Enzymatic Cascade Reaction Research Articles

Bimetallic FeCo metal–organic framework based cascade reaction system: Enhanced peroxidase activity for antibacterial performance

Metal-organic frameworks (MOFs), as a peroxidase (POD), can catalyze the conversion of H2O2 to reactive oxygen species (ROS) for antibacterial application. To achieve strong antibacterial activity, it is necessary to improve the enzyme-like activity of MOFs. In this study, FexCoMOF was synthesized by incorporating Co(II) to improve the electron transfer of Fe(III)/Fe(II), which enhanced its redox capacity as a nanozyme and further promoted the generation of hydroxyl radical (⋅OH), exhibiting higher POD activity. Doping with different amounts of Co(II) altered the particle size, specific surface area, and surface defects of FexCoMOF, thus exhibiting differential enzyme-like activities. Additionally, a glucose-responsive enzyme cascade reaction system based on Fe4CoMOF/glucose oxidase (GOx) was established. In the presence of glucose, the in situ-generated substrate H2O2 was in contact with the catalytic site and the generated gluconic acid enabled Fe4CoMOF to maintain maximum enzyme activity under physiological pH conditions, avoiding damage caused by the use of exogenous high concentrations of H2O2. In the in vitro antibacterial experiment, the minimum inhibitory concentration (MIC) of Fe4CoMOF/GOx was 10 μg mL−1 for Escherichia coli (E. coli) and 5 μg mL−1 for Staphylococcus aureus (S. aureus) (∼108 CFU mL−1). The increase in enzyme activity resulted in a considerable reduction in the dose of the antibacterial agent, which was conducive to improving bio-safety. The in vivo experiment in mice demonstrated that the glucose-responsive Fe4CoMOF-based cascade reaction system had excellent antibacterial properties and remarkably promoted wound healing. The antibacterial agent based on bimetallic MOF developed in this work provides a new idea for cascade catalytic antibacterial therapy and will have remarkable application prospects in biomaterials and nanomedicine.

Palladium–platinum bimetallic modified MXene nanozyme for highly sensitive detection of active substances with acetylcholinesterase inhibitory effect

Alzheimer's disease (AD) is a chronic neurodegenerative disease that threatens to the health of global elderly population. Acetylcholinesterase (AChE) inhibitors are an effective therapeutic agent for AD, and screening of these substances is important for AD treatment. In this work, a Pd–Pt MXene nanoenzyme was successfully synthesized by using the in-situ reduction technique. A colorimetric method for sensitive AChE inhibitor detection was designed based on enzymatic cascade reaction between Pd–Pt MXene and AChE. Briefly, The Pd–Pt MXene material exhibited excellent peroxidase (POD)-like activity due to its bimetallic composition, effectively catalyzing the oxidation of colorless 3,3,5,5-tetramethylbenzidine (TMB) to generate blue oxidized TMB (oxTMB). Under the presence of AChE and acetylthiocholine chloride (ATCh), the POD-like activity of Pd–Pt MXene was significantly inhibited. The activity of this nanoenzyme could be restored after the addition of AChE inhibitors. Using donepezil as an example, colorimetric detection was conducted within a linear range of 0.1 nmol/L to 10 nmol/L and the lowest detection boundary was only 0.35 nmol/L (S/N = 3). Finally, a paper-based platform was designed and constructed, and it has been successfully employed for AChE inhibitor detection in real samples with the aid of a smartphone. In all, this work paves a new way for designing nanoenzyme-based devices towards medicine determination or screening like AChE inhibitor.

Molecular Architecture @ MOFs: Designing a Multifunctional Catalyst for the Cascade Reaction of Olefins via Epoxides to Cyclic Carbonates

Employing enzymatic reaction cascade principles to synthesize artificial materials with multiple autonomously operating active sites is one of the holy grails in modern catalysis research. In this regard, metal‐organic frameworks (MOFs) are promising host platforms. Yet, applying MOFs as enzyme‐mimicking catalysts is synthetically challenging. Herein, we present a design strategy for the synthesis of porphyrin‐based MOFs for the cascade catalysis of the conversion of olefins to epoxides and their cycloaddition with CO2 to cyclic carbonates. The MOFs feature tunable dual active sites with synthetically controllable metal variations. A clear dependence of the metal combination on the catalytic performance of the MOF catalysts is shown. This work advances the understanding essential for designing sophisticated, multifunctional porphyrin MOFs for efficient one‐pot cascade catalysis.

