The 235th R-CCS Cafe - part 3

Cellular functions, such as intracellular transport/mitosis/movement with microtubules, transmembrane ion/molecule transport with channel proteins, and transcription with ribosomes, are mostly realized by polymerization, depolymerization, and conformational change of proteins and biological complexes. In general, “seeing” their structures is the prerequisite to understanding their dynamics and functions. While well-established techniques such as X-ray crystallography and cryo-electron microscopy investigate their structures in crystallized or frozen conditions, fluctuation X-ray scattering (FXS) utilizes X-ray Free-Electron Laser (XFEL) and can measure non-crystallized biological particles dispersed in solutions in near-physiological conditions. This emerging technique is not only experimentally challenging but also has a theoretical difficulty of interpreting experimental data. In the experiment, thousands or millions of 2D X-ray coherent diffraction images are collected. Each image averages the information of many randomly oriented biological particles. Reconstruction to 3D structures requires not only an explicit mathematical theory but also high-performance computation. In this talk, I will introduce my recent progress of theoretical work. Results with simulated experimental data will be shown.