Active Metal Ions Research Articles

Interference of metal ions on the bioluminescent signal of firefly, Renilla, and NanoLuc luciferases in high-throughput screening assays

Bioluminescent high-throughput screening (HTS) assays, based largely on the activity of firefly (FLuc), Renilla (RLuc), and/or NanoLuc (NLuc) luciferases, are widely utilised in research and drug discovery. In this study, we quantify the luciferase-based real-life HTS assay interference from biologically and environmentally relevant metal ions ubiquitously present in buffers, environmental and biological matrices, and as contaminants in plastics and compound libraries. We also provide insights into the cross-effects of metal ions and other key experimental and biological reagents (e.g., buffer types, EDTA, and glutathione) to inform HTS assay design, validation, and data interpretation. A total of 21 ions were screened in three robust HTS assays (“SC” assays) based on the luminescence of FLuc, RLuc, and NLuc luciferases. Three newly optimised HEPES buffer variants (“H” assays) were developed for direct luciferase comparison. Interference in bioluminescent signal generation was quantified by calculating the IC50 values from concentration-dependent experiments for selected highly active and relevant metal ions. Metal ion inhibition mechanisms were probed by variations in specific reagents, EDTA, GSH, and the sequence of addition and buffer composition. In this study, we revealed a significant impact of metal ions’ salts on luciferase-mediated bioluminescence, even at biologically and environmentally relevant concentrations. The extent of signal interference largely aligned with the Irving–Williams series of metal ion–ligand affinities (Cu > Zn > Fe > Mn > Ca > Mg), supporting previous reports on metal ion-dependent FLuc inhibition. However, the absolute magnitude and relative extent of signal reduction by metal ions’ salts differed between SC and H assays and between luciferases, suggesting a complex network of metal ions’ interactions with enzymes, substrates, reactants, and buffer elements. The diversity of the tested conditions and variability of responses provided insights into potential interference mechanisms and synergies that may exacerbate or alleviate interference. The beneficial influence of EDTA and the impact of glutathione, present natively in cells, on bioluminescence readout were pinpointed. Given the ubiquity of metal ions in analysed samples, the causative role in false-positive generation in drug discovery, and the wide breadth of luciferase-based assays used in screening, awareness and quantification of metal influence are crucial for developing assay validation protocols and ensuring reliable screening data, ultimately increasing the critical robustness of bioluminescence-based HTS assays.

DFT Study on the Interaction Between Flotation Agents and Lepidolite-1M Surfaces

The surface chemical properties of Lepidolite-1M crystals are closely related to their flotation properties. This paper uses density functional theory (DFT) to analyze the band structure, population, and state density of ideal Lepidolite-1M crystals. The results show that lepidolite-1M is an insulator, and its most probable positively charged active site is Al, and its negatively charged active sites are O and F. To further investigate the adsorption mechanism of Lepidolite-1M during comminution and flotation processes, we calculated the surface energy, population, state density, and differential charge density of its most common (001) surface. The results show that its surface energy is 0.9934 J/m2, occurred in the valence electron configurations, population values, and bond lengths of the surface atoms. Furthermore, oxygen atoms on the (001) surface showed different activities, with F and O atoms in the lithium-rich region showing significant electron enrichment. Overall, our results demonstrated that anion collectors react mainly with the Al sites on the surface of Lepidolite-1M, and the cationic collectors and metal ion activators can be adsorbed on the surface of Lepidolite-1M to produce better trapping and activation capabilities.

Exiguolysin, a Novel Thermolysin (M4) Peptidase from Exiguobacterium oxidotolerans.

