Presence Of Magnesium Ions Research Articles

Hybrid Protocells Based on Coacervate-Templated Fatty Acid Vesicles Combine Improved Membrane Stability with Functional Interior Protocytoplasm.

Prebiotically-plausible compartmentalization mechanisms include membrane vesicles formed by amphiphile self-assembly and coacervate droplets formed by liquid-liquid phase separation. Both types of structures form spontaneously and can be related to cellular compartmentalization motifs in today's living cells. As prebiotic compartments, they have complementary capabilities, with coacervates offering excellent solute accumulation and membranes providing superior boundaries. Herein, protocell models constructed by spontaneous encapsulation of coacervate droplets by mixed fatty acid/phospholipid and by purely fatty acid membranes are described. Coacervate-supported membranes form over a range of coacervate and lipid compositions, with membrane properties impacted by charge-charge interactions between coacervates and membranes. Vesicles formed by coacervate-templated membrane assembly exhibit profoundly different permeability than traditional fatty acid or blended fatty acid/phospholipid membranes without a coacervate interior, particularly in the presence of magnesium ions (Mg2+). While fatty acid and blended membrane vesicles are disrupted by the addition of Mg2+, the corresponding coacervate-supported membranes remain intact and impermeable to externally-added solutes. With the more robust membrane, fluorescein diacetate (FDA) hydrolysis, which is commonly used for cell viability assays, can be performed inside the protocell model due to the simple diffusion of FDA and then following with the coacervate-mediated abiotic hydrolysis to fluorescein.

Magnesium-Induced Rapid Nucleation of Tetrahydrofuran Hydrates.

Hydrates are ice-like crystalline structures of hydrogen-bonded water molecules that trap a guest molecule. Hydrates have several applications, including carbon sequestration, gas separation, desalination, etc. A classical major challenge associated with artificial hydrate formation is the very long induction time to nucleate hydrates. This has spurred the development of multiple chemical, mechanical, and electrical strategies to promote nucleation. Presently, we discover that magnesium can significantly promote the nucleation of tetrahydrofuran (THF) hydrates. While magnesium has been recently shown (by our group) to promote the formation of carbon dioxide hydrates (gas-liquid system), this study discovers that the benefits of magnesium extend to liquid-liquid hydrate systems as well. Experiments show that magnesium reduces the induction time for THF hydrate nucleation with deionized (DI) water and saltwater by six and eight times, respectively. Magnesium-induced nucleation rate enhancements for hydrate formation with DI water and saltwater were 12 and 99 times, respectively. Importantly, we demonstrate near-instantaneous nucleation when magnesium is introduced after the hydrate-forming system reaches suitable thermodynamic conditions. We conduct statistically significant measurements of nucleation and XPS analysis to identify the underlying mechanisms responsible for nucleation. We discuss multiple phenomena at play, including chemical and mechanistic promotion pathways. The formation of hydrogen bubbles and the presence of magnesium ions in solution are seen as important to magnesium-based nucleation promotion. Importantly, very low amounts of Mg are consumed in this process unlike in traditional chemical promotion techniques. Overall, our discovery can enable on-demand nucleation of liquid-liquid hydrate systems, which is critical to the development of several applications.

Highly stable Saccharomyces cerevisiae L-BC capsids with versatile packing potential.

Virus-like particles (VLPs) are promising nanoscaffolds in development of vaccines and nanodelivery systems. Along with efficient production in various expression systems, they also offer extensive functionalization options. Nevertheless, the ultimate integrity of VLPs is an important burden for the applicability in nanobiotechnology. In this study, we characterize the Saccharomyces cerevisiae L-BC VLPs synthesized and purified from Escherichia coli and Saccharomyces cerevisiae cells. The particles exhibited prominent size stability in buffers within a range of ionic strength conditions, pH environment and presence of magnesium ions during the long-term storage at temperatures up to 37°C. Bacteria-derived particles exhibited alleviated stability in acidic pH values, higher ionic strength and temperature compared to yeast-derived particles. Taking advantage of gene engineering, 120 copies of red fluorescent protein mCherry were successfully encapsulated into both preparations of L-BC VLPs, while passive diffusion enabled encapsulation of antimicrobial peptide nisin into the yeast-derived unmodified VLPs. Our findings indicate that L-BC VLPs generally exhibit high long-term stability under various conditions, while yeast-derived L-BC VLPs are more stable under the elevated temperatures than bacteria-derived particles. Stability studies and encapsulation of particles by different molecules involving alternative strategies delineate the L-BC VLP potential to be developed into versatile nanodelivery system.

