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Sample records for bind calcium ions

  1. Increased Binding of Calcium Ions at Positively Curved Phospholipid Membranes

    Czech Academy of Sciences Publication Activity Database

    Magarkar, Aniket; Jurkiewicz, Piotr; Allolio, Christoph; Hof, Martin; Jungwirth, Pavel

    2017-01-01

    Roč. 8, č. 2 (2017), s. 518-523 ISSN 1948-7185 R&D Projects: GA ČR(CZ) GA16-01074S; GA ČR(CZ) GAP207/12/0919 Grant - others:AV ČR(CZ) AP1102 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:61388963 ; RVO:61388955 Keywords : molecular dynamics * fluorescence spectroscopy * calcium * phospholipids Subject RIV: CF - Physical ; Theoretical Chemistry ; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Physical chemistry ; Physical chemistry (UFCH-W) Impact factor: 9.353, year: 2016

  2. All three Ca[superscript 2+]-binding loops of photoproteins bind calcium ions: The crystal structures of calcium-loaded apo-aequorin and apo-obelin

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Lu; Vysotski, Eugene S.; Markova, Svetlana V.; Liu, Zhi-Jie; Lee, John; Rose, John; Wang, Bi-Cheng (Georgia)

    2010-07-13

    The crystal structures of calcium-loaded apoaequorin and apo-obelin have been determined at resolutions 1.7 {angstrom} and 2.2 {angstrom}, respectively. A calcium ion is observed in each of the three EF-hand loops that have the canonical calcium-binding sequence, and each is coordinated in the characteristic pentagonal bipyramidal configuration. The calcium-loaded apo-proteins retain the same compact scaffold and overall fold as the unreacted photoproteins containing the bound substrate, 2-hydroperoxycoelenterazine, and also the same as the Ca{sup 2+}-discharged obelin bound with the product, coelenteramide. Nevertheless, there are easily discerned shifts in both helix and loop regions, and the shifts are not the same between the two proteins. It is suggested that these subtle shifts are the basis of the ability of these photoproteins to sense Ca{sup 2+} concentration transients and to produce their bioluminescence response on the millisecond timescale. A mechanism of intrastructural transmission of the calcium signal is proposed.

  3. Structural properties of the intrinsically disordered, multiple calcium ion-binding otolith matrix macromolecule-64 (OMM-64).

    Science.gov (United States)

    Poznar, Monika; Hołubowicz, Rafał; Wojtas, Magdalena; Gapiński, Jacek; Banachowicz, Ewa; Patkowski, Adam; Ożyhar, Andrzej; Dobryszycki, Piotr

    2017-11-01

    Fish otoliths are calcium carbonate biominerals that are involved in hearing and balance sensing. An organic matrix plays a crucial role in their formation. Otolith matrix macromolecule-64 (OMM-64) is a highly acidic, calcium-binding protein (CBP) found in rainbow trout otoliths. It is a component of high-molecular-weight aggregates, which influence the size, shape and polymorph of calcium carbonate in vitro. In this study, a protocol for the efficient expression and purification of OMM-64 was developed. For the first time, the complete structural characteristics of OMM-64 were described. Various biophysical methods were combined to show that OMM-64 occurs as an intrinsically disordered monomer. Under denaturing conditions (pH, temperature) OMM-64 exhibits folding propensity. It was determined that OMM-64 binds approximately 61 calcium ions with millimolar affinity. The folding-unfolding experiments showed that calcium ions induced the collapse of OMM-64. The effect of other counter ions present in trout endolymph on OMM-64 conformational changes was studied. The significance of disordered properties of OMM-64 and the possible function of this protein is discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Sequential binding of calcium ions to the B-repeat domain of SdrD from Staphylococcus aureus.

    Science.gov (United States)

    Roman, Andrei Yu; Devred, François; Lobatchov, Vladimir M; Makarov, Alexander A; Peyrot, Vincent; Kubatiev, Aslan A; Tsvetkov, Philipp O

    2016-02-01

    Biofilms of live bacteria forming on medical devices and implants contribute significantly to bacterial blood dissemination and to the spread of nosocomial infections. Cell surface SdrD protein plays a key role in the attachment of Staphylococcus aureus to the extracellular matrix (ECM) and in the formation of biofilm. SdrD binds calcium ions using its B1-B5 region bearing EF-hand Ca-binding sites, leading to conformational changes in the structure of SdrD. This alters the distance between the bacterial surface and the ECM-interacting domain of SdrD in a spring-like fashion, participating in bacterial attachment. In this study we investigated calcium binding to EF-hand sites of SdrD using isothermal titration calorimetry and determined the impact of this process on SdrD's thermodynamic stability. This allowed us to propose a model of B1-B5 reorganization upon binding of calcium and to get new insight into the molecular mechanism of SdrD's action.

  5. Calcium binding by dietary fibre

    International Nuclear Information System (INIS)

    James, W.P.T.; Branch, W.J.; Southgate, D.A.T.