This study details a comprehensive biochemical and structural characterization of exiguolysin, a novel thermolysin-like, caseinolytic peptidase secreted by a marine isolate of Exiguobacterium oxidotolerans strain BW26. Exiguolysin demonstrated optimal proteolytic activity at 37 °C and pH 3, retaining 85% activity at 50 °C, highlighting its potential stability under broad reaction conditions. SDS-PAGE and LC-MS analysis identified the enzyme as a 32 kDa M4-family metalloprotease. Exiguolysin activity was inhibited by 1,10-phenanthroline, confirming its dependence on metal ions for activity. Zymographic analysis and substrate specificity assays revealed selective hydrolysis of matrix metalloproteinase (MMP) substrates but no activity against elastase substrates. Analysis of the predicted gene sequence and structural predictions using AlphaFold identified the presence and position of HEXXH and Glu-Xaa-Xaa-Xaa-Asp motifs, crucial for zinc binding and catalytic activity, characteristic of 'Glu-zincins' and members of the M4 peptidase family. High-throughput screening of a 20 × 20 N-alpha mercaptoamide dipeptide inhibitor library against exiguolysin identified SH-CH2-CO-Met-Tyr-NH2 as the most potent inhibitor, with a Ki of 1.95 μM. Notably, exiguolysin selectively inhibited thrombin-induced PAR-1 activation in PC-3 cells, potentially indicating a potential mechanism of virulence in modulating PAR-1 signalling during infection by disarming PARs. This is the first detailed characterization of a peptidase of the M4 (thermolysin) family in the genus Exiguobacterium which may have industrial application potential and relevance as a putative virulence factor.

“On-demand” nanosystem-integrated microneedles for amplified triple therapy against recalcitrant bacteria and biofilm growth

Phototherapy has emerged to eradicate recalcitrant bacteria without causing drug resistance, but it is often accompanied by considerable limitations owing to a high tolerance of recalcitrant bacteria to heat and oxidative damage, leading to low efficiency of monotherapy and unwanted side effects. Assuming that employing antimicrobial peptides (AMPs) to disrupt bacterial membranes could reduce bacterial tolerance, a multifunctional “on-demand” nanosystem based on zeolitic imidazolate framework-8 (ZIF-8) with metal ions for intrinsic antibacterial activity was constructed to potently kill methicillin-resistant Staphylococcus aureus (MRSA). Then, microneedles (MNs) were used to transdermally deliver the ZIF-8-based nanosystem for localized skin infection. After MNs insertion, the nanoplatform could specifically deliver the loaded therapeutic components to bacterial infection sites through employing hyaluronic acid (HA) as a capping agent, thus realizing the “on-demand” payload release triggered by excess hyaluronidase secreted by MRSA. The prepared nanosystem and MNs were confirmed to exert an amplified triple therapy originating from membranolytic effect, phototherapy, and ion therapy, thus displaying a powerful bactericidal and MRSA biofilm destruction ability. This intelligent antimicrobial strategy may bring a dawn of hope for eradicating multidrug-resistant bacteria and biofilms.

Bispidine-based Ligands as Bifunctional Chelators for Radiopharmaceuticals

Abstract: Novel bispidine skeleton has been extensively designed as bifunctional chelators (BFCs) for their special stereochemical structure and variable dentate numbers. Bispidine-based ligands (BBLs) as BFCs generally integrate the benefits of conventional acyclic and macrocyclic BFCs, demonstrating exceptional radiolabeling kinetics, thermodynamic stability and kinetic inertness for their metal complexes. The accessible inherent spatial asymmetry in bispidine skeleton is well-suited for Jahn-Teller active metal ions, notably Cu(II). Currently, BBLs have already been studied to coordinate with radionuclides such as 52Mn, 64/67Cu, 68Ga, 111In, 133La, 177Lu, 212Pb, 212/213Bi, and 225Ac for radiopharmaceuticals application. Among them, the 64Cu, 52Mn, 111In, 177Lu, and 225Ac complexes with BBLs have particularly made significant research progress. In this review, we introduce the synthesis of BBLs and their applications in chelating the above five metallic radionuclides for the development of radiopharmaceuticals are discussed.

Self-Assembly-Activated Engineered Magnetic Biohybrids Loaded with Phosphotriesterase for Sustainable Decontamination and Detection of Organophosphorus Pesticides.

