Catalytic Function Research Articles

Comparative characterisation of an ecto-5'-nucleotidase (CD73) in non-tumoral MCF10-A breast cells and triple-negative MDA-MB-231 breast cancer cells.

Ecto-5'-nucleotidase (CD73) hydrolyses 5'AMP to adenosine and inorganic phosphate. Breast cancer cells (MDA-MB-231) express high CD73 levels, and this enzyme has been found to play a tumour-promoting role in breast cancer. However, no studies have sought to investigate whether CD73 has differential affinity or substrate preferences between noncancerous and cancerous breast cells. In the present study, we aimed to biochemically characterise ecto-5'-nucleotidase in breast cancer cell lines and assess whether its catalytic function and tumour progression are correlated in breast cancer cells. The results showed that compared to nontumoral breast MCF-10A cells, triple-negative breast cancer MDA-MB-231 cells had a higher ecto-5'-nucleotidase expression leveland enzymatic activity. Although ecto-5'-nucleotidase activity in the MDA-MB-231 cell line showed no selectivity among monophosphorylated substrates, 5'AMP was preferred by the MCF-10A cell line. Compared to the MCF-10A cell line, the MDA-MB-231 cell line has better hydrolytic ability, lower substrate affinity, and high inhibitory potential after treatment with a specific CD73 inhibitor α,β‑methylene ADP (APCP). Therefore, we demonstrated that a specific inhibitor of the ecto-5-nucleotidase significantly reduced the migratory and invasive capacity of MDA-MB-231 cells, suggesting that ecto-5-nucleotidase activity might play an important role in metastatic progression.

Insights into microwave‐promoted synthesis of 3‐methyl‐4‐phenyl‐4,9‐dihydro‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine derivatives catalyzed using new Pd (II),Cu (II),VO (II), and Ag(I) complexes as a heterogeneous catalyst and computational studies

Four novel Pd (II), Cu (II), VO (II), and Ag(I) complexes were prepared from benzimidazole ligand through bidentate chelating mode. Alternative spectral and analytical tools were applied to elucidate their structural and molecular formulae. This study was extended to investigate stability and stoichiometry of complexes in solution, using standard methods. In addition, the best atomic distribution within structural forms was obtained via the density functional theory (DFT) method. This computational study fed us with significant physical characteristics for differentiation. Also, DFT/time‐dependent DFT computations were performed applying (B3LYP/6‐311++G[d,p]/aug‐cc‐pVTZ/aug‐cc‐pVTZ‐PP) level in order to investigate the electronic behavior of the compounds. These results demonstrated good agreement with the experimental data. Computational data discriminate Pd (II) complex by some physical features, which may be promising in the catalytic field. This complex was selected to play a catalytic function to synthesize 3‐methyl‐4‐phenyl‐4,9‐dihydro‐1H‐pyrazolo[3,4‐d][1,2,4]triazolo[1,5‐a]pyrimidine derivatives using microwave irradiation in a one‐pot reaction. The catalyst was selected for this application based on the history of Pd (II) complexes and the properties expected theoretically. A condensation reaction for 3‐methyl‐5‐pyrazolone, aromatic aldehyde, and 5‐aminotetrazole was carried out under mild reaction conditions by microwave irradiation. All reaction conditions were optimized among those variable Lewis acid catalysts in comparison with our new complexes. DOBPAPd catalyst displayed superiority in overall trials with high yield, short time, and green conditions (solvent H2O/EtOH). Also, the recovery of hetero catalyst was succeeded and reused by the same efficiency up to five times after that the efficiency was reduced. The mechanism of action was proposed based on the ability of Pd (II) for adding extra‐bonds over z‐axis and supported by theoretical aspects.

Semi-rational design of nitroarene dioxygenase for catalytic ability toward 2,4-dichloronitrobenzene.

