SAXS Beamline Research Articles

The SOLCRYS and SAXS beamlines at the SOLARIS National Research Centre

The SOLCRYS and SAXS beamlines at the SOLARIS National Research Centre

Picosecond pump-probe X-ray scattering at the Elettra SAXS beamline.

A new setup for picosecond pump-probe X-ray scattering at the Austrian SAXS beamline at Elettra-Sincrotrone Trieste is presented. A high-power/high-repetion-rate laser has been installed on-site, delivering UV/VIS/IR femtosecond-pulses in-sync with the storage ring. Data acquisition is achieved by gating a multi-panel detector, capable of discriminating the single X-ray pulse in the dark-gap of the Elettra hybrid filling mode. Specific aspects of laser- and detection-synchronization, on-line beam steering as well protocols for spatial and temporal overlap of laser and X-ray beam are also described. The capabilities of the setup are demonstrated by studying transient heat-transfer in an In/Al/GaAs superlattice structure and results are confirmed by theoretical calculations.

Online Size-exclusion and Ion-exchange Chromatography on a SAXS Beamline

Biological small angle X-ray scattering (BioSAXS) is a powerful technique in molecular and structural biology used to determine solution structure, particle size and shape, and surface-to-volume ratio of macromolecules. The technique is applicable to a very wide variety of solution conditions spanning a broad range of concentrations, pH values, ionic strengths, temperatures, additives, etc., but the sample is required to be monodisperse. This caveat led to the implementation of liquid chromatography systems on SAXS beamlines. Here, we describe the upstream integration of size-exclusion (SEC) and ion-exchange chromatography (IEC) on a beamline, different methods for optimal background subtraction, and data reduction. As an example, we describe how we use SEC- and IEC-SAXS on a fragment of the essential vaccinia virus protein D5, consisting of a D5N helicase domain. We determine its overall shape and molecular weight, showing the hexameric structure of the protein.

Online Size-exclusion and Ion-exchange Chromatography on a SAXS Beamline.

Biological small angle X-ray scattering (BioSAXS) is a powerful technique in molecular and structural biology used to determine solution structure, particle size and shape, and surface-to-volume ratio of macromolecules. The technique is applicable to a very wide variety of solution conditions spanning a broad range of concentrations, pH values, ionic strengths, temperatures, additives, etc., but the sample is required to be monodisperse. This caveat led to the implementation of liquid chromatography systems on SAXS beamlines. Here, we describe the upstream integration of size-exclusion (SEC) and ion-exchange chromatography (IEC) on a beamline, different methods for optimal background subtraction, and data reduction. As an example, we describe how we use SEC- and IEC-SAXS on a fragment of the essential vaccinia virus protein D5, consisting of a D5N helicase domain. We determine its overall shape and molecular weight, showing the hexameric structure of the protein.

Architecture and Assembly of HIV Integrase Multimers in the Absence of DNA Substrates

We have applied small angle x-ray scattering and protein cross-linking coupled with mass spectrometry to determine the architectures of full-length HIV integrase (IN) dimers in solution. By blocking interactions that stabilize either a core-core domain interface or N-terminal domain intermolecular contacts, we show that full-length HIV IN can form two dimer types. One is an expected dimer, characterized by interactions between two catalytic core domains. The other dimer is stabilized by interactions of the N-terminal domain of one monomer with the C-terminal domain and catalytic core domain of the second monomer as well as direct interactions between the two C-terminal domains. This organization is similar to the "reaching dimer" previously described for wild type ASV apoIN and resembles the inner, substrate binding dimer in the crystal structure of the PFV intasome. Results from our small angle x-ray scattering and modeling studies indicate that in the absence of its DNA substrate, the HIV IN tetramer assembles as two stacked reaching dimers that are stabilized by core-core interactions. These models of full-length HIV IN provide new insight into multimer assembly and suggest additional approaches for enzyme inhibition.

1SEP-05 フォトンファクトリーにおける小角散乱ビームラインの刷新(1SEP 新学術領域「天然変性タンパク質の分子認識機構と機能発現-生理的準安定状態を捉える新技術-」共催,相関構造生物学とX線溶液散乱,シンポジウム,日本生物物理学会第51回年会(2013年度))

1SEP-05 フォトンファクトリーにおける小角散乱ビームラインの刷新(1SEP 新学術領域「天然変性タンパク質の分子認識機構と機能発現-生理的準安定状態を捉える新技術-」共催,相関構造生物学とX線溶液散乱,シンポジウム,日本生物物理学会第51回年会(2013年度))

Structural biology and SAXS beamlines at the Photon Factory

Structural biology and SAXS beamlines at the Photon Factory

Evaluation of the Particle Growth of Amorphous Calcium Carbonate in Water by Means of the Porod Invariant from SAXS

