X-ray lasers for structure and dynamics in biology

Recent advances in the application of X-ray lasers to structural biology are providing time-resolved high-resolution imaging of many processes, from enzyme kinetics to the riboswitch in action, drug action, and light-sensitive proteins.

Sample manipulation and data assembly for robust microcrystal synchrotron crystallography

Micro-sized polyimide well-mounts for the manipulation of microcrystals and a data-assembly method for rotation data sets from many microcrystals are described.

Multiple-scale structures: from Faraday waves to soft-matter quasicrystals

Models describing the thermodynamic stability of soft-matter quasicrystals are reviewed and expanded. New analytical methods for treating them are presented, and a number of new stable quasicrystalline structures are reported.

Epoxide hydrolysis as a model system for understanding flux through a branched reaction scheme

Kinetic rates and computer simulations can explain regioselectivity and stereoconfiguration in the products of enzyme-catalyzed epoxide hydrolysis.

Enzyme catalysis captured using multiple structures from one crystal at varying temperatures

MSOX (multiple serial structures from one crystal) serial crystallography experiments were carried out using controlled X-ray radiolysis and photon-counting detectors to determine sequences of low-dose yet high-resolution structures of copper nitrite reductase. Working at 190 K and at room temperature provides greater dynamic freedom, allowing more of the catalytic cycle to be observed than at the usual cryogenic temperature of 100 K. The approach demonstrates the potential to obtain MSOX structural movies at variable temperatures, thus providing an unparalleled level of structural information during catalysis for redox enzymes.

Exploitation of knowledge databases in the synthesis of zinc(II) malonates with photo-sensitive and photo-insensitive N,N′-containing linkers

Crystallographic analysis of zinc(II) complexes allows the construction of hydrogen-bonded and coordination networks with 1,2-bis(pyridin-4-yl)ethylene groups situated in photoreactive positions to allow solid-state [2 + 2] cycloaddition reactions.

Polymorphism of terthio­phene with surface confinement

The appearance of a new polymorphic phase is observed for terthio­phene as a result of adaptation to a flat substrate surface present during the crystallization process. This new polymorph can be attributed to the confinement of the molecular packing within the plane of the substrate surface accompanied by a tremendous increase in the unit-cell size and partial molecular disorder.

Structural studies of crystalline forms of triamterene with carboxylic acid, GRAS and API molecules

This work discusses the preparation and characterization of crystalline forms of the drug triamterene with various carboxylic acids including Generally Regarded as Safe and Active Pharmaceutical Ingredients using liquid-assisted grinding and solvent-evaporative crystallization; a method of potential benefit to the pharmaceutical industry. Triamterene is selected as an appropriate model compound because it has poor water solubility which can have an impact on its bioavailability as a drug and it contains numerous hydrogen-bonding sites, thereby allowing a study of the competition between the different potential supramolecular synthons. Cambridge Structural Database studies show good agreement between this and previous studies using similar compounds.

Molecular dynamics study of tridymite

Polymorphic structural changes in tridymite have been investigated by molecular dynamics simulation. The main polymorphic transitions were reproduced and their mechanisms are explained.

π–π-Induced aggregation and single-crystal fluorescence anisotropy of 5,6,10b-tri­aza­acephenanthrylene

The influence of π–π overlap in centrosymmetric dimers on the aggregation type, single-crystal absorption and fluorescence anisotropy of the new heterocyclic system 5,6,10b-tri­aza­acephenanthrylene is presented.

Ionic scattering factors of atoms that compose biological molecules

Ionic scattering factors of atoms that compose biological molecules have been computed by the multi-configuration Dirac–Fock method and parameterized for major curve models in X-ray and electron protein crystallography and single-particle cryo-EM.

Heterogeneous local order in self-assembled nanoparticle films revealed by X-ray cross-correlations

An X-ray cross-correlation study of the self-assembly of soft-shell nanoparticles is presented. It is demonstrated that the assembled films are structurally heterogeneous, with dominant hexagonal and cubic symmetries forming patches of 10⁴–10⁵ particles.

Decoupling anion-ordering and spin-Peierls transitions in a strongly one-dimensional organic conductor with a chessboard structure, (o-Me₂TTF)₂NO₃

Anion-ordering (AO) and spin-Peierls (SP) structural/electronic transitions are fully decoupled in the molecular conductor (o-Me₂TTF)₂NO₃.