Статті в журналах: "Divalent metal ions release"

1

Mustafa, S., B. Dilara, A. Naeem, N. Rehana, and K. Nargis. "Temperature and pH Effect on the Sorption of Divalent Metal Ions by Silica Gel." Adsorption Science & Technology 21, no. 4 (May 2003): 297–307. http://dx.doi.org/10.1260/026361703322405033.

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The sorption of Zn2+, Ni2+ and Cd2+ ions by silica gel was studied as a function of ion concentration, pH and temperature. An increase in all three parameters led to an increase in the extent of sorption for all the metal cations studied. The selectivity of the solid was observed to be in the order Zn2+ > Ni2+ > Cd2+. Sorption of the metal cations was accompanied by the release of H+ ions into the bulk phase. On average two moles of H+ ions were released per mole of metal cation sorbed. The sorption data fitted the linear forms of both the Kurbatov and Langmuir adsorption equations. The values of the binding constants were used to estimate the apparent thermodynamic parameters, ΔH and ΔS, for the adsorption process. FT-IR spectroscopic studies also showed that the uptake of metal cations by the silica gel occurred via a cation-exchange process.

2

Knape, Matthias J., Mike Ballez, Nicole C. Burghardt, Bastian Zimmermann, Daniela Bertinetti, Alexandr P. Kornev, and Friedrich W. Herberg. "Divalent metal ions control activity and inhibition of protein kinases." Metallomics 9, no. 11 (2017): 1576–84. http://dx.doi.org/10.1039/c7mt00204a.

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Metals like Zn²⁺ and Mn²⁺ can assist in the catalytic cycle of a protein kinase by facilitating substrate binding and phosphotransfer, however, in contrast to Mg²⁺ they also hamper product release.

3

Kim, Bongsu, and Tae Hyun Kim. "Electrochemical Studies for Cation Recognition with Diazo-Coupled Calix[4]arenes." Journal of Analytical Methods in Chemistry 2015 (2015): 1–7. http://dx.doi.org/10.1155/2015/579463.

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The electrochemical properties of diazophenylcalix[4]arenes bearingortho-carboxyl group (o-CAC) andortho-ester group (o-EAC), respectively, in the presence of various metal ions were investigated by voltammetry in CH3CN.o-CAC ando-EAC showed voltammetric changes toward divalent metal ions and no significant changes with monovalent alkali metal ions. However,o-CAC preferentially binds with alkaline earth and transition metal ions, whereas no significant changes in voltammetric signals are observed ino-EAC with alkaline earth metal ions.o-EAC only binds with other transition metal ions. This can be explained on metal ion complexation-induced release of proton from the azophenol to the quinone-hydrazone tautomer followed by internal complexation of the metal ion with aid of nitrogen atoms andortho-carbonyl groups in the diazophenylazocalix[4]arenes.

4

Sieme, Daniel, Christian Griesinger, and Nasrollah Rezaei-Ghaleh. "Metal Binding to Sodium Heparin Monitored by Quadrupolar NMR." International Journal of Molecular Sciences 23, no. 21 (October 29, 2022): 13185. http://dx.doi.org/10.3390/ijms232113185.

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Heparins and heparan sulfate polysaccharides are negatively charged glycosaminoglycans and play important roles in cell-to-matrix and cell-to-cell signaling processes. Metal ion binding to heparins alters the conformation of heparins and influences their function. Various experimental techniques have been used to investigate metal ion-heparin interactions, frequently with inconsistent results. Exploiting the quadrupolar 23Na nucleus, we herein develop a 23Na NMR-based competition assay and monitor the binding of divalent Ca2+ and Mg2+ and trivalent Al3+ metal ions to sodium heparin and the consequent release of sodium ions from heparin. The 23Na spin relaxation rates and translational diffusion coefficients are utilized to quantify the metal ion-induced release of sodium ions from heparin. In the case of the Al3+ ion, the complementary approach of 27Al quadrupolar NMR is employed as a direct probe of ion binding to heparin. Our NMR results demonstrate at least two metal ion-binding sites with different affinities on heparin, potentially undergoing dynamic exchange. For the site with lower metal ion binding affinity, the order of Ca2+ > Mg2+ > Al3+ is obtained, in which even the weakly binding Al3+ ion is capable of displacing sodium ions from heparin. Overall, the multinuclear quadrupolar NMR approach employed here can monitor and quantify metal ion binding to heparin and capture different modes of metal ion-heparin binding.

5

Xu, Kui, Mi Zhou, Ming Li, Weizhen Chen, Yabin Zhu, and Kaiyong Cai. "Metal-phenolic networks as a promising platform for pH-controlled release of bioactive divalent metal ions." Applied Surface Science 511 (May 2020): 145569. http://dx.doi.org/10.1016/j.apsusc.2020.145569.

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6

Dahal, Madhav P., Geoffrey A. Lawrance, and Marcel Maeder. "Kinetics of Heavy Metal Ion Adsorption on to, and Proton Release from, Electrolytic Manganese Dioxide." Adsorption Science & Technology 16, no. 1 (February 1998): 39–50. http://dx.doi.org/10.1177/026361749801600106.

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The kinetics of adsorption of lead(II), as well as of copper (II), zinc(II) and thallium(I), on commercial electrolytic manganese dioxide (EMD) powder of different size fractions has been followed by a pH-stat method involving the computer-controlled neutralisation of released protons from the EMD at a fixed pH with hydroxide ion. Base uptake versus time profiles in all cases indicated a rapid initial change followed by a slower process. These can be interpreted in terms of either a solution kinetic model or an adsorption kinetic model. In the former analysis, the adsorption-time profile can be interpreted in terms of two, or at most three, exponentials. The contribution of the first fast step increases with decreasing average particle size (or increasing surface area), consistent with its interpretation as being associated with the replacement of accessible protons on the exposed surface of the EMD by metal ions. The slower rate processes can be considered to be associated with adsorption in less accessible clefts or pores in the structure. In the diffusion model, the experimental data were fitted to the equation of diffusion in a sphere, fitting again requiring a first initial step followed by a slower step, with one diffusion coefficient having typically an upper limit of 10-9 and the other a lower limit of 10-11 cm2/s. For the complete reaction, the moles of protons released per mole of metal ion adsorbed were also measured and found to be relatively insensitive with respect to pH, metal ion concentration, electrolyte concentration and EMD size fraction. At pH 4, the H+: Mn+ ratio ranged from 1.4 to 2.1 (±0.1) for divalent transition metal ions, consistent with dominant chelation of the divalent metal ion to two adjacent oxygen sites on the surface; for thallium(I), a low ratio (0.5) indicated a different mode of surface attachment.

7

Chou, Chiu L., John F. Uthe, and Robert D. Guy. "Determination of Free and Bound Cd, Zn, Cu, and Ag Ions in Lobster (Homarus americanus) Digestive Gland Extracts by Gel Chromatography Followed by Atomic Absorption Spectrophotometry and Polarography." Journal of AOAC INTERNATIONAL 76, no. 4 (July 1, 1993): 794–98. http://dx.doi.org/10.1093/jaoac/76.4.794.

