Non-enzymatic oligonucleotide ligation in photoswitchable coacervate protocells sustains compartment-content coupling

Modern cells are adaptive chemical compartments tightly regulated by an underlying DNA-encoded program. Reproducing such a coupling between information content and chassis in synthetic compartments represents a key step to the assembly of evolvable protocells, but remains challenging. Here, we rationally exploit complexation between end-reactive oligonucleotides able to stack into long physical polymers and a cationic azobenzene photoswitch to produce three different phases – soft solids, liquid crystalline or isotropic coacervates droplets – that promote non-enzymatic oligonucleotide ligation, with a marked phase-dependent reaction efficiency. Changes in the population of polynucleotides during polymerization induce in turn phase transitions that dramatically alter the physical properties of the compartments. Dynamical modulation of coacervate assembly and dissolution via trans-cis azobenzene photoisomerisation is last used to demonstrate cycles of light-actuated oligonucleotide ligation. Overall, by combining a tight reaction-structure coupling and environmental responsiveness, our light-responsive reactive coacervates provide a novel general route to the non-enzymatic synthesis of polynucleotides, and pave the way to the emergence of a primitive genotype-phenotype coupling in membrane-free protocells.

Visible-Light-Induced Catalytic Selective Halogenation with Photocatalyst

Halide moieties are essential structures of compounds in organic chemistry due to their popularity and wide applications in many fields such as natural compounds, agrochemicals, and pharmaceuticals. Thus, many methods have been developed to introduce halides into various organic molecules. Recently, visible-light-driven reactions have emerged as useful methods of organic synthesis. Particularly, halogenation strategies using visible light have significantly improved the reaction efficiency and reduced toxicity, as well as promoted reactions under mild conditions. In this review, we have summarized recent studies in visible-light-mediated halogenation (chlorination, bromination, and iodination) with photocatalysts.

Interaction between Cement Clinker Constituents and Clay Minerals and their Influence on the Strength of Cement-Based Stabilized Soft Clay

The strength of cement stabilized clay is less than that of concrete and mortar and shows a distinct variability owing to the existence of various clay minerals. To better understand the cement-clay reactions and the strength generation, two artificial clays with the unique clay mineral and major strength-producing constituents of cement clinker were investigated via mechanical, compositional, and microstructural analyses. Results show that C3A-stabilized clay gains strength rapidly in the first three days, but this favourable tendency vanishes over time. After 90 days of curing, the strength of C3S-stabilized clay is about four times that of the corresponding C3A-stabilized clay, indicating the remarkable long-term stabilization efficiency of C3S. Furthermore, clay minerals primarily draw into strength evolution in the reaction process. Despite that bentonite is more reactive than kaolin as long as the highly alkaline conditions persist, it has a higher probability to flocculate into large aggregates during the mixing process, which may impair the reaction efficiency and even brings adverse stabilization effects, suggesting the importance of uniformity control.

Photoredox Catalyzed Dealkylative Aromatic Halogen Substitution with Tertiary Amines

A reaction of aromatic halides bearing electron-withdrawing groups with tertiary amines in the presence of an iridium catalyst under blue light irradiation is described. Products of the aromatic substitution of the halide by the dialkylamino fragment are obtained. The interaction of aryl radicals with tertiary amines to generate zwitterionic radical species is believed to be the key factor responsible for the reaction efficiency.

New insights into the molecular mechanism behind mannitol and erythritol fructosylation by β-fructofuranosidase from Schwanniomyces occidentalis

The β-fructofuranosidase from Schwanniomyces occidentalis (Ffase) is a useful biotechnological tool for the fructosylation of different acceptors to produce fructooligosaccharides (FOS) and fructo-conjugates. In this work, the structural determinants of Ffase involved in the transfructosylating reaction of the alditols mannitol and erythritol have been studied in detail. Complexes with fructosyl-erythritol or sucrose were analyzed by crystallography and the effect of mutational changes in positions Gln-176, Gln-228, and Asn-254 studied to explore their role in modulating this biocatalytic process. Interestingly, N254T variant enhanced the wild-type protein production of fructosyl-erythritol and FOS by $$\sim$$ ∼ 30% and 48%, respectively. Moreover, it produced neokestose, which represented $$\sim$$ ∼ 27% of total FOS, and yielded 31.8 g l−1 blastose by using glucose as exclusive fructosyl-acceptor. Noteworthy, N254D and Q176E replacements turned the specificity of Ffase transferase activity towards the synthesis of the fructosylated polyols at the expense of FOS production, but without increasing the total reaction efficiency. The results presented here highlight the relevance of the pair Gln-228/Asn-254 for Ffase donor-sucrose binding and opens new windows of opportunity for optimizing the generation of fructosyl-derivatives by this enzyme enhancing its biotechnological applicability.