Impact Of Calcium Ions Research Articles

Impact of oxytosis on the cross-talk of mTORC with mitochondrial proteins in drug-resistant cancer stem cells.

By delivering the environmental inputs to transport nutrients and growth factors, Mechanistic Target of Rapamycin (mTOR) plays a significant role in the growth and metabolism of eukaryotic cells through the regulation of numerous elementary cellular processes such as autophagy, protein synthesis, via translation of mitochondrial protein transcription factor A mitochondrial, mitochondrial ribosomal proteins, and mitochondrial respiratory complexes I &V that are encoded in the nucleus with the help of translation initiation factor 4E-BP. These mitochondrial proteins are involved in cell signaling to regulate proper cell growth, proliferation, and death which are essential for tumor growth and proliferation. This suggests that tumor cells are dependent on mTORC1 for various metabolic pathways. However, this crucial regulator is activated and regulated by calcium homeostasis. Mounting evidence suggests the role of calcium ions in regulating mitochondrial enzymes and proteins. Hence, disrupting calcium homeostasis leads to calcium-dependent cell death called "Oxytosis" through hampering the expression of various mitochondrial proteins. "Oxytosis" is a novel non-apoptotic cell death characterized by glutamate cytotoxicity and ferritin degradation. The present review focuses on the crosstalk between mTORC1 and mitochondrial proteins in the cancer pathophysiology and the impact of calcium ions on disrupting mTORC1 leading to the induction of "Oxytosis."

Impact of calcium ions at physiological concentrations on the adsorption behavior of proteins on silica nanoparticles

The adsorption of proteins on nanoparticles (NPs) largely decides the fate and bioeffects of NPs in vivo. However, bio-fluids are too complicated to directly study in them to reveal related mechanisms, and current studies on model systems often ignore some important biological factors, such as metal ions. Herein, we evaluate the effect of Ca2+ at physiological concentrations on the protein adsorption on negatively-charged silica NP (SNP50). It is found that Ca2+, as well as Mg2+ and several transition metal ions, significantly enhances the adsorption of negatively-charged proteins on SNP50. Moreover, the Ca2+-induced enhancement of protein adsorption leads to the reduced uptake of SNP50 by HeLa cells. A double-chelating mechanism is proposed for the enhanced adsorption of negatively-charged proteins by multivalent metal ions that can form 6 (or more) coordinate bonds, where the metal ions are chelated by both the surface groups of NPs and the surface residues of the adsorbed proteins. This mechanism is consistent with all experimental evidences from metal ions-induced changes of physicochemical properties of NPs to protein adsorption isotherms, and is validated with several model proteins as well as complicated serum. The findings highlight the importance of investigating the influences of physiological factors on the interaction between proteins and NPs.

Silicate Scaling Formation: Impact of pH in High-Temperature Reservoir and Its Characterization Study

Silicate scaling tends to form and be aggravated during high pH Alkaline Surfactant Polymer (ASP) floods and this silicate scale deposition affects oil production. Hence, it is important to examine the conditions that lead to silicate scale forming. The severity of the silicate scaling reaction, the type and morphology of silica/silicate scale formed in an experimental ASP flood were studied for pH values 5, 8.5, and 11, whilst the temperature was kept constant at 90 ℃. In addition, the impact of calcium ion was studied and spectroscopic analyses were used to identify the extent of scaling reaction, morphology type and the functional group present in the precipitates. This was performed using imagery of the generated precipitates. It was observed that the silica/silicate scale is most severe at the highest pH and Ca:Mg molar ratios examined. Magnesium hydroxide and calcium hydroxide were observed to precipitate along with the silica and Mg-silicate/Ca-silicate scale at pH 11. The presence of calcium ions altered the morphology of the precipitates formed from amorphous to microcrystalline/crystalline. In conclusion, pH affects the type, morphology, and severity of the silica/silicate scale produced in the studied scaling system. The comprehensive and conclusive data showing how pH affects the silicate scaling reaction reported here are vital in providing the foundation to further investigate the management and prevention of this silicate scaling. Copyright © 2022 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Elucidation of the interactome of the sucrose transporter StSUT4: sucrose transport is connected to ethylene and calcium signalling.