Rieske non-heme dioxygenase family enzymes play an important role in the aerobic biodegradation of nitroaromatic pollutants, but no active dioxygenases are available in nature for initial reactions in the degradation of many refractory pollutants like 2,4-dichloronitrobenzene (24DCNB). Here, we report the engineering of hotspots in 2,3-dichloronitrobenzene dioxygenase from Diaphorobacter sp. strain JS3051, achieved through molecular dynamic simulation analysis and site-directed mutagenesis, with the aim of enhancing its catalytic activity toward 24DCNB. The computationally predicted activity scores were largely consistent with the detected activities in wet experiments. Among them, the two most beneficial mutations (E204M and M248I) were obtained, and the combined mutant reached up to a 62-fold increase in activity toward 24DCNB, generating a single product, 3,5-dichlorocatechol, which is a naturally occurring compound. In silico analysis confirmed that residue 204 affected the substrate preference for meta-substituted nitroarenes, while residue 248 may influence substrate preference by interaction with residue 295. Overall, this study provides a framework for manipulating nitroarene dioxygenases using computational methods to address various nitroarene contamination problems.IMPORTANCEAs a result of human activities, various nitroaromatic pollutants continue to enter the biosphere with poor degradability, and dioxygenation is an important kickoff step to remove toxic nitro-groups and convert them into degradable products. The biodegradation of many nitroarenes has been reported over the decades; however, many others still lack corresponding enzymes to initiate their degradation. Although rieske non-heme dioxygenase family enzymes play extraordinarily important roles in the aerobic biodegradation of various nitroaromatic pollutants, prediction of their substrate specificity is difficult. This work greatly improved the catalytic activity of dioxygenase against 2,4-dichloronitrobenzene by computer-aided semi-rational design, paving a new way for the evolution strategy of nitroarene dioxygenase. This study highlights the potential for using enzyme structure-function information with computational pre-screening methods to rapidly tailor the catalytic functions of enzymes toward poorly biodegradable contaminants.

Synthesis of High-Entropy Perovskite Hydroxides as Bifunctional Electrocatalysts for Oxygen Evolution Reaction and Oxygen Reduction Reaction.

Oxygen reduction reaction (ORR) and oxygen evolutionc reaction (OER) are important chemical reactions for a rechargeable lithium-oxygen battery (LOB). Recently, high-entropy alloys and oxides have attracted much attention because they showed good electrocatalytic performance for oxygen evolution reaction (OER) and/or oxygen reduction reaction (ORR). In this study, we aimed to synthesize and characterize CoSn(OH)6 and two types of high-entropy perovskite hydroxides, that is, (Co0.2Cu0.2Fe0.2Mn0.2Mg0.2)Sn(OH)6 (CCFMMSOH) and (Co0.2Cu0.2Fe0.2Mn0.2Ni0.2)Sn(OH)6 (CCFMNSOH). TEM observation and XRD measurements revealed that the high-entropy hydroxides CCFMMSOH and CCFMNSOH had cubic crystals with sides of approximately 150-200 nm and crystal structures similar to those of perovskite-type CSOH. LSV measurement results showed that the high-entropy hydroxides CCFMMSOH and CCFMNSOH showed bifunctional catalytic functions for the ORR and OER. CCFMNSOH showed better catalytic performance than CCFMMSOH.

Lattice strain induced rapid structural reconstruction of NiCo hydroxide for efficient water oxidation

In the realm of catalysis, the efficiency of nickel-cobalt (NiCo) based catalysts is hampered by the sluggish kinetics of electrochemical reconstruction. The research herein proposes an innovative strategy centered on the induction of lattice strain to surmount this challenge. We successfully engineer lattice strain and distortion within nickel-cobalt hydroxide by the strategic incorporation of iridium. The X-ray absorption spectroscopy, charge density of elements simulation, ultraviolet photoelectron spectra combined with in-situ Raman results demonstrate that the electronic coupling between iridium and nickel-cobalt is enhanced by lattice strain, which narrows the band gap, and then boosts the electrochemical reconstruction of NiCo hydroxide. Furthermore, the in-situ EIS, methanol oxidation reaction, and DFT calculations collectively indicate that lattice strain can expedite the kinetic adsorption and desorption of intermediates during the OER process. The reconstructed voltage and overpotential are reduced by 50 mV and 77 mV after introducing lattice distortion, and a high stability for more than 500 h, respectively. This unique insight into lattice strain modification provides a way to optimize catalytic functions.