    1978-01-01

    Dietary fibre from plants low in phytate bound calcium in proportion to its uronic-acid content. This binding by the non-cellulosic fraction of fibre reduces the availability of calcium for small-intestinal absorption, but the colonic microbial digestion of uronic acids liberates the calcium. Thus the ability to maintain calcium balance on high-fibre diets may depend on the adaptive capacity on the colon for calcium. (author)

  6. Calcium carbonate phosphate binding ion exchange filtration and accelerated denitrification improve public health standards and combat eutrophication in aquatic ecosystems.

    Science.gov (United States)

    Yanamadala, Vijay

    2005-01-01

    Hektoen agar. Initial analyses suggest a strong correlation between phosphate concentrations and bacterial populations; a 66% decrease in phosphate resulted in a 35% reduction in bacterial populations and a 45% reduction in enteropathogenic populations. Likewise, a strong correlation was shown between calcium carbonate concentrations and bacterial reduction greater than that which can be attributed to the phosphate reduction alone. This was followed by the construction of various phosphate binding calcium carbonate filters, which used the ion exchange principle, including a spring loading filter, PVC pipe filter, and a galvanized filter. All were tested with the aid of Stoke's law formulation. The experiment was extremely successful in designing a working phosphate-binding and ammonia-reducing filter, and a large-scale agitator-clarifier filter system is currently being planned for construction in Madrona Marsh; this filter will reduce phosphate and ammonia levels substantially in the following years, bringing ecological, economical, and health-related improvements to the overall ecosystem and habitat.

  7. Kinetic study of the effects of calcium ions on cationic artichoke (Cynara scolymus L.) peroxidase: calcium binding, steady-state kinetics and reactions with hydrogen peroxide.

    Science.gov (United States)

    Hiner, Alexander N P; Sidrach, Lara; Chazarra, Soledad; Varón, Ramón; Tudela, José; García-Cánovas, Francisco; Rodríguez-López, José Neptuno

    2004-01-01

    The apparent catalytic constant (k(cat)) of artichoke (Cynara scolymus L.) peroxidase (AKPC) with 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) increased 130-fold in the presence of calcium ions (Ca2+) but the affinity (K(m)) of the enzyme for ABTS was 500 times lower than for Ca2+-free AKPC. AKPC is known to exhibit an equilibrium between 6-aquo hexa-coordinate and penta-coordinate forms of the haem iron that is modulated by Ca2+ and affects compound I formation. Measurements of the Ca2+ dissociation constant (K(D)) were complicated by the water-association/dissociation equilibrium yielding a global value more than 1000 times too high. The value for the Ca2+ binding step alone has now been determined to be K(D) approximately 10 nM. AKPC-Ca2+ was more resistant to inactivation by hydrogen peroxide (H(2)O(2)) and exhibited increased catalase activity. An analysis of the complex H(2)O(2) concentration dependent kinetics of Ca2+-free AKPC is presented.

  8. ALG-2, a multifunctional calcium binding protein?

    DEFF Research Database (Denmark)

    Tarabykina, Svetlana; Mollerup, Jens; Winding Gojkovic, P.

    2004-01-01

    ALG-2 was originally discovered as a pro-apoptotic protein in a genetic screen. Due to its ability to bind calcium with high affinity it was postulated to provide a link between the known effect of calcium in programmed cell death and the molecular death execution machinery. This review article d...

  9. Binding energy of protonium ions

    Science.gov (United States)

    Assad Abdel-Raouf, Mohamed

    2009-11-01

    The goal of the present work is to calculate the binding energy of the protonium ions bar PPe+ and bar PPe- using Rayleigh- Ritz variational method. It is indicated that an employment of 21 components of the trial wavefunction yields -0.08793 eV as the ground state energy of these ions. Our result agrees quite well with recently obtained results based on elaborate Monte Carlo approximations. It confirms the possible formation of these ions in laboratory.

  10. Calcium ion currents mediating oocyte maturation events

    Directory of Open Access Journals (Sweden)

    Tosti Elisabetta

    2006-05-01

    Full Text Available Abstract During maturation, the last phase of oogenesis, the oocyte undergoes several changes which prepare it to be ovulated and fertilized. Immature oocytes are arrested in the first meiotic process prophase, that is morphologically identified by a germinal vesicle. The removal of the first meiotic block marks the initiation of maturation. Although a large number of molecules are involved in complex sequences of events, there is evidence that a calcium increase plays a pivotal role in meiosis re-initiation. It is well established that, during this process, calcium is released from the intracellular stores, whereas less is known on the role of external calcium entering the cell through the plasma membrane ion channels. This review is focused on the functional role of calcium currents during oocyte maturation in all the species, from invertebrates to mammals. The emerging role of specific L-type calcium channels will be discussed.

  11. Calcium-binding proteins from human platelets

    International Nuclear Information System (INIS)

    Gogstad, G.O.; Krutnes, M.B.; Solum, N.O.