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Abstract Gel-permeation chromatography followed by atomic absorption spectrophotometric and polarographic analyses were used to measure free and bound divalent metal ions in lobster digestive gland extracts prepared with or without oc-toluenesulfonyl fluoride, a protease inhibitor. Chromatography on Sephadex G-50 or G-100 yielded 3 UV-absorbing peaks, which corresponded, respectively, to the void volume, a medium molecular weight fraction, and a low molecular weight fraction that contained free divalent metal ions. In protease-inhibited extracts, only Zn+2 was found, whereas Cd, Cu, and Ag were bound in high and medium molecular weight fractions. Cd+2 and Zn+2 were rapidly released from their bound forms in the absence of a protease inhibitor, and their presence was confirmed by polarography with EDTA. Gel-permeation chromatography coupled with atomic absorption spectrophotometry offers a rapid method for following changes in the concentrations of bound and free metal ions during processing of shellfishbased foodstuffs.

8

Facchin, F., S. Catalani, E. Bianconi, D. De Pasquale, S. Stea, A. Toni, S. Canaider, and A. Beraudi. "Albumin as marker for susceptibility to metal ions in metal-on-metal hip prosthesis patients." Human & Experimental Toxicology 36, no. 4 (May 20, 2016): 319–27. http://dx.doi.org/10.1177/0960327116650011.

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Metal-on-metal (MoM) hip prostheses are known to release chromium and cobalt (Co), which negatively affect the health status, leading to prosthesis explant. Albumin (ALB) is the main serum protein-binding divalent transition metals. Its binding capacity can be affected by gene mutations or modification of the protein N-terminal region, giving the ischaemia-modified albumin (IMA). This study evaluated ALB, at gene and protein level, as marker of individual susceptibility to Co in MoM patients, to understand whether it could be responsible for the different management of this ion. Co was measured in whole blood, serum and urine of 40 MoM patients. A mutational screening of ALB was performed to detect links between mutations and metal binding. Finally, serum concentration of total ALB and IMA were measured. Serum total ALB concentration was in the normal range for all patients. None of the subjects presented mutations in the investigated gene. Whole blood, serum and urine Co did not correlate with serum total ALB or IMA, although IMA was above the normal limit in most subjects. The individual susceptibility is very important for patients’ health status. Despite the limited results of this study, we provide indications on possible future investigations on the toxicological response to Co.

9

YAMADA, Masaki, Noriyuki KISHII, Koji ARAKI, and Shinsaku SHIRAISHI. "Extraction and release of divalent metal ions by 6,6'-diamino-2,2'-bipyridine supported on polymer beads." NIPPON KAGAKU KAISHI, no. 6 (1989): 988–92. http://dx.doi.org/10.1246/nikkashi.1989.988.

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10

Torabi, Seyed-Fakhreddin, Peiwen Wu, Claire E. McGhee, Lu Chen, Kevin Hwang, Nan Zheng, Jianjun Cheng, and Yi Lu. "In vitro selection of a sodium-specific DNAzyme and its application in intracellular sensing." Proceedings of the National Academy of Sciences 112, no. 19 (April 27, 2015): 5903–8. http://dx.doi.org/10.1073/pnas.1420361112.

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Over the past two decades, enormous progress has been made in designing fluorescent sensors or probes for divalent metal ions. In contrast, the development of fluorescent sensors for monovalent metal ions, such as sodium (Na+), has remained underdeveloped, even though Na+is one the most abundant metal ions in biological systems and plays a critical role in many biological processes. Here, we report the in vitro selection of the first (to our knowledge) Na+-specific, RNA-cleaving deoxyribozyme (DNAzyme) with a fast catalytic rate [observed rate constant (kobs) ∼0.1 min−1], and the transformation of this DNAzyme into a fluorescent sensor for Na+by labeling the enzyme strand with a quencher at the 3′ end, and the DNA substrate strand with a fluorophore and a quencher at the 5′ and 3′ ends, respectively. The presence of Na+catalyzed cleavage of the substrate strand at an internal ribonucleotide adenosine (rA) site, resulting in release of the fluorophore from its quenchers and thus a significant increase in fluorescence signal. The sensor displays a remarkable selectivity (>10,000-fold) for Na+over competing metal ions and has a detection limit of 135 µM (3.1 ppm). Furthermore, we demonstrate that this DNAzyme-based sensor can readily enter cells with the aid of α-helical cationic polypeptides. Finally, by protecting the cleavage site of the Na+-specific DNAzyme with a photolabileo-nitrobenzyl group, we achieved controlled activation of the sensor after DNAzyme delivery into cells. Together, these results demonstrate that such a DNAzyme-based sensor provides a promising platform for detection and quantification of Na+in living cells.

11

Singh, Sarita, Jyoti Singh, Sunita Gulia, and Rita Kakkar. "Metal Ion Selectivity of Kojate Complexes: A Theoretical Study." Journal of Theoretical Chemistry 2013 (July 7, 2013): 1–9. http://dx.doi.org/10.1155/2013/342783.

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Density functional calculations have been performed on four-coordinate kojate complexes of selected divalent metal ions in order to determine the affinity of the metal ions for the kojate ion. The complexation reactions are characterized by high energies, showing that they are highly exothermic. It is found that Ni(II) exhibits the highest affinity for the kojate ion, and this is attributed to the largest amount of charge transfer from the ligand to the metal ion. The Ni(II) complex has distorted square planar structure. The HOMOs and LUMOs of the complexes are also discussed. All complexes display a strong band at ~1500 cm−1 corresponding to the stretching frequency of the weakened carbonyl bond. Comparison of the complexation energies for the two steps shows that most of the complexation energy is realized in the first step. The energy released in the second step is about one-third that of the first step.

12

Xiong, Wenming, Yongjun Li, Jidong Ying, Chuxia Lin, and Junhao Qin. "Behaviors of Organic Ligands and Phosphate during Biochar-Driven Nitrate Adsorption in the Presence of Low-Molecular-Weight Organic Acids." Molecules 27, no. 18 (September 8, 2022): 5811. http://dx.doi.org/10.3390/molecules27185811.

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A batch experiment was conducted to examine the behavior of nitrate, organic ligands, and phosphate in the co-presence of biochar and three common low-molecular-weight organic acids (LMWOAs). The results show that citrate, oxalate, and malate ions competed with nitrate ion for the available adsorption sites on the biochar surfaces. The removal rate of LMWOA ligands by the biochar via adsorption grew with increasing solution pH. The adsorbed divalent organic ligands created negatively charged sites to allow binding of cationic metal nitrate complexes. A higher degree of biochar surface protonation does not necessarily enhance nitrate adsorption. More acidic conditions formed under a higher dose of LMWOAs tended to make organic ligands predominantly in monovalent forms and failed to create negatively charged sites to bind cationic metal nitrate complexes. This could adversely affect nitrate removal efficiency in the investigated systems. LMWOAs caused significant release of phosphate from the biochar. The phosphate in the malic acid treatment tended to decrease over time, while the opposite was observed in the citric- and oxalic-acid treatments. This was caused by re-immobilization of phosphate in the former due to the marked increase in solution pH over time.

13

Zygiel, Emily M., and Elizabeth M. Nolan. "Transition Metal Sequestration by the Host-Defense Protein Calprotectin." Annual Review of Biochemistry 87, no. 1 (June 20, 2018): 621–43. http://dx.doi.org/10.1146/annurev-biochem-062917-012312.