Enzyme-Like Catalysis of Vinyl Copolymer Carrying Boron Directly Connected to Backbone: Catalytic Esterification through Cooperation of Boron with Neighboring Carboxylic Anhydride.

Alternating-rich copolymer of vinylboronic acid pinacol ester (VBpin) and maleic anhydride (MAH) was found to catalyze direct dehydrative esterification of carboxylic acid and alcohol. The key to the catalytic function is the activation of the MAH unit by the neighboring Lewis acidic boron directly connected to the backbone through the formation of five-membered ring. The effects of the side-chain cooperation were clarified through comparisons with the polymers having similar structures and a conventional titanium catalyst as well as the analyses of reactions with carboxylic acid or alcohol. The catalytic activity was enhanced as the molecular weight was higher, which is owing to the structural feature that boron is directly attached to the backbone. The cooperative catalysis is of interest because of its conceptual similarity with enzyme.

A photocatalyst coupled amphiphobic membrane with enhanced antifouling and self-regenerating properties for oily aerosol filtration

Oily aerosols as the most adhesive particles in the air can cause irreversible fouling of filters. Amphiphobic surface of filters can to some extent reduce membrane fouling, but complex oil fouling will still adhere to the membrane surface, leading to a decrease in membrane separation performance over long-term use. Herein, a silicon carbide (SiC) membrane with amphiphobic properties and catalytic functions was developed to collaboratively combat pollution. Low surface free energy 1H,1H,2H,2H perfluorooctyltrichlorosilane (FOTS) monomer and TiO2 nanoparticles were individually applied to the SiC membrane. PDMS was utilized to protect the monomer from degradation by the catalyst. The membrane exhibits good anti-adhesion and photocatalysis performance for oily aerosols. The membrane exhibits excellent oily aerosol filtration efficiency (98.6 %) with a comparative low filtration resistance of 6.4 kPa, as well as a high capacity for regeneration. Under UV light, the membrane can degrade oily fouling to recover its amphiphobic property. After 5 cycles of filtration, it still maintains good repeatability for oily matter separation and degradation. This study offers a practical approach to designing a membrane that enables long-term and efficient cleaning of oily aerosols.

Proteogenomic Reprogramming to a Functional Human Totipotent Stem Cell State via a PARP-DUX4 Regulatory Axis.