    1983-01-01

    Calcium-binding platelet proteins were examined by crossed immunoelectrophoresis of solubilized platelets against antibodies to whole platelets followed by incubation of the immunoplates with 45 Ca 2 + and autoradiography. When the immunoplates had been pretreated with EDTA at pH 9.0 in order to remove divalent cations, three immunoprecipitates were markedly labelled with 45 Ca 2 + . These corresponded to the glycoprotein IIb-IIIa complex, glycoprotein Ia and a presently unidentified antigen termed G18. These antigens were membrane-bound and surface-oriented. When an excess of EDTA was introduced in the incubation media the results revealed that the glycoprotein IIb-IIIa complex and antigen G18, but not glycoprotein Ia, contained sites with a stronger affinity for calcium than has EDTA at pH 7.4 Immunoprecipitates of the separate glycoproteins IIb and IIIa both bound calcium in the same manner as the glycoprotein IIb-IIIa complex. As another approach, platelet-rich plasma was incubated with 45 Ca 2 + prior to crossed immunoelectrophoresis of the solubilized platelets. A single immunoprecipitate was wekly labelled. This did not correspond to any of the immunoprecipitates which were visible after staining with Coomassie blue. The labelling of this antigen was markedly increased when the platelt-rich plasma had been preincubated with EDTA and in this case a weak labelling of the glycoprotein IIB-IIIa precipitate also became apparent. No increased incorporation of calcium occured in any of these immunoprecipitates when the platelets were aggregated with ADP in the presence of 45 Ca 2 + . (orig.)

  12. Apolipoprotein B is a calcium binding protein

    Energy Technology Data Exchange (ETDEWEB)

    Dashti, N.; Lee, D.M.; Mok, T.

    1986-05-29

    Human hepatocarcinoma Hep G2 cells were grown in culture medium containing (/sup 45/Ca/sup 2 +/). The secreted lipoproteins of d < 1.063 g/ml and d 1.063-1.21 g/ml were isolated from the culture media and analyzed by 3.3% and 7% SDS-polyacrylamide gel electrophoresis. Radioactivity profiles of (/sup 45/Ca) from the gels showed that the peak of radioactivity corresponded to the apolipoprotein B band. The molar ratio of the incorporated (/sup 45/Ca/sup 2 +/) and apolipoprotein B was close to unity. No radioactivity was found associated with any other secreted apolipoproteins. To confirm these findings, apolipoprotein B-containing lipoproteins were precipitated with anti-apolipoprotein B and high density lipoproteins were precipitated with anti-apolipoprotein A-I. Only the former precipitate was radioactive. These results suggest that apolipoprotein B is a calcium binding protein.

  13. Novel Peptide with Specific Calcium-Binding Capacity from Schizochytrium sp. Protein Hydrolysates and Calcium Bioavailability in Caco-2 Cells

    Directory of Open Access Journals (Sweden)

    Xixi Cai

    2016-12-01

    Full Text Available Peptide-calcium can probably be a suitable supplement to improve calcium absorption in the human body. In this study, a specific peptide Phe-Tyr (FY with calcium-binding capacity was purified from Schizochytrium sp. protein hydrolysates through gel filtration chromatography and reversed phase HPLC. The calcium-binding capacity of FY reached 128.77 ± 2.57 μg/mg. Results of ultraviolet spectroscopy, fluorescence spectroscopy, and infrared spectroscopy showed that carboxyl groups, amino groups, and amido groups were the major chelating sites. FY-Ca exhibited excellent thermal stability and solubility, which were beneficial to be absorbed and transported in the basic intestinal tract of the human body. Moreover, the calcium bioavailability in Caco-2 cells showed that FY-Ca could enhance calcium uptake efficiency by more than three times when compared with CaCl2, and protect calcium ions against dietary inhibitors, such as tannic acid, oxalate, phytate, and Zn2+. Our findings further the progress of algae-based peptide-calcium, suggesting that FY-Ca has the potential to be developed as functionally nutraceutical additives.

  14. The distribution of free calcium ions in the cholesteatoma epithelium

    DEFF Research Database (Denmark)

    Svane-Knudsen, Viggo; Rasmussen, Gurli; Ottosen, Peter D

    2005-01-01

    The distribution of free calcium ions in normal skin and cholesteatoma epithelium was investigated using the oxalate precipitation method. In agreement with previous observations, we could demonstrate a calcium ion gradient in normal epidermis where the cells in stratum basale and spinosum reside...

