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Quaternary ammonium compounds (QACs) are a class of compounds that were widely used as disinfectants during the COVID-19 pandemic and continue to be used as disinfecting agents.

 

Animals synthesize simple lipids using a distinct fatty acid synthase (FAS) related to the type I polyketide synthase (PKS) enzymes that produce complex specialized metabolites. The evolutionary origin of the animal FAS and its relationship to the diversity of PKSs remain unclear despite the critical role of lipid synthesis in cellular metabolism. Recently, an animal FAS-like PKS (AFPK) was identified in sacoglossan molluscs. Here, we explore the phylogenetic distribution of AFPKs and other PKS and FAS enzymes across the tree of life. We found AFPKs widely distributed in arthropods and molluscs (>6300 newly described AFPK sequences). The AFPKs form a clade with the animal FAS, providing an evolutionary link bridging the type I PKSs and the animal FAS. We found molluscan AFPK diversification correlated with shell loss, suggesting AFPKs provide a chemical defense. Arthropods have few or no PKSs, but our results indicate AFPKs contributed to their ecological and evolutionary success by facilitating branched hydrocarbon and pheromone biosynthesis. Although animal metabolism is well studied, surprising new metabolic enzyme classes such as AFPKs await discovery.

 

Abstract Metal-free electrocatalysts represent a main branch of active materials for oxygen evolution reaction (OER), but they excessively rely on functionalized conjugated carbon materials, which substantially restricts the screening of potential efficient carbonaceous electrocatalysts. Herein, we demonstrate that a mesostructured polyacrylate hydrogel can afford an unexpected and exceptional OER activity – on par with that of benchmark IrO 2 catalyst in alkaline electrolyte, together with a high durability and good adaptability in various pH environments. Combined theoretical and electrokinetic studies reveal that the positively charged carbon atoms within the carboxylate units are intrinsically active toward OER, and spectroscopic operando characterizations also identify the fingerprint superoxide intermediate generated on the polymeric hydrogel backbone. This work expands the scope of metal-free materials for OER by providing a new class of polymeric hydrogel electrocatalysts with huge extension potentials. 

Integrative studies have revealed cryptic radiations in several Caribbean lineages of heterobranch sea slugs, raising questions about the evolutionary mechanisms that promote speciation within the tropical Western Atlantic. Cyerce Bergh, 1871 is a genus comprising 12 named species in the family Caliphyllidae that lack the photosynthetic ability of other sacoglossans but are noted for vibrant colours on the large cerata (dorsal leaf-like appendages) that characterize many species. Two species are widely reported from the Caribbean: Cyerce cristallina (Trinchese, 1881) and Cyerce antillensis Engel, 1927. Here, we present an integrative assessment of diversity in Caribbean Cyerce. Four methods of molecular species delimitation supported seven species in samples from the Caribbean and adjacent subtropical Western Atlantic. Six delimited species formed a monophyletic lineage in phylogenetic analyses but were > 9% divergent at the barcoding COI locus and could be differentiated using ecological, reproductive and/or morphological traits. We redescribe C. antillensis, a senior synonym for the poorly known Cyerce habanensis Ortea & Templado, 1988, and describe five new species. Evolutionary shifts in algal host use, penial armature and larval life history might have acted synergistically to promote the rapid divergence of endemic species with restricted distributions in this radiation, substantially increasing global diversity of the genus.

 

Animal cytoplasmic fatty acid synthase (FAS) represents a unique family of enzymes that are classically thought to be most closely related to fungal polyketide synthase (PKS). Recently, a widespread family of animal lipid metabolic enzymes has been described that bridges the gap between these two ubiquitous and important enzyme classes: the animal FAS–like PKSs (AFPKs). Although very similar in sequence to FAS enzymes that produce saturated lipids widely found in animals, AFPKs instead produce structurally diverse compounds that resemble bioactive polyketides. Little is known about the factors that bridge lipid and polyketide synthesis in the animals. Here, we describe the function of EcPKS2 fromElysia chlorotica, which synthesizes a complex polypropionate natural product found in this mollusc. EcPKS2 starter unit promiscuity potentially explains the high diversity of polyketides found in and among molluscan species. Biochemical comparison of EcPKS2 with the previously described EcPKS1 reveals molecular principles governing substrate selectivity that should apply to related enzymes encoded within the genomes of photosynthetic gastropods. Hybridization experiments combining EcPKS1 and EcPKS2 demonstrate the interactions between the ketoreductase and ketosynthase domains in governing the product outcomes. Overall, these findings enable an understanding of the molecular principles of structural diversity underlying the many molluscan polyketides likely produced by the diverse AFPK enzyme family.

 

We show in this work how lithium tellurolate Li(X)_nTeCH₂SiMe₃(X = THF,n= 1, 1; X = 12-crown-4,n= 2, 2), can serve as an effective Te-atom transfer reagent to all group 5 transition metal halide precursors irrespective of their oxidation state.

 

Multicopper active sites for small molecule activation in materials and enzymatic systems rely on controlled but adaptable coordination spheres about copper clusters for enabling challenging chemical transformations. To translate this constrained flexibility into molecular multicopper complexes, developments are needed in both ligand design for clusters and synthetic strategies for modifying the cluster cores. The present study investigates the chemistry of a class of pyridyldiimine-derived macrocycles with geometrically flexible aliphatic linkers of varying lengths (nPDI2, n = 2, 3). A series of dicopper complexes bound by the nPDI2 ligands are described and found to exhibit improved solubility over their parent analogs due to the incorporation of 4-tBu groups on the pyridyl units and the use of triflate counterions. The ensuing synthetic study investigated methods for introducing various bridging ligands (µ-X; X = F, Cl, Br, N3, NO2, OSiMe3, OH, OTf) between the two copper centers within the macrocycle-supported complexes. Traditional anion metathesis routes were unsuccessful, but the abstraction of bridging halides resulted in “open-core” complexes suitable for capturing various anions. The geometric flexibility of the nPDI2 macrocycles was reflected in the various solid-state geometries, Cu–Cu distances, and relative Cu coordination spheres on variation in the identity of the captured anion.

 

A high-deposition-area, robust inorganic scaffold, unique in its reproducible anisotropic macropores, is reported. This scaffold has a Young’s modulus of 455 ± 34 kPa and a yield strength of 215 ± 10 kPa in compression. It supports 3.5 ± 1.0 mL min−1 cm−2 volumetric flux of water with a modest 4.4 kPa head pressure. The scaffold is generated by freeze-casting a low-pH, concentrated silicic acid solution, followed by supercritical drying (SCD), changing the way water glass is used to generate support substrates. The scaffold enables facile immobilization of molecules or nanoparticles for liquid-phase applications, including heterogeneous catalysis, separations, biomedical devices, and energy storage.