PARP1 (ARTD1) and Tankyrases (TNKS1/TNKS2; PARP5a/5b) are poly-ADP-ribose polymerases (PARPs) with catalytic and non-catalytic functions that regulate both the genome and proteome during zygotic genome activation (ZGA), totipotent, and pluripotent embryonic stages. Here, we show that primed, conventional human pluripotent stem cells (hPSC) cultured continuously under non-specific TNKS1/TNKS2/PARP1-inhibited chemical naive reversion conditions underwent epigenetic reprogramming to clonal blastomere-like stem cells. TIRN stem cells concurrently expressed hundreds of gene targets of the ZGA-priming pioneer factor DUX4, as well as a panoply of four-cell (4C)-specific (e.g., TPRXL, HOX clusters), eight-cell (8C)-specific (e.g., DUXA, GSC, GATA6), primitive endoderm-specific (e.g., GATA4, SOX17), trophectoderm-specific (e.g., CDX2, TFAP2C), and naive epiblast-specific (e.g., DNMT3L, NANOG, POU5F1(OCT4)) factors; all in a hybrid, combinatorial single-cell manner. Mapping of proteomic and single-cell expressions of TIRN cells against human preimplantation embryo references identified them as relatively homogenous 4C-8C stage populations. Injection of TIRN cells into murine 8C-16C-staged embryos resulted in efficient totipotent-like single cell contributions of human cells to both extra-embryonic (trophectoderm, placenta) and embryonic (neural, fetal liver, hematopoietic) lineages in human-murine blastocyst and fetal chimeras. Pairing of proteome with ubiquitinome analyses of TIRN cells revealed a global shutdown of ADP-ribosylation, and a perturbed TNKS/PARP1 equilibrium which not only impacted the protein levels of hundreds of TNKS/PARP1 substrates via a rewiring of the ubiquitin-proteosome system (UPS), but also de-repressed expression of hundreds of developmental genes associated with PARP1 suppression. ChIP-Seq analysis of core NANOG-SOX2-OCT4 (NSO) pluripotency factors in TIRN cells identified reprogrammed DUX4-accessible distal and cis-regulatory enhancer regions that were co-bound by PARP1 (NSOP). These NSOP enhancer regions possessed co-binding motifs for hundreds of the same ZGA-associated, embryonic, and extraembryonic lineage-specifying pioneer factors (e.g., HOX, FOX, GATA, SOX, TBX, CDX families) that were concurrently co-expressed in TIRN cells; suggesting that PARP1 and DUX4 cooperate with NSO pluripotency core factors to regulate the epigenetic plasticity of a human totipotency program. These findings provide the first demonstration that global, proteome-wide perturbations of post-translational modifications (i.e., ADP-ribosylation, ubiquitination) can regulate epigenetic reprogramming during human embryogenesis. Totipotent TIRN stem cells will provide a valuable cell culture model for studying the proteogenomic regulation of lineage specification from human blastomere stages and may facilitate the efficient generation of human organs in interspecies chimeras.

Sex Differences and Role of Lysyl Oxidase Like 2 (LOXL2) in Angiotensin II-Induced Hypertension in Mice.

Hypertension, a disease with known sexual dimorphism, accelerates aging associated arterial stiffening, in part due to the activation of matrix remodeling caused by increased biomechanical load. In this study, we tested the effect of biological sex and the role of the matrix remodeling enzyme lysyl oxidase like 2 (LOXL2) in hypertension induced arterial stiffening. Angiotensin II (Ang II) was delivered using osmotic pumps in Loxl2+/- and WT male and female mice. Blood pressure and pulse wave velocity (PWV) were measured noninvasively to assess hypertension and aortic stiffness. Wire myography and uniaxial tensile testing were used to test aortic vasoreactivity and mechanical properties. Aortic wall composition was examined by histology and Western blotting. The effect of biomechanical strain on LOXL2 expression and secretion by vascular smooth muscle (VSMC) and endothelial cells (EC) was evaluated by uniaxial cyclic stretching of cultured cells. The role of LOXL2 catalytic function on VSMC alignment in response to mechanical loading was determined with LOXL2 inhibition and knockout. Ang II infusion induced hypertension in WT and Loxl2+/- mice of both sexes and increased PWV in WT males but not in Loxl2+/- males, WT females, or Loxl2+/- females. LOXL2 depletion protected males from Ang II mediated potentiation of vasoconstriction but worsened in females and improved aortic mechanical properties in both sexes. Histological analysis showed increased aortic wall thickness in hypertensive WT males but not females and increased intralamellar distance in both sexes, that was ameliorated in Loxl2+/- mice. Western blotting revealed increased collagen I, decreased collagen IV, and increased LOXL2 accumulation and processing in hypertensive mice. Hypertensive cyclic strain contributed to LOXL2 upregulation in the cell-derived matrix in VSMCs but not ECs. LOXL2 catalytic function facilitated VSMC alignment in response to biomechanical strain. In males, arterial stiffening in hypertension is driven both by VSMC response and matrix remodeling. Females exhibit a delayed onset of Ang II-induced hypertension with minimal ECM remodeling but with VSMC dysfunction. LOXL2 depletion ameliorates arterial stiffening and preserves functional contractility and aortic structure in male hypertensive mice. LOXL2 depletion improves aortic mechanics but worsens aortic contractility in hypertensive females. VSMCs are the primary source of LOXL2 in the aorta and hypertension increases LOXL2 processing and shifts to collagen I accumulation. Overall, LOXL2 depletion offers protection in young hypertensive males and females.