  15. Protein arginine deiminase 2 binds calcium in an ordered fashion: implications for inhibitor design.

    Science.gov (United States)

    Slade, Daniel J; Fang, Pengfei; Dreyton, Christina J; Zhang, Ying; Fuhrmann, Jakob; Rempel, Don; Bax, Benjamin D; Coonrod, Scott A; Lewis, Huw D; Guo, Min; Gross, Michael L; Thompson, Paul R

    2015-04-17

    Protein arginine deiminases (PADs) are calcium-dependent histone-modifying enzymes whose activity is dysregulated in inflammatory diseases and cancer. PAD2 functions as an Estrogen Receptor (ER) coactivator in breast cancer cells via the citrullination of histone tail arginine residues at ER binding sites. Although an attractive therapeutic target, the mechanisms that regulate PAD2 activity are largely unknown, especially the detailed role of how calcium facilitates enzyme activation. To gain insights into these regulatory processes, we determined the first structures of PAD2 (27 in total), and through calcium-titrations by X-ray crystallography, determined the order of binding and affinity for the six calcium ions that bind and activate this enzyme. These structures also identified several PAD2 regulatory elements, including a calcium switch that controls proper positioning of the catalytic cysteine residue, and a novel active site shielding mechanism. Additional biochemical and mass-spectrometry-based hydrogen/deuterium exchange studies support these structural findings. The identification of multiple intermediate calcium-bound structures along the PAD2 activation pathway provides critical insights that will aid the development of allosteric inhibitors targeting the PADs.

  16. The role of uncoupling protein 3 regulating calcium ion uptake into mitochondria during sarcopenia

    Science.gov (United States)

    Nikawa, Takeshi; Choi, Inho; Haruna, Marie; Hirasaka, Katsuya; Maita Ohno, Ayako; Kondo Teshima, Shigetada

    Overloaded mitochondrial calcium concentration contributes to progression of mitochondrial dysfunction in aged muscle, leading to sarcopenia. Uncoupling protein 3 (UCP3) is primarily expressed in the inner membrane of skeletal muscle mitochondria. Recently, it has been reported that UCP3 is associated with calcium uptake into mitochondria. However, the mechanisms by which UCP3 regulates mitochondrial calcium uptake are not well understood. Here we report that UCP3 interacts with HS-1 associated protein X-1 (Hax-1), an anti-apoptotic protein that is localized in mitochondria, which is involved in cellular responses to calcium ion. The hydrophilic sequences within the loop 2, matrix-localized hydrophilic domain of mouse UCP3 are necessary for binding to Hax-1 of the C-terminal domain in adjacent to mitochondrial innermembrane. Interestingly, these proteins interaction occur the calcium-dependent manner. Indeed, overexpression of UCP3 significantly enhanced calcium uptake into mitochondria on Hax-1 endogenously expressing C2C12 myoblasts. In addition, Hax-1 knock-down enhanced calcium uptake into mitochondria on both UCP3 and Hax-1 endogenously expressing C2C12 myotubes, but not myoblasts. Finally, the dissociation of UCP3 and Hax-1 enhances calcium uptake into mitochondria in aged muscle. These studies identify a novel UCP3-Hax-1 complex regulates the influx of calcium ion into mitochondria in muscle. Thus, the efficacy of UCP3-Hax-1 in mitochondrial calcium regulation may provide a novel therapeutic approach against mitochondrial dysfunction-related disease containing sarcopenia.

  17. A Specific Peptide with Calcium-Binding Capacity from Defatted Schizochytrium sp. Protein Hydrolysates and the Molecular Properties

    Directory of Open Access Journals (Sweden)

    Xixi Cai

    2017-03-01

    Full Text Available Marine microorganisms have been proposed as a new kind of protein source. Efforts are needed in order to transform the protein-rich biological wastes left after lipid extraction into value-added bio-products. Thus, the utilization of protein recovered from defatted Schizochytrium sp. by-products presents an opportunity. A specific peptide Tyr-Leu (YL with calcium-binding capacity was purified from defatted Schizochytrium sp. protein hydrolysates through gel filtration chromatography and RP-HPLC. The calcium-binding activity of YL reached 126.34 ± 3.40 μg/mg. The calcium-binding mechanism was investigated through ultraviolet, fluorescence and infrared spectroscopy. The results showed that calcium ions could form dative bonds with carboxyl oxygen atoms and amino nitrogen atoms as well as the nitrogen and oxygen atoms of amide bonds. YL-Ca exhibited excellent thermal stability and solubility, which was beneficial for its absorption and transport in the basic intestinal tract of the human body. Moreover, the cellular uptake of calcium in Caco-2 cells showed that YL-Ca could enhance calcium uptake efficiency and protect calcium ions against precipitation caused by dietary inhibitors such as tannic acid, oxalate, phytate and metal ions. The findings indicate that the by-product of Schizochytrium sp. is a promising source for making peptide-calcium bio-products as algae-based functional supplements for human beings.

  18. Binding of corroded ions to human saliva.

    Science.gov (United States)

    Mueller, H J

    1985-05-01

    Employing equilibrium dialysis, the binding abilities of Cu, Al, Co and Cr ions from corroded Cu-Al and Co-Cr dental casting alloys towards human saliva and two of its gel chromatographic fractions were determined. Results indicate that both Cu and Co bind to human saliva i.e. 0.045 and 0.027 mg/mg protein, respectively. Besides possessing the largest binding ability, Cu also possessed the largest binding capacity. The saturation of Cu binding was not reached up to the limit of 0.35 mg protein/ml employed in the tests, while Co reached full saturation at about 0.2 mg protein/ml. Chromium showed absolutely no binding to human saliva while Al ions did not pass through the dialysis membranes. Compared to the binding with solutions that were synthetically made up to contain added salivary-type proteins, it is shown that the binding to human saliva is about 1 order of magnitude larger, at least for Cu ions.