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In response to microbial infection, the human host deploys metal-sequestering host-defense proteins, which reduce nutrient availability and thereby inhibit microbial growth and virulence. Calprotectin (CP) is an abundant antimicrobial protein released from neutrophils and epithelial cells at sites of infection. CP sequesters divalent first-row transition metal ions to limit the availability of essential metal nutrients in the extracellular space. While functional and clinical studies of CP have been pursued for decades, advances in our understanding of its biological coordination chemistry, which is central to its role in the host–microbe interaction, have been made in more recent years. In this review, we focus on the coordination chemistry of CP and highlight studies of its metal-binding properties and contributions to the metal-withholding innate immune response. Taken together, these recent studies inform our current model of how CP participates in metal homeostasis and immunity, and they provide a foundation for further investigations of a remarkable metal-chelating protein at the host–microbe interface and beyond.

14

Sultana, Ruhi, and Lauren F. Greenlee. "(Digital Presentation) Enhanced Electrochemical Phosphate Recovery from Wastewater: Implications of Pulsating Anode Potential." ECS Meeting Abstracts MA2022-01, no. 40 (July 7, 2022): 1813. http://dx.doi.org/10.1149/ma2022-01401813mtgabs.

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Electrochemical recovery of phosphorus (P) as struvite (or magnesium ammonium phosphate hexahydrate, MgNH4PO4.6H2O) fertilizer using a sacrificial pure magnesium (Mg) anode is considered a sustainable strategy to deal with the limited availability of rock phosphate. However, the formation of an electrically passive film of magnesium hydroxide (Mg(OH)2) and/or struvite on the surface of Mg upon immediate immersion in aqueous phosphate solution limits the release of divalent Mg ions and decreases struvite precipitation. The present work highlights struvite recovery by an electrochemical method upon application of a dynamic voltage with a sinusoidal waveform. Our results demonstrate that a dynamic potential, when compared to a constant potential, can enhance the rupture of the passivating film, and facilitate the release of Mg2+ from the metal thereby overcoming the problems related to electrical passivation.Aqueous solutions of ammonium dihydrogen phosphate (NH4H2PO4, 10 mM) at neutral pH were used as test solutions. Mg2+ release was notably increased by ~48% relative to constant voltage applications, which subsequently led to ~20% higher phosphate recovery. Characterization studies including X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated the presence of struvite in the recovered precipitate. Surface characterization of electrodes using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) also confirms a higher extent of passivating film breakdown in the presence of dynamic voltage.

15

Zhang, Jiao, Pan Wang, Zhiqiang Zhang, Pengyu Xiang, and Siqing Xia. "Biosorption Characteristics of Hg(II) from Aqueous Solution by the Biopolymer from Waste Activated Sludge." International Journal of Environmental Research and Public Health 17, no. 5 (February 26, 2020): 1488. http://dx.doi.org/10.3390/ijerph17051488.

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The divalent mercury ion (Hg(II)) is one of the most hazardous toxic heavy-metal ions, and an important industrial material as well. It is essential to remove and recover Hg(II) from wastewater before it is released into the environment. In this study, the biosorption characteristics of Hg(II) from aqueous solution by the biopolymer from waste activated sludge (WAS) are investigated. The major components of the biopolymer consisted of proteins, carbohydrates, and nucleic acids. The adsorption kinetics fit for the pseudo-second-order kinetic model, and the adsorption isotherms were well described by Langmuir equation. The adsorption capacity of the biopolymer increased along with rising temperature, and the maximal adsorption capacity was up to 477.0 mg Hg(II)/g biopolymer at 308 K. The infrared spectroscopy analyses showed that the complexation of Hg(II) by the biopolymer was achieved by the functional groups in the biopolymer, including hydroxyl (–OH), amino (–NH2), and carboxylic (–COOH). From the surface morphology, the special reticulate structure enabled the biopolymer to easily capture the metal ions. From the elemental components analyses, a part of Hg(II) ions was removed due to ion exchange with the Na+, K+, and Ca2+, in the biopolymer. Both complexation and ion exchange played key roles in the adsorption of Hg(II) by the biopolymer. These results are of major significance for removal and recovery of Hg(II) from wastewater.

16

Liu, Yao-Jen, Wen-Ta Su, and Po-Hung Chen. "Magnesium and zinc borate enhance osteoblastic differentiation of stem cells from human exfoliated deciduous teeth in vitro." Journal of Biomaterials Applications 32, no. 6 (November 9, 2017): 765–74. http://dx.doi.org/10.1177/0885328217740730.

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Various biocompatible and biodegradable scaffolds blended with biochemical signal molecules with adequate osteoinductive and osteoconductive properties have attracted significant interest in hard tissue engineering regeneration. We evaluated the distinct effects of magnesium borate, zinc borate, and boric acid blended into chitosan scaffold for osteogenic differentiation of stem cells from exfoliated deciduous teeth. Stem cells from exfoliated deciduous teeth cells are a potential source of functional osteoblasts for applications in bone tissue engineering, but the efficiency of osteoblastic differentiation is low, thereby significantly limiting their clinical applications. Divalent metal borates have potential function in bone remodeling because they can simulate bone formation and decrease bone resorption. These magnesium, zinc, and B ions can gradually be released into the culture medium from the scaffold and induce advanced osteoblastic differentiation from stem cells from exfoliated deciduous teeth. Stem cells from exfoliated deciduous teeth with magnesium borate or zinc borate as inducer demonstrated more osteoblastic differentiation after 21 days of culture. Differentiated cells exhibited activity of alkaline phosphatase, bone-related gene expression of collagen type I, runt-related transcription factor 2, osteopontin, osteocalcin, vascular endothelial growth factor, and angiopoietin-1, as noted via real-time polymerase chain reaction analysis, as well as significant deposits of calcium minerals. Divalent mental magnesium and zinc and nonmetal boron can be an effective inducer of osteogenesis for stem cells from exfoliated deciduous teeth. This experiment might provide useful inducers for osteoblastic differentiation of stem cells from exfoliated deciduous teeth for tissue engineering and bone repair.

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Tomson, Mason B., Amy T. Kan, Gongmin Fu, Dong Shen, Hisham A. Nasr-El-Din, H. A. Saiari, and Musaed M. Al Thubaiti. "Mechanistic Understanding of Rock/Phosphonate Interactions and Effect of Metal Ions on Inhibitor Retention." SPE Journal 13, no. 03 (September 1, 2008): 325–36. http://dx.doi.org/10.2118/100494-pa.