Lipase activated endocytosis-like behavior of oil-in-water emulsion

Oil-in-water emulsion is a system with extensive applications in foods, cosmetics and coating industries, and it could also be designed into an artificial lipid droplet in recent works. However, the insights into the biophysical dynamic behaviors of such artificial lipid droplets are lacking. Here, we reveal an enzymatic reaction triggered endocytosis-like behavior in the oil-in-water emulsion lipid droplets. A thermodynamically favored recruitment of lipases onto the membrane of the droplets is demonstrated. We confirm that the hydrolysis of tributyrin by lipases can decrease the interfacial tension and increase the compressive force on the membrane, which are the two main driving forces for triggering the endocytosis-like behavior. The endocytosis-like behavior induced various emerging functionalities of the lipid droplets, including proteins, DNA or inorganic particles being efficiently sequestered into the oil droplet with reversible release as well as enhanced cascade enzymatic reaction. Overall, our studies are expected to open up a way to functionalize oil-in-water emulsions capable of life-inspired behaviors and tackle emerging challenges in bottom-up synthetic biology, revealing the unknown dynamic behaviors of lipid droplets in living organisms.

Biochemical approaches for decoding the information stored with metabolites

Molecular data storage is an emerging supplement to conventional information storage methods. In addition to the information storage with DNA or synthetic polymers, a recently proposed strategy that uses small molecule mixtures as information carriers has sparked interest since it is a synthesis-free method. Here, we demonstrate two methods for decoding digital information stored in two sets of small-molecule metabolites. The information is stored as binary code, 0 or 1, based on the absence or presence of each particular metabolite in the mixture. In the first approach, the information was encoded by five metabolites (sarcosine, cholesterol, xanthine, glucose, and galactose) and stored as mixture solutions in a 384-well microplate. The information was read out by cascade enzymatic reactions that can specifically convert the metabolites to a colorimetric product, which was then assayed by a microplate reader. We stored a 60×32-pixel picture (1920 bits) with 384 mixtures of small molecules with a reading accuracy of 96.68 %, and also demonstrated the encoding of a 220-bit text message. Alternatively, another set of six metabolites (bilirubin, uric acid, urea, creatinine, glucose, and triglyceride) was deployed to encode a 78×102-pixel picture (7956 bits) with 1326 mixtures, which was decoded automatically by a biochemistry analyzer with a 98.96 % accuracy. This work showcases that common metabolites can be used as digital molecules for information storage, and the information decoding can be done by accessible instruments in an ordinary biochemical laboratory.

Redesigning glycolaldehyde synthase for the synthesis of biorefinery feedstock D-xylulose from C1 compounds.

Global climate deterioration intensifies the demand for exploiting efficient CO2 utilization approaches. Converting CO2 to biorefinery feedstock affords an alternative strategy for third-generation biorefineries. However, upcycling CO2 into complex chiral carbohydrates remains a major challenge. Previous attempts at sugar synthesis from CO2 either produce mixtures with poor stereoselectivity or require ATP as a cofactor. Here, by redesigning glycolaldehyde synthase, the authors constructed a synthetic pathway for biorefinery feedstock D-xylulose from CO2 that does not require ATP as a cofactor. The artificial D-xylulose pathway only requires a three-step enzyme cascade reaction to achieve the stereoselective synthesis of D-xylulose at a concentration of 1.2gL-1. Our research opens up an alternative route toward future production of chemicals and fuels from CO2.

