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Artificial intrinsically disordered proteins (A-IDPs) have now been shown to form exclusionary, intracellular droplets that can be designed using simple principles that are based on the aromatic/aliphatic ratio and molecular weight. Droplets that sequester an enzyme and modulate enzyme efficiency on the basis of the molecular weight of the A-IDPs were also engineered using A-IDPs as a minimal condensate scaffold.
Reversible nanoscale knotting and unknotting of a molecular strand can be used to control the handedness of helical organizations at macroscopic length scales. Dopant knotted and unknotted strands induce supramolecular helical structures of opposite handedness in achiral liquid crystals, and the left- and right-handed forms can be switched in situ.
Three crystalline complexes comprising a linear [UN2] moiety that is isoelectronic to the ubiquitous uranyl cation [UO2]2+ have been prepared by reaction of UCl5 or UBr5 with liquid ammonia. Quantum chemical calculations showed that the bonding in the [UN2] moieties is best described with two U≡N triple bonds.
CD44 is a cell-surface adhesion receptor associated with many biological processes that rely on cellular plasticity. Now, CD44 has been shown to mediate endocytosis of iron-bound hyaluronates. Furthermore, iron catalyses the demethylation of repressive histone marks, thereby unlocking the expression of genes regulating cellular plasticity.
The biosynthesis of goadvionins—hybrid lipopeptide antibiotics—is not fully understood. An unusual acyltransferase, GdvG, has now been identified and shown to catalyse a condensation reaction between an acyl-carrier-protein-tethered very-long-chain fatty acid and an eight-residue ribosomally synthesized and post-translationally modified peptide. The position of functional groups in the very-long acyl chain have been determined by tandem mass spectrometry.
Using readily accessible tropones and γ-methylidene-δ-valerolactones, the divergent synthesis of three classes of challenging [5.5.0] or [4.4.1] bicyclic systems has been achieved—with high efficiency and stereoselectivity—through Pd-catalysed higher-order cycloaddition. Mechanistic studies and density functional theory calculations indicate that the divergent reactions arise from the different reactivity of two diastereomeric intermediates.
Chemical reactions usually proceed through either a radical, concerted or ionic mechanism; transformations in which all three mechanisms occur are rare. Now, the mechanical dissociation of an N-heterocyclic carbene precursor has been shown to proceed with the rupture of a C–C bond through concomitant heterolytic, concerted and homolytic pathways.
Photoinduced isomerization reactions, including ring-opening reactions, lie at the heart of many chemical processes in nature. The pathway and dynamics of the ring opening of a model heterocycle have now been investigated by femtosecond photoelectron spectroscopy combined with ab initio theory, enabling the visualization of rich dynamics in both the ground and excited electronic states.
Visualization of endogenous G-quadruplexes (G4s) in living cells by fluorescence microscopy has been hampered by the high concentrations of G4-binding probes required, which can artificially induce additional G4 formation. Now, a G4-specific fluorescent probe (SiR-PyPDS) has been developed that enables single-molecule and real-time detection of individual G4 structures in living cells without perturbing G4 formation and dynamics.
Engineering reverse transcriptases for modified or unnatural nucleic acids is challenging, but now a versatile method has been developed that enables the discovery of efficient reverse transcriptases. The method works with a wide range of template structures, including xeno-nucleic acids and can also be used to produce high-fidelity reverse transcriptases for RNA.
Multivalent binding is a common strategy to enhance the interactions between weak binding partners. Now, following this principle, DNA origami scaffolds have been used to arrange DNA aptamers into specific geometries and to optimize linker spacings and flexibilities, which results in artificial binding sites with very high affinities for their corresponding ligands.
Molecular rotors have been engineered within the bicyclopentane–dicarboxylate struts of a metal–organic framework—the bicyclic unit is the rotator and the carboxylate groups serve as the stator. In a zinc-based metal–organic framework, the crossed conformation of the strut–metal nodes enables fast rotation of the bicyclic moiety, but in the corresponding zirconium metal–organic framework a change in the conformation results in much slower rotation.
Many bacterial pathogens release effector enzymes belonging to the large Fic family, which modify host targets with nucleotide monophosphates. Now, recombinantly produced Fic enzymes have been equipped with synthetic thiol-reactive nucleotide derivatives to make covalent binary probes. The reaction of modified Fic enzymes with their targets permits covalent substrate capture and the structural determination of low-affinity ternary enzyme–nucleotide–substrate complexes.
The invariable core of a type II polyketide synthase has been characterized using X-ray crystallography, simulations, mutagenesis experiments and functional assays. The characterization of the ternary acyl carrier protein complexes provides a mechanistic understanding of the reactivity and could inform future engineering of this complex biosynthetic machinery.
The strength of electrostatic interactions in semiconductors strongly affects their performance in optoelectronic devices. Now, doping two-dimensional naphthalene-based lead halide perovskites with tetrachloro-1,2-benzoquinone has been shown to introduce donor–acceptor interactions within the organic network, without disrupting the inorganic sublattice. This in turn altered the energy of the materials’ electron–hole electrostatic Coulomb interactions.
Access to both enantiomers of a chiral target compound typically relies on reversing the absolute configuration of the chiral component in the reaction system that is used to make them. A time-dependent enantiodivergent synthesis is reported in which the same enantiomer of a chiral catalyst can give both enantiomers of the product, depending on the reaction time.
A general method for the enantioselective hydrocyanation of alkenes has been a long-standing synthetic challenge. Now, using a dual electrocatalytic approach that combines two synergistic redox catalytic cycles, a wide variety of chiral nitriles can be synthesized from conjugated alkenes in high enantioselectivity.
The reduction of N2 to NH3 is mediated in living systems by the enzyme nitrogenase and in the chemical industry by the Haber–Bosch process; both systems rely on iron-based catalysis. Now, a molecular tri(iron)bis(nitrido) complex, prepared by reduction of a bis(iron)bis(iodo) precursor under an N2 atmosphere, has been isolated and shown to promote the formation of NH3 from H2.
The highly frustrated spin-1/2 kagome lattice antiferromagnet, predicted to exhibit unconventional magnetic behaviours, has remained difficult to synthesize without structural imperfections. Now, a d1-titanium fluoride kagome lattice antiferromagnet has been prepared in which there is only one crystallographically distinct Ti3+ site and one type of bridging fluoride, and it is shown to be a frustrated magnet with unusual magnetic properties.
The integration of replication with metabolism represents a key step in the transition of chemistry into biology. Now, it has been shown that a self-replicator can recruit and activate two different photocatalytic cofactors, which then catalyse the synthesis of the precursors for the replicator.