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Summary This paper discusses the effects of Ca2+, Mg2+, and Fe2+ on inhibitor retention and release. Better understanding of phosphonate reactions during inhibitor squeeze treatments has direct implication on how to design and improve scale inhibitor squeeze treatments for optimum scale control. Putting various amounts of metal ions in the inhibitor pill adds another degree of freedom in squeeze design, especially in controlling return concentrations and squeeze life. Phosphonate reactions during squeeze treatments involve a series of self-regulating reactions with calcite and other minerals. However, excess calcite does not improve the retention of phosphonate due to the surface poisoning effect of Ca2+. The squeeze can be designed so that maximum squeeze life is achieved by forming a low solubility phase in the formation. Addition of Ca2+, Mg2+, and Fe2+ in the pill solution at 0.1 to 1 molar ratios significantly improves the retention of phosphonate. Alternatively, these metal ions can be dissolved from the formation while an acidic inhibitor pill is in contact with the formation minerals. Both BHPMP and DTPMP returns were significantly extended by the addition of metal ions (e.g., Ca2+ and Fe2+). The addition of Mg2+ may increase the long-term return concentration, which is important for some wells where a higher inhibitor return concentration is needed. The laboratory squeeze simulations were compared to return data obtained from squeeze treatments performed on two wells located in a sandstone reservoir in Saudi Arabia. The sandstone formation contains significant amounts of iron-bearing minerals. Introduction Mineral scale formation is a persistent problem in oil and gas production, especially in older reservoirs with increased water production and drawdown. Inhibitor squeezes are commonly used to deposit a suitable scale inhibitor in the formation. During an inhibitor squeeze treatment, a predetermined volume of the inhibitor solution is pumped into the formation and followed by injecting another volume of brine or diesel to place the inhibitor further away from the wellbore and allowing it to react with the existing rock. During production following a squeeze treatment, the inhibitor is slowly desorbed or dissolved into the formation water. Earlier efforts have focused on describing what happens and when to resqueeze (Hong and Shuler 1988; Rogers et al. 1990). More recent papers have advanced the knowledge of inhibitor reactions under various production conditions (Benton et al. 1993; Sweeney and Cooper 1993; Lawless et al. 1993; Sorbie et al. 1994; Jordan et al. 1994; Jordan et al. 1995; Jordan et al. 1997; Lawless and Smith 1998; Smith et al. 2000; Collins 2003). The primary conclusions from several previous studies (Al-Thubaiti et al. 2004; Kan et al. 2004a; Kan et al. 2004b; Tomson et al. 2006) of NTMP(aminotri(methylene phosphonic acid))-calcite reaction are:The extent of NTMP retention by carbonate-rich formation rock is limited by the amount of calcite that can dissolve prior to inhibitor-induced surface poisoning;calcite-surface poisoning effect is observed after approximately 20 molecular layers of phosphonate surface coverage that retards further calcite dissolution; andthe consequence of retarded calcite dissolution is that less basic ion, CO2-3, is released into solution, leaving the solution more acidic; therefore, more soluble calcium phosphonate solid phases form. The inhibitor return concentration can be altered by changing the inhibitor concentration in the pill. The ability to control the high inhibitor return may be useful in initial water breakthrough where high inhibitor return is desired. Kan et al. (2005) also compared the retention of NTMP, DTPMP (diethylenetriamine penta (methylene phosphonic acid)), BHPMP (bis-hexamethylenetriamine penta (methylene phosphonic acid)), and PPCA (phosphinopolycarboxylic acid) with pure calcite, a calcite-rich chalk rock, a calcite and clay-rich formation rock from Guerra Ranch, McAllen, Texas, and a quartz sandstone with very little calcite from Frio formation, Galveston County, Texas. Similar inhibitor returns were observed in both calcite-rich and low-calcite rock, suggesting that calcite is the primary solid responsible for phosphonate retention. Clays or other minerals play a secondary role in phosphonate retention. The retention of the polymer-based inhibitors is much lower than phosphonates. The data show that BHPMP provides the highest squeeze life at MIC > 50 mg/L. DTPMP is the preferred inhibitor at MIC between 1 and 50 mg/L and NTMP is the preferred inhibitor at MIC < 0.3 mg/L. Calcium ion (Ca2+) is the predominant divalent metal ion in most oilfield produced waters. Previously, several reports indicated that Ca2+ and Mg2+ have a strong effect on inhibition of barite by common inhibitors (Fernandez-Diaz et al. 1990; Boak et al. 1999; Collins 1999). Collins (1999) observed a clear change in crystal habit between barite growth in the presence and absence of Ca. Xiao et al. (2001) noted that Ca significantly enhanced the inhibitor efficiency; however, Ca had no effect on barite nucleation time in the absence of scale inhibitor. Collins (1999) reported a similar effect of Ca with polyaspartate as a barite inhibitor. The enhanced inhibition efficiency may be attributed to the reduction of net negative charge of the polyion due to complexation of the polyaspartate with divalent cations (Tomson et al. 2003). In the present paper, the influence of metal ions, e.g., Ca2+, Mg2+, and Fe2+ on the inhibitor retention and release was evaluated in both laboratory simulation and field case studies. These metal ions were either originally added to the inhibitor pill solutions or generated in-situ because of the dissolution of reservoir minerals by acidic inhibitors.

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Hong, Dae Ki, A. Ra Kho, Song Hee Lee, Beom Seok Kang, Min Kyu Park, Bo Young Choi, and Sang Won Suh. "Pathophysiological Roles of Transient Receptor Potential (Trp) Channels and Zinc Toxicity in Brain Disease." International Journal of Molecular Sciences 24, no. 7 (April 3, 2023): 6665. http://dx.doi.org/10.3390/ijms24076665.

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Maintaining the correct ionic gradient from extracellular to intracellular space via several membrane-bound transporters is critical for maintaining overall cellular homeostasis. One of these transporters is the transient receptor potential (TRP) channel family that consists of six putative transmembrane segments systemically expressed in mammalian tissues. Upon the activation of TRP channels by brain disease, several cations are translocated through TRP channels. Brain disease, especially ischemic stroke, epilepsy, and traumatic brain injury, triggers the dysregulation of ionic gradients and promotes the excessive release of neuro-transmitters and zinc. The divalent metal cation zinc is highly distributed in the brain and is specifically located in the pre-synaptic vesicles as free ions, usually existing in cytoplasm bound with metallothionein. Although adequate zinc is essential for regulating diverse physiological functions, the brain-disease-induced excessive release and translocation of zinc causes cell damage, including oxidative stress, apoptotic cascades, and disturbances in energy metabolism. Therefore, the regulation of zinc homeostasis following brain disease is critical for the prevention of brain damage. In this review, we summarize recent experimental research findings regarding how TRP channels (mainly TRPC and TRPM) and zinc are regulated in animal brain-disease models of global cerebral ischemia, epilepsy, and traumatic brain injury. The blockade of zinc translocation via the inhibition of TRPC and TRPM channels using known channel antagonists, was shown to be neuroprotective in brain disease. The regulation of both zinc and TRP channels may serve as targets for treating and preventing neuronal death.

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Bramley, T. A., D. Stirling, I. A. Swanston, G. S. Menzies, and D. T. Baird. "Specific binding sites for LH/chorionic gonadotrophin, low-density lipoprotein, prolactin and FSH in homogenates of human corpus luteum. I: Validation of methods." Journal of Endocrinology 113, no. 2 (May 1987): 305–15. http://dx.doi.org/10.1677/joe.0.1130305.