  19. Intracellular Calcium Mobilization in Response to Ion Channel Regulators via a Calcium-Induced Calcium Release Mechanism

    OpenAIRE

    Petrou, Terry; Olsen, Herv?r L.; Thrasivoulou, Christopher; Masters, John R.; Ashmore, Jonathan F.; Ahmed, Aamir

    2017-01-01

    Free intracellular calcium ([Ca2+]i), in addition to being an important second messenger, is a key regulator of many cellular processes including the cell membrane potential, proliferation and apoptosis. In many cases, the mobilization of [Ca2+]i is controlled by intracellular store activation and calcium influx. We have investigated the effect of several ion channel modulators, which have been used to treat a range of human diseases, on [Ca2+]i release, by ratiometric calcium imaging. We sho...

  20. Calcium binding to calmodulin by molecular dynamics with effective polarization

    Czech Academy of Sciences Publication Activity Database

    Kohagen, Miriam; Lepšík, Martin; Jungwirth, Pavel

    2014-01-01

    Roč. 5, č. 22 (2014), s. 3964-3969 ISSN 1948-7185 R&D Projects: GA ČR GBP208/12/G016; GA MŠk LH12001 Institutional support: RVO:61388963 Keywords : EF-hand motif * free energy calculations * charge scaling * calcium -binding protein * umbrella sampling Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 7.458, year: 2014

  1. Engineering of specific uranyl-coordination sites in the calcium-binding motif of Calmodulin

    International Nuclear Information System (INIS)

    Beccia, M.; Pardoux, R.; Sauge-Merle, S.; Bremond, N.; Lemaire, D.; Berthomieu, C.; Delangle, P.; Guilbaud, P.

    2014-01-01

    Complete text of publication follows: Characterization of heavy metals interactions with proteins is fundamental for understanding the molecular factors and mechanisms governing ions toxicity and speciation in cells. This line of research will also help in developing new molecules able to selectively and efficiently bind toxic metal ions, which could find application for bio-detection or bioremediation purposes. We have used the regulatory calcium-binding protein Calmodulin (CaM) from A. thaliana as a structural model and, starting from it, we have designed various mutants by site-directed mutagenesis. We have analysed thermodynamics of uranyl ion binding to both sites I and II of CaM N-terminal domain and we have identified structural factors governing this interaction. Selectivity for uranyl ion has been tested by studying reactions of the investigated peptides with Ca 2+ , in the same conditions used for UO 2 2+ . Spectro-fluorimetric titrations and FTIR analysis have shown that the affinity for uranyl increases by phosphorylation of a threonine in site I, especially approaching the physiological pH, where the phospho-threonine side chain is deprotonated. Based on structural models obtained by Molecular Dynamics, we tested the effect of a two residues deletion on site I properties. We obtained an almost two orders of magnitude increase in affinity for uranyl, with a sub-nanomolar dissociation constant for the uranyl complex with the non phosphorylated peptide, and an improved uranyl/calcium selectivity. Allosteric effects depending on Ca 2+ and UO 2 2+ binding have been investigated by comparing thermodynamic parameters obtained for mutants having both sites I and II able to chelate metal ions with those of mutants consisting of just one active site

  2. Antioxidant activity and calcium binding of isomeric hydroxybenzoates

    Directory of Open Access Journals (Sweden)

    Zichen Zhao

    2018-04-01

    Full Text Available The association constant for calcium binding to hydroxybenzoates in aqueous 0.16 M NaCl at 25 °C was found electrochemically to have the value Kass = 280 mol L−1 with ΔHo = −51 kJ mol−1, ΔSo = −122 J mol−1 K−1 for the 2-isomer (salicylate, Kass = 7 mol L−1 with ΔHo = −39 kJ mol−1, ΔSo = −116 J mol−1 K−1 for the 3-isomer, and Kass = 8 mol L−1 with ΔHo = −51 kJ mol−1, ΔSo = −155 J mol−1 K−1 for the 4-isomer. The 3- and 4-isomers were found more efficient as antioxidants than the 2-isomer in decreasing oxygen consumption rate in a peroxidating methyl linoleate emulsion and less sensitive to presence of calcium. All isomers were found prooxidative for iron-catalyzed initiation of oxidation due to enhanced radical formation as shown by electron spin resonance spectroscopy. Calcium salicylate was found to have low solubility with a solubility product Ksp = 4.49·10−6 based on activity with ΔHo = 67 kJ mol−1, ΔSo = 123 J mol−1 K−1 for dissolution in water, when corrected for the strong complex formation. Calcium in food and beverages may thus lower antioxidant activity of plant phenols through complexation or by precipitation. Keywords: Antioxidant activity, Calcium binding, 2-Hydroxybenzoate, 3-Hydroxybenzoate, 4-Hydroxybenzoate

  3. Three-dimensional structure of recombinant carboxypeptidase T from Thermoactinomyces vulgaris without calcium ions

    Science.gov (United States)

    Akparov, V. Kh.; Timofeev, V. I.; Kuranova, I. P.