Phosphotriesterase (PTE) biodegradation of organophosphorus pesticides (OPs) is an efficient and environmentally friendly method. However, the instability and nonreusability of free PTE become the key factors restricting its practical application. In this study, a novel cross-linked magnetic hybrid nanoflower (CLMNF) was prepared. Molecular dynamics (MD) simulations were performed to further investigate the enhanced catalytic efficiency of the enzymes. The recovery rate of enzyme activity was 298% due to the large specific surface area and metal ion activation effect. More importantly, the immobilization scheme greatly improved the stability and reuse performance of the catalyst and simplified the recovery operation. CLMNFs retained 90.32% relative activity after 5 consecutive cycles and maintained 84.8% relative activity after 30 days at 25 °C. It has a good practical application prospect in the degradation and detection of OPs. Consequently, the immobilized enzyme as a biocatalyst has the characteristics of high efficiency, stability, safety, and easy separation, establishing the key step in a biodetoxification system to control organophosphorus contamination in food and the environment.

Mn2+ activated Boroaluminosilicate glass-ceramics with Al4B2O9 nanocrystals for tunable Emission

Mullite-type glass ceramics (GCs) are a promising solid-state luminescence matrix material due to their excellent stability and abundant Al-O polyhedral structural units for accommodating active transition metal ions. In this work, Mn2+ activated Al4B2O9 GCs were prepared by the melt-quenching method and subsequent heat treatment. Our results show that the prepared GC samples exhibit four different luminescence peaks under 360 nm excitation, corresponding to the Mn2+ ions located at [AlO4] and [AlO6] coordination sites of Al4B2O9 grains and glass matrix. Both the concentration of Mn2+ and crystallinity of Al4B2O9 crystals affect the emission spectra of the GC. The obtained GCs with good resistance for thermally induced luminescence quenching and moisture tolerance could be used in customizing LEDs with tunable emission characateritics.

Study on the mechanism of different metal ions synergistic with alkali etching treatment in the flotation of lepidolite and feldspar

The two minerals were separated through alkali etching on the surface of lepidolite and feldspar, in conjunction with metal ion activation flotation. The activation of calcium (Ca2+) ion, magnesium (Mg2+) ion, copper (Cu2+) ion, and ferric (Fe3+) ion under alkali and non-alkali corrosion conditions was investigated, respectively. Micro-flotation experiments demonstrate that Ca2+ and Mg2+ can selectively recover lepidolite but not feldspar when the pH is above 6.5 during alkali etching. The activation of Cu2+ and Fe3+ flotation is not selective and can activate lepidolite and feldspar to some extent, irrespective of alkali etching. Through the valence bond theory, the selectivity of lepidolite and feldspar to dissolve and break bonds under alkali etching in a solution system was calculated. The adsorption differences and mechanisms of four types of metal ions were analyzed using solution chemistry, particle size analysis, and X-ray photoelectron spectroscopy (XPS) detections.

Cytoplasmic binding partners of the Integrator endonuclease INTS11 and its paralog CPSF73 are required for their nuclear function

INTS11 and CPSF73 are metal-dependent endonucleases for Integrator and pre-mRNA 3'-end processing, respectively. Here, we show that the INTS11 binding partner BRAT1/CG7044, a factor important for neuronal fitness, stabilizes INTS11 in the cytoplasm and is required for Integrator function in the nucleus. Loss of BRAT1 in neural organoids leads to transcriptomic disruption and precocious expression of neurogenesis-driving transcription factors. The structures of the human INTS9-INTS11-BRAT1 and Drosophila dIntS11-CG7044 complexes reveal that the conserved C terminus of BRAT1/CG7044 is captured in the active site of INTS11, with a cysteine residue directly coordinating the metal ions. Inspired by these observations, we find that UBE3D is a binding partner for CPSF73, and UBE3D likely also uses a conserved cysteine residue to directly coordinate the active site metal ions. Our studies have revealed binding partners for INTS11 and CPSF73 that behave like cytoplasmic chaperones with a conserved impact on the nuclear functions of these enzymes.