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ABSTRACT The specific binding of 125I-labelled human chorionic gonadotrophin (hCG), human low-density lipoprotein (hLDL), human FSH (hFSH) and human prolactin (hPRL) to homogenates of human corpus luteum tissue was measured. Specific binding of 125I-labelled hCG was dependent on the temperature and duration of incubation, was inhibited by divalent metal ions or chelating agents, and increased linearly with homogenate concentration. Recovery of bound hormone was more effective using Millipore filtration or polyethylene glycol precipitation compared with centrifugation alone. Binding of 125I-labelled hCG was inhibited specifically by low levels of hCG and human LH (hLH) but not by ovine LH or bovine LH. Incubation of human luteal tissue with ice-cold citrate buffer (pH 3) released more than 90% of specifically bound 125I-labelled hCG within 5 min. This treatment inactivated LH receptors, but did not affect the immunoactivity of hLH released, enabling the measurement of released hormone by radioimmunoassay. Scatchard plots of binding of 125I-labelled LDL to human corpus luteum demonstrated a single class of binding sites. Binding was saturable, increased linearly with increasing concentration of homogenate, and was displaceable by low concentrations of unlabelled LDL. Binding of 125I-labelled hPRL to human luteal homogenates was increased by Mg2+ and was specific for lactogenic hormones (human prolactin, human growth hormone and ovine prolactin). Binding of 125I-labelled hFSH was not dependent on divalent metal ion concentration (in marked contrast to hFSH binding to immature pig granulosa cell receptors) and was displaced by hFSH preparations but not by hPRL, ovine LH or hCG at 1 μg/ml. These results establish optimal conditions and hormone specificities for the measurement of human luteal gonadotrophin and LDL receptors, and methods for the estimation of hLH/hCG endogenously bound to human corpus luteum tissue. J. Endocr. (1987) 113, 305–315

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Juntachai, Weerapong, Takahiro Oura, and Susumu Kajiwara. "Purification and characterization of a secretory lipolytic enzyme, MgLIP2, from Malassezia globosa." Microbiology 157, no. 12 (December 1, 2011): 3492–99. http://dx.doi.org/10.1099/mic.0.054528-0.

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Malassezia globosa is a lipid-dependent yeast that is found on the human skin and is associated with various skin disorders, including dandruff and seborrhoeic dermatitis (SD). Despite its important role in skin diseases, the molecular basis for its pathogenicity is poorly understood. The current hypothesis is that dandruff and SD are linked to fatty acid metabolism and secretory lipolytic enzymes, which hydrolyse sebaceous lipids and release irritating free fatty acids. A previous genomic analysis of M. globosa identified a family of 13 homologous genes predicted to encode secreted lipases. We have also reported that M. globosa had significantly higher extracellular lipase activity compared with other species. To identify the major secretory lipases of this yeast during its growth, we successfully purified and characterized an extracellular lipase MgLIP2. Based on MALDI-TOF MS, the peptide mass fingerprint of a tryptically digested protein MgLIP2 corresponded to ORF MGL_4054 of M. globosa. This lipase showed high esterase activity against 4-nitrophenyl palmitate and 1-naphthyl palmitate but not 1-naphthyl acetate. This enzyme had optimal activity at 30 °C and pH 5.0. Furthermore, the activity significantly increased in the presence of Triton X-100 and was partially inhibited by PMSF but was unaffected by univalent and divalent metal ions.

21

Bayeshova, A., A. Bayeshov, A. Kadirbayeva, and F. Zhumabay. "Dissolution of iron in sodium chloride solution during alternating current polarization." Kompleksnoe Ispolʹzovanie Mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik Shikisattardy Keshendi Paidalanu 318, no. 3 (September 12, 2021): 51–62. http://dx.doi.org/10.31643/2021/6445.28.

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Iron compounds are widely used in many industries and engineering, and even in medicine. The existing methods of obtaining iron compounds are multi-stage and complex. The purpose of this work is to obtain iron (II) hydroxide and oxide from metal waste under alternating current action using one and two half-cycles. For the first time, the electrochemical behavior of iron electrode was studied by electrolysis method during alternating current polarization of industrial frequency in sodium chloride solutions. The iron polarization was carried out in pair with titanium, while the current density on the iron electrode varied in the range of 200-1200 A/m2, and on the titanium is in the range of 20-100 kA/m2. It is established that in the anode half-cycle of alternating current, iron is oxidized to form divalent ions. At this moment, the titanium electrode is in the cathode half-cycle, hydrogen is released on it, hydroxyl ions are formed in the cathode space. In the solution, ions interact with iron (II) ions to produce iron hydroxide. At temperatures above 600C, iron (II) hydroxide is dehydrated with the production of iron (II) oxide. The electrolysis was carried out in two electrolyzers connected to each other in parallel with the immersion of pair of “titanium-iron” electrodes into each electrolyzer. The iron dissolution occurs simultaneously in two half-cycles of alternating current and this approach is proposed for the first time. The process productivity increases by more than 1.5 times.

22

Eric, R. H. "Chromous capacities of ferrochromium and matte smelting slags." Archives of Materials Science and Engineering 2, no. 93 (October 1, 2018): 49–58. http://dx.doi.org/10.5604/01.3001.0012.7354.

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Purpose: of this paper is to extend the slag capacity concept to sparingly soluble cationic species encountered for example in matte smelting and ferrochromium processing in terms of chromous capacities. Design/methodology/approach: In this context in order to develop the chromous capacity the experimental data on slag-metal equilibrium for ferrochromium smelting and on chromium distribution between slag and matte phases encountered in sulphide smelting of PGM (Platinum Group Metals) and chromium containing copper nickel concentrates were used. Findings: The calculated chromous capacities were in the 10-8 range for ferrochrome smelting slags and 10-4 range for matte smelting slags. These values indicate the very low and moderate chromous ion dissolving ability of ferrochromium smelting slags and matte smelting slags respectively. Research limitations/implications: Due to highly reducing conditions in ferrochromium smelting and the imposed low oxygen partial pressures in sulphide smelting of chromium and PGM containing concentrates chromium in the slag was assumed to be in its divalent state. The slag-metal/matte reaction for dissolution of chromium into the slag as a cation under reducing conditions -in contrast to reactions for dissolution of species such as sulphur and phosphorus into the slag as anions under oxidizing conditions – required the release of electrons. Thus to maintain charge neutrality the dissolution of chromium from the metal or the matte phases into the slag as Cr2+ ions was accompanied by consumption of these electrons by reduction of Fe2+ ions in the slag into metallic Fe which dissolved in the metal/ matte phase. This was supported by the experimental equilibrium data. Hence the slagmetal/ matte reaction defining the chromous capacity involved both O2- and Fe2+ ions of the slag phase. Moreover for matte smelting the thermodynamic activities of species in the matte phase were assumed to conform to ideal associated solution model due to lack of data. For future work it is advisable to determine such activities. Practical implications: The calculated chromous capacities were in the 10-8 range for ferrochrome smelting slags and 10-4 range for matte smelting slags. The results clearly indicate that in matte smelting lower basicity slags would be preferable to render chromium more soluble in the slag in contrast to ferrochromium smelting where higher basicity slags would be suitable to minimize chromium losses to the slag. Originality/value: This research and hence the paper is probably the first on dissolution of chromium as chromous ion in slags, thus it is novel and original.

23

Zeng, Xiaoyan, Hedi An, Fei Yu, Kai Wang, Lanlan Zheng, Wei Zhou, Yiwen Bao, Jie Yang, Nan Shen, and Dongya Huang. "Benefits of Iron Chelators in the Treatment of Parkinson’s Disease." Neurochemical Research 46, no. 5 (March 1, 2021): 1239–51. http://dx.doi.org/10.1007/s11064-021-03262-9.