Control of Geometric Structure and Catalytic Function of Platinum-Containing Polymers Linked with Bidentate Phosphine Ligands

Control of Geometric Structure and Catalytic Function of Platinum-Containing Polymers Linked with Bidentate Phosphine Ligands

Distinct small RNAs are expressed at different stages of Phytophthora capsici and play important roles in development and pathogenesis.

Small RNAs (sRNAs) are important non-coding RNA regulators that play key roles in the development and pathogenesis of plant pathogens, as well as in other biological processes. However, whether these abundant and varying sRNAs are involved in Phytophthora development or infection remains enigmatic. In this study, sRNA sequencing of 4 asexual stages of Phytophthora capsici (P. capsici), namely, as mycelia (HY), sporangia (SP), zoospores (ZO), cysts (CY), and pepper infected with P. capsici (IN), were performed, followed by sRNA analysis, microRNA (miRNA) identification, and miRNA target prediction. sRNAs were mainly distributed at 25-26nt in HY, SP, and ZO but distributed at 18-34nt in CY and IN. 92, 42, 176, 39, and 148 known miRNAs and 15, 19, 54, 13, and 1 novel miRNA were identified in HY, SP, ZO, CY, and IN, respectively. It was found that the expression profiles of known miRNAs vary greatly at different stages and could be divided into 4 categories. Novel miRNAs mostly belong to part I. Gene ontology (GO) analysis of known miRNA-targeting genes showed that they are involved in the catalytic activity pathway, binding function, and other biological processes. Kyoto Encyclopedia of Gene and Genome (KEGG) analysis of novel miRNA-targeting genes showed that they are involved in the lysine degradation pathway. The expression of candidate miRNAs was validated using quantitative reverse transcription-polymerase chain reaction (qRT-PCR), and miRNAs were downregulated in PcDCL1 or PcAGO1 mutants. To further explore the function of the detected miRNAs, the precursor of a novel miRNA, miR91, was knockout by CRISPR-Cas9, the mutants displayed decreased mycelial growth, sporangia production, and zoospore production. It was found that 503142 (Inositol polyphosphate 5-phosphatase and related proteins) can be predicted as a target of miR91, and the interaction between miR91 and 503142 was verified using the tobacco transient expression system. Overall, our results indicate that the diverse and differentially expressed sRNAs are involved in the development and pathogenesis of P. capsici.

Photocatalytic activity of ZnO doped Nano hydroxyapatite/GO derived from waste oyster shells for removal of Methylene blue.

Hydroxyapatite (HAp) stands as an inorganic compound, recognized as a non-toxic, bioactive ceramic, and its composition closely resembles that of bone material. In this study, nHAp was prepared from waste oyster shells, which are biowaste rich in calcium carbonate. nHAp with its unique catalytic property can be used as an adsorbent in various fields, including wastewater treatment. nHAp with an exceptional surface adsorbent with excellent chemical stability, enabling its catalytic function. Nano hydroxyapatite doped with Zinc oxide (ZnO) by wet chemical precipitation and made into a composite with Graphene oxide (GO) by modified hummers method followed by grinding, which was taken as 9:1 ratio (nHAp/ZnO and GO) of weight, enhances its tensile and mechanical strength. The energy band gap of nHAp photocatalyst was evaluated as 3.39eV and that of the in nHAp/ZnO/GO photocatalyst was narrowed to 1.77eV. The ternary nanocomposites are very efficient in generating the photogenerated electrons and holes, thereby improving the degradation potential of dye effluents to by-products such as CO2 and H2O. The nanocomposites photocatalyst were characterized by FTIR, XRD, SEM, TEM, EDS, XPS, DRS, and BET techniques. The UV-visible study shows the complete dye degradation efficiency of the prepared nanocomposites photocatalyst. In this study, the prepared nanocomposites nHAp/ZnO/GO have studied their efficiency for the removal of MB dye in a batch process by varying the dosage from 0.1 to 0.5g, and the effects of dosage variations, pH, kinetic, scavenger study were evaluated at a time interval of 30min. The removal of dye was found to be 99% at 150min of 0.3g dosage and pH = 12 is most favorable as it reached the same percentage at 90min. The as-prepared nanocomposite nHAp/ZnO/GO fits the kinetic rate constant equation and shows a pseudo-first-order reaction model. This study indicates the suitability for dye removal due to the synergistic effect and electrostatic interaction of the synthesized ternary nanocomposite, which shows the potential, socially active, low-cost-effective, eco-friendly, and safe for photocatalytic degradation of MB from wastewater.

