One of the challenges in photosynthesis research lies in linking the structure and dynamics of photosynthetic complexes to function. Scientists have now successfully determined the three-dimensional structure of photosynthetic protein complexes using nuclear magnetic resonance (NMR) techniques and X-ray crystallography, providing an experimental basis for addressing this challenge. Although crystallographic techniques provide the most accurate and detailed information about the molecular structure, the measurements are limited to a specific crystalline state. This approach limits the measurements of the amplitude, range, and time scales of molecular motions and the study of how these conformational landscapes are coupled to biological functions.
NMR methods overcome the limitations of crystallography by resolving molecular structures in solids and liquids, but these methods are focusing on a set of short-range distance constraints and thus cannot directly determine the complete molecular structure. Currently, the development of synchrotron X-ray scattering offers new opportunities for direct characterization of photosynthetic protein conformations in non-crystalline media based on crystallographic, NMR, and molecular dynamics databases.
Fig.1 Schematic diagram of the X-ray scattering experiment. (Tiede, 2009)