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AbstractAs a novel discovered regulated cell death pattern, ferroptosis has been associated with the development of Parkinson’s disease (PD) and has attracted widespread attention. Nevertheless, the relationship between ferroptosis and PD pathogenesis is still unclear. This study aims to investigate the effect of iron overload on dopaminergic (DA) neurons and its correlation with ferroptosis. Here we use nerve growth factor (NGF) induced PC12 cells which are derived from pheochromocytoma of the rat adrenal to establish a classical PD in vitro model. We found significantly decreased cell viability in NGF-PC12 cell under ammonium ferric citrate (FAC) administration. Moreover, excessive intracellular iron ions induced the increase of (reactive oxygen species) ROS release as well as the decrease of mitochondrial membrane potential in PC12-NGF cells. In addition, we also found that overloaded iron can activate cell apoptosis and ferroptosis pathways, which led to cell death. Furthermore, MPP-induced PD cells were characterized by mitochondrial shrinkage, decreased expression of glutathione peroxidase 4 (Gpx4) and ferritin heavy chain (FTH1), and increased divalent metal transporter (DMT1) and transferrin receptor 1 (TfR1) expression level. In contrast, Lip-1 and DFO increased the expression level of GPX4 and FTH1 compared to MPP-induced PD cell. In conclusion, we indicated that overloaded intracellular iron contributes to neurons death via apoptosis and ferroptosis pathways, while DFO, an iron chelator, can inhibit ferroptosis in order to protect the neurons in vitro.

24

Zuo, Pengjian, and Geping Yin. "Chelated electrolytes for divalent metal ions." Science 374, no. 6564 (October 8, 2021): 156. http://dx.doi.org/10.1126/science.abi6643.

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25

Braha, Orit, Li-Qun Gu, Li Zhou, Xiaofeng Lu, Stephen Cheley, and Hagan Bayley. "Simultaneous stochastic sensing of divalent metal ions." Nature Biotechnology 18, no. 9 (September 2000): 1005–7. http://dx.doi.org/10.1038/79275.

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26

Mustafa, S., S. Murtaza, A. Naeem, and K. Farina. "Sorption of divalent metal ions on CrPO4." Journal of Colloid and Interface Science 283, no. 2 (March 2005): 287–93. http://dx.doi.org/10.1016/j.jcis.2004.09.049.

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Birdsall, W. J. "Complexes of theophylline with divalent metal ions." Inorganica Chimica Acta 99, no. 1 (April 1985): 59–62. http://dx.doi.org/10.1016/s0020-1693(00)86048-x.

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Rosenbach, Hannah, Jan Borggräfe, Julian Victor, Christine Wuebben, Olav Schiemann, Wolfgang Hoyer, Gerhard Steger, Manuel Etzkorn, and Ingrid Span. "Influence of monovalent metal ions on metal binding and catalytic activity of the 10–23 DNAzyme." Biological Chemistry 402, no. 1 (November 18, 2020): 99–111. http://dx.doi.org/10.1515/hsz-2020-0207.

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AbstractDeoxyribozymes (DNAzymes) are single-stranded DNA molecules that catalyze a broad range of chemical reactions. The 10–23 DNAzyme catalyzes the cleavage of RNA strands and can be designed to cleave essentially any target RNA, which makes it particularly interesting for therapeutic and biosensing applications. The activity of this DNAzyme in vitro is considerably higher than in cells, which was suggested to be a result of the low intracellular concentration of bioavailable divalent cations. While the interaction of the 10–23 DNAzyme with divalent metal ions was studied extensively, the influence of monovalent metal ions on its activity remains poorly understood. Here, we characterize the influence of monovalent and divalent cations on the 10–23 DNAzyme utilizing functional and biophysical techniques. Our results show that Na+ and K+ affect the binding of divalent metal ions to the DNAzyme:RNA complex and considerably modulate the reaction rates of RNA cleavage. We observe an opposite effect of high levels of Na+ and K+ concentrations on Mg2+- and Mn2+-induced reactions, revealing a different interplay of these metals in catalysis. Based on these findings, we propose a model for the interaction of metal ions with the DNAzyme:RNA complex.

29

Strzelbicki, Jerzy, Witold Charewicz, Jorg Beger, and Lutz Hinz. "Transfer of divalent metal ions into the organic phase of the systems water–chloroform–ZnCl2–CdCl2–HgCl2–NaOH–(NaCl)–n-alkyltri(oxyethylene)carboxylic acid." Canadian Journal of Chemistry 66, no. 10 (October 1, 1988): 2640–46. http://dx.doi.org/10.1139/v88-414.

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The influence of the length of an n-alkyl chain incorporated into the molecule of an n-alkyltri(oxyethylene) carboxylic acid of a general formula CnH(2n+1)(OCH2CH2)3OCH2CO2H(n = 6, 8, 10, and 12, respectively) on transfer of the zinc group element ions into chloroform was investigated. Metal ions were transferred from the aqueous solutions of ZnCl2, CdCl2, and HgCl2 at initial concentrations of 0.835 mM and 1.67 mM with, and without, added NaCl. From the aqueous solutions to which no NaCl was added, the selectivity of transfer of divalent metal ions into the organic phase was low.The selectivity of transfer of the divalent metal ions improved remarkably when NaCl was added to the aqueous phase due to the chemical equilibria involving complexation of the divalent metal ions by Cl−, OH−, and n-alkyltri(oxyethylene) carboxylic acid. In most systems (with NaCl added), Zn(II) was separated from Cd(II) and Hg(II). Less lipophilic n-alkyltri(oxyethylene) carboxylic acids (with a shorter n-alkyl chain incorporated) exhibited higher selectivity and efficiency as divalent metal ion carriers.

30

Mustafa, S., P. Shahida, A. Naeem, B. Dilara, and N. Rehana. "Sorption Studies of Divalent Metal Ions on ZnO." Langmuir 18, no. 6 (March 2002): 2254–59. http://dx.doi.org/10.1021/la0014149.

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31

Wang, Guoshou, Wenta Su, Pohung Chen, and Teyang Huang. "Divalent Metal Ions Induced Osteogenic Differentiation of MC3T3E1." IOP Conference Series: Materials Science and Engineering 275 (December 2017): 012004. http://dx.doi.org/10.1088/1757-899x/275/1/012004.

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32

Naeem, A., S. Mustafa, N. Rehana, B. Dilara, and S. Murtaza. "The Sorption of Divalent Metal Ions on AlPO4." Journal of Colloid and Interface Science 252, no. 1 (August 2002): 6–14. http://dx.doi.org/10.1006/jcis.2002.8425.

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33

Ashfaq, Ahsan, Taseer Ahmed Khan, and Sadia Fatima. "Divalent Metal Ions; Key factor towards Pulmonary Tuberculosis." ANNALS OF ABBASI SHAHEED HOSPITAL AND KARACHI MEDICAL & DENTAL COLLEGE 26, no. 4 (December 31, 2021): 186–91. http://dx.doi.org/10.58397/ashkmdc.v26i4.516.