A new di-recognition and di-functional nanosurface aptamer molecularly imprinted polymer probe for trace glyphosate with SERS/RRS/Abs trimode technique

A new di-recognition nitrogen-doped carbon dot nanosurface aptamer molecularly imprinted polymer (CDNAg@MIPApt) nanocatalytic di-functional probe was prepared by microwave irradiation. The probe was utilized nitrogen-doped silver carbon dots (CDNAg) as the matrix, glyphosate (Gly) as the template molecule, α-methyl acrylate as the monomer, ethylene glycol dimethacrylate as the cross-linker, and aptamer as the biorecognition element. It could not only recognize Gly but also exhibits catalytic amplification function. It was found that CDNAg@MIPApt catalyzed the redox reaction of polyethylene glycol 400 (PEG400)-AgNO3 to generate silver nanoparticles (AgNPs). The AgNPs indicator component exhibit the effects of surface-enhanced Raman scattering (SERS), resonance Rayleigh scattering (RRS) and surface plasmon resonance absorption (Abs). In the presence of Gly, it binds to the surface imprinted site of CDNAg@MIPApt, to reduce AgNPs generation due to the catalytic activity of CDNAg@MIPApt decreasing. Thus, the SERS/RRS/Abs signal values decreased linearly. The linear ranges of SERS/RRS/Abs assay were 0.1–2.5 nM, 0.25–2.75 nM and 0.5–5 nM respectively. The detection limits were 0.034 nM, 0.071 nM and 0.18 nM Gly.

Identification and characterization of FBA genes in moso bamboo reveals PeFBA8 related to photosynthetic carbon metabolism

Fructose 1,6-bisphosphate aldolase (FBA) is a pivotal enzyme, which plays a critical role in fixing CO2 through the process of in the Calvin cycle. In this study, a comprehensive exploration of the FBA family genes in moso bamboo (Phyllostachys edulis) was conducted by the bioinformatics and biological analyses. A total of nine FBA genes (PeFBA1-PeFBA9) were identified in the moso bamboo genome. The expression patterns of PeFBAs across diverse tissues of moso bamboo suggested that they have multifaceted functionality. Notably, PeFBA8 might play an important role in regulating photosynthetic carbon metabolism. Co-expression and cis-element analyses demonstrated that PeFBA8 was regulated by a photosynthetic regulatory transcription factor (PeGLK1), which was confirmed by yeast one-hybrid and dual-luciferase assays. In-planta gene editing analysis revealed that the edited PeFBA8 mutants displayed compromised photosynthetic functionality, characterized by reduced electron transport rate and impaired photosystem I, leading to decreased photosynthesis rate overall, compared to the unedited control. The recombinant protein of PeFBA8 from prokaryotic expression exhibited enzymatic catalytic function. The findings suggest that the expression of PeFBA8 can affect photosynthetic efficiency of moso bamboo leaves, which underlines the potential of leveraging PeFBA8's regulatory mechanism to breed bamboo varieties with enhanced carbon fixation capability.