Taxifolin-iron nanozymes with excellent RONS scavenging ability for alleviating ethanol-induced gastric ulcer

Gastric ulcer, a chronic disease of the digestive system, presents a high incidence rate and poses significant health risks. It is closely associated with the excessive production of reactive nitrogen and oxygen species (RONS), inflammation and cell apoptosis. In this study, taxifolin (Tax)-iron nanozymes (Fe-Tax) was developed by conjugating Tax with iron ions (Fe3+), which exhibited the activities of catalase and superoxide dismutase in the gastrointestinal environment. Our results revealed that Fe-Tax nanozymes effectively scavenge RONS, mitigate oxidative damage, inflammation and cell apoptosis in vitro. Additionally, Fe-Tax could alleviate tissue inflammation and gastric mucosal damage by regulating NRF2, NF-κB, Bax/Bcl-2, and VEGF signal pathways in gastric ulcer ethanol-induced. Crucially, the Fe-Tax has been shown to have excellent biocompatibility in vitro and in vivo. Overall, this study developed Fe-Tax nanozymes with enzyme cascade reactions and provided a highly efficient strategy to prevent and alleviate gastric ulcers.

Dihydro-β-ionone production by a one-pot enzymatic cascade of a short-chain dehydrogenase NaSDR and enoate reductase AaDBR1

Dihydro-β-ionone, a high-value compound with distinctive fragrance, is widely utilized in the flavor and fragrance industries. However, its low abundance in plant sources poses a significant challenge to its application through traditional extraction methods. Development of an enzyme cascade reaction with artificial design offers a promising alternative. Herein, a short-chain dehydrogenase NaSDR, was identified from Novosphingobium aromaticivorans DSM 12444, which exhibited a high activity in converting β-ionol to β-ionone. A novel biosynthesis route to produce dihydro-β-ionone from β-ionol was developed, by utilizing alcohol dehydrogenase NaSDR and enoate reductase AaDBR1. Under the optimized conditions (0.29 mg/mL NaSDR, 0.39 mg/mL AaDBR1, 1 mM NADP+ and 2.5 mM β-ionol at 40 °C for 2 h), a maximum yield (173.11 mg/L) of dihydro-β-ionone was achieved with a molar conversion rate of 35.6 %, which was 2.7-fold higher than that before optimization. Additionally, this cascade reaction achieved self-sufficient NADPH regeneration through the actions of NaSDR and AaDBR1. This study offered a fresh perspective for achieving a green and sustainable synthesis of dihydro-β-ionone and could inspire on another natural products biosynthesis.

Zwitterionic Polyelectrolyte Complex Vesicles Assembled from Homopoly(2-Oxazoline)s as Enzyme Catalytic Nanoreactors for Potent Anti-Tumor Efficiency.

Enzymes are known for their remarkable catalytic efficiency across a wide range of applications. Here, we present a novel and convenient nanoreactor platform based on zwitterionic polyelectrolyte complex vesicles (PCVs), assembled from oppositely charged homopoly(2-oxazoline)s, facilitating enzyme immobilization. We show remarkable enhancements in catalytic activity and stability by encapsulation of lipase as a model enzyme. Even as the temperature rises, the performance of the lipase remains robust. Further, the structural characteristics of PCVs, including hollow architecture and semipermeable membranes, endow them with unique advantages for enzyme cascade reactions involving glucose oxidase (GOx) and horseradish peroxidase (HRP). A decline in catalytic efficiency is shown when the enzymes are individually loaded and subsequently mixed, in contrast to the coloaded GOx-HRP-PCV group. We demonstrate that the vesicle structures establish confined environments where precise enzyme-substrate interactions facilitate enhanced catalytic efficiency. In addition, the nanoreactors exhibit excellent biocompatibility and efficient anti-tumor activity, which hold significant promise for biomedical applications within enzyme-based technologies.

Boosting of enzymatic cascades by intermediates: Theoretical analysis and model-based optimization

A recent paper demonstrated that adding intermediates of an enzymatic cascade reaction at the start of the reaction process can increase the space-time yield significantly. This method was coined boosting by intermediates (BBI) and can potentially increase the productivity of enzymatic cascade reaction systems. BBI remains largely unexplored, and its mechanism, potential, and limitations are not fully understood. In this short communication, the theoretical background of the method is revealed by studying four chemical reaction networks that exhibit boosting through intermediates. The dynamics of these networks are studied via the quasi-steady state approximation and numerical solutions. A novel graphical method that can be used to deduce which intermediates boost linear, redox-neutral enzymatic cascade reaction networks is presented. Further, how such a reaction process can be designed using model-based optimization is demonstrated.

