ray crystallography (XRD). The average crystallite size of the BaTiO3 particles in the composite films has been found to be lies in between ∼ 20 -70 nm. It has been found that the peak intensities increase with increasing the wt. % of BaTiO3 in the composite films at room temperature (RT). The XRD analysis revealed that the addition of TiO2 has played a crucial role to enhance the crystalline nature of the composite films at room temperature. Efforts have been made to correlate the results with investigated XRD results of pure BaTiO3 and its composites as observed by other workers at room temperature. [ABSTRACT FROM AUTHOR]

We have proposed tert-butyl 2-pyridyl nitroxide radicals as a promising paramagnetic chelating ligand, where the direct radical-metal bond leads to strong magnetic interaction. We successfully synthesized and isolated PyBN derivatives (pyridine-2,6-diyl bis(tert-butyl nitroxides)). The molecular and crystal structures of the target biradicals, MesPyBN, AntPyBN and tBuOPyBN were determined from the X-ray crystal structure analysis, which possess mesityl, 9-anthryl and tert-butoxy groups at the 5-position of the pyridine ring, respectively. The ground triplet state was characterized by means of SQUID susceptometry for each compound. On heating, the ÷mT values of all the PyBN derivatives increased and reached a plateau at ca. 1.0 cm³ K mol-1 at 300 K. It implies that biradicals behaved as triplet molecules even at room temperature, or 2J/kB >> 300 K. From the decay monitored in solution electron-spin resonance spectroscopy, MesPyBN was the most persistent, while tBuOPyBN was the most reactive, of the three. [ABSTRACT FROM AUTHOR]

N,N'-bis(2-chlorobenzamidothiocarbonyl)hydrazine was synthesized from 2-chlorobenzoylisothiocyanate and hydrazine in acetone. The compound was characterized by infrared, 1H and 13C NMR, and UV-Vis spectroscopies. X-ray crystallography study showed the molecule adopt trans configuration at both N-N and C-N bonds. The compound showed high antioxidant activity, EC50 of 374.89 µM, compared to ascorbic acid (EC50 of 561.36 µM). [ABSTRACT FROM AUTHOR]

The complexation of nickel acetate with tetraaza involves deprotonation of protonated amine nitrogen to form neutral ligand coordinated to the nickel via the four nitrogen atom. The dication complex is paired with thiocyanate anions. The complex was characterized by elemental analysis, UV-VIS and FTIR spectroscopic method. The crystal structure of nickel complex characterized by X-Ray crystallography and adopts square planar geometry. [ABSTRACT FROM AUTHOR]

A two dimensional metal organic framework containing cerium sufate layers and ethylenediaminium between layers was obtained by refluxing the mixture of cerium sulphate and 5,5,7,12,12,14-hexamethyl-1,4,8,11- tetraazacyclotetradeca-7,14-diene bromide. The complex was characterized by infrared spectroscopy and microelemental analysis. X-ray study showed that the complex adopts eleven coordination environments about the central atom. Thermogravimetric study showed the removal of water molecules at about 70 °C followed by a gradual mass loss until the whole structure collapsed at about 400 °C. [ABSTRACT FROM AUTHOR]

We report on the classification of protein crystallisation data via decision trees using N-fold cross validation. Protein crystallisation images were obtained over a period of time ranging from days to months. All the images taken of a single experiment are arranged according to the time they were obtained and aligned according to the position of the experimental droplet. Difference between consecutive images in a time course was determined and the background noise was removed using filtering techniques. Image analysis is performed on the area inside the droplet of each difference image to compute statistical texture features. Classification is carried out by testing and training with 1000 sample images and an accuracy rate of ∼75% was achieved. [ABSTRACT FROM AUTHOR]

Bioactive natural products have been extensively studied worldwide because natural products compounds with their great structural diversity have traditionally provided most of the drugs in use. Nevertheless the most important step in the drug discovery process is the structural characterization of isolated compounds with interesting biological activities. X-ray structure determination is a powerful technique for characterization because this technique is able to provide a lot of informations on stereochemistry and the detailed three-dimension structures made available can be corelated to activities of these structures. The advancement of X-ray crystallography makes the characterization procedure more precise, much easier and less time consumable. Moreover, this technique can directly and easily confirm whether these compounds are enantiomerically pure or racemate. In addition the absolute configuration of a natural products molecule can be easily determined by this technique. This work shall be based on the results from our natural products research. The absolute configuration of 6-Hydroxysalvinolone and Horminone, which were isolated from Premna obtusifolia will be presented. Three racemates, namely Panduratin A, Caged xanthone and Murrayazoline, which were isolated from the natural products sources will also be presented. [ABSTRACT FROM AUTHOR]

