ChemSystemsChem最新文献

The front cover artwork is provided by the Spruijt group from the Radboud University in Nijmegen. The image shows a metabolic reaction pathway projected over a microscopy image of metabolite coacervates. Read the full text of the Research Article at 10.1002/syst.202200004.

Mackinawite has unique structural properties and reactivities when compared to other iron sulfides. Herein we provide evidence for the mackinawite-supported reduction of KCN into various reduced compounds under primordial conditions. We proposed a reaction mechanism based on the nucleophilic attack by the deprotonated mackinawite -SH surface groups at the carbon atom of HCN. The initial binding of the substrate and the subsequent reduction events are supported by DFT calculations and further experiments using other substrates, such as KSCN, KOCN and CS₂. Until now, conversion of CN⁻ into CH₄ and NH₃ has been limited to nitrogenase cofactors or molecular Fe-CN complexes. Our study provides evidence for mackinawite-supported cleavage of the C−N bond under ambient conditions, which opens new avenues for investigation of other substrates for mackinawite-supported reactions while shedding light on the relevance of this type of reaction to the origin of life on Earth.

Addition of CaCl₂ into a highly alkaline phosphate buffer results in the generation of submerged transparent chemobrionic bubbles mimicking jellyfish that are stable and malleable. A compartmentalized O₂-generating reaction triggered the growth of regular vertical chemical gardens from the bubble through a gas micro-rocket propelled mechanism. The bubbles can mechanically separate to yield two daughter bubbles in a process reminiscent of cytokinesis or natural jellyfish regeneration, and then re-grow through new injection of CaCl₂. Finally, loading of E. coli bacteria genetically engineered to exert green fluorescence inside the bubbles was demonstrated in a biomimetic analogue of “symbiosis”.

Lipid rafts are ordered lipid domains that are enriched in saturated lipids, such as the ganglioside GM1. While lipid rafts are believed to exist in cells and to serve as signaling platforms through their enrichment in signaling components, they have not been directly observed in the plasma membrane without treatments that artificially cluster GM1 into large lattices. Here, we report that microscopic GM1-enriched domains can form in the plasma membrane of live mammalian cells expressing the EphA2 receptor tyrosine kinase in response to its ligand ephrinA1-Fc. The GM1-enriched microdomains form concomitantly with EphA2-enriched microdomains. To gain insight into how plasma membrane heterogeneity controls signaling, we quantify the degree of EphA2 segregation and study initial EphA2 signaling steps in both EphA2-enriched and EphA2-depleted domains. By measuring dissociation constants, we demonstrate that the propensity of EphA2 to oligomerize is similar in EphA2-enriched and -depleted domains. However, surprisingly, EphA2 interacts preferentially with its downstream effector SRC in EphA2-depleted domains. The ability to induce microscopic GM1-enriched domains in live cells using a ligand for a transmembrane receptor will give us unprecedented opportunities to study the biophysical chemistry of lipid rafts.

The front cover artwork is provided by İrep Gözen group at the University of Oslo. The image shows primitive cell-like compartments which have spontaneously emerged from a crack in rock-forming mineral oligoclase. Read the full text of the Article at 10.1002/syst.202100040.

The Front Cover shows primitive cell-like compartments which have spontaneously emerged from a crack in rock-forming mineral oligoclase. More information can be found in the Article by Irep Gözen and co-workers.

This report describes a method to obtain multicellular shaped compartments made by lipids growing from a sponge-like porous structure. Each compartment is several tens of micrometers in diameter and separated by membranes comprised of phospholipid and amphipathic molecules. The multi-compartment structure spontaneously grew to a millimeter scale, driven by an ionic concentration difference between the interior and exterior environments of the sponge. These compartments can also easily incorporate hydrophilic species as a well as smaller materials such as liposomes. Additionally, we showed that mechanical squeezing of the sponge was also effective in producing multicellular bodies. These simple methods to obtain large-scale multicellular compartment of lipid membrane will help future designs and trials of chemical communications on artificial cells.

The cell is a crowded environment where a relevant fraction of the available space is occupied by proteins, nucleic acids, and metabolites. Here we discuss recent advancements in the understanding of crowding effects on intrinsically disordered proteins. Differently from their structured counterparts, these proteins do not adopt a stable three-dimensional structure and remain flexible and dynamic in solution. The physics of polymers and colloids provides a framework to interpret how crowding modulates conformations, dynamics, and interactions of disordered proteins. Flory-Huggins models enable rationalizing the different degree of compaction induced by crowding agents in terms of depletion interactions. The same interactions modulate the diffusion of the disordered proteins in a crowded milieu and the association and dissociation rates when interacting with a ligand. Altogether, this theoretical framework provides new insights into the interpretation of the effects of the cellular environment on disordered proteins.

The bottom-up construction of an artificial cell model system starting from inanimate components helps people better understand the working mechanism of cells. Phospholipids are natural components of the cell membrane system, which are widely used to construct artificial cells. However, it is difficult to synthesize natural phospholipids in situ. Chemically synthesized lipid analogues are similar in structure to natural phospholipids, so they can be used to mimic phospholipids to build vesicles. Here, four methods of the chemical synthesis of lipid analogues (including enzyme reactions, click chemistry reactions, native chemical ligation reactions, imine condensation and decomposition reactions) are described. The construction of artificial cells based on the lipid analogues, and their growth and division are also summarized. Finally, the challenges and future directions in the field of construction and division of artificial cells based on lipid analogues are proposed.

Supramolecular gels formed by the combination of different organic molecules are of significant interest in the search of new functional materials. When two different molecules are mixed to form gels, the self-assembled fibres can be a result of self-sorting or co-assembly. A key challenge is to control the network type. Here, we demonstrate that control over the network type can be achieved either by varying the hydrophobicity of a component or by employing a pH-switch method.