Dopamine modified electrodes for indirect voltammetric determination of magnesium ions

This article outlines the fabrication process of an electrochemical sensor designed for the innovative determination of magnesium ions based on the electrochemistry of dopamine. The sensor operates under voltammetric conditions, accounting for variations in the electrochemical reversibility of immobilized dopamine in the presence of magnesium ions under conditions of square-wave voltammetry. The immobilization of dopamine on the glassy carbon electrode is achieved through the electrochemical oxidation of its side amino group, leading to covalent grafting onto the electrode surface. All stages of the proposed electrode surface modification procedure were carefully optimized. The dopamine sensor exhibited a linear response in the concentration range of magnesium ions from 0.1 to 10 mmol L−1, with a limit of detection (LOD) value equal to 1.3 × 10−5 mol L−1. To validate the electroanalytical significance of the developed methodology, real food supplement samples were quantitatively analyzed, demonstrating a highly satisfactory rate of recovery. The proposed voltammetric method serves as a simple and cost-effective procedure for the indirect determination of magnesium ions. Additionally, this approach allows for the analysis of real samples without the need for time-consuming preparation steps, as the complex matrices of food supplement samples did not adversely affect the registered currents.

Electrochemical Aptasensing Platform for the Detection of Retinol Binding Protein-4.

Here, we present the results of our the electrochemical aptasensing strategy for retinol binding protein-4 (RBP-4) detection based on a thiolated aptamer against RBP-4 and 6-mercaptohexanol (MCH) directly immobilized on a gold electrode surface. The most important parameters affecting the magnitude of the analytical signal generated were optimized: (i) the presence of magnesium ions in the immobilization and measurement buffer, (ii) the concentration of aptamer in the immobilization solution and (iii) its folding procedure. In this work, a systematic assessment of the electrochemical parameters related to the optimization of the sensing layer of the aptasensor was carried out (electron transfer coefficients (α), electron transfer rate constants (k0) and surface coverage of the thiolated aptamer probe (ΓApt)). Then, under the optimized conditions, the analytical response towards RBP-4 protein, in the presence of an Fe(CN)63-/4- redox couple in the supporting solution was assessed. The proposed electrochemical strategy allowed for RBP-4 detection in the concentration range between 100 and 1000 ng/mL with a limit of detection equal to 44 ng/mL based on electrochemical impedance spectroscopy (EIS). The specificity studies against other diabetes biomarkers, including vaspin and adiponectin, proved the selectivity of the proposed platform. These preliminary results will be used in the next step to miniaturize and test the sensor in real samples.

Sequence-Dependent Orientational Coupling and Electrostatic Attraction in Cation-Mediated DNA-DNA Interactions.

Condensation of DNA is vital for its biological functions and controlled nucleic acid assemblies. However, the mechanisms of DNA condensation are not fully understood due to the inability of experiments to access cation distributions and the complex interplay of energetic and entropic forces during assembly. By constructing free energy surfaces using exhaustive sampling and detailed analysis of cation distributions, we elucidate the mechanism of DNA condensation in different salt conditions and with different DNA sequences. We found that DNA condensation is facilitated by the correlated dynamics of the localized cations at the grooves of DNA helices. These dynamics are strongly dependent on the salt conditions and DNA sequences. In the presence of magnesium ions, major groove binding facilitates attraction. In contrast, in the presence of polyvalent cations, minor groove binding serves to create charge patterns, leading to condensation. Our findings present a novel advancement in the field and have broad implications for understanding and controlling nucleic acid complexes in vivo and in vitro.