Kwaśna modyfikacja gruzińskiego heulandytu naturalnego

Acid treatment is a powerful tool for improving the performance of natural zeolites, and the purpose of our work was to study chemical composition, structure and properties of acid-treated heulandite from the Tedzami-Dzegvi deposit. Samples of heulandite-containing tuff from the Rkoni plot with zeolite phase content up to 90%, consisting of heulandite and chabazite in a ratio of 8:1, and having chemical composition described by empirical formula |Na0.25K0.06Ca0.19Mg0.15)|[AlSi3.6O9.2].3H2O were treated with hydrochloric acid solutions with concentration up to 2.0 N. It was established that acid treatment leads to significant dealumination (the molar ratio of Si/Al increases from 3.6 to 9.5) and decationization (the total charge per aluminium atom decreases from 1 to 0.68), sodium and magnesium are mainly leached, calcium and potassium does not take part in the decationization process. Powder X-ray diffraction patterns show that hydrochloric acid solutions with a concentration up to 2.0 N do not lead to amorphization of the zeolite microporous crystal structure, but can gradually dissolve it. The adsorption of water vapor indicates the availability of micropores for the entry of small polar molecules, benzene adsorption shows a slight increase of hydrophobicity of the surface as a result of acid treatment. Nitrogen adsorption-desorption isotherms show acid-mediated sharp increase of adsorption in micropores and of the surface area, as well as changes in the mesoporous system, leading to the prevalence of pores with a diameter of 3 – 10 nm. The concentration of dilute solutions of hydrochloric acid is determined, which provides availability of micropores for large ions and nonpolar molecules, but at which dealumination is insignificant and ion-exchange capacity remains at a sufficient level. Materials obtained by acid treatment of heulandite can be used as adsorbents, ion exchangers, and carriers of biologically active substances and metal ions.

UV-metal ion synergistic activation of ferrate(VI) for the degradation of dimethoate

The improvement in the degradation efficiency of dimethoate was achieved through the activation of UV light and metal ions. The study found that Fe(VI) was effectively activated by Cu(II), Fe(III), and Fe(II), resulting in an improved removal rate of dimethoate in water, with the activation efficiency of Cu(II) > Fe(III) > Fe(II). Under UV irradiation, the synergistic activation effects of UV-Cu(II) and UV-Fe(III) were most pronounced and positively correlated with light intensity. The mineralization rate of dimethoate by UV-Fe(III)-Fe(VI) reached up to 37 %, significantly outperforming the Cu(II)-Fe(VI) system. The main active species in the Cu(II)-Fe(VI) and Fe(III)-Fe(VI) systems were Cu(III) and Fe(IV)/Fe(V), while those in the UV-Fe(III)-Fe(VI) were ·OH and ·O2- radicals, respectively. In the UV-metal ions activated Fe (VI) system, the main degradation mechanisms of dimethoate were hydrolysis, cleavage, oxidation, and recombination. The impacts of water quality parameters on degradation efficiency were also investigated, finding that Cl- had almost no effect, while SO42- had a slight repression effect, and HCO3-, CO32- and NO2- exhibited strong inhibitory effects. Finally, the promising application of the UV-metal ion-Fe(VI) system in actual water environments was proposed, achieving effective removal with minimal environmental risks.

Synthesis, characterization and antimicrobial analysis of metal-doped (Zn2+ and Ag+) brushite powder for bone regeneration

Brushite, or Dicalcium phosphate dihydrate (CaHPO4·2H2O), is a well-known calcium phosphate (CaP) found in mineralized tissues and is utilized in medical treatment, particularly in bone powder for bone repair. Brushites with Zn2+ and Ag + ions concentration were synthesized in an aqueous solution using the conventional precipitation procedure. The synthesized brushites were characterized using techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Powder X-ray diffraction (PXRD), Scanning Electron Microscopy (SEM), and bioassays were carried out to evaluate their antibacterial and antifungal activities. The alterations in PXRD and FTIR peak locations demonstrated that zinc and silver ions were effectively inserted into the brushite crystals. Initial tests revealed that the powders were innocuous, which make them potentially beneficial for mineralized tissue engineering. These brushites exhibited remarkable antimicrobial activities. Zn-doped brushite completely controlled the growth of fungi namely Macrophomina phaseolina and Sclerotium rolfsii at a concentration of 0.0039 mg mL−1 while Ag-doped brushite completely arrested the growth of these fungi at 0.0312 and 0.0039 mg mL−1, respectively. Likewise, both the brushite exhibited remarkable antibacterial activity against Bacillus thuringiensis and moderate activity against Escherichia coli. Brushite compounds coupled with active metal ions, notably Ag+ and Zn2+, demonstrated promise as a distinct class of reactive materials for bone-related applications.