    2011-07-01

    Crystals of recombinant carboxypeptidase T (CPT) from Thermoactinomyces vulgaris were grown in a capillary by the counterdiffusion method in the absence of calcium ions. The three-dimensional structure of CPT was solved at 1.69-Å resolution using the X-ray diffraction data collected from the crystals of the enzyme on the SPring-8 synchrotron radiation facility and was then refined to Rfact = 16.903% and Rfree = 18.165%. The coordinates of the refined model were deposited in the Protein Data Bank (PDB ID: 3QNV). A comparison of this structure with the structure of wild-type CPT containing bound calcium ions, which was determined earlier, revealed a number of conformational changes both in the calcium-binding sites and the enzyme active site. Based on the results of this comparison, the possible factors responsible for the difference in the catalytic activity of the two forms of the enzyme are considered.

  4. Ion release and mechanical properties of calcium silicate and calcium hydroxide materials used for pulp capping.

    Science.gov (United States)

    Natale, L C; Rodrigues, M C; Xavier, T A; Simões, A; de Souza, D N; Braga, R R

    2015-01-01

    To compare the ion release and mechanical properties of a calcium hydroxide (Dycal) and two calcium silicate (MTA Angelus and Biodentine) cements. Calcium and hydroxyl ion release in water from 24-h set cements were calculated from titration with HCl (n = 3). Calcium release after 7, 14, 21 and 28 days at pH 5.5 and 7.0 was measured using ICP-OES (n = 6). Flexural strength (FS) and modulus (E) were tested after 48-h storage, and compressive strength (CS) was tested after 48 h and 7 days (n = 10). Ion release and mechanical data were subjected to anova/Tukey and Kruskal-Wallis/Mann-Whitney tests, respectively (α = 0.05). Titration curves revealed that Dycal released significantly fewer ions in solution than calcium silicates (P pH 7.0, whilst at pH 5.5, it dropped significantly by 24% after 21 days (P pH 5.5, MTA Angelus released significantly more calcium than Dycal (P pH 7.0 (P pH conditions. Biodentine had substantially higher strength and modulus than MTA Angelus and Dycal, both of which demonstrated low stress-bearing capabilities. © 2014 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  5. Asporin competes with decorin for collagen binding, binds calcium and promotes osteoblast collagen mineralization

    DEFF Research Database (Denmark)

    Kalamajski, Sebastian; Aspberg, Anders; Lindblom, Karin

    2009-01-01

    The interactions of the ECM (extracellular matrix) protein asporin with ECM components have previously not been investigated. Here, we show that asporin binds collagen type I. This binding is inhibited by recombinant asporin fragment LRR (leucine-rich repeat) 10-12 and by full-length decorin......, but not by biglycan. We demonstrate that the polyaspartate domain binds calcium and regulates hydroxyapatite formation in vitro. In the presence of asporin, the number of collagen nodules, and mRNA of osteoblastic markers Osterix and Runx2, were increased. Moreover, decorin or the collagen-binding asporin fragment...... LRR 10-12 inhibited the pro-osteoblastic activity of full-length asporin. Our results suggest that asporin and decorin compete for binding to collagen and that the polyaspartate in asporin directly regulates collagen mineralization. Therefore asporin has a role in osteoblast-driven collagen...

  6. Effects of calcium ions on titanium surfaces for bone regeneration.

    Science.gov (United States)

    Anitua, Eduardo; Piñas, Laura; Murias, Alia; Prado, Roberto; Tejero, Ricardo

    2015-06-01

    The chemistry and topography of implant surfaces are of paramount importance for the successful tissue integration of load-bearing dental and orthopedic implants. Here we evaluate in vitro and in vivo titanium implant surfaces modified with calcium ions (Ca(2+) surfaces). Calcium ions produce a durable chemical and nano-topographical modification of the titanium oxide interface. Time of flight secondary ion mass spectrometry examination of the outermost surface composition, shows that calcium ions in Ca(2+) surfaces effectively prevent adventitious hydrocarbon passivation of the oxide layer. In aqueous solutions Ca(2+) surfaces release within the first minute, 2/3 of the total measured Ca(2+), the rest is released over the following 85 days. Additionally, Ca(2+) surfaces significantly increase human fetal osteoblasts-like cell adhesion, proliferation and differentiation, as measured by the autocrine synthesis of osteopontin. Relevant for clinical application, after 12 weeks of healing in sheep tibia, microcomputer tomography and histomorphometric analysis show that Ca(2+) surfaces develop significantly more bone contacts and higher bone density in the 1mm region around the implant. Consequently, titanium implants modified with calcium ions represent a valuable tool to improve endosseous integration in the clinical practice. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Evaluation of pH and calcium ion release of calcium hydroxide pastes containing different substances.