The crystal structure, the solid NMR spectroscopy and the complex impedance study have been carried out on [C2H10N2]CdCl2(SCN)2. Characterization by single crystal X-ray crystallography shows that the cadmium atoms have à 2N2S2Cl hexa-coordination sphere, exhibiting pseudo-octahedral geometry. The cadmium atoms are bridged by two thiocyanate ions generating 1-D polymeric-chains. These chains are themselves interconnected by means of N-H...Cl(NCS) hydrogen bonds originating from the organic cation [(NH3)2(CH2)2] 2+. 111 Cd isotropic chemical shifts span a range of 268ppm. The cadmium atom exhibits multiplets that result from 111Cd- 14N spin-spin coupling. Examination of 111Cd and 13C MAS line shapes shows direct measurement of the indirect spin-spin coupling constant ²J(111Cd, 14N) = 105Hz and the dipolar coupling constant of 1381Hz . Impedance spectroscopy measurements of [C2H10N2]CdCl2(SCN)2 have been studied from 209Hz to 5 MHz over the temperature range 300-370 K. The Cole-Cole (Z" versus Z') plots are fitted to two equivalent circuits models. The formalism of complex permittivity and impedance were employed to analyze the experimental data. The dc conductivity follows the Arrhenius relation with an activation energy Ea = 0.54 (3) eV [ABSTRACT FROM AUTHOR]

At the High Energy X-ray laboratory (HEX-lab, Department of Engineering Science, University of Oxford, UK) we carry out studies of deformation and structure of engineering materials and components. Laboratory and synchrotron X-ray beams provide the principal means of analysis and measurement. A variety of other techniques are also in use. We present a range of applications and case studies in high performance engineering materials. [ABSTRACT FROM AUTHOR]

Here we are reporting about the x-ray structure investigation of two intercalates InGaS3 with 4-aminopyridine NH2C5H4N (4-AP), were the final products are also single crystals. As matrix crystals were used the single crystals of orthorhombic and hexagonal phases of InGaS3. [ABSTRACT FROM AUTHOR]

X-ray microtomography can visualize 3D structures of biological soft tissues at cellular to subcellular resolution. Such 3D structures are composed of a great number of cells and extracellular matrices that should be assigned separately as tissue constituents. Here, we report a method for building a skeletonized model of the human brain network in a 3D distribution map of linear absorption coefficients determined by microtomography. The 3D models of neurons were automatically built by using a Sobel filter and manually edited via a graphical interface. The simplification of the 3D coefficient map facilitates understanding of microtomographic structures composed of huge numbers of voxels. We suggest that x-ray microtomography along with model building in the 3D coefficient map is a potential method for understanding 3D microstructures relevant to biological functions, like x-ray crystallography in molecular biology. [ABSTRACT FROM AUTHOR]

The effect of artificial temperature anisotropy of crystals in X-ray frequency range was observed for the first time and an effort to theoretically interpret this effect in Bragg-Laue diffraction case was made. It was established that an isotropic crystal optically turns into an artificially anisotropic one with optical axis along the direction of applied external influence as a symmetry axis, giving rise to the double refraction. [ABSTRACT FROM AUTHOR]

Main challenge of fighting with the HIV-1 is to eliminate the latent viral reservoir from the body. This reservoir is resistant to antiretroviral drug therapy and can cause viral rebound if the treatment is stopped. The removal of the reservoir enables HIV eradication, is urgently desired in HIV-AIDS research. For this purpose, a strategy called "kick and kill" was proposed, based on the hypothesis that activation of latent HIV ("kick") leads to cell death ("kill") by physical damage and/or immune activation. However, in clinical tests "kill" process was found to be not enough to reach HIV eradication. To eradicate HIV from the body, our work has recently suggested a new strategy called "lock-in and apoptosis" instead of "kick and kill". In development of this strategy, nonnatural derivative of inositol hexaphosphate (IP6) named as L-HIPPO has been developed to suppress membrane localization of HIV-1 Gag protein (Pr55gag) and to induce strong apoptosis of the host cell containing the latent viruses (1). For identification of the key interaction between L-HIPPO and MA, three highresolution crystal structures of the MA domain in complex with IP6 molecules were revealed at cryotemperature (2.40 Å, and 2.72 Å resolution), and ambient-temperature (3.5 Å resolution) (2,3). Then, we rationally designed 8 new anti-HIV drug candidates on the basis of the structure of two acyl groups of L-HIPPO and examined their binding affinities to HIV-1 MA by molecular docking using the crystal structure of MA in complex with IP6 (PDB IDs: 7E1I), which was enlightened by our research group (3). Benzene-inserted compounds were detected to possess the most promising docking scores, which guided us to create a library involving 213 new aromatic group-inserted L-HIPPO derivatives. According to the results, 3-methoxy-4-hydroxyphenyl carrying compound was determined as the most effectively binding L-HIPPO derivative to the MA. [ABSTRACT FROM AUTHOR]