Applications of Metals and Metal Compounds in Improving the Sensitivity of Microfluidic Biosensors - A Review.

The enhancement of detection sensitivity in microfluidic sensors has been a continuously explored field. Initially, many strategies for sensitivity improvement involved introducing enzyme cascade reactions, but enzyme-based reactions posed challenges in terms of cost, stability, and storage. Therefore, there is an urgent need to explore enzyme-free cascade amplification methods, which are crucial for expanding the application range and improving detection stability. Metal or metal compound nanomaterials have gained great attention in the exploitation of microfluidic sensors due to their ease of preparation, storage, and lower cost. The unique physical properties of metallic nanomaterials, including surface plasmon resonance, surface-enhanced Raman scattering, metal-enhanced fluorescence, and surface-enhanced infrared absorption, contribute significantly to enhancing detection capabilities. The metal-based catalytic nanomaterials, exemplified by Fe3O4 nanoparticles and metal-organic frameworks, are considered viable alternatives to biological enzymes due to their excellent performance. Herein, we provide a detailed overview of the applications of metals and metal compounds in improving the sensitivity of microfluidic biosensors. This review not only highlights the current developments but also critically analyzes the challenges encountered in this field. Furthermore, it outlines potential directions for future research, contributing to the ongoing development of microfluidic biosensors with improved detection sensitivity.

Boosting Microfluidic Enzymatic Cascade Reactions with pH-Responsive Polymersomes by Spatio-Chemical Activity Control.

Microfluidic flow reactors permit the implementation of sensitive biocatalysts in polymeric environments (e.g., hydrogel dots), mimicking nature through the use of diverse microstructures within defined confinements. However, establishing complex hybrid structures to mimic biological processes and functions under continuous flow with optimal utilization of all components involved in the reaction process represents a significant scientific challenge. To achieve spatial, chemical, and temporal control for any microfluidic application, compartmentalization is required, as well as the unification of different sensitive compartments in the reaction chamber for the microfluidic flow design. This study presents a self-regulating microfluidic system fabricated by a sequential photostructuring process with an intermediate chemical process step to realize pH-sensitive hybrid structures for the fabrication of a microfluidic double chamber reactor for controlled enzymatic cascade reaction (ECR). The key point is the adaptation and retention of the function of pH-responsive horseradish peroxidase-loaded polymersomes in a microfluidic chip under continuous flow. ECR is successfully triggered and controlled by an interplay between glucose oxidase-converted glucose, the membrane state of pH-responsive polymersomes, and other parameters (e.g., flow rate and fluid composition). This study establishes a promising noninvasive regulatory platform for extended spatio-chemical control of current and future ECR and other cascade reaction systems.

A pH-dependent shift of redox cofactor specificity in a benzyl alcohol dehydrogenase of aromatoleum aromaticum EbN1

We characterise a reversible bacterial zinc-containing benzyl alcohol dehydrogenase (BaDH) accepting either NAD+ or NADP+ as a redox cofactor. Remarkably, its redox cofactor specificity is pH-dependent with the phosphorylated cofactors favored at lower and the dephospho-forms at higher pH. BaDH also shows different steady-state kinetic behavior with the two cofactor forms. From a structural model, the pH-dependent shift may affect the charge of a histidine in the 2′-phosphate-binding pocket of the redox cofactor binding site. The enzyme is phylogenetically affiliated to a new subbranch of the Zn-containing alcohol dehydrogenases, which share this conserved residue. BaDH appears to have some specificity for its substrate, but also turns over many substituted benzyl alcohol and benzaldehyde variants, as well as compounds containing a conjugated C=C double bond with the aldehyde carbonyl group. However, compounds with an sp3-hybridised C next to the alcohol/aldehyde group are not or only weakly turned over. The enzyme appears to contain a Zn in its catalytic site and a mixture of Zn and Fe in its structural metal-binding site. Moreover, we demonstrate the use of BaDH in an enzyme cascade reaction with an acid-reducing tungsten enzyme to reduce benzoate to benzyl alcohol.Key points•Zn-containing BaDH has activity with either NAD+or NADP+at different pH optima.•BaDH converts a broad range of substrates.•BaDH is used in a cascade reaction for the reduction of benzoate to benzyl alcohol.