    Science.gov (United States)

    Duarte, Marco Antônio Húngaro; Midena, Raquel Zanin; Zeferino, Márcia A; Vivan, Rodrigo Ricci; Weckwerth, Paulo Henrique; Dos Santos, Fernando; Guerreiro-Tanomaru, Juliane Maria; Tanomaru-Filho, Mário

    2009-09-01

    The objective of this study was to evaluate the pH and calcium ion release of calcium hydroxide pastes associated with different substances. Forty acrylic teeth with simulated root canals were divided into 4 groups according to the substance associated to the calcium hydroxide paste: chlorhexidine (CHX) in 2 formulations (1% solution and 2% gel), Casearia sylvestris Sw extract, and propylene glycol (control). The teeth with pastes and sealed coronal accesses were immersed in 10 mL deionized water. After 10 minutes, 24 hours, 48 hours, and 7, 15, and 30 days, the teeth were removed to another container, and the liquid was analyzed. Calcium ion release was measured by atomic absorption spectrophotometry, and pH readings were made with a pH meter. Data were analyzed statistically by analysis of variance and Tukey test (alpha = 0.05). Calcium analysis revealed significant differences (P .05) were observed among groups in the other periods. Regarding the pH, there were significant differences (P .05) were observed among groups. All pastes behaved similarly in terms of pH and calcium ion release in the studied periods.

  8. FhCaBP1 (FH22): A Fasciola hepatica calcium-binding protein with EF-hand and dynein light chain domains.

    Science.gov (United States)

    Cheung, Sarah; Thomas, Charlotte M; Timson, David J

    2016-11-01

    FH22 has been previously identified as a calcium-binding protein from the common liver fluke, Fasciola hepatica. It is part of a family of at least four proteins in this organism which combine an EF-hand containing N-terminal domain with a C-terminal dynein light chain-like domain. Here we report further biochemical properties of FH22, which we propose should be renamed FhCaBP1 for consistency with other family members. Molecular modelling predicted that the two domains are linked by a flexible region and that the second EF-hand in the N-terminal domain is most likely the calcium ion binding site. Native gel electrophoresis demonstrated that the protein binds both calcium and manganese ions, but not cadmium, magnesium, strontium, barium, cobalt, copper(II), iron (II), nickel, zinc, lead or potassium ions. Calcium ion binding alters the conformation of the protein and increases its stability towards thermal denaturation. FhCaBP1 is a dimer in solution and calcium ions have no detectable effect on the protein's ability to dimerise. FhCaBP1 binds to the calmodulin antagonists trifluoperazine and chlorpromazine. Overall, the FhCaBP1's biochemical properties are most similar to FhCaBP2 a fact consistent with the close sequence and predicted structural similarity between the two proteins. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Adsorption studies of phosphate ions on alginate-calcium carbonate ...

    African Journals Online (AJOL)

    Alginate-calcium carbonate composite beads was prepared by the sol-gel method and characterized by Fourier transform infra-red spectroscopy (FT-IR) and scanning electron microscope (SEM) instruments. Adsorption potential of phosphate ions have been studied on laboratory scale. The effects of contact time, adsorbent ...

  10. Adsorption studies of phosphate ions on alginate- calcium ...

    African Journals Online (AJOL)

    user

    Alginate-calcium carbonate composite beads was prepared by the sol-gel method and characterized by. Fourier transform infra-red spectroscopy (FT-IR) and scanning electron microscope (SEM) instruments. Adsorption potential of phosphate ions have been studied on laboratory scale. The effects of contact.

  11. Intracellular Calcium Mobilization in Response to Ion Channel Regulators via a Calcium-Induced Calcium Release Mechanism.

    Science.gov (United States)

    Petrou, Terry; Olsen, Hervør L; Thrasivoulou, Christopher; Masters, John R; Ashmore, Jonathan F; Ahmed, Aamir

    2017-02-01

    Free intracellular calcium ([Ca 2+ ] i ), in addition to being an important second messenger, is a key regulator of many cellular processes including cell membrane potential, proliferation, and apoptosis. In many cases, the mobilization of [Ca 2+ ] i is controlled by intracellular store activation and calcium influx. We have investigated the effect of several ion channel modulators, which have been used to treat a range of human diseases, on [Ca 2+ ] i release, by ratiometric calcium imaging. We show that six such modulators [amiodarone (Ami), dofetilide, furosemide (Fur), minoxidil (Min), loxapine (Lox), and Nicorandil] initiate release of [Ca 2+ ] i in prostate and breast cancer cell lines, PC3 and MCF7, respectively. Whole-cell currents in PC3 cells were inhibited by the compounds tested in patch-clamp experiments in a concentration-dependent manner. In all cases [Ca 2+ ] i was increased by modulator concentrations comparable to those used clinically. The increase in [Ca 2+ ] i in response to Ami, Fur, Lox, and Min was reduced significantly (P calcium was reduced to nM concentration by chelation with EGTA. The data suggest that many ion channel regulators mobilize [Ca 2+ ] i We suggest a mechanism whereby calcium-induced calcium release is implicated; such a mechanism may be important for understanding the action of these compounds. Copyright © 2017 by The Author(s).

