CuII‐Containing 1‐Aminocyclopropane Carboxylic Acid Oxidase Is an Efficient Stereospecific Diels–Alderase

In the context of developing ecofriendly chemistry, artificial enzymes are now considered as promising tools for synthesis. They are prepared in particular with the aim to catalyze reactions that are rarely, if ever, catalyzed by natural enzymes. We discovered that 1‐aminocyclopropane carboxylic acid oxidase reconstituted with Cu^II served as an efficient artificial Diels–Alderase. The kinetic parameters of the catalysis of the cycloaddition of cyclopentadiene and 2‐azachalcone were determined (K_M=230 μm , k_app=3 h^?1), which gave access to reaction conditions that provided quantitative yield and >99 % ee of the (1S,2R,3R,4R) product isomer. This unprecedented performance was rationalized by molecular modeling as only one docking pose of 2‐azachalcone was possible in the active site of the enzyme and this was the one that leads to the (1S,2R,3R,4R) product isomer.     

GOx@ZIF‐8(NiPd) Nanoflower: An Artificial Enzyme System for Tandem Catalysis

We report a facile approach to prepare an artificial enzyme system for tandem catalysis. NiPd hollow nanoparticles and glucose oxidase (GOx) were simultaneously immobilized on the zeolitic imidazolate framework 8 (ZIF‐8) via a co‐precipitation method. The as‐prepared GOx@ZIF‐8(NiPd) nanoflower not only exhibited the peroxidase‐like activity of NiPd hollow nanoparticles but also maintained the enzymatic activity of GOx. A colorimetric sensor for rapid detection of glucose was realized through the GOx@ZIF‐8(NiPd) based multi‐enzyme system. Moreover, the GOx@ZIF‐8(NiPd) modified electrode showed good bioactivity of GOx and high electrocatalytic activity for the oxygen reduction reaction (ORR), which could also be used for electrochemical detection of glucose.     

Switchable Hydrolase Based on Reversible Formation of Supramolecular Catalytic Site Using a Self‐Assembling Peptide

The reversible regulation of catalytic activity is a feature found in natural enzymes which is not commonly observed in artificial catalytic systems. Here, we fabricate an artificial hydrolase with pH‐switchable activity, achieved by introducing a catalytic histidine residue at the terminus of a pH‐responsive peptide. The peptide exhibits a conformational transition from random coil to β‐sheet by changing the pH from acidic to alkaline. The β‐sheet self‐assembles to form long fibrils with the hydrophobic edge and histidine residues extending in an ordered array as the catalytic microenvironment, which shows significant esterase activity. Catalytic activity can be reversible switched by pH‐induced assembly/disassembly of the fibrils into random coils. At higher concentrations, the peptide forms a hydrogel which is also catalytically active and maintains its reversible (de‐)activation.     

Nanozyme‐Catalyzed Cascade Reactions for Mitochondria‐Mimicking Oxidative Phosphorylation

Multiple‐enzyme‐involving cascade reactions that yield bioenergy are necessary in natural oxidative phosphorylation. However, in vitro applications are hampered by the sensitivity of catalytic activity to environmental adaptation. Herein, we explore nanozyme‐catalyzed cascade reactions in an assembled hybrid architecture for mitochondria‐mimicking oxidative phosphorylation. Hollow silica microspheres containing trapped gold nanoparticles were synthesized to promote two enzyme‐like catalytic reactions that transform glucose into gluconic acid in the presence of oxygen. The resulting transmembrane proton gradient drives natural ATP synthase reconstituted on the surface to convert ADP and inorganic phosphate into ATP. The assembled architecture possesses high activity for oxidative phosphorylation, comparable to that of natural mitochondria. This study provides a new natural–artificial hybrid prototype for exploring bioenergy supply systems and holds great promise for ATP‐powered bioapplications.     