P-636 Effects of maternal circadian rhythm changes: intergenerational influences on testicular steroidogenesis in offspring

Abstract Study question Do alterations in the maternal circadian rhythm during pregnancy and lactation result in changes to the male offspring’s testicular steroidogenesis intergenerationally? Summary answer The expression of proteins associated with steroidogenesis is altered due to maternal circadian rhythm changes during pregnancy and lactation periods. What is known already Circadian rhythms impact diverse physiological processes, including reproduction. Several clock genes have been linked to reproductive function. However, there is a complex interaction between hormones, fertility, and the circadian clock. It has been shown that disruption of the circadian clock machinery has negative effects on reproductive biology. Current literature indicates a potential relationship between the circadian clock, testicular steroidogenic-related gene expression profiles, and testosterone synthesis. Steroidogenesis involves a complex cascade of enzymatic reactions. An increasing body of evidence from animal studies suggests a relationship between maternal chronodisruption and long-term offspring health and fertility. Study design, size, duration Male offspring from pregnant Wistar rats (n = 60) were exposed to control (12 hours light/12 hours dark), short day (SD) (8 hours light/16 hours dark), or long day (LD) periods (16 hours light/8 hours dark) during only pregnancy, only lactation, or both periods (n = 6/group) categorized as control, SD pregnancy (SD-P), SD lactation (SD-L), SD pregnancy and lactation (SD-P+L), LD pregnancy (LD-P), LD lactation (LD-L), LD pregnancy and lactation (LD-P+L) groups. Participants/materials, setting, methods The expression of critical components of testicular steroidogenesis, including steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme (cytochrome p450scc), 17-beta hydroxysteroid dehydrogenase 3 (HSD17B3), androgen receptor (AR), and luteinizing hormone receptor (LHR), was analyzed in the testis by counting the percentage of positively-stained Leydig cells and ImageJ analysis of immunohistochemistry and western blot. Serum FSH, LH, and testosterone hormones were measured at four zeitgeber time (ZT) points (ZT0, ZT6, ZT12, and ZT18) using ELISA. Main results and the role of chance All of these testicular steroidogenic enzymes were localized in the Leydig cell, and AR was predominantly observed in the Sertoli cell. Although there are no significant differences between the groups in terms of immunolocalization patterns, the expressions of p450scc and AR proteins were significantly decreased in the SD-P and SD-L groups compared to the control group (p < 0.001). In addition, western blot data indicated a decreased expression of p450scc in the SD-P+L group. However, an increased expression of HSD17B3 was detected in both SD-P+L and LD-P+L groups compared to the control group (p = 0.003, p < 0.001, respectively). Among the steroidogenesis-related proteins evaluated, the protein expression levels of StAR and LHR proteins were not altered. FSH showed a statistically significant increase in the LD-L (ZT0), SD-P+L (ZT12), LD-L (ZT12), and LD-P+L (ZT18) groups when compared to the corresponding control groups at the respective time points (p < 0.05). In contrast, LH levels decreased significantly in the LD-P+L (ZT0) group (p < 0.05). Nevertheless, no statistical difference was determined for testosterone levels between groups. Limitations, reasons for caution Most studies on circadian rhythm have used rodent models. Results from animal models are often informative. However, there is a limitation in the appropriate translation of findings in rodents to human studies. Wider implications of the findings The effects triggered by maternal chronodisruption can be intergenerationally transmitted, potentially affecting offspring health. Our results indicate alterations in the expression of proteins involved in testicular steroidogenesis and time-point-dependent changes in the FSH and LH hormone levels due to maternal circadian rhythm changes, further supporting the potential implications for offspring. Trial registration number This work was supported by research grants from the Scientific and Technological Research Council of Turkey (TUBITAK) (SBAG 219S636) and Akdeniz University, The Scientific Research Projects Coordination Unit (TYL-2018-3580).

