STRUCTURAL MOLECULAR BIOLOGY SMALL ANGLE X-RAY SCATTERING STATION BEAM LINE 4-2

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The SSRL Structural Molecular Biology small-angle x-ray scattering station BL4-2 is dedicated to structural biology studies, providing state-of-the-art experimental facilities for structural biology studies on proteins, protein assemblies, virus particles, biological fibers and lipid membranes. The beam line rebuild/upgrade to SPEAR3 500 mA operation, including new optics, was completed in early summer 2008 and had a highly successful commissioning run near the end of FY08 user run. We observed highly improved beam characteristics, in particular much improved beam focus quality and a higher flux (a factor of five) due to the new mirror and full-field wiggler operation, respectively. We also completed the upgrade of the in-hutch instrumentation, featuring a completely rebuilt pin-hole geometry small angle scattering camera with an automated distance change mechanism, which can be configured to accommodate several data collection modes, including solution scattering, single crystal diffraction, fiber diffraction and gracing-incidence scattering. The camera system covers the characteristic length scale in the range of 2 A to 2000 A with seven discrete sample-to-detector distances. A Bonse-Hart geometry ultra-small angle scattering setup is being redeveloped to extend the range up to a few microns. A new CCD detector (Rayonix MX225-HE) was received and commissioned, and verified excellent characteristics, namely higher photon sensivity and electronic stability. We continue sofware developments for biological x-ray scattering studies with strong emphasis on high-throughput solution x-ray scattering studies.