IN-SITU UV/VIS SPECTROSCOPY FOR MACROMOLECULAR CRYSTALLOGRAPHY

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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 goal of this project is to enable the simultaneous acquisition of x-ray diffraction data and single crystal absorption spectra in the UV/Visible and infrared regions. Analysis of the absorption spectrum in the UV (190 - 400 nm) and visible (400 - 800 nm) regions provides information about the electronic state of proteins while in the crystalline state. During diffraction experiments, spectroscopic measurements will be analyzed to confirm the redox state or the presence of reaction intermediates or to potentially monitor degradation products that may be produced either by photolysis or by x-rays. A single crystal microspectrophotometer was set up on BL9-2 to record spectra from crystals on the goniometer. Positioning of the optics and a 2nd microscope were refined for ease of use. Attempts at recording spectra from several crystal systems provided important feedback for the development process, in particular to define how the positioning system will be refined, adding additional degrees of freedom to the optics for precise alignment and focusing of the light beam.