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ABSTRACT Introduction: In tuberculosis disease infection, trace elements perform a significant role as their insufficiencies may be related to weakened immunity. The purpose of this study was to compare demographic profile and divalent metal Ions in Tuberculosis and Non-Tuberculosis individuals. Methodology: This case control study was carried out on 345 subjects. Patients were grouped into two categories i.e. Pulmonary Tuberculosis (cases group) with 115 patients and without Pulmonary Tuberculosis (control group) with 230 subjects. Demographic and dietary profile was recorded through already designed proforma. 4 to 5 ml sterile gel tube was used to collect blood samples. The samples, which were then centrifuged, and the serum were examined to check the levels of iron and copper. Data was evaluated using SPSS version 25. Results: Male patients are more likely to have TB in comparison of female patient. In comparison of patient with normal serum copper, patient with serum copper below normal are less likely for TB and patient with serum copper above normal are more likely to develop TB. Patient with serum iron below normal are also more likely to develop TB in comparison of patients with normal serum iron. Conclusion: Male patients in productive age groups were commonly affected with tuberculosis. In Tuberculosis patients, we found low serum iron concentrations along with significantly high concentration of serum of copper when compared to healthy controls. Subsequently, low iron concentrations synergistically with increased serum copper levels may increase the human susceptibility to the infection of mycobacterium tuberculosis Keywords: Mycobacterium tuberculosis, Iron, Copper ,BMI, Nutritional status.

34

Yussupov, Khalidilla, Erbolat Aben, Dalelkhan Akhmetkanov, Khairulla Abenk, and Saltanat Yussupova. "Investigation of the solid oxidizer effect on the metal geotechnology efficiency." Mining of Mineral Deposits 17, no. 4 (December 30, 2023): 12–17. http://dx.doi.org/10.33271/mining17.04.012.

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Purpose. The research is aimed at increasing the useful component content in a pregnant solution during in-situ leaching (ISL) using a solid oxidizer and increasing the ferric iron concentration in the leaching solution based on laboratory research. Methods. Laboratory research is performed on a specially developed model electrolyzer for obtaining comparative data on divalent iron oxidation to trivalent iron and the change in the useful component content in a pregnant solution. Firstly, tests are conducted with a basic leaching solution, then on the oxidation of the leaching solution with a solid oxidizer in the form of a lead dioxide plate. Tests are conducted by changing sulphuric acid concentration within 5-50 g/l, amount of divalent iron ions in the solution from 0.5 up to 4.0 g, lead dioxide plate surface area from 19 to 76 cm2. The leaching time is up to 10 hours. Findings. The results of laboratory research on determining the oxidation degree of divalent iron ions and change in the oxidation-reduction potential (ORP) depending on the sulphuric acid concentration and on the initial concentration of divalent iron ions in the initial solution are presented. With a change in the sulphuric acid concentration from 5 to 50 g/l, the oxidation value of divalent iron ions increases from 26.5 to 96.5%, and with an increase in the initial solution concentration of divalent iron, the oxidation degree of divalent iron naturally decreases from 95.2 to 58.8%. In the initial leaching solution, the divalent solution concentration is 312 mg/l, and that of the trivalent solution is 288 mg/l. After oxidation with a solid oxidizer, the divalent and trivalent iron concentrations are 56 and 392 mg/l, respectively. In the course of further laboratory research using core materials from a uranium deposit, it has been revealed that when leaching with a basic solution, the uranium content in the pregnant solution is 19.36 mg/l, and when leaching with a solution after oxidation with a solid oxidizer, it is 27.9 mg/l, which is by 8.54 mg/l more. Originality. New dependences have been determined of the oxidation degree of divalent iron ions to trivalent one on the sulphuric acid concentration and on the initial concentration of divalent iron ions, as well as the useful component content in the pregnant solution on the leaching time when using a solid oxidizer. Practical implications. Using of a solid oxidizer, it is possible to increase the trivalent iron concentration in the leaching solution and the useful component content in the pregnant solution compared with the basic technology, thereby reducing the time of mining uranium reserves. Proposed technology is environmentally friendly, with low capital costs.

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Hassan, Refat M., S. A. El-Shatoury, and M. Th Makhlouf. "Alginate Polyelectrolyte Ionotropic Gels-XII. Chromatographic Separation of Divalent Transition Metal Ions using Alginates as Ion Exchangers." High Performance Polymers 4, no. 1 (February 1992): 49–54. http://dx.doi.org/10.1088/0954-0083/4/1/006.

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The separation of divalent metal ion mixtures has been investigated chromatographically on columns of either gel or sol forms of alginate polyelectrolyte. Separation was obtained in the form of narrow sharp zones for the metal ions. Ion exchange selectivity indicated that Cu2+ ions were most strongly retained among the divalent metal ions studied. The factors which affect the ion exchange selectivity, such as the strength of chelation and the mobility and radii of the metal ions, are discussed. The selectivity coefficient for the separation of a mixture of Cu2+ and Co2+ ions on columns of calcium alginate gel or sodium alginate sol was determined and found to be 1.9 ± 0.1 in both ion exchangers at 25°C.

36

Mandal, Suraj Kumar, and Shankar Prasad Kanaujia. "Structural and thermodynamic insights into a novel Mg²⁺–citrate-binding protein from the ABC transporter superfamily." Acta Crystallographica Section D Structural Biology 77, no. 12 (November 11, 2021): 1516–34. http://dx.doi.org/10.1107/s2059798321010457.

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More than one third of proteins require metal ions to accomplish their functions, making them obligatory for the growth and survival of microorganisms in varying environmental niches. In prokaryotes, besides their involvement in various cellular and physiological processes, metal ions stimulate the uptake of citrate molecules. Citrate is a source of carbon and energy and is reported to be transported by secondary transporters. In Gram-positive bacteria, citrate molecules are transported in complex with divalent metal ions, whereas in Gram-negative bacteria they are translocated by Na+/citrate symporters. In this study, the presence of a novel divalent-metal-ion-complexed citrate-uptake system that belongs to the primary active ABC transporter superfamily is reported. For uptake, the metal-ion-complexed citrate molecules are sequestered by substrate-binding proteins (SBPs) and transferred to transmembrane domains for their transport. This study reports crystal structures of an Mg2+–citrate-binding protein (MctA) from the Gram-negative thermophilic bacterium Thermus thermophilus HB8 in both apo and holo forms in the resolution range 1.63–2.50 Å. Despite binding various divalent metal ions, MctA possesses the coordination geometry to bind its physiological metal ion, Mg2+. The results also suggest an extended subclassification of cluster D SBPs, which are known to bind and transport divalent-metal-ion-complexed citrate molecules. Comparative assessment of the open and closed conformations of the wild-type and mutant MctA proteins suggests a gating mechanism of ligand entry following an `asymmetric domain movement' of the N-terminal domain for substrate binding.

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Aberuagba, Adepeju, Enoch B. Joel, Adebayo J. Bello, Adedoyin Igunnu, Sylvia O. Malomo, and Femi J. Olorunniji. "Thermophilic PHP Protein Tyrosine Phosphatases (Cap8C and Wzb) from Mesophilic Bacteria." International Journal of Molecular Sciences 25, no. 2 (January 19, 2024): 1262. http://dx.doi.org/10.3390/ijms25021262.

