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A new x-ray methodology, Diffracted X-ray Tracking (DXT), has been proven to be a valuable tool in observing intramolecular conformational changes of individual single molecules in real time and space. In order to achieve DXT, the fabrication of dispersive nanocrystals is one of the most important technologies, because DXT system monitors the diffracted x-ray (Laue) spots from nanocrystals labeled with single bio-molecules. In this study, we fabricated one-dimensional gold nanocrystals with an average diameter size of 16 nm using vacuum evaporation. Furthermore, using these nanocrystals, we succeeded in observing normal Brownian motions and momentary structural changes of a single-membrane protein (Bacteriorhodopsin: BR) in a membrane due to the expression of its function. The average movement of the momentarily structural changes in the 35th residue of BR was 76 ± 48 pm, and this agrees with estimated movements from known x-ray crystallography data. This result is an important step toward realizing in-vivo observations of single-molecular conformational changes in membrane proteins. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present subnanosecond-resolved X-ray diffraction experiments at the SPring-8 high flux beamline BL40XU by use of time structure of synchrotron radiation. A phase-locked mechanical chopper (x-ray pulse selector), which is made by Forschungszentrum Jülich, has minimum opening time of 400 nanoseconds and generates single-bunch x-ray pulse trains with variable intervals of 1–2 millisecond (0.5–1 kHz) depending on the rotation speed and with the x-ray pulse duration of ∼ 30 picoseconds from the hybrid bunch mode (D-mode) of the SPring-8 ring operation. The interval of pulse trains is further expanded to more than 1 second by another slower shutter, if necessary. The pulse train is applicable to time-resolved diffraction experiments with both monochromatic and pink beams. An observed Laue data set from lysozyme crystal showed sufficient quality to refine the protein structure at 1.9 Å resolution. A 10-nanosecond pulse from a Nd:YAG laser initiating photoreaction in a crystal can be synchronized with the X-ray pulse. Installation of a mode-locked Ti:sapphire laser/regenerative amplifier system which has a pulse duration of ∼ 2 picoseconds for further pump-probe experiments is also planed. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

BL40B2 and BL40XU were built at SPring-8 in 1999. They are now open for public users and many kinds of small angle x-ray scattering experiments are carried out using these beamlines. We report the present status of these two beamlines. Also some examples of experimental results that were obtained at these beamlines are shown. BL40B2 is for recording small-angle x-ray scattering from non-crystalline biological materials. The light source is a bending magnet and the white x-rays generated by are monochromatized using a double crystal monochromator and focused by a 1-m-long rhodium-coated bent-cylinder mirror. The photon flux is 1×1011 photons/sec at 12.4 keV. The tunable energy range is 7 keV ∼ 18 keV. As a detector, an imaging plate area detector (RIGAKU R-AXIS IV++) is installed. Two fixed-length vacuum paths allow camera lengths of 400 mm and 1000 mm. This beamline is suitable for static measurements with high accuracy and high resolution. The aim of BL40XU is to provide very high flux of x-rays for various experiments. On this concept, BL40XU was designed to use the fundamental undulator radiation as a quasi-monochromatic x-ray beam so that the use of the crystal monochromator was eliminated. The x-ray source of BL40XU is a helical undulator and its flux is estimated to be 1×10∧15 photons/sec at 12.4 keV. The x-ray is focused horizontally and vertically by bending two water-cooled focusing mirrors. So far, various time-resolved diffraction and scattering experiments on biomaterials and polymers have been carried out. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]