Joint neutron and X-ray protein crystallography - Zoe Fisher скачать в хорошем качестве

Joint neutron and X-ray protein crystallography - Zoe Fisher

Joint neutron and X-ray protein crystallography: complementary tools in the detailed analysis of enzyme structures Neutron protein crystallography (NPX) provides a unique and powerful approach for exploring the structural and functional aspects of proteins, particularly in areas where X-ray crystallography has limitations. As neutrons scatter strongly from atomic nuclei of light atoms such as hydrogen (¹H) and its isotope deuterium (²H), NPX enables direct visualization of hydrogen atoms and their interactions within proteins. This includes hydrogen bonds, water networks, charged states of amino acid side chains, and solvent-mediated interactions. Due to the weak scattering of H atoms, these are all challenging if not impossible atomic details to observe when using X-ray diffraction alone. Including deuterium labeling with NPX, the signal-to-noise ratios and neutron scattering length density maps can be greatly improved, creating a clearer depiction of hydrogen- related interactions. In addition to structure-function studies of proteins, NPX can also be used for detailed studies of ligand binding interactions. Neutrons can reveal the charged states of ligands, their electrostatic interactions and H-bonding arrangements to the target protein, and give insight into how these influence binding specificity and affinity. Combining data from both NPX and X-ray crystallography with strategic isotope labeling methods, can provide a more complete picture of protein function. X-ray diffraction data are in fact essential for solving, refining, and interpreting neutron crystal structures, offering complementary information on the electron density maps that guide the interpretation of neutron scattering data. There are some practical challenges in the workflow with regards to sample preparation, availability, and timing that require careful planning and coordination. The European Spallation Source (ESS) supports NPX studies through its NPX beamline (so-called NMX, under construction) and the Deuteration and Macromolecular Crystallization (DEMAX) support facility. Together, the ESS supports structural biologists with access to beamtime and sample preparation assistance, which enables researchers to leverage NPX for high-quality structure determination.