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Protein tyrosine phosphatases (PTPs) of the polymerase and histidinol phosphatase (PHP) superfamily with characteristic phosphatase activity dependent on divalent metal ions are found in many Gram-positive bacteria. Although members of this family are co-purified with metal ions, they still require the exogenous supply of metal ions for full activation. However, the specific roles these metal ions play during catalysis are yet to be well understood. Here, we report the metal ion requirement for phosphatase activities of S. aureus Cap8C and L. rhamnosus Wzb. AlphaFold-predicted structures of the two PTPs suggest that they are members of the PHP family. Like other PHP phosphatases, the two enzymes have a catalytic preference for Mn2+, Co2+ and Ni2+ ions. Cap8C and Wzb show an unusual thermophilic property with optimum activities over 75 °C. Consistent with this model, the activity–temperature profiles of the two enzymes are dependent on the divalent metal ion activating the enzyme.

38

Lin, Lin, Lei Jiang, Hongzhen Guo, Li Yang, and Zizheng Liu. "Optimization of divalent metal cations for maximal concentration of Monacolin K in Monascus M1 by response surface methodology." Czech Journal of Food Sciences 37, No. 5 (October 31, 2019): 312–18. http://dx.doi.org/10.17221/74/2019-cjfs.

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Inorganic salts are important factors in the growth and secondary metabolites production of microorganisms. This study investigated the influences of divalent metal cations, Mn2+, Zn2+, and Mg2+ on the cell growth and Monacolin K production in Monascus M1. Then the concentration of the three kinds of divalent metal cations was optimized by response surface methodology, and the optimum conditions for the highest production of Monacolin K were determined. The optimum concentrations of the three divalent metal ions were selected as follow: Mn2+ 0.33%, Zn2+ 0.16%, and Mg2+ 1%. In this condition the concentration of Monacolin K reached 9.57mg/g which was close to the predicted values, indicating that the model was adequate for the Monacolin K production. The yield of Monacolin K in Monascus can be increased by adding metal ions during industrial production.

39

Pehlivan, E., and F. Gode. "Batch Sorption of Divalent Metal Ions onto Brown Coal." Energy Sources, Part A: Recovery, Utilization, and Environmental Effects 28, no. 16 (December 2006): 1493–508. http://dx.doi.org/10.1080/15567030600817936.

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40

Wyttenbach, Thomas, Dengfeng Liu, and Michael T. Bowers. "Interactions of the Hormone Oxytocin with Divalent Metal Ions." Journal of the American Chemical Society 130, no. 18 (May 2008): 5993–6000. http://dx.doi.org/10.1021/ja8002342.

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41

Materazzi, S., C. Nugnes, A. Gentili, and R. Curini. "Complexes of adrenaline with some divalent transition-metal ions." Thermochimica Acta 369, no. 1-2 (March 2001): 167–73. http://dx.doi.org/10.1016/s0040-6031(00)00753-x.

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42

Tomida, Tahei, Masahiko Tomida, Yoshikazu Nishihara, Ichiro Nakabayashi, Tatsuya Okazaki, and Seizo Masuda. "Properties of polyacryloylacetone for adsorption of divalent metal ions." Polymer 31, no. 1 (January 1990): 102–5. http://dx.doi.org/10.1016/0032-3861(90)90357-5.

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43

Zhou, Jinwei, Fuqun Zhao, Yiting Li, Fushi Zhang, and Xinqi Song. "Novel chelation of photochromic spironaphthoxazines to divalent metal ions." Journal of Photochemistry and Photobiology A: Chemistry 92, no. 3 (December 1995): 193–99. http://dx.doi.org/10.1016/1010-6030(95)04136-0.

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44

Xu, Y. "Winding of the DNA helix by divalent metal ions." Nucleic Acids Research 25, no. 20 (October 15, 1997): 4067–71. http://dx.doi.org/10.1093/nar/25.20.4067.

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Das, Babulal, and Jubaraj B. Baruah. "Coordinated cations in dipicolinato complexes of divalent metal ions." Inorganica Chimica Acta 363, no. 7 (April 2010): 1479–87. http://dx.doi.org/10.1016/j.ica.2010.01.025.

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Rossi, Claudio, Maria Rosaria Sansoni, and Alessandro Donati. "Coordination behaviour of gibberellic acid towards divalent metal ions." Journal of Inorganic Biochemistry 43, no. 2-3 (August 1991): 159. http://dx.doi.org/10.1016/0162-0134(91)84153-z.

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47

Sorokin, Victor A., Vladimir A. Valeev, Marina V. Degtyar, Galina O. Gladchenko, and Yuri P. Blagoi. "Interaction of divalent metal ions with poly(riboinosinic acid)." Macromolecular Chemistry and Physics 201, no. 17 (November 1, 2000): 2408–16. http://dx.doi.org/10.1002/1521-3935(20001101)201:17<2408::aid-macp2408>3.0.co;2-p.

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48

Mallet, A. M., A. B. Davis, D. R. Davis, J. Panella, K. J. Wallace, and M. Bonizzoni. "A cross reactive sensor array to probe divalent metal ions." Chemical Communications 51, no. 95 (2015): 16948–51. http://dx.doi.org/10.1039/c5cc05489c.

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49

Mel'gunov, V. I., E. I. Akimova, and K. S. Krasavchenko. "Effect of divalent metal ions on annexin-mediated aggregation of asolectin liposomes." Acta Biochimica Polonica 47, no. 3 (September 30, 2000): 675–83. http://dx.doi.org/10.18388/abp.2000_3988.

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Annexins belong to a family of Ca2+- and phospholipid-binding proteins that can mediate the aggregation of granules and vesicles in the presence of Ca2+. We have studied the effects of different divalent metal ions on annexin-mediated aggregation of liposomes using annexins isolated from rabbit liver and large unilamellar vesicles prepared from soybean asolectin II-S. In the course of these studies, we have found that annexin-mediated aggregation of liposomes can be driven by various earth and transition metal ions other than Ca2+. The ability of metal ions to induce annexin-mediated aggregation decreases in the order: Cd2+ > Ba2+, Sr2+ > Ca2+ > Mn2+ > Ni2+ > Co2+. Annexin-mediated aggregation of vesicles is more selective to metal ions than the binding of annexins to membranes. We speculate that not every type of divalent metal ion can induce conformational change sufficient to promote the interaction of annexins either with two opposing membranes or with opposing protein molecules. Relative concentration ratios of metal ions in the intimate environment may be crucial for the functioning of annexins within specialized tissues and after treatment with toxic metal ions.

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Wang, Jian, and Yi Fan Zhang. "The Study of Divalent Metal Ion Catalysts on Phenol-Formaldehyde Resol Resins." Applied Mechanics and Materials 71-78 (July 2011): 818–21. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.818.

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The curing characteristic of phenol-formaldehyde resol resins catalyzed with magnesium hydroxide, calcium hydroxide and barium hydroxide was studied in this study.The effects of catalysts on chemical structure of phenol formaldehyde resin was investigated by fourier transform infrared.The results indicated that divalent metal ions catalysts played an important role influence both the cure rate and cure time.Phenol formaldehyde resin catalysed by diffierent catalysts showed diffierent addition of formaldehyde onto ortho positions of phenolic rings.The order of the divalent metal ions effectiveness studied in alkaline conditions is calcium hydroxide, barium hydroxide and magnesium hydroxide.

Статті в журналах з теми "Divalent metal ions release"

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