Cryptic enzymatic assembly of peptides armed with β-lactone warheads

Nature has evolved biosynthetic pathways to molecules possessing reactive warheads that inspired the development of many therapeutic agents, including penicillin antibiotics. Peptides armed with electrophilic warheads have proven to be particularly effective covalent inhibitors, providing essential antimicrobial, antiviral and anticancer agents. Here we provide a full characterization of the pathways that nature deploys to assemble peptides with β-lactone warheads, which are potent proteasome inhibitors with promising anticancer activity. Warhead assembly involves a three-step cryptic methylation sequence, which is likely required to reduce unfavorable electrostatic interactions during the sterically demanding β-lactonization. Amide-bond synthetase and adenosine triphosphate (ATP)-grasp enzymes couple amino acids to the β-lactone warhead, generating the bioactive peptide products. After reconstituting the entire pathway to β-lactone peptides in vitro, we go on to deliver a diverse range of analogs through enzymatic cascade reactions. Our approach is more efficient and cleaner than the synthetic methods currently used to produce clinically important warhead-containing peptides.

Photoelectrochemical Solution Gated Graphene Field-Effect Transistor Functionalized by Enzymatic Cascade Reaction for Organophosphate Detection.

Solution Gated Graphene Field-Effect Transistors (SGGT) are eagerly anticipated as an amplification platform for fabricating advanced ultra-sensitive sensors, allowing significant modulation of the drain current with minimal gate voltage. However, few studies have focused on light-matter interplay gating control for SGGT. Herein, this challenge is addressed by creating an innovative photoelectrochemical solution-gated graphene field-effect transistor (PEC-SGGT) functionalized with enzyme cascade reactions (ECR) for Organophosphorus (OPs) detection. The ECR system, consisting of acetylcholinesterase (AChE) and CuBTC nanomimetic enzymes, selectively recognizes OPs and forms o-phenylenediamine (oPD) oligomers sediment on the PEC electrode, with layer thickness related to the OPs concentration, demonstrating time-integrated amplification. Under light stimulation, the additional photovoltage generated on the PEC gate electrode is influenced by the oPD oligomers sediment layer, creating a differentiated voltage distribution along the gate path. PEC-SGGT, inherently equipped with built-in amplification circuits, sensitively captures gate voltage changes and delivers output with an impressive thousandfold current gain. The seamless integration of these three amplification modes in this advanced sensor allows a good linear range and highly sensitive detection of OPs, with a detection limit as low as 0.05pm. This work provides a proof-of-concept for the feasibility of light-assisted functionalized gate-controlled PEC-SGGT for small molecule detection.

Multi-compartmentalized electrochemical sensing platforms for monitoring cascade enzymatic reactions

Designing an electrochemical biosensor with the required features is a complex process involving multiple factors. For instance, nanocomposite materials used ensure the adaptation of the sensor to specific parameters on demand. But beyond making more versatile sensors, these materials likely offer excellent sensing platforms to mimic biological processes (e.g. cell communication) on the electrode surface. For this, developed methods are needed to integrate non-conductive nanoreactors for molecular communication into a biocompatible matrix on electrode surfaces with the request of spatially separated and controlled enzyme localization. Here, we present a novel reduced graphene oxide hybrid material to immobilize polymeric nanoreactors supported by an alginate network as a matrix on the electrode surface. The possibility of introducing cascade reactions in an electrochemical biosensor has the advantage of broadening the target substrates as well as their selectivity using enzymes in different nanocompartments (=compartmentalization). The polymeric vesicles allow the loading of enzymes or artificial enzymes, offering active center retention and long-term enzyme stability. Firstly, the inclusion of spatially separated polymeric active nanocompartments into the matrix on the electrode surface is used to monitor a simple enzyme reaction. However, the study’s accomplishment lies in its successful ability to monitor an enzyme cascade reaction, one producing and the other consuming hydrogen peroxide, hosting natural and artificial enzymes. This proof-of-concept generates an important contribution to the design of analytical platforms capable of detecting complex environments or even monitoring communication between cell-like structures, extremely useful for fields such as synthetic biology, biomimetics and advanced biosensors.

