Probing cationic selectivity of cardiac calsequestrin and its CPVT mutants

CASQ (calsequestrin) is a Ca2+-buffering protein localized in the muscle SR (sarcoplasmic reticulum); however, it is unknown whether Ca2+ binding to CASQ2 is due to its location inside the SR rich in Ca2+ or due to its preference for Ca2+ over other ions. Therefore a major aim of the present study was to determine how CASQ2 selects Ca2+ over other metal ions by studying monomer folding and subsequent aggregation upon exposure to alkali (monovalent), alkaline earth (divalent) and transition (polyvalent) metals. We additionally investigated how CPVT (catecholaminergic polymorphic ventricular tachycardia) mutations affect CASQ2 structure and its molecular behaviour when exposed to different metal ions. Our results show that alkali and alkaline earth metals can initiate similar molecular compaction (folding), but only Ca2+ can promote CASQ2 to aggregate, suggesting that CASQ2 has a preferential binding to Ca2+ over all other metals. We additionally found that transition metals (having higher co-ordinated bonding ability than Ca2+) can also initiate folding and promote aggregation of CASQ2. These studies led us to suggest that folding and formation of higher-order structures depends on cationic properties such as co-ordinate bonding ability and ionic radius. Among the CPVT mutants studied, the L167H mutation disrupts the Ca2+-dependent folding and, when folding is achieved by Mn2+, L167H can undergo aggregation in a Ca2+-dependent manner. Interestingly, domain III mutants (D307H and P308L) lost their selectivity to Ca2+ and could be aggregated in the presence of Mg2+. In conclusion, these studies suggest that CPVT mutations modify CASQ2 behaviour, including folding, aggregation/polymerization and selectivity towards Ca2+.

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Extraction properties of β-aminophosphine oxides towards lanthanides and alkaline earth metals

Open Chemistry ◽

10.2478/s11532-012-0124-0 ◽

2012 ◽

Vol 10 (6) ◽

pp. 1933-1941 ◽

Cited By ~ 4

Author(s):

Ekaterina Matveeva ◽

Elena Sharova ◽

Alexander Turanov ◽

Vasilii Karandashev ◽

Irina Odinets

Keyword(s):

Ionic Liquid ◽

Metal Ions ◽

Phosphine Oxide ◽

Separation Factor ◽

Alkaline Earth ◽

Extraction Efficiency ◽

Alkaline Earth Metals ◽

Neutral Media ◽

Extraction Properties

AbstractThe investigation of the extraction properties of a series of polyoligodentate β-aminophosphine oxides 1–8 bearing from one to six phosphine oxide groups in a molecule towards Ln(III) and alkaline earth metals ions from neutral media has revealed that, using common diluents, the extraction efficiency increases with an increase of a number of P=O functions in a ligand. The addition of ionic liquid, namely 1-butyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([bmim][NTf2]), significantly increasing the extraction efficiency and application of IL concentration of 0.05 M (in 1,2-dichloroethane) providing the maximum recovery of metal ions with Lu/La separation factor reaching up to 91. Hexapodal tris[bis(2-diphenylphosphorylethyl)aminoethyl]amine 8 demonstrates the highest extraction under all conditions applied and the separation factor for U and Eu of this compound exceeded 103.

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Zeta potential of clay minerals and quartz contaminated by heavy metals

Canadian Geotechnical Journal ◽

10.1139/t05-048 ◽

2005 ◽

Vol 42 (5) ◽

pp. 1280-1289 ◽

Cited By ~ 73

Author(s):

A Kaya ◽

Y Yukselen

Keyword(s):