Polyelectrolyte multilayer catalysts in electrospun bipolar membranes

Here we utilize the layer-by-layer (LbL) technique to homogenously integrate polyelectrolyte (PE) multilayers with multiple different catalytic functionalities inside an electrospun BPM without forming an electrically and/or ionically non-conductive catalyst layer. BPMs were fabricated by coating an electrospun cation exchange layer alternately with polyethyleneimine (PEI)-poly (acrylic acid) (PAA), followed by hot-pressing between pristine electrospun anion and cation exchange layers. This resulted in a BPM having a thin entangled 3D junction with high surface area and well-integrated catalysts. Optical reflectometry shows that the amount of PE catalysts inside the BPM can be controlled by tuning coating parameters such as the amount of bilayers and the ionic strength of the coating solution, where especially a higher ionic strength resulted in a significantly higher mass adsorption. The BPMs coated at higher ionic strength (500 mM NaCl) showed the lowest water dissociation potential of 0.84 V. Furthermore, it was found that incorporating the PE multilayers diminished the effect of the electric field and that the catalytic activity becomes more dominant in facilitating the water dissociation reaction. The advantage of creating a 3D junction using electrospinning in combination with the versatility of the LbL deposition technique allows for further optimization to create high performance BPMs that can be tailored to specific applications.

Redox dynamics and surface structures of an active palladium catalyst during methane oxidation

Catalysts based on palladium are among the most effective in the complete oxidation of methane. Despite extensive studies and notable advances, the nature of their catalytically active species and conceivable structural dynamics remains only partially understood. Here, we combine operando transmission electron microscopy (TEM) with near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) and density functional theory (DFT) calculations to investigate the active state and catalytic function of Pd nanoparticles (NPs) under methane oxidation conditions. We show that the particle size, phase composition and dynamics respond appreciably to changes in the gas-phase chemical potential. In combination with mass spectrometry (MS) conducted simultaneously with in situ observations, we uncover that the catalytically active state exhibits phase coexistence and oscillatory phase transitions between Pd and PdO. Aided by DFT calculations, we provide a rationale for the observed redox dynamics and demonstrate that the emergence of catalytic activity is related to the dynamic interplay between coexisting phases, with the resulting strained PdO having more favorable energetics for methane oxidation.

ArPAOs from A. roxburghii showed essential roles in polyamine mediating water stress tolerance

Anoectochilus roxburghii is a precious Chinese herb with excellent pharmacological effects. When meet stress, plants produced polyamines (PAs) which are identified in active tissues and play crucial roles in stress responses. Nevertheless, the molecular mechanism of PAs responding to stress in A. roxburghii were largely unknown. Here, for the first time, three PAOs in A. roxburghii were identified from transcriptome data and functionally analyzed. Expression analysis was performed using fluorescence quantitative PCR and eventually, transgenic Arabidopsis thaliana were created to confirm the biological function of ArPAOs. It was found that the highest expression was in young flower buds and the expression levels of three ArPAO genes in various tissues were also different, which indicated their different catalytic preferences and functions. Under the treatment of exogenous spermine and spermidine, the expression of three ArPAOs fluctuated and the overall expression level increased. Overexpression (OE) of ArPAOs could enhance water stress tolerance through mediating polyamine catabolism. It might because the excessive expression of ArPAOs reduce the content of spermine and spermidine, creating a negative feedback regulation upstream and causes plants manufacturing PAs which reinforce water stress tolerance. Taken together, the study firstly reported the overexpression of ArPAOs enhance plant water stress tolerance and regulate the content of polyamines. This work will provide a vital theoretical foundation for uncovering the operation and regulatory mechanism of ArPAOs in promoting plant development and managing stress.

Synthesis of a Family of Pd(II) Complexes Using Pyridyl-Ketone Ligands: Crystal Structure, Thermal, Physicochemical, XRD/HSA, Docking, and Heck Reaction Application.