Cascaded Nanozyme Based pH-Responsive Oxygenation for Targeted Eradication of Resistant Helicobacter Pylori.

Nanozymes, as substitutes for natural enzymes, are constructed as cascade catalysis systems for biomedical applications due to their inherent catalytic properties, high stability, tunable physicochemical properties, and environmental responsiveness. Herein, a multifunctional nanozyme is reported to initiate cascade enzymatic reactions specific in acidic environments for resistant Helicobacter pylori (H. pylori) targeting eradication. The cobalt-coated Prussian blue analog based FPB-Co-Ch NPs displays oxidase-, superoxide dismutase-, peroxidase-, and catalase- mimicking activities that trigger • and H2O2 to supply O2, thereby killing H. pylori in the stomach. To this end, chitosan is modified on the surface to exert bacterial targeted adhesion and improve the biocompatibility of the composite. In the intestinal environment, the cascade enzymatic activities are significantly inhibited, ensuring the biosafety of the treatment. In vitro, sensitive and resistant strains of H. pylori are cultured and the antibacterial activity is evaluated. In vivo, murine infection models are developed and its success is confirmed by gastric mucosal reculturing, Gram staining, H&E staining, and Giemsa staining. Additionally, the antibacterial capacity, anti-inflammation, repair effects, and biosafety of FPB-Co-Ch NPs are comprehensively investigated. This strategy renders a drug-free approach that specifically targets and kills H. pylori, restoring the damaged gastric mucosa while relieving inflammation.

Rearranging Spin Electrons by Axial-Ligand-Induced Orbital Splitting to Regulate Enzymatic Activity of Single-Atom Nanozyme with Destructive d-π Conjugation.

Most of the nanozymes have been obtained based on trial and error, for which the application is usually compromised by enzymatic activity regulation due to a vague catalytic mechanism. Herein, a hollow axial Mo-Pt single-atom nanozyme (H-MoN5@PtN4/C) is constructed by a two-tier template capture strategy. The axial ligand can induce Mo 4d orbital splitting, leading to a rearrangement of spin electrons (↑ ↑ → ↑↓) to regulate enzymatic activity. This creates catalase-like activity and enhances oxidase-like activity to catalyze cascade enzymatic reactions (H2O2 → O2 → O2•-), which can overcome tumor hypoxia and accumulate cytotoxic superoxide radicals (O2•-). Significantly, H-MoN5@PtN4/C displays destructive d-π conjugation between the metal and substrate to attenuate the restriction of orbitals and electrons. This markedly improves enzymatic performance (catalase-like and oxidase-like activity) of a Mo single atom and peroxidase-like properties of a Pt single atom. Furthermore, the H-MoN5@PtN4/C can deplete overexpressed glutathione (GSH) through a redox reaction, which can avoid consumption of ROS (O2•- and •OH). As a result, H-MoN5@PtN4/C can overcome limitations of a complex tumor microenvironment (TME) for tumor-specific therapy based on TME-activated catalytic activity.

NEDD4 and NEDD4L: Ubiquitin Ligases Closely Related to Digestive Diseases.

Protein ubiquitination is an enzymatic cascade reaction and serves as an important protein post-translational modification (PTM) that is involved in the vast majority of cellular life activities. The key enzyme in the ubiquitination process is E3 ubiquitin ligase (E3), which catalyzes the binding of ubiquitin (Ub) to the protein substrate and influences substrate specificity. In recent years, the relationship between the subfamily of neuron-expressed developmental downregulation 4 (NEDD4), which belongs to the E3 ligase system, and digestive diseases has drawn widespread attention. Numerous studies have shown that NEDD4 and NEDD4L of the NEDD4 family can regulate the digestive function, as well as a series of related physiological and pathological processes, by controlling the subsequent degradation of proteins such as PTEN, c-Myc, and P21, along with substrate ubiquitination. In this article, we reviewed the appropriate functions of NEDD4 and NEDD4L in digestive diseases including cell proliferation, invasion, metastasis, chemotherapeutic drug resistance, and multiple signaling pathways, based on the currently available research evidence for the purpose of providing new ideas for the prevention and treatment of digestive diseases.