Melting calorimetry of rat liver nuclei in the presence of magnesium ions

Differential scanning calorimetry was used to determine thermodynamic parameters of decondensation of intranuclear rat liver chromatin was induced by a decrease in the concentration of magnesium ions from 5 mM to 0 mM. The process of chromatin melting in the temperature range of 70-100°C occurs in the following order: melting of core-histones, melting of relaxed DNA, and melting of topologically constrained DNA. It was found that Tm and Д H of individual peaks also depend on the concentration of Mg2+ ions in the buffer. In nuclei with condensed chromatin, Mg2+ ions at a concentration of 5 mM increased significantly the Tm of core histones (by ~7°C), as compared to that in unfolded chromatin but at the same time lowered the Tm of nuclear DNA both in the relaxed and constrained state (by ~2.5°С and ~7.5°С, respectively). In the presence of Mg2+ ions, melting enthalpy for peaks increased significantly. At the same time, a decrease in molecular weights of intranuclear DNA levels out a stabilizing effect of Mg2+ ions on core histones. A rise in the concentration of Mg2+ ions above 5 mM leads to the appearance of a new peak with Tm above 100°С, which probably reflects the thermal behavior of some Mg-induced aggregates. Possible mechanisms underlying thermal behavior of chromatin inside the nucleus are discussed.

In vitro radical-scavenging mechanism of melatonin and its in vivo protective effect against radiation-induced lipid peroxidation

Melatonin (N-acetyl-5-methoxytryptamine, MLT), an evolutionarily conserved indoleamine, is known to act as an antioxidant. However, the evidence indicating the role of MLT as a powerful chain-breaking antioxidant by scavenging peroxyl radical remains controversial. The radical-scavenging rate of MLT determined in this study in methanol using galvinoxyl radical (GO•) was much lower than that of an α-tocopherol model compound. The acceleration of the GO•-scavenging reaction by MLT was observed in the presence of magnesium ion (Mg2+), a bio-related redox-inactive metal ion, suggesting that this reaction may proceed via a rate-determining electron transfer followed by proton transfer. The coordination of Mg2+ to the carbonyl oxygen in the one-electron reduced species of GO• (GO–) may stabilize the product, resulting in the acceleration of the electron-transfer process. We also demonstrated that prophylactically administrated MLT efficiently inhibited the lipid peroxide-derived protein modification, which can be detected by a sensitive marker, Nε-(hexanoyl)lysine adduct, in the plasma of X-irradiated mice. The relatively weak GO•-scavenging activity of MLT suggests that the ameliorative effect of MLT against in vivo lipid peroxidation does not result from the direct scavenging of lipid peroxyl radicals by MLT. Therefore, the observed superior protective efficiency of MLT against in vivo lipid peroxidation may partly support the earlier studies, which reported the synergistic antioxidative effect of the metabolites of MLT.

Melting Calorimetry of Rat Liver Nuclei in the Presence of Magnesium Ions

Melting Calorimetry of Rat Liver Nuclei in the Presence of Magnesium Ions

Magnesium Hydroxide Nanoparticles Inhibit the Biofilm Formation of Cariogenic Microorganisms.

Although various caries-preventive agents have been developed, dental caries is still a leading global disease, mostly caused by biological factors such as mutans streptococci. Magnesium hydroxide nanoparticles have been reported to exhibit antibacterial effects; however, they are rarely used in oral care practical applications. In this study, we examined the inhibitory effect of magnesium hydroxide nanoparticles on biofilm formation by Streptococcus mutans and Streptococcus sobrinus-two typical caries-causing bacteria. Three different sizes of magnesium hydroxide nanoparticles (NM80, NM300, and NM700) were studied, all of which inhibited biofilm formation. The results showed that the nanoparticles were important for the inhibitory effect, which was not influenced by pH or the presence of magnesium ions. We also determined that the inhibition process was mainly contact inhibition and that medium (NM300) and large (NM700) sizes were particularly effective in this regard. The findings of our study demonstrate the potential applications of magnesium hydroxide nanoparticles as caries-preventive agents.