Sucrose transporters of the SUT4 clade show dual targeting to both the plasma membrane as well as to the vacuole. Previous investigations revealed a role for the potato sucrose transporter StSUT4 in flowering, tuberization, shade avoidance response, and ethylene production. Down-regulation of StSUT4 expression leads to early flowering, tuberization under long days, far-red light insensitivity, and reduced diurnal ethylene production. Sucrose export from leaves was increased and a phase-shift of soluble sugar accumulation in source leaves was observed, arguing for StSUT4 to be involved in the entrainment of the circadian clock. Here, we show that StSUT4, whose transcripts are highly unstable and tightly controlled at the post-transcriptional level, connects components of the ethylene and calcium signalling pathway. Elucidation of the StSUT4 interactome using the split ubiquitin system helped to prove direct physical interaction between the sucrose transporter and the ethylene receptor ETR2, as well as with the calcium binding potato calmodulin-1 (PCM1) protein, and a calcium-load activated calcium channel. The impact of calcium ions on transport activity and dual targeting of the transporter was investigated in detail. For this purpose, a reliable esculin-based transport assay was established for SUT4-like transporters. Site-directed mutagenesis helped to identify a diacidic motif within the seventh transmembrane spanning domain that is essential for sucrose transport activity and targeting, but not required for calcium-dependent inhibition. A link between sucrose, calcium and ethylene signalling has been previously postulated with respect to pollen tube growth, shade avoidance response, or entrainment of the circadian clock. Here, we provide experimental evidence for the direct interconnection of these signalling pathways at the molecular level by direct physical interaction of the main players.

Impact of calcium ions on the structural and dynamic properties of heparin oligosaccharides by computational analysis

Heparin (HP) belongs to glycosaminoglycans (GAGs), anionic linear polysaccharides composed of repetitive disaccharide units. They are key players in many biological processes occurring in the extracellular matrix and at the cell surface. GAGs are challenging molecules for computational research due to their high chemical heterogeneity, flexibility, periodicity, pseudosymmetry, predominantly electrostatics-driven nature of interactions with their protein partners and potential multipose binding. The molecular mechanisms underlying GAG interactions mediated by divalent ions, which are important for GAG binding to several proteins, are not well understood. The goal of this study was to characterize the binding of Ca2+ to two HP oligosaccharides of different lengths (dp10 and dp18, dp: degree of polymerization) and their impact on HP conformational space and their dynamic behavior with the use of molecular dynamics (MD)-based approaches with two Ca2+ parameter sets. MD data suggested that the flexibility of the monosaccharides, the glycosidic linkages and ring puckering were not affected by the presence of Ca2+, in contrast to H-bond propensities and the calculated Rg for a fraction of the oligosaccharide populations in both dp10 and dp18. Moreover, the essential differences in the data obtained by using two Ca2+ parameter sets were reported.

Impact of calcium ions and degree of oxidation on the structural, physicochemical, and in-vitro release properties of resveratrol-loaded oxidized gellan gum hydrogel beads

Oxidized gellan gum (OGG) hydrogel beads as delivery systems for resveratrol were fabricated by ionic cross-linking with calcium chloride (CaCl2). The degree of oxidation (DO) and CaCl2 concentration had significant influences on the formation and functional properties of hydrogel beads. The resveratrol encapsulation efficiency (66.43%–79.84%) and loading capacity (4.15%–5.05%) of OGG hydrogel beads were enhanced as DO increased. The hydrogel beads exhibited a uniform spherical shape as observed by scanning electron microscope. Fourier transform infrared spectroscopy analysis confirmed that hydrogen bonds and ionic interaction participated in the formation of hydrogel beads. X-ray diffraction analysis revealed that the physical state of resveratrol was changed from crystalline to amorphous form after encapsulation. Furthermore, the physical stability and antioxidant capacity evaluation demonstrated that the hydrogel bead fabricated with DO80 OGG and CaCl2 concentration of 1.0 M could provide high protection for resveratrol against degradation by environmental stresses and maintain its antioxidant capacity. The DO and CaCl2 concentrations could modulate the in-vitro release behaviors of hydrogel beads and obtain a good small intestinal-targeted release of resveratrol at high DO and medium CaCl2 concentration. These findings suggested that a promising delivery system for encapsulating bioactive ingredients can be fabricated by rational design.

