Low-Resolution Refinement of the DNA and Protein Complex Structures

Macromolecular complexes of protein and DNA are often resolved in a low resolution structure (3.0 angstroms or lower). Because nucleic acids suffer radiation damage more than amino acids, the resulting temperature factors for DNA are generally higher than those for protein. Recognition of DNA-specific interactions with protein is a challenge at low resolution. The use of low-resolution refinement ([1]) or the reference high resolution model could improve DNA densities. A number of DNA/protein and nucleosome complexes (i.e. RAGE-DNA [2], CENP-C-NCP[3]) that we have recently refined demonstrated the validation of these methods.

Synthesis, structure and water sorption in Zr metal-organic frameworks

Metal-organic frameworks (MOFs) based on zirconium secondary building units (SBUs) have proven to have great thermal and chemical stability,[1,2] which make them ideal for their use in different applications. We have prepared a series of six new MOFs made from the Zr₆O₄(OH)₄(-CO₂)_n secondary building units (n = 6, 8, 10, or 12) and variously shaped carboxyl organic linkers to make extended porous frameworks, with the aim of studying their performance as water adsorbents. Thus, we have evaluated the water adsorption properties of these new MOFs and other reported porous materials to identify the compounds with the most promising materials for use in applications such as thermal batteries or delivery of drinking water in remote areas. An X-ray single-crystal and a powder neutron diffraction study reveal the position of the water adsorption sites in one of the best performing materials, and highlight the importance of the intermolecular interactions between adsorbed water molecules within the pores.