A Novel DNAzyme-Based Fluorescent Biosensor for Detection of RNA-Containing Nipah Henipavirus

Nipah virus (NiV) is a zoonotic RNA virus which infects humans and animals in Asian countries. Infection in humans occurs in different forms, from asymptomatic infection to fatal encephalitis, and death occurred in 40-70% of those infected in outbreaks that occurred between 1998 and 2018. Modern diagnostics is carried out by real-time PCR to identify pathogens or by ELISA to detect antibodies. Both technologies are labor-intensive and require the use of expensive stationary equipment. Thus, there is a need to develop alternative simple, fast and accurate test systems for virus detection. The aim of this study was to develop a highly specific and easily standardized system for the detection of Nipah virus RNA. In our work, we have developed a design for a Dz_NiV biosensor based on a split catalytic core of deoxyribozyme 10-23. It was shown that the assembly of active 10-23 DNAzymes occurred only in the presence of synthetic target Nipah virus RNA and that this was accompanied by stable fluorescence signals from the cleaved fluorescent substrates. This process was realized at 37 °C, pH 7.5, and in the presence of magnesium ions, with a 10 nM limit of detection achieved for the synthetic target RNA. Constructed via a simple and easily modifiable process, our biosensor may be used for the detection of other RNA viruses.

Progress in the Study of Coronary Atherosclerosis and Prevention of Acute Myocardial Infarction

Cardiovascular disease stands as the leading cause of global mortality, with coronary atherosclerosis emerging as the prevailing pathological alteration within this condition. This lesion is distinguished by a notable escalation in oxidative stress. The prevalence of coronary atherosclerosis has exhibited a steady rise over time, leading to a consequential escalation in fatalities resulting from acute myocardial infarction caused by this condition. This alarming trend poses a significant threat to the well-being of our population. To address the imperative issue of preventing acute myocardial infarction caused by coronary atherosclerosis, this study offers a novel theoretical framework elucidating the pathogenesis and progression of acute myocardial infarction. By presenting and consolidating the findings of our research, this project aims to contribute to the prevention of acute myocardial infarction in recent years. The prevention of atherosclerotic plaque formation, narrowing of blood vessel lumen, obstruction, and myocardial ischemic infarction resulting from heightened oxidative stress in the human body, diminished vitamin C levels, impaired collagen formation, and unregulated cardiac wall repair system necessitates the reduction of oxidative intake, elimination of oxidative accumulation within the body, or augmentation of antioxidant intake. Furthermore, a substantial body of epidemiological evidence indicates that aberrant lipid metabolism serves as the primary predisposing factor for acute myocardial infarction. Additionally, both intermittent fasting and fat reduction therapy have demonstrated efficacy in preventing acute myocardial infarction. Moreover, it is worth noting that reducing non-high-density lipoprotein cholesterol (nHDL-C) is considered a secondary objective of fat reduction therapy. Moreover, magnesium is a significant dietary component that is frequently disregarded, yet numerous scientific investigations have substantiated the inverse relationship between the presence of magnesium ions in potable water and the prevalence of mortality due to coronary heart disease. However, iron, as an additional constituent, significantly contributes to the susceptibility of individuals to coronary artery disease and myocardial infarction.

Mutagenesis, purification, and characterization of lipase from Aspergillus eucalypticola CBS 122712 and exhibiting efficient removal of vehicle oil stains

Microbial lipases are known for their industrial applications. Aspergillus eucalypticola was used for mutagenesis using Ethyl methanesulfonate. Mutagen-treated strain (MTS-03) of A. eucalypticola resulted in 119.05 ± 0.14 IU/ml/min lipase activity as compared to Lipolytic fungal strain (LFS-7) of A. eucalypticola which resulted in 88.98 ± 0.21 IU/ml/min. The purified enzyme resulted 51.03 fold increase for MTS-03 lipase and 23.06 fold increase for LFS-7 lipase. The MTS-03 lipase was found stable between 25 °C to 55 °C and alkaline pH 8 to pH 11. The residual activity of MTS-03 and LFS-7 lipase was increased to 124.42 % and 114.23 %, respectively in the presence of magnesium ion. The MTS-03 lipase was found to be highly stable in methanol solvent with 127.82 % residual activity and exhibited 111.16 % residual activity in presence of 15 % (v/v) Triton X-100 and stable in presence of Patanjali detergent with 120.14 % residual activity. The efficient stability of obtained lipase suggests its potential usage in industries.

The structure of succinyl-CoA synthetase bound to the succinyl-phosphate intermediate clarifies the catalytic mechanism of ATP-citrate lyase.