Impact of calcium ion on cytotoxic effect of the boroxine derivative, K2[B3O3F4OH

The effect of Ca2+ ions on the cytotoxic ability of boron heterocyclic compound dipotassium-trioxohydroxytetrafluorotriborate (K2[B3O3F4OH]), on in vitro tumor cells (mammary adenocarcinoma 4T1, melanoma B16F10 and squamous cell carcinoma SCCVII) and non-tumoral fibroblast cells (mouse dermal L929 and hamster lung V79) was examined. At small concentrations of Ca2+ ions (0.42 mM), K2[B3O3F4OH] (3.85 mM) has a very strong cytotoxic effect on all cancer cells tested (89.1, 85.6 and 84.6%) and significantly less effect on normal cells (19.5 and 24.2%), respectively. Applying larger concentrations of Ca2+ ions (9.42–72.42 mM), at the same concentration of K2[B3O3F4OH], no significant cytotoxic effect was detected on cancer cells and normal cells investigated. The selective ability of K2[B3O3F4OH], in the medium with a low concentration of Ca2+ ions has a strong cytotoxic effect on cancer cells and very weak effect in normal cells, opens up the possibility of its application in antitumor therapy.

Impact of calcium ions leaching caused by biogenic acid attack on durability of cement composites

Leaching of calcium ions increases the porosity of cement-based materials, consequently resulting in a negative effect on durability since it provides an entry for aggressive harmful ions, causing corrosion of concrete. Sulphuric acid corrosion of concrete can be caused due to attack of aggressive media naturally existing in the environment. Another possibility of corrosion formation is biogenic acid effect through the agency of microorganisms. The paper is focused on the investigation of the influence of biogenic acid attack on the cement composites affected with bacteria Acidithiobacillus thiooxidans. The concrete specimens with 95% wt. addition of antimicrobial activated granulated blast furnace slag as durability increasing factor as well as without any addition were studied. The experiments proceeded during the nine 7-day cycles. The pH values and chemical composition of leachates were measured and evaluated after each cycle. The higher resistance of concrete samples with the addition of 95% wt. of antimicrobial activated granulated blast furnace slag to the aggressive environment was confirmed. The leaching of calcium ions of concrete sample affected with bacteria Acidithiobacillus thiooxidans was 1.13 times lower (736.6 mg/L of leachate) for concrete sample with antimicrobial activated granulated blast furnace slag addition comparing to concrete sample of ordinary CEM I Portland cement without any additives (832.0 mg/L of leachate).