A time-resolved SAXS study has been carried out on the formation of amorphous calcium carbonate from supersaturated aqueous solutions at an initial concentration of 5 mmol/L CaCO(3). Particle formation was induced by mixing equal volumes of equinormal CaCl(2) and Na(2)CO(3) solutions with a stopped-flow device installed at the SAXS beamline. The resulting scattering curves were analyzed without any model assumption with respect to the particle shape. The analysis is based on the intercept of the scattering curve, its initial slope, and the Porod invariant. These parameters give access to the average particle mass, the average particle size, and the mass concentration of the particles, respectively. The evolution of particle mass and concentration with time gives access to the trend in the particle number density. The size and mass values were found to be correlated by characteristic exponents. Two different mass values can be used for this correlation: direct use of the intercept of the scattering curve or alternatively a ratio of this intercept with the corresponding Porod invariant. The resulting exponents depend on the particle growth mechanism. These exponents, together with the evolution of the number density, are capable of discriminating between a monomer-addition mechanism and a particle-particle coagulation mechanism as two alternative building mechanisms for the resulting amorphous CaCO(3) nanoparticles. A detailed description of the data analysis and its merit in establishing a particle growth mechanism is presented.

In situ high pressure phase transition of alcohol intercalated zirconium phosphate observed by synchrotron X-ray scattering

Measurements made on the SAXS beamline at Sincrotrone Elettra in Trieste indicated that a phase transition in which the alkanol chains undergo a change from an all trans-conformation to a conformation in which the O–C 1–C 2–C 3 torsion angle changes from 180 to 136° could be induced by a pressure change. p– T phase diagrams of 1-octanol, 1-nonanol, and 1-decanol intercalated alpha zirconium hydrogenphosphate were constructed. From them, the existence of both phases with different basal spacings is obvious. It can be deduced from the comparison of the data for the 1-octanol and 1-nonanol intercalates that the pressure at which this transition occurs, decreases with increasing length of the alkanol chain.

Synchrotron SAXS Studies of Nanostructured Materials and Colloidal Solutions: A Review

Structural characterisations using the SAXS technique in a number of nanoheterogeneous materials and liquid solutions are reviewed. The studied systems are protein (lysozyme)/water solutions, colloidal ZnO particles/water sols, nanoporous NiO-based xerogels, hybrid organic-inorganic siloxane-PEG and PPG nanocomposites and PbTe semiconductor nanocrystals embedded in a glass matrix. These investigations also focus on the transformations of time-varying structures and on structural changes related to variations in temperature and composition. The reviewed investigations aim at explaining the unusual and often interesting properties of nanostructured materials and solutions. Most of the reported studies were carried out using the SAXS beamline at the National Synchrotron Light Laboratory (LNLS), Campinas, Brazil.

Use of Ultra-Small-Angle X-ray Scattering To Measure Grain Size of Lamellar Styrene−Butadiene Block Copolymers

Simultaneous determination of the lamellar morphological length scale and the grain size of several low molecular weight heterogeneous styrene−butadiene block copolymers was accomplished through the use of ultra-small-angle X-ray scattering measurements. NIST's X23A3 Ultra SAXS beamline of the National Synchotron Light Source in the Brookhaven National Laboratory provided a scattering vector, q, from 0.0004 to 0.1 Å-1. Many of the block copolymer specimens display a clearly resolvable peak in the Ultra SAXS region, and grain size was determined using the spherical form factor. Determination of Porod's law constant and the value of the scattering invariant provided a preliminary verification of the proposed scattering mechanism by solving for the contrast factor and the volume fraction of the grain boundaries in these specimens. Grain size in a given polymer was a function of annealing temperature and time. For the case of a block copolymer swollen with varying amounts of cumene, both the lamellar repeat distance, d, and the grain size, D, increased with the cube root of the volume fraction of solvent over the concentration range examined.

Fast PC-based data acquisition system for gas-filled position sensitive detectors

The high flux of the new generation of synchrotron radiation sources requires fast position sensitive detectors with high count rate data acquisition systems capability. Though the local count rate in a gas-filled position-sensitive detector is limited by the space charge effect, the integral rate will increase with the area of the detector. Thus, more than several 10 6 events per second can be achieved. Therefore, we developed a new PC-based histogramming and control interface (HCl) with an intrinsic dead time lower than 200 ns for linear and area X-ray detectors for time-resolved measurement applications. An overview of the complete acquisition system including a fast time-to-digital converter and image processing software will be given. The design principles and operating characteristics including experimental results obtained with a 100 mm linear delay-line detector at the SAXS beamline 5.2 in Elettra (Trieste) will be presented.