Heavy Metals ◽

Zeta Potential ◽

Metal Ions ◽

Alkaline Earth ◽

Alkaline Earth Metals ◽

Ion Concentration ◽

Test Results ◽

Ζ Potential ◽

Pore Fluid Chemistry ◽

Electrokinetic Decontamination

Laboratory and in situ test results show that electrokinetic decontamination is a promising subsurface decontamination method. However, it has also been reported that several problems arise, such as reverse flow and pH gradient across the anode and the cathode during the electrokinetic decontamination process. Variation in pH alters the zeta (ζ) potential of soils, which is one of the factors affecting the efficiency of contaminant removal by the electrokinetic method. The magnitude of the ζ potential controls the fluid flow rate, whereas its sign controls the flow direction. However, research on how the ζ potential of soils changes under various chemical conditions is limited. In this paper, the effect of pore-fluid chemistry on the ζ potential of kaolinite, montmorillonite, and quartz powder is determined with NaCl, LiCl, CaCl2·2H2O, MgCl2·6H2O, CuCl2, CoCl2, ZnCl2, AlCl3, and Pb(NO3)2. The test results reveal that the ζ potential of the minerals with alkali and alkaline-earth metals changes according to the diffuse electrical double-layer theory. The hydrolyzable metal ions produce two points of zero charge (PZCs), one of which is that of the soil; and the other, that of hydrolyzable oxide. The ζ potential of minerals with hydrolyzable metal ions becomes increasingly positive and reaches its maximum value at neutral pH. It then decreases and again reaches very negative values at alkaline pH values (pH ∼ 10), depending on ion concentration and the bulk precipitation pH of hydrolyzable metals as hydrolyzable oxides. On the basis of the results of this study, it is recommended that the ζ potential of the soils be determined before electrokinetic decontamination.Key words: alkaline-earth metals, electrokinetic decontamination, heavy metals, zeta potential.

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Simultaneous Removal of Heavy-Metal Ions by MnO2 Loaded D301 Resin

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.255-260.2791 ◽

2011 ◽

Vol 255-260 ◽

pp. 2791-2796 ◽

Cited By ~ 2

Author(s):

Hong Mei Ma ◽

Zhi Liang Zhu ◽

Yong Qian Cheng

Keyword(s):

Aqueous Solution ◽

Heavy Metal ◽

Metal Ions ◽

Heavy Metal Ions ◽

Alkaline Earth ◽

Removal Rate ◽

Alkaline Earth Metals ◽

Simultaneous Removal ◽

High Concentration ◽

Solution Ph

MnO2-loaded D301 weak basic anion exchange resin was used as adsorbent to simultaneously remove Co2+, Ni2+, Cd2+, Zn2+ andCu2+ from aqueous solution contained high concentration of alkali and alkaline-earth metals ions. The effects of solution pH and coexistent ions on the adsorption were investigated. The results indicated that Co2+, Ni2+, Cd2+, Zn2+ andCu2+ can be simultaneously removed in the wide pH range of 3 to 8. The coexistence of PO43− decreased the heavy metal ions removal rate, but for other high concentrations coexistence cations and anions such as Na+, K+, Cl−, NO3−, SO42− and HCO3−, there is no significant impact on removal rate of heavy metals. The adsorption isotherm can be well described by Langmuir isotherm. The adsorption processes followed the pseudo first-order kinetics model. High adsorption capacity makes it a good promising candidate material for simultaneous removal of Co2+, Ni2+, Cd2+, Zn2+ andCu2+ from aqueous solution with the co-existence of high concentration of alkali and alkaline-earth metals ions.

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High Temperature Resistance Effect of SrO/(SrO+CaO) in Alkali-Free Boro-Aluminosilicate Glasses

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.704.149 ◽

2013 ◽

Vol 704 ◽

pp. 149-154 ◽

Cited By ~ 2

Author(s):

Ying Liang Tian ◽

Xian Long Guo ◽

Man Kang Zhu ◽

Shi Bing Sun ◽

Yong Li Li ◽

...

Keyword(s):

Electrical Resistivity ◽

High Temperature ◽

Alkaline Earth ◽

Ionic Radius ◽

Alkaline Earth Metals ◽

Glass Melts ◽

Arrhenius Plots ◽

Temperature Resistance ◽

Nonlinear Variation ◽

Aluminosilicate Glasses

This paper studied the change regulation of the electrical resistivity of alkali-free boro-aluminosilicate glasses with the rate of SrO/(CaO + SrO) in the range 600~1600°C.The results showed that a mixed alkaline effect was observed with the increase of SrO content in alkali-free aluminoborosilcate glasses: the maximam resistivity of 178Ωcm appeared at SrO/(CaO+SrO) ratio =0.24, which is much larger than 108Ωcm at SrO=0. Meanwhile, the experiment results showed that the SrO makes stronger influence on the resistivity of the glass than CaO does. The Arrhenius plots, which showed the change of the resistivity with temperature in range of 1100~1625°C, present nonlinear variation, and an inflection at about 1100°C. It proved that the electrical resistivity of the alkali-free aluminoborosilcate glasses were controlled by the ionic radius of alkaline earth metals and the viscosity of glass melts.

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