Identification of RNF213 as a Potential Suppressor of Local Invasion in Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is a lethal cancer with poor survival especially when it spreads. The histopathology of its rare intraductal papillary neoplasm of the bile duct type (IPNB) characteristically shows cancer cells originating within the confined bile duct space. These cells eventually invade and infiltrate the nearby liver tissues, making it a good model to study the mechanism of local invasion, which is the earliest step of metastasis. To discover potential suppressor genes of local invasion in ICC, we analyzed the somatic mutation profiles and performed clonal evolution analyses of the 11 pairs of macrodissected locally invasive IPNB tissues (LI-IPNB) and IPNB tissues without local invasion from the same patients. We identified a protein-truncating variant in an E3 ubiquitin ligase, RNF213 (c.6967C>T; p.Gln2323X; chr17: 78,319,102 [hg19], exon 29), as the most common protein-truncating variant event in LI-IPNB samples (4/11 patients). Knockdown of RNF213 in HuCCT1 and YSCCC cells showed increased migration and invasion, and reduced vasculogenic mimicry but maintained normal proliferation. Transcriptomic analysis of the RNF213-knockdown vs control cells was then performed in the HuCCT1, YSCCC, and KKU-100 cells. Gene ontology enrichment analysis of the common differentially expressed genes revealed significantly altered cytokine and oxidoreductase-oxidizing metal ion activities, as confirmed by Western blotting. Gene Set Enrichment Analysis identified the most enriched pathways being oxidative phosphorylation, fatty acid metabolism, reactive oxygen species, adipogenesis, and angiogenesis. In sum, loss-of-function mutation of RNF213 is a common genetic alteration in LI-IPNB tissues. RNF213 knockdown leads to increased migration and invasion of ICC cells, potentially through malfunctions of the pathways related to inflammation and energy metabolisms.

Nontraditional Roles of Magnesium Ions in Modulating Sav2152: Insight from a Haloacid Dehalogenase-like Superfamily Phosphatase from Staphylococcus aureus.

Methicillin-resistant Staphylococcus aureus (MRSA) infection has rapidly spread through various routes. A genomic analysis of clinical MRSA samples revealed an unknown protein, Sav2152, predicted to be a haloacid dehalogenase (HAD)-like hydrolase, making it a potential candidate for a novel drug target. In this study, we determined the crystal structure of Sav2152, which consists of a C2-type cap domain and a core domain. The core domain contains four motifs involved in phosphatase activity that depend on the presence of Mg2+ ions. Specifically, residues D10, D12, and D233, which closely correspond to key residues in structurally homolog proteins, are responsible for binding to the metal ion and are known to play critical roles in phosphatase activity. Our findings indicate that the Mg2+ ion known to stabilize local regions surrounding it, however, paradoxically, destabilizes the local region. Through mutant screening, we identified D10 and D12 as crucial residues for metal binding and maintaining structural stability via various uncharacterized intra-protein interactions, respectively. Substituting D10 with Ala effectively prevents the interaction with Mg2+ ions. The mutation of D12 disrupts important structural associations mediated by D12, leading to a decrease in the stability of Sav2152 and an enhancement in binding affinity to Mg2+ ions. Additionally, our study revealed that D237 can replace D12 and retain phosphatase activity. In summary, our work uncovers the novel role of metal ions in HAD-like phosphatase activity.

Metal ion activation and DNA recognition by the Deinococcus radiodurans manganese sensor DR2539.