Impact of calcium ions on frog sciatic nerve compound action potential

IZVOD Uvod. Funkcija nervnih ćelija, prije svega aksonskog produžetka, može se procijeniti pomoću parametara zbirnog akcionog potencijala izolovanog nerva. Cilj rada. Cilj istraživanja je ispitati uticaj jona kalcijuma na parametre: amplitudu, latentni period pojavljivanja i latentni period pika zbirnog akcionog potencijala izolovanog n. ischiadicus-a žabe pri pojedinačnom nadraživanju. Metod rada. Ispitivano je 30 n.ischiadicus-a žabe, podijeljenih u tri grupe od po 10 nerava. Nakon dvočasovne inkubacije u Ringerovom rastvoru za hladnokrvne životinje (2.0 mmol/l rastvor kalcijuma) i prvog mjerenja parametara nervi su 30 minuta inkubirani u rastvorima 0.0 mmol/l, 2.0 mmol/l i 10.0 mmol/l i vršena su eksperimentalna mjerenja. Zbirni akcioni potencijal nerva je izazivan stimulisanjem nerava pomoću stimulatora pojedinačnim električnim dražima i očitavan je na digitalnom osciloskopu. Podaci su statistički obrađeni pomoću kompjuterskog programa GraphPad Prism, verzija 5.0. Rezultati. Rezultati istraživanja su pokazali da nema statistički značajne razlike između srednjih vrijednosti procentualnog smanjenja (u odnosu na kontrolno mjerenje) amplitude, (p≥0,05), a postoji između srednjih vrijednosti procentualnog produženja latentnog perioda pojavljivanja i latentnog perioda pika (p<0,05) zbirnog akcionog potencijala nerava inkubiranih u rastvorima jona kalcijuma koncentracije 0.0 mmol/l, 2.0 mmol/l i 10.0 mmol/l Zaključak. S obzirom da latentni period pojavljivanja predstavlja vrijeme provođenja impulsa duž brzih, a latentni period pika predstavlja vrijeme provođenja duž sporih vlakana, to se najvjerovatnije pri djelovanju visokih koncentracija jona kalcijuma smanjuje brzina provođenja impulsa duž odgovarajućih vlakana.

Complete starch hydrolysis by the synergistic action of amylase and glucoamylase: impact of calcium ions

Starch hydrolysis was performed by the synergistic action of amylase and glucoamylase. For that purpose glucoamylase (Dextrozyme) and two amylases (Liquozyme and Termamyl) in different combinations were investigated. Experiments were carried out in the repetitive- and fed-batch modes at 65 °C and pH 5.5 with and without the addition of Ca(2+) ions. 100 % conversion of starch to glucose was achieved in batch experiments. Calcium ions significantly enhanced stability of the amylase Termamyl. The intensity of synergism between amylase Termamyl and glucoamylase Dextrozyme was higher than in the experiments carried out with amylase Liquozyme and Dextrozyme. Mathematical model of the complete reaction system was developed. Using the model, a possible explanation of the synergism between the amylase and glucoamylase was provided.

Starch hydrolysis by the synergistic action of amylase and glucoamylase

Starch hydrolysis is highly investigated chemical process which is usually carried out in two stages: the first step is liquefaction catalyzed by  -amylase, and the second step is the saccharification process catalyzed by glucoamylase. High energy demand of saccharification and liquefaction processes results in the necessity to study them on lower temperatures. Since amylase exhibits lower activity at lower temperature ( 50 °C for glucoamylase used in this work) and addition of calcium ions can caused the inhibition or deactivation effect on this enzyme. Impact of calcium ions on the starch hydrolysis catalyzed by synergistic action of amylase and glucoamylase was studied in this work. For that purpose two amylases -Termamyl and Liquozyme and glucoamylase – Dextrozyme were used. The experiments were performed at pH 5.5 and 65 oC. These conditions were chosen as a compromise for the activity of both enzymes. Before investigation of synergistic action of amylase and glucoamylase, enzymes were studied separately. Amylases were studied in the reaction of starch hydrolysis and glucoamylase was studied in the reaction of maltose hydrolysis. For each system mathematical model was developed. α -amylase deactivation rate was described by two-step model that assumed formation of an intermediate before complete deactivation. First order kinetics was used to describe glucoamylase deactivation. All experiments were performed with and without presence of calcium ions. It was found out that calcium ions contributed to the operational stability of native form of both amylases. In the case of Termayml presence of calcium did not affect the intermediate form of enzyme, while for Liquozyme intermediate, it had slightly negative impact. From the results it was concluded that possible inhibition and deactivation of glucoamylase with calcium ions could be excluded. Integrated process of liquefaction and saccharification was successfully performed and nearly 100 % conversion of starch to glucose was achieved. Among investigated amylases, Termamyl is most promising for use in the integrated process of starch hydrolysis since its deactivation rate is more than 100 times lower than that of the Liquozyme.