Challenges in the structural science of materials

Articles published recently in IUCrJ continue to exemplify the developments and challenges in the structural science of materials.

Imaging enzyme kinetics at atomic resolution

Serial crystallography at a synchrotron has been used to obtain time-resolved atomic resolution density maps of enzyme catalysis in copper nitrite reductase. Similar XFEL studies, intended to out-run radiation damage, will also soon appear.

Mysteries of icosahedral quasicrystals: how are the atoms arranged?

Higher-dimensional structure analysis of quasicrystals is now possible. Yamada et al. [IUCrJ (2016), 3, 247–258] have solved the atomic structure of icosahedral ScZn_7.33 including the characteristic imperfections.

Isolation and evolution of labile sulfur allotropes via kinetic encapsulation in interactive porous networks

Reported here are the isolation and direct observation of extremely reactive S₂ and its conversion into bent-S₃ via a cyclo-S₃²⁺ intermediate on interactive sites in porous coordination networks.

Quantum crystallographic charge density of urea

A charge-density model of urea was calculated using quantum theory and was refined against publicly available ultra-high-resolution X-ray diffraction data. The quantum model differs from a multipole model but agrees comparably with the data; quantum crystallography therefore can provide unique and accurate charge density models.

Atomic structure and phason modes of the Sc–Zn icosahedral quasicrystal

The detailed atomic structure of the binary icosahedral ScZn_7.33 quasicrystal has been investigated by means of high-resolution synchrotron single-crystal X-ray diffraction and absolute scale measurements of diffuse scattering.

Residue contacts predicted by evolutionary covariance extend the application of ab initio molecular replacement to larger and more challenging protein folds

Residue-contact predictions extend the range of ab initio molecular replacement.

Serial crystallography captures enzyme catalysis in copper nitrite reductase at atomic resolution from one crystal

Serial crystallography has been used to drive copper nitrite reductase through its enzymatic cycle while sampling the same volume of a single cryogenically maintained crystal. A structural movie of X-ray-driven enzyme catalysis has thus been obtained, revealing the structural changes that occur during the catalytic reaction in unprecedented detail.

Structure of a heterogeneous, glycosylated, lipid-bound, in vivo-grown protein crystal at atomic resolution from the viviparous cockroach Diploptera punctata

This article presents the features and structures of protein crystals naturally grown in vivo within developing embryos of the only known viviparous cockroach, D. punctata. This study reveals the heterogeneous nature of the crystalline protein with respect to amino-acid sequence, glycosylation and bound fatty acid at atomic resolution.