Enzyme Activity by Design: An Artificial Rhodium Hydroformylase for Linear Aldehydes

Artificial metalloenzymes (ArMs) are hybrid catalysts that offer a unique opportunity to combine the superior performance of natural protein structures with the unnatural reactivity of transition‐metal catalytic centers. Therefore, they provide the prospect of highly selective and active catalytic chemical conversions for which natural enzymes are unavailable. Herein, we show how by rationally combining robust site‐specific phosphine bioconjugation methods and a lipid‐binding protein (SCP‐2L), an artificial rhodium hydroformylase was developed that displays remarkable activities and selectivities for the biphasic production of long‐chain linear aldehydes under benign aqueous conditions. Overall, this study demonstrates that judiciously chosen protein‐binding scaffolds can be adapted to obtain metalloenzymes that provide the reactivity of the introduced metal center combined with specifically intended product selectivity.     

Ultrafast and Highly Selective Uranium Extraction from Seawater by Hydrogel‐like Spidroin‐based Protein Fiber

For the practical extraction of uranium from seawater, adsorbents with high adsorption capacity, fast equilibrium rate, high selectivity, and long service life are needed. Herein, a chimeric spidroin‐based super uranyl‐binding protein (SSUP) fiber was designed by fusing the gene of super uranyl‐binding protein (SUP) with the gene of spidroin. SUP endowed the SSUP fiber with high affinity and selectivity to uranium, and spidroin gave the SSUP fiber with high mechanical strength and high reusability. The wet SSUP fiber is a water‐rich hydrogel‐like structure, which provided abundant hydrophilic intermolecular space for the entrance of uranyl ions, and could accelerate the rate for uranium adsorption. In seawater, the SSUP fiber achieved a breakthrough uranium extraction capacity of 12.33 mg g^?1 with an ultrashort equilibration time of 3.5 days, suggesting that SSUP fiber might be a promising adsorbent for uranium extraction from the natural seawater.     

Barcoding Biological Reactions with DNA‐Functionalized Vesicles

Targeted vesicle fusion is a promising approach to selectively control interactions between vesicle compartments and would enable the initiation of biological reactions in complex aqueous environments. Here, we explore how two features of vesicle membranes, DNA tethers and phase‐segregated membranes, promote fusion between specific vesicle populations. Membrane phase‐segregation provides an energetic driver for membrane fusion that increases the efficiency of DNA‐mediated fusion events. The orthogonality provided by DNA tethers allows us to direct fusion and delivery of DNA cargo to specific vesicle populations. Vesicle fusion between DNA‐tethered vesicles can be used to initiate in vitro protein expression to produce model soluble and membrane proteins. Engineering orthogonal fusion events between DNA‐tethered vesicles provides a new strategy to control the spatiotemporal dynamics of cell‐free reactions, expanding opportunities to engineer artificial cellular systems.     

Control of Metal–Organic Framework Crystallization by Metastable Intermediate Pre‐equilibrium Species

There is an increasing amount of interest in metal–organic frameworks (MOFs) for a variety of applications, from gas sensing and separations to electronics and catalysis. However, the mechanisms by which they crystallize remain poorly understood. Herein, an important new insight into MOF formation is reported. It is shown that, prior to network assembly, crystallization intermediates in the canonical ZIF‐8 system exist in a dynamic pre‐equilibrium, which depends on the reactant concentrations and the progress of reaction. Concentration can, therefore, be used as a synthetic handle to directly control particle size, with potential implications for industrial scale‐up and gas sorption applications. These findings enable the rationalization of apparent contradictions between previous studies of ZIF‐8 and opens up new opportunities for the control of crystallization in network solids more generally.     

Dark Photocatalysis: Storage of Solar Energy in Carbon Nitride for Time‐Delayed Hydrogen Generation

While natural photosynthesis serves as the model system for efficient charge separation and decoupling of redox reactions, bio‐inspired artificial systems typically lack applicability owing to synthetic challenges and structural complexity. We present herein a simple and inexpensive system that, under solar irradiation, forms highly reductive radicals in the presence of an electron donor, with lifetimes exceeding the diurnal cycle. This radical species is formed within a cyanamide‐functionalized polymeric network of heptazine units and can give off its trapped electrons in the dark to yield H₂, triggered by a co‐catalyst, thus enabling the temporal decoupling of the light and dark reactions of photocatalytic hydrogen production through the radical′s longevity. The system introduced here thus demonstrates a new approach for storing sunlight as long‐lived radicals, and provides the structural basis for designing photocatalysts with long‐lived photo‐induced states.