The accumulation of manganese ions is crucial for scavenging reactive oxygen species and protecting the proteome of Deinococcus radiodurans (Dr). However, metal homeostasis still needs to be tightly regulated to avoid toxicity. DR2539, a dimeric transcription regulator, plays a key role in Dr manganese homeostasis. Despite comprising three well-conserved domains - a DNA-binding domain, a dimerisation domain, and an ancillary domain - the mechanisms underlying both, metal ion activation and DNA recognition remain elusive. In this study, we present biophysical analyses and the structure of the dimerisation and DNA-binding domains of DR2539 in its holo-form and in complex with the 21 base pair pseudo-palindromic repeat of the dr1709 promoter region, shedding light on these activation and recognition mechanisms. The dimer presents eight manganese binding sites that induce structural conformations essential for DNA binding. The analysis of the protein-DNA interfaces elucidates the significance of Tyr59 and helix α3 sequence in the interaction with the DNA. Finally, the structure in solution as determined by small-angle X-ray scattering experiments and supported by AlphaFold modeling provides a model illustrating the conformational changes induced upon metal binding.

Theoretical Study on The Effect of Metal Ions on The Structural Properties of Base

Metal ions play an important role in living organisms, for example Mg2+ is a cofactor for many biological enzymes (including DNA and RNA synthesis), Ca2+ is an important component of bone composition, and metal ions such as Fe, Co, Zn, Ni and Cu also play an important role in the normal functioning of living organisms. One of the main targets of metal ions in living organisms is deoxyribonucleic acid (DNA), which is an important carrier of information stored and transmitted by organisms. The direct interaction between DNA base pairs and metal ions have a significant impact on the structure and function of DNA base pairs, which is demonstrated as following: the binding of metals to bases usually breaks the hydrogen bonds of the base pairs. The N7 atom of a purine residue or the N3 atom of a pyrimidine residue, as well as the outer ring O atom and the phosphate oxygen atom, are the preferred sites for metal binding. The binding of metals to DNA and RNA also indirectly affects the conformation of the sugar ring. REDOX active metal ions have the ability to bind to DNA and can mediate oxidative DNA damage by reacting with endogenous oxidants. According to studies of antioxidants in the field of metal-mediated oxidative DNA damage, metal ion coordination also plays a key role in the mechanism of some antioxidants. Also, metal-DNA interactions are the basis for many anti-cancer drugs, anti-viral drugs and anti-bacterial agents. Metal-mediated oxidative DNA damage is associated with a variety of diseases and conditions, and understanding the binding interactions and subsequent reactivity can facilitate the management or prevention of oxidative damage. It can be seen that the study of the effect of metal ions on the structural properties of DNA bases has far-reaching implications, providing a theoretical basis for the development of novel anticancer drugs, DNA-based metal nanodevice technologies and the fabrication of spectroscopic and reactive probes.

Lead species formation on pure hemimorphite surface and its performance for subsequent sulfidization

Hemimorphite is important-supplementary resource for the commercial zinc production, but it easy loses into tailings due to extreme difficulty for its surface sulfidization. Adding active metal ions after sulfidization have been widely proposed for enhancing hemimorphite floatability, but its desired efficiency in flotation practice has not yet been completely achieved caused by the instability of sulfide layer. Whereas pre-adsorption of active metal ions to modify the hemimorphite surface has strong potential to make up for this shortcoming. Herein, the feasibility and appropriate environment of free Pb<sup>2+</sup> for modifying the pure hemimorphite surface was evaluated. Subsequently, the performance of Pb<sup>2+</sup> adsorption for enhancing sulfidization stability and floatability of hemimorphite were investigated. The X-ray photoelectron spectroscopy results indicated that the Pb<sup>2+</sup> adsorption on hemimorphite surface was achieved through the Pb ions displacement for Zn ions, and it was bond to oxygen-containing groups on hemimorphite surface. Such adsorption was strengthened with the increasing of solution pH, owing to the abundant Pb hydroxyl species precipitated on mineral under alkaline conditions, in term of the results of visual MINTEQ modeling and time-of-flight secondary-ion mass spectrometry. In addition, the X-ray photoelectron spectroscopy results showed dominant Pb hydroxyl species further reacted with sulfur during subsequent sulfidization to generate much more S species than that of without Pb<sup>2+</sup> pre-modification. Meanwhile, such sulfide layer composed by Pb<sup>2+</sup> on the mineral surface presented much higher stability than Zn-S species, which was verified via adsorption and desorption tests. As a result, the sulfidization and flotation recovery of hemimorphite increased after Pb<sup>2+</sup> pre-adsorption.

