Triosephosphate isomerase: the perfect enzyme, but how does it work?

Insights are offered on the study by Kelpšas et al. [IUCrJ (2021). 8, 633–643], who have combined neutron and X-ray crystallography then QM (quantum mechanics) calculations on triosephosphate isomerase (TIM). The authors dissect three possible enzyme mechanisms of TIM that have arisen in the decades since the first X-ray crystal structure of this enzyme was published in 1975.

Making sense of SFX data: standards for data and structure validation for a non-standard experiment that has come of age

SFX diffraction data collection at XFELs is becoming more accessible. To extract the most useful biological information from these non-standard experiments, standards for SFX data analysis and structure validation must be redefined.

Structural chemistry of layered lead halide perovskites containing single octahedral layers

A comprehensive review of hybrid lead halide perovskites based on [PbX₄]_∞ layers is presented. We use a crystallographic approach based on symmetry mode analysis to systematize key types of distortions, particularly octahedral tilting and layer shifts, in this extensive and diverse family of materials.

Structural and biophysical aspects of L-asparaginases: a growing family with amazing diversity

The structural and biophysical aspects of a diversified group of enzymes that hydrolyze L-asparagine are reviewed in the context of their mechanism and biological function, and as therapeutic agents for the treatment of leukemia.

Discerning best practices in XFEL-based biological crystallography – standards for nonstandard experiments

Serial femtosecond crystallography is coming of age. Therefore, it is time to consider best practices and appropriate standards.

The 3D structure of fibrous material is fully restorable from its X-ray diffraction pattern

Non-rotationally averaged 3D structures of fibers can be restored from their rotationally averaged diffraction patterns.

Crystal structures of Aspergillus oryzae Rib2 deaminase: the functional mechanism involved in riboflavin biosynthesis

Crystal structures of Rib2 deaminase reveal its substrate specificity and catalytic mechanism.

Improved grain mapping by laboratory X-ray diffraction contrast tomography

The present laboratory diffraction contrast tomography suffers from poor spatial resolution – only grains larger than 40 µm can be reliably imaged. In this work, it is shown how this serious limitation can be lifted and the spatial resolution improved significantly.

Putative hexameric glycosyltransferase functional unit revealed by the crystal structure of Acinetobacter baumannii MurG

The glycosyltransferase MurG from the human pathogen A. baumannii was characterized and its hexameric crystal structure was unveiled. This is the first homo-oligomeric structure to be described in the MurG family and the Mur family. The homo-oligomerization mechanism of MurG is clarified, thus opening the door for the design of next-generation antibiotics that target MurG.

Distinct pathways of solid-to-solid phase transitions induced by defects: the case of DL-me­thio­nine

Ubiquitous defects in polycrystalline powders and single crystals affect the pathways of polymorphic solid-to-solid phase transitions. Dependent on the density of crystal defects, the phase transition mechanism can be dominated by either the cooperative molecular motion pathway or the nucleation and growth pathway.

Detection and characterization of folded-chain clusters in the structured melt of isotactic polypropyl­ene

A complete set of new methods have been proposed that can determine lamellar thickness, long period and lateral size of lamellar crystals readily and accurately.

Relativistic Hirshfeld atom refinement of an organo-gold(I) compound

A series of Hirshfeld atom refinements (HARs) has been performed for an organo-gold(I) compound at different levels of theory. The influences of the relativistic effect, electron correlation and anharmonic thermal motion have been studied based on aspherical charge density models obtained with HAR.

Decellularized pericardium tissues at increasing glucose, galactose and ribose concentrations and at different time points studied using scanning X-ray microscopy

Decellularized pericardium tissue exposed to solutions of sugars like glucose, galactose and ribose could potentially be a model system for diseases like diabetes and the effects of aging. Scanning X-ray diffraction and scattering reveals the different nano-structural changes of collagen induced by glucose, galactose and ribose.

Neutron structures of Leishmania mexicana triosephosphate isomerase in complex with reaction-intermediate mimics shed light on the proton-shuttling steps

The high-resolution neutron structure of triosephosphate isomerase was determined in complex with two inhibitors that mimic intermediate states in the reaction mechanism. This shows clear protonation states of the catalytic residues, which allow a computational investigation of the disputed reaction mechanism.

Charge density studies of multicentre two-electron bonding of an anion radical at non-ambient temperature and pressure

The procedure for study of charge density at high pressures and/or high temperatures by the transferrable aspherical atom model (TAAM) is described and discussed. The experimental charge densities were verified and corroborated by periodic DFT computation. This method was tested on a salt of 5,6-di­chloro-2,3-di­cyano­semi­quinone radical anion which comprises two-electron multicentre bonding between the radicals.

The mechanism driving a solid–solid phase transition in a biomacromolecular crystal

The mechanism of a solid–solid phase transition in an RNA crystal is presented.

Fixed-target serial femtosecond crystallography using in cellulo grown microcrystals

A rapid fixed-target method is described for serial femtosecond crystallography diffraction data collection using in cellulo grown protein crystals directly within living insect cells.

X-ray crystallographic studies of RoAb13 bound to PIYDIN, a part of the N-terminal domain of C-C chemokine receptor 5

C-C chemokine receptor 5 (CCR5) is a major co-receptor molecule used by HIV-1 to enter cells. Two X-ray crystallographic studies are presented of the antibody RoAb13, which binds to the peptide PIYDIN, which is part of the N-terminal domain of CCR5. The results may provide the basis for active immunization vaccines to stimulate an antibody response to native CCR5 that will block HIV infection.

Characterization of high-H₂O₂-tolerant bacterial cytochrome P450 CYP105D18: insights into papaverine N-oxidation

The crystal structure of CYP105D18 and its unique structural features for papaverine N-oxidation are presented.

Tuneable local order in thermoelectric crystals

Distinct `hidden' phases of a technologically relevant thermoelectric material, which are identical in terms of composition and periodic crystal structure, but differ on a local scale, are observed and can be controlled through synthesis conditions. The local structure is explained in terms of a vacancy repulsion model, and relaxations around vacancies are characterized.