Amyloid fibrils are associated with many neurodegenerative diseases. The application of conventional biophysical techniques including solution NMR and X-ray crystallography for structural characterization of fibrils is limited because they are neither crystalline nor soluble. The Bayesian approach was utilized for extracting the deep UV resonance Raman (DUVRR) spectrum of the lysozyme fibrillar β-sheet based on the hydrogen-deuterium exchange spectral data. The problem was shown to be unsolvable when using blind source separation or conventional chemometrics methods because of the 100% correlation of the concentration profiles of the species under study. Information about the mixing process was incorporated by forcing the columns of the concentration matrix to be proportional to the expected concentration profiles. The ill-conditioning of the matrix was removed by concatenating it to the diagonal matrix with entries corresponding to the known pure spectra (sources). Prior information about the spectral features and characteristic bands of the spectra was taken into account using the Bayesian signal dictionary approach. The extracted DUVRR spectrum of the cross-β sheet core exhibited sharp bands indicating the highly ordered structure. Well resolved sub-bands in Amide I and Amide III regions enabled us to assign the fibril core structure to anti-parallel β-sheet and estimate the amide group facial angle Ψ in the cross-β structure. The elaborated Bayesian approach was demonstrated to be applicable for studying correlated biochemical processes. [ABSTRACT FROM AUTHOR]

Three combination photon beam position monitor (PBPM) and slits are in use at the photon transfer line (PTL) of the high flux macromolecular X-ray crystallography (HFMX) beamline at the Pohang Light Source. Each slit, based on a common basic design, drives its two slit plates through a double bellows assembly by two motors. The slits also adopt a turned-grazing inclination of 30° to restrict the passage of scattered photon beams and to enhance cooling efficiency. One of the slits has been successfully applied with cooling function in order to cool the heat load from a multi-pole wiggler. This paper describes the design details and design features of the slits and discusses the results of performance tests for their PBPM function. The combined PBPM function can be used for the analysis of the position behaviors of photon beams at the beamline. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

Macromolecular crystals can be compressed hydrostatically at room temperature in a diamond anvil cell. The quality of diffraction data recorded on the ESRF ID30/ID27 beamlines using a parallel X-ray beam of ultra-short wavelength can meet usual standards. The 3D structures of proteins (monomeric, dimeric and tetrameric) and of a virus have been refined both at atmospheric and at high pressure. High pressure is a way to explore the high energy landscape of macromolecular systems, from the fully folded state to the unfolded state. High energy conformers of biological significance can be selected and trapped under high pressure. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

While routine Macromolecular x-ray (MX) crystallography has relied on well established techniques for some years all the synchrotrons around the world are improving the throughput of their MX beamlines. Third generation synchrotrons provide small intense beams that make data collection of 5–10 microns sized crystals possible. The EMBL/ESRF MX Group in Grenoble has developed a new generation of instruments to easily collect data on 10 μm size crystals in an automated environment. This work is part of the Grenoble automation program that enables FedEx like crystallography using fully automated data collection and web monitored experiments. Seven ESRF beamlines and the MRC BM14 ESRF/CRG beamline are currently equipped with these latest instruments. We describe here the main features of the MD2x diffractometer family and the SC3 sample changer robot. Although the SC3 was primarily designed to increase the throughput of MX beamlines, it has also been shown to be efficient in improving the quality of the data collected. Strategies in screening a large number of crystals, selecting the best, and collecting a full data set from several re-oriented micro-crystals can now be run with minimum time and effort. The MD2x and SC3 instruments are now commercialised by the company ACCEL GmbH. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

X-ray crystallography is the most used and effective technique for obtaining the structure of proteins and protein complexes. As of today, the x-ray structure of tens of thousand proteins is known and this number is continuously increasing, also thanks to the efforts of structural genomics projects aimed at providing representative examples of the protein structural space. In an x-ray diffraction experiment, crystals of the protein of interest are irradiated with x-ray, and interference effects give rise to a characteristic diffraction pattern. The amplitudes and phases of each reflection can be used to compute the electron density. However only, the intensity of the reflected waves can be measured, while their phase needs to be obtained by other means. One way to obtain the phase information is to use prior knowledge of the protein structure (search model). In some cases, the structure of a homologous protein or a model of the target protein can be sufficient to approximate the relative position of the atoms in the structure and allow the phases to be computed. This strategy is known under the name of molecular replacement. We have extensively investigated the relationship between the quality of a model and its usefulness as a search model in MR and discuss here our results. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]