Four Pd(II) complexes, (dpk)PdCl2 (complex-1), and (dpk)Pd(OAc)2 (complex-2) have been prepared using di(2-pyridyl) ketone as the chelate ligand (dpk). The (dpk·EtOH)PdCl2 (complex-3) and (dpk·EtOH)Pd(OAc)2 (complex-4) were synthesized by selectively introducing complex-1 and complex-2 to an EtOH in situ nucleophilic addition reaction on the O=C of the dpk ligand, respectively. All complexes were characterized using CHN-EA, UV-vis, FT-IR, FAB-MS, EDX, TGA, and NMR physicochemical tools. The XRD-crystallography technique was employed to ascertain the structure of complex-3. The analysis revealed a monoclinic/P21/c crystal system characterized by a square planar structure oriented in the cis direction around the Pd center. Several C-H···Cl and O-H···O H-bonds constructing 2D-S12 and S7 synthons were confirmed via XRD/HSA interactions. The influence of EtOH addition to the O=C group of dpk in (dpk)PdCl2 was documented by using UV-vis/FT-IR spectra and TGA analysis. As catalysts, all complexes have demonstrated a notable catalytic function in the Heck reaction, resulting in a high yield under gentle conditions using iodobenzene and methyl acrylate as model reactions. Moreover, the complex-1 and complex-3 docking activity was evaluated against 1BNA-DNA.

Enzymatization of mouse monoclonal antibodies to the corresponding catalytic antibodies

Catalytic antibodies possess a dual function that enables both antigen recognition and degradation. However, their time-consuming preparation is a significant drawback. This study developed a new method for quickly converting mice monoclonal antibodies into catalytic antibodies using site-directed mutagenesis. Three mice type monoclonal antibodies targeting hemagglutinin molecule of influenza A virus could be transformed into the catalytic antibodies by deleting Pro95 in CDR-3 of the light chain. No catalytic activity was observed for monoclonal antibodies and light chains. In contrast, the Pro95-deleted light chains exhibited a catalytic activity to cleave the antigenic peptide including the portion of conserved region of hemagglutinin molecule. The affinity of the Pro95-deleted light chains to the antigen increased approximately 100-fold compared to the wild-type light chains. In the mutants, three residues (Asp1, Ser92, and His93) come closer to the appropriate position to create the catalytic site and contributing to the enhancement of both catalytic function and immunoreactivity. Notably, the Pro95-deleted catalytic light chains could suppress influenza virus infection in vitro assay, whereas the parent antibody and the light chain did not. This strategy offers a rapid and efficient way to create catalytic antibodies from existing antibodies, accelerating the development for various applications in diagnostic and therapeutic applications.

Michaelis-like complex of mouse ketohexokinase isoform C.

Over the past forty years there has been a drastic increase in fructose-related diseases, including obesity, heart disease and diabetes. Ketohexokinase (KHK), the first enzyme in the liver fructolysis pathway, catalyzes the ATP-dependent phosphorylation of fructose to fructose 1-phosphate. Understanding the role of KHK in disease-related processes is crucial for the management and prevention of this growing epidemic. Molecular insight into the structure-function relationship in ligand binding and catalysis by KHK is needed for the design of therapeutic inhibitory ligands. Ketohexokinase has two isoforms: ketohexokinase A (KHK-A) is produced ubiquitously at low levels, whereas ketohexokinase C (KHK-C) is found at much higher levels, specifically in the liver, kidneys and intestines. Structures of the unliganded and liganded human isoforms KHK-A and KHK-C are known, as well as structures of unliganded and inhibitor-bound mouse KHK-C (mKHK-C), which shares 90% sequence identity with human KHK-C. Here, a high-resolution X-ray crystal structure of mKHK-C refined to 1.79 Å resolution is presented. The structure was determined in a complex with both the substrate fructose and the product of catalysis, ADP, providing a view of the Michaelis-like complex of the mouse ortholog. Comparison to unliganded structures suggests that KHK undergoes a conformational change upon binding of substrates that places the enzyme in a catalytically competent form in which the β-sheet domain from one subunit rotates by 16.2°, acting as a lid for the opposing active site. Similar kinetic parameters were calculated for the mouse and human enzymes and indicate that mice may be a suitable animal model for the study of fructose-related diseases. Knowledge of the similarity between the mouse and human enzymes is important for understanding preclinical efforts towards targeting this enzyme, and this ground-state, Michaelis-like complex suggests that a conformational change plays a role in the catalytic function of KHK-C.