1. Center for Functional Nanomaterials Seminar

    "Reconstruction of Hilical Bio-Structure Using X-ray Diffraction Experiment"

    Presented by Dr. Miraj Uddin, University of Wisconsin-Milwaukee, Physics Department

    Thursday, April 2, 2015, 9:45 am
    CFN Bldg. 735 - Second Floor Conference Room B

    Hosted by: Kevin Yager

    Recovery of three-dimensional structure from single particle X-ray scattering of completely randomly oriented diffraction patterns as predicted few decades back has been real due to advent of the new emerging XFEL (X-ray free electron laser) technology. Some of the best-known structure determination of helical objects such as helical viruses or deoxyribonucleic acid has been done by fiber diffraction. Layer line intensities of fiber diffraction pattern as expressed by cylindrical harmonics can be transformed into equivalent spherical harmonic expansion leaving the clue behind that structure of helical objects may be recovered from single particle scattering of randomly oriented helical molecules thus avoiding the tedious challenge of single axis alignment. In this work we have solved the structure of TMV (tobacco mosaic virus) helices from a set of randomly oriented simulated diffraction patterns exploiting symmetry and internal constraint of the diffraction volume thus proving the above claim on step ahead. As the world's first XFEL is in operation starting from June 2009 at SLAC National Lab at Stanford, the very first few experiments being conducted on larger objects such as viruses. We have analyzed a set of experimental diffraction patterns of chlorella virus deposited on cxidb.org and recovered a quadratic coefficients of Fourier shell correlation whose angular momentum selection rule proves that the collected data is primarily from an icosahedral object.