Succinyl-CoA synthetase (SCS) catalyzes a three-step reaction in the citric acid cycle with succinyl-phosphate proposed as a catalytic intermediate. However, there are no structural data to show the binding of succinyl-phosphate to SCS. Recently, the catalytic mechanism underlying acetyl-CoA production by ATP-citrate lyase (ACLY) has been debated. The enzyme belongs to the family of acyl-CoA synthetases (nucleoside diphosphate-forming) for which SCS is the prototype. It was postulated that the amino-terminal portion catalyzes the full reaction and the carboxy-terminal portion plays only an allosteric role. This interpretation was based on the partial loss of the catalytic activity of ACLY when Glu599 was mutated to Gln or Ala, and on the interpretation that the phospho-citryl-CoA intermediate was trapped in the 2.85 Å resolution structure from cryogenic electron microscopy (cryo-EM). To better resolve the structure of the intermediate bound to the E599Q mutant, the equivalent mutation, E105αQ, was made in human GTP-specific SCS. The structure of the E105αQ mutant shows succinyl-phosphate bound to the enzyme at 1.58 Å resolution when the mutant, after phosphorylation in solution by Mg2+-ATP, was crystallized in the presence of magnesium ions, succinate and desulfo-CoA. The E105αQ mutant is still active but has a specific activity that is 120-fold less than that of the wild-type enzyme, with apparent Michaelis constants for succinate and CoA that are 50-fold and 11-fold higher, respectively. Based on this high-resolution structure, the cryo-EM maps of the E599Q ACLY complex reported previously should have revealed the binding of citryl-phosphate and CoA and not phospho-citryl-CoA.

Exploring Coral Calcification by Calcium Carbonate Overgrowth Experiments

The Scleractinia coral biomineralization process is a representative example of a heterogeneous process of nucleation and growth of biogenic CaCO3 over a mineral phase. Indeed, even if the biomineralization process starts before settlement, the bulk formation of the skeleton takes place only when the larvae attach to a solid substrate, which can be Mg-calcite from coralline algae, and the following growth proceeds on the Mg-calcite surface of the formed baseplate of the planula. Despite this peculiarity and central role of the Mg-calcite substrate, the in vitro overgrowth of CaCO3 on single crystals of Mg-calcite, or calcite, in the presence of magnesium ions and the soluble organic matrix (SOM) extracted from coral skeletons has not been performed until now. In this study, the SOMs from Stylophora pistillata and Oculina patagonica skeletons were used in a set of overgrowth experiments. The overgrown CaCO3 was characterized by microscopic, diffractometric, and spectroscopic techniques. Our results showed that CaCO3 overgrowth in the presence of S. pistillata or O. patagonica SOM produces different effects. However, there appears to be a minor distinction between samples when magnesium ions are present in solution. Moreover, the Mg-calcite substrate appears to be a favorable substrate for the overgrowth of aragonite, differently from calcite. These observations fit with the observed settling of coral larvae on Mg-calcite-based substrates and with the in vivo observation that in the planula aragonite forms on first-formed Mg-calcite crystals. The overall results of this study highlight the importance of magnesium ions, either in the solution or in the substrate, in defining the shape, morphology, and polymorphism of biodeposited CaCO3. They also suggest a magnesium-dependent biological control on the deposition of coral skeletons.

Ultracentrifugation-Free Enrichment and Quantification of Small Extracellular Vesicles.

Cancer is a malignant tumor with the highest mortality of human diseases. The early diagnosis of cancer can greatly reduce its mortality. Ultracentrifugation is the most commonly employed technique to separate small extracellular vesicles (sEVs) due to their small size and rare abundance, but the low separation efficiency is a major concern. Herein, we proposed a DNAzyme-triggered assembly and disassembly system that converted single nano-sized sEVs into clusters that could be conveniently enriched by ordinary centrifugation and then be broken into single sEVs in the presence of magnesium ions. The simultaneous quantification of sEVs was realized by recording the increase in fluorescence upon nucleic acid cleavage, and a detection limit as low as 54 particles/μL was achieved. The whole analytical procedure could be completed in 1.5 h without the assistance of ultracentrifugation. Efficient enrichment and accurate quantification of sEVs are enabled through the proposed approach, broadening the potentials of sEVs in biological science, biomedical engineering, and personalized medicine.