Heterokaryotic transition-metal dimers embedded monolayer g-C3N3 as promising anchoring and electrocatalytic materials for lithium-sulfur battery: First-principles calculations

g-C3N3 not only has high content of pyridine nitrogen, but also has a special two-dimensional porous structure, which is an ideal diatomic catalytic host materials. In this work, homonuclear and heteronuclear dual-atom catalysts (DACs, TM-TM@g-C3N3, TM = Mn, Fe, Co, Ni) were constructed using single-layer g-C3N3 as the carrier material of DACs, and their potential as sulfur-hosting materials and electrocatalytic materials for lithium-sulfur batteries was explored through first principles comprehensively. The results show that the coupling between the two metal atoms in heteronuclear DACs can regulate the spin state of each other's d-electrons, so that the anchoring and catalytic effects of heteronuclear DACs on polysulfide are more excellent than that of homonuclear DACs. Co-Mn@g-C3N3, when utilized as the cathode material in lithium-sulfur batteries, offers exceptional properties due to the hybridization between Mn2+ high-spin state d electron and Co2+ half-filled dz2 orbital. This unique interaction not only enables the polysulfide to exhibit the lowest Gibbs free energy during conversion, but also results in the lowest reaction energy barrier of 0.26 eV for the conversion of Li2S2 to Li2S. Furthermore, it is found that when 3d transition metal atoms act as heteronuclear DACs, the coupling between metal ions with high-spin states at the active site and metal ions with empty orbitals or half-full d-electrons has the most significant catalytic effect on polysulfides.

Investigating the Combined Toxicity of Cu(II) and Carbon Monoxide (CO); Cellular CO Delivery Using a Cu(II) Flavonolato Complex.

Carbon monoxide (CO) delivery molecules are of significant current interest as potential therapeutics, including for anticancer applications. A recent approach toward generating new types of materials-based anticancer agents involves combining the Fenton reactivity of a redox active metal ion with CO delivery. However, small molecule examples of these types of entities have not been systematically studied to evaluate the combined effect on cellular toxicity. Herein we describe a Cu(II) flavonolato complex which produces anticancer effects through a combination of copper-mediated reactive oxygen species (ROS) generation and light-induced flavonol CO release. Confocal microscopy studies provide evidence of enhanced flavonol uptake in the copper flavonolato system relative to the free flavonol, which leads to an increased amount of CO delivery within cells. Importantly, this work demonstrates that a metal flavonolato species can be used to produce enhanced toxicity effects resulting from both metal ion-induced Fenton reactivity and increased cellular uptake of a flavonol CO donor.

New Insights into the Dependence of CPEB3 Ribozyme Cleavage on Mn2+ and Mg2.

CPEB3 ribozyme is a self-cleaving RNA that occurs naturally in mammals and requires divalent metal ions for efficient activity. Ribozymes exhibit preferences for specific metal ions, but the exact differences in the catalytic mechanisms of various metal ions on the CPEB3 ribozyme remain unclear. Our findings reveal that Mn2+ functions as a more effective cofactor for CPEB3 ribozyme catalysis compared to Mg2+, as confirmed by its stronger binding affinity to CPEB3 by EPR. Cleavage assays of CPEB3 mutants and molecular docking analyses further showed that excessive Mn2+ ions can bind to a second binding site near the catalytic site, hindering CPEB3 catalytic efficiency and contributing to the Mn2+ bell-shaped curve. These results implicate a pivotal role for the local nucleobase-Mn2+ interactions in facilitating RNA folding and modulating the directed attack of nucleophilic reagents. Our study provides new insights and experimental evidence for exploring the divalent cation dependent cleavage mechanism of the CPEB3 ribozyme.