Trimethylplatinum hydroxy-fluorides

[Me<sub>3</sub>PtF]<sub>4</sub>) can be prepared from the action of AgF on [Me<sub>3</sub>PtI]<sub>4</sub>. In the presence of moisture it hydrolyses to give progressively [(Me<sub>3</sub>PtF)<sub>3</sub>(Me<sub>3</sub>PtOH)], [(Me<sub>3</sub>PtF)<sub>2</sub>(Me<sub>3</sub>PtOH)<sub>2</sub>], [(Me<sub>3</sub>PtF)(Me<sub>3</sub>PtOH)<sub>3</sub>] and [Me<sub>3</sub>PtOH]<sub>4</sub>. Variable temperature NMR spectroscopy of these partially hydrolysed tetra-platinum fluorides shows that at higher temperatures the methyl groups within each Me<sub>3</sub>Pt unit rapidly exchange sites by an intramolecular mechanism, but the cubic Pt<sub>4</sub>X<sub>4</sub> cages retain their integrity

Structural virology. Near-atomic cryo-EM structure of the helical measles virus nucleocapsid.

International audienceMeasles is a highly contagious human disease. We used cryo-electron microscopy and single particle-based helical image analysis to determine the structure of the helical nucleocapsid formed by the folded domain of the measles virus nucleoprotein encapsidating an RNA at a resolution of 4.3 angstroms. The resulting pseudoatomic model of the measles virus nucleocapsid offers important insights into the mechanism of the helical polymerization of nucleocapsids of negative-strand RNA viruses, in particular via the exchange subdomains of the nucleoprotein. The structure reveals the mode of the nucleoprotein-RNA interaction and explains why each nucleoprotein of measles virus binds six nucleotides, whereas the respiratory syncytial virus nucleoprotein binds seven. It provides a rational basis for further analysis of measles virus replication and transcription, and reveals potential targets for drug design

Structural virology. Near-atomic cryo-EM structure of the helical measles virus nucleocapsid.

International audienceMeasles is a highly contagious human disease. We used cryo-electron microscopy and single particle-based helical image analysis to determine the structure of the helical nucleocapsid formed by the folded domain of the measles virus nucleoprotein encapsidating an RNA at a resolution of 4.3 angstroms. The resulting pseudoatomic model of the measles virus nucleocapsid offers important insights into the mechanism of the helical polymerization of nucleocapsids of negative-strand RNA viruses, in particular via the exchange subdomains of the nucleoprotein. The structure reveals the mode of the nucleoprotein-RNA interaction and explains why each nucleoprotein of measles virus binds six nucleotides, whereas the respiratory syncytial virus nucleoprotein binds seven. It provides a rational basis for further analysis of measles virus replication and transcription, and reveals potential targets for drug design

Binding site asymmetry in human transthyretin: insights from a joint neutron and X-ray crystallographic analysis using perdeuterated protein

Human transthyretin has an intrinsic tendency to form amyloid fibrils and is heavily implicated in senile systemic amyloidosis. Here, detailed neutron structural studies of perdeuterated transthyretin are described. The analyses, which fully exploit the enhanced visibility of isotopically replaced hydrogen atoms, yield new information on the stability of the protein and the possible mechanisms of amyloid formation. Residue Ser117 may play a pivotal role in that a single water molecule is closely associated with the γ-hydrogen atoms in one of the binding pockets, and could be important in determining which of the two sites is available to the substrate. The hydrogen-bond network at the monomer–monomer interface is more extensive than that at the dimer–dimer interface. Additionally, the edge strands of the primary dimer are seen to be favourable for continuation of the β-sheet and the formation of an extended cross-β structure through sequential dimer couplings. It is argued that the precursor to fibril formation is the dimeric form of the protein