Evaluation of spice and herb as phyto-derived selective modulators of human retinaldehyde dehydrogenases using a simple in vitro method.

Selective modulation of retinaldehyde dehydrogenases (RALDHs)—the main aldehyde dehydrogenase (ALDH) enzymes converting retinal into retinoic acid (RA), is very important not only in the RA signaling pathway but also for the potential regulatory effects on RALDH isozyme-specific processes and RALDH-related cancers. However, very few selective modulators for RALDHs have been identified, partly due to variable overexpression protocols of RALDHs and insensitive activity assay that needs to be addressed. In the present study, deletion of the N-terminal disordered regions is found to enable simple preparation of all RALDHs and their closest paralog ALDH2 using a single protocol. Fluorescence-based activity assay was employed for enzymatic activity investigation and screening for RALDH-specific modulators from extracts of various spices and herbs that are well-known for containing many phyto-derived anti-cancer constituents. Under the established conditions, spice and herb extracts exhibited differential regulatory effects on RALDHs/ALDH2 with several extracts showing potential selective inhibition of the activity of RALDHs. In addition, the presence of magnesium ions was shown to significantly increase the activity for the natural substrate retinal of RALDH3 but not the others, while His-tag cleavage considerably increased the activity of ALDH2 for the non-specific substrate retinal. Altogether we propose a readily reproducible workflow to find selective modulators for RALDHs and suggest potential sources of selective modulators from spices and herbs.

Synergistic effects of magnesium and EDTA on polymorphism and morphology of CaCO3 and its influence on scale

Calcium carbonate scale formation in the presence of magnesium ions has been studied between 60 and 100 °C. The samples were characterized using XRD, FTIR and FE-SEM techniques. The effect of EDTA on the polymorphism and morphology of calcium carbonate in presence of magnesium ions also have been reported. The study revealed that both magnesium and EDTA influence the crystallization behavior and morphology of the CaCO3 formed. The study also revealed that the effect need not be same under different temperatures and environments and the morphological transformation need not compulsorily represent the polymorphic transformation. The findings are explained by a two stage mechanism which revealed that the magnesium ions present in the system can favorably or adversely affect the scale inhibition property of the inhibitor depending on the concentration and temperature.

Investigation of Mammoth Tusk Mammuthus Primigenius by Thermogravimetry and X-ray Diffraction Analysis

The article represents the results of the research of the mammoth tusk Mammuthus Primigenius using thermogravimetric (TGA) and X-ray diffraction analysis (XRD). The stages of thermal destruction of mammoth tusk components and their temperature limits are revealed. XRD of mammoth tusk showed that heat treatment leads to a change in the structure of the mineral component of the material under study from hydroxyapatite (HAP) to whitlockite. It was found that this process is caused by the presence of magnesium ions in the crystal lattice of HAP.

Affinity-based proteomics reveals novel targets of inositol pyrophosphate (5-IP7 )-dependent phosphorylation and binding in Trypanosoma cruzi replicative stages.

Diphosphoinositol-5-pentakisphosphate (5-PP-IP5 ), also known as inositol heptakisphosphate (5-IP7 ), has been described as a high-energy phosphate metabolite that participates in the regulation of multiple cellular processes through protein binding or serine pyrophosphorylation, a posttranslational modification involving a β-phosphoryl transfer. In this study, utilizing an immobilized 5-IP7 affinity reagent, we performed pull-down experiments coupled with mass spectrometry identification, and bioinformatic analysis, to reveal 5-IP7 -regulated processes in the two proliferative stages of the unicellular parasite Trypanosoma cruzi. Our protein screen clearly defined two cohorts of putative targets either in the presence of magnesium ions or in metal-free conditions. We endogenously tagged four protein candidates and immunopurified them to assess whether 5-IP7 -driven phosphorylation is conserved in T. cruzi. Among the most interesting targets, we identified a choline/o-acetyltransferase domain-containing phosphoprotein that undergoes 5-IP7 -mediated phosphorylation events at a polyserine tract (Ser578-580 ). We also identified a novel SPX domain-containing phosphoribosyltransferase [EC 2.7.6.1] herein termed as TcPRPPS4. Our data revealed new possible functional roles of 5-IP7 in this divergent eukaryote, and provided potential new targets for chemotherapy.