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Although amorphous calcium carbonate represents an important biomineralization precursor, its structure has been difficult to understand. Now, amorphous calcium carbonate’s structure is shown to arise from the different bridging modes available to the calcium ions. This effective multi-well potential that drives calcium arrangements creates a geometric incompatibility between preferred Ca–Ca distances and frustrates crystallization.

Understanding of the molecular mechanisms underlying the maturation of protein condensates into amyloid fibrils associated with neurodegenerative diseases has so far remained elusive. Now it has been shown that in condensates formed by the low-complexity domain of the amyotrophic lateral sclerosis-associated protein hnRNPA1, fibril formation is promoted at the interface, which provides a potential therapeutic target for counteracting aberrant protein aggregation.

An infrared laser-induced temperature jump provides a rapid and broadly applicable perturbation to protein dynamics. Temperature-jump crystallography was paired with time-resolved X-ray crystallography to study the dynamic enzyme lysozyme. Measurements with and without a functional inhibitor revealed different patterns in the propagation of motion throughout the enzyme.

While aromaticity is a useful concept for assessing the reactivity of organic compounds, the connection between aromaticity and on-surface chemistry remains largely unexplored. Now, scanning probe experiments on cyclization reactions of porphyrins on Au(111) show that the peripheral carbon atoms outside of the aromatic 18-π electron pathway exhibit a higher reactivity.

Covalent organic frameworks offer a highly tunable class of materials for a range of applications, although their dynamic structural transformations are challenging to analyse. Now single-crystal X-ray diffraction is shown to demonstrate single-crystal-to-single-crystal transformations of the imine linkages, showing a well-defined interpenetrating topology and affording structures that have high positive thermal expansion and anhydrous proton-conduction properties.

Shifts in temperature alter the structure and dynamics of macromolecules. Now, infra-red laser-induced temperature jump is combined with X-ray crystallography to observe protein structural dynamics in real time. Using this method, motions related to the catalytic cycle of lysozyme, a model enzyme, are visualized at atomic resolution and across broad timescales.

Experimental and computational studies establish the operation of Fe(iii)-based metalloradical catalysis for the asymmetric cyclopropanation of alkenes with different classes of diazo compounds. The reaction proceeds through a stepwise radical mechanism involving α-Fe(iv)-alkyl and γ-Fe(iv)-alkyl radical intermediates. This work provides a future direction for the development of metalloradical catalysis.

Deuterated compounds are used in many applications such as mass-spectrometry standards, drugs or in organic light-emitting diodes. Now, hydrogen-activated homogeneous pincer complex catalysts can be used to perform selective alkene deuteration with the cheapest available deuterium source, D₂O.

The discovery of biomarkers remains challenging owing to a lack of methods sensitive enough to identify such rare molecules. Now, by simultaneously exploiting the catalysis and affinity of a DNAzyme, candidate biomarkers with low abundance in cancers can be pulled down for identification and validation.

Biological membranes are asymmetric bilayers, but little is known about how this asymmetry modulates membrane protein folding or stability. Now, folding and stability assays with bacterial outer membrane proteins reveal an exquisite sensitivity to asymmetric membrane charge distribution and a required matching of protein charge for efficient folding.

Phase separation is being revealed as important in many biological processes. Most attempts to mimic and deconstruct this use engineered natural proteins. Now it is shown that de novo proteins can be designed from first principles to undergo liquid–liquid phase separation in cells, with the potential to organize multi-enzyme pathways.

Aryl ethers are useful intermediates in organic synthesis and are found in countless biologically active compounds. Now, through palladium/norbornene cooperative catalysis and incorporation of a polarity-reversed N–O reagent as the O-electrophile, an efficient arene methoxylation approach has been successfully developed.

Medicinal chemistry efforts typically focus on drug–protein interactions and overlook RNA binding as a source of off-target pharmacology. Now, a new method has been developed to map the interactions of small-molecule drugs with RNA in cells and characterize how these interactions can exert functional effects.

Merging carbonyls to form an alkene by removing their oxygens is rare, yet synthetically useful, and the selective combination of two different carbonyls is especially challenging. Now, two strategies for cross-metathesis of unbiased carbonyls have been developed. An Fe-catalysed carbene/ylide strategy affords Z-alkenes, while Cr-catalysed gem-di-metals yield E-alkenes.

Cobalt(II) complexes of porphyrins have dominated the development of metalloradical catalysts. Now it has been shown that five-coordinate iron(III) complexes of porphyrins with an axial ligand are also potent metalloradical catalysts for olefin cyclopropanation. They are shown to react with different classes of diazo compounds via a stepwise radical mechanism.

Deuterogenation methods typically introduce only two deuterium atoms per unsaturation. Now the single-step hydrogenative perdeuteration of alkenes has been achieved using H₂ and D₂O, with incorporation of up to 4.9 D atoms per C=C double bond. The reaction is catalysed by a ruthenium pincer complex with a catalytic amount of thiol, which serves as a transient cooperative ligand.

Ribozyme-mediated post-transcriptional RNA modification is a powerful method for site-specific RNA labelling and analysis of RNA functions. Now, an alkyltransferase ribozyme—termed SAMURI—has been shown to catalyse the transfer of a propargyl group from a stabilized synthetic S-adenosylmethionine analogue to a specific adenosine on the target RNA within cells.

Molecular systems with coincident cyclic and superhelical symmetry axes have considerable advantages for materials design as they can be lengthened or shortened by changing the length of the monomers. Now a systematic approach to generate modular repeat protein oligomers with combined symmetry that can be extended by repeat propagation has been developed.

Clinton Veale and Fanie van Heerden discuss the story of natamycin. From its humble telluric origins in Pietermaritzburg, this unique antimicrobial agent has risen to become a mainstay of the food and beverages industry.

The onset of eco-evolutionary dynamics marks a stepping stone in the transition from chemistry to biology. Now a minimal replicator system showing such dynamics has been developed. The replicators adapt to changes in their environment that they themselves induced through photoredox catalysis.