  12. Neuronal Calcium Sensor 1 Has Two Variants with Distinct Calcium Binding Characteristics.

    Science.gov (United States)

    Wang, Baisheng; Boeckel, Göran R; Huynh, Larry; Nguyen, Lien; Cao, Wenxiang; De La Cruz, Enrique M; Kaftan, Edward J; Ehrlich, Barbara E

    2016-01-01

    Neuronal calcium sensor-1 (NCS-1 Var1) is a calcium-binding protein expressed in most tissues. We examined a poorly characterized variant of NCS-1 (Var2), identified only in humans where the N-terminal 22 amino acid residues of native NCS-1(MGKSNSKLKPEVVEELTRKTY) were replaced with 4 different residues (MATI). Because alterations in the level of expression of NCS-1 Var1 and the expression of NCS-1 variants have been correlated with several neurological diseases, the relative expression and functional role of NCS-1 Var2 was examined. We found that NCS-1 Var2 mRNA levels are not found in mouse tissues and are expressed at levels ~1000-fold lower than NCS-1 Var1 in three different human cell lines (SHSY5Y, HEK293, MB231). Protein expression of both variants was only identified in cell lines overexpressing exogenous NCS-1 Var2. The calcium binding affinity is ~100 times weaker in purified NCS-1 Var2 than NCS-1 Var1. Because truncation of NCS-1 Var1 has been linked to functional changes in neurons, we determined whether the differing properties of the NCS-1 variants could potentially contribute to the altered cell function. In contrast to previous reports showing that overexpression of NCS-1 Var1 increases calcium-dependent processes, functional differences in cells overexpressing NCS-1 Var2 were undetectable in assays for cell growth, cell death and drug (paclitaxel) potency. Our results suggest that NCS-1 Var1 is the primary functional version of NCS-1.

  13. Effects of Calcium Ion, Calpains, and Calcium Channel Blockers on Retinitis Pigmentosa

    Directory of Open Access Journals (Sweden)

    Mitsuru Nakazawa

    2011-01-01

    Full Text Available Recent advances in molecular genetic studies have revealed many of the causative genes of retinitis pigmentosa (RP. These achievements have provided clues to the mechanisms of photoreceptor degeneration in RP. Apoptosis is known to be a final common pathway in RP and, therefore, a possible therapeutic target for photoreceptor rescue. However, apoptosis is not a single molecular cascade, but consists of many different reactions such as caspase-dependent and caspase-independent pathways commonly leading to DNA fractionation and cell death. The intracellular concentration of calcium ions is also known to increase in apoptosis. These findings suggest that calpains, one of the calcium-dependent proteinases, play some roles in the process of photoreceptor apoptosis and that calcium channel antagonists may potentially inhibit photoreceptor apoptosis. Herein, the effects of calpains and calcium channel antagonists on photoreceptor degeneration are reviewed.

  14. Evaluation of calcium ion, hydroxyl ion release and pH levels in various calcium hydroxide based intracanal medicaments: An in vitro study.

    Science.gov (United States)

    Fulzele, Punit; Baliga, Sudhindra; Thosar, Nilima; Pradhan, Debaprya

    2011-10-01

    Evaluation of calcium ion and hydroxyl ion release and pH levels in various calcium hydroxide based intracanal medicaments. The purpose of this study was to evaluate calcium and hydroxyl ion release and pH levels of calcium hydroxide based products, namely, RC Cal, Metapex, calcium hydroxide with distilled water, along with the new gutta-percha points with calcium hydroxide. The materials were inserted in polyethylene tubes and immersed in deionized water. The pH variation, Ca(++) and OH(-) release were monitored periodically for 1 week. Statistical analysis was carried out using one-way analysis of variance and Tukey's post hoc tests with PASW Statistics version 18 software to compare the statistical difference. After 1 week, calcium hydroxide with distilled water and RC Cal raised the pH to 12.7 and 11.8, respectively, while a small change was observed for Metapex, calcium hydroxide gutta-percha points. The calcium released after 1 week was 15.36 mg/dL from RC Cal, followed by 13.04, 1.296, 3.064 mg/dL from calcium hydroxide with sterile water, Metapex and calcium hydroxide gutta-percha points, respectively. Calcium hydroxide with sterile water and RC Cal pastes liberate significantly more calcium and hydroxyl ions and raise the pH higher than Metapex and calcium hydroxidegutta-percha points.

  15. Radiation-induced radical ions in calcium sulfite

    Science.gov (United States)

    Bogushevich, S. E.

    2006-07-01

    We have used EPR to study the effect of γ radiation on calcium sulfite. We have observed and identified the radiation-induced radical ions SO 2 - (iso) with g = 2.0055 and SO 2 - (orth-1) with g1 = 2.0093, g2 = 2.0051, g3 = 2.0020, identical to the initial and thermally induced SO 2 - respectively, SO 3 - (iso) with g = 2.0031 and SO 3 - (axial) with g⊥ = 2.0040, g∥ = 2.0023, identical to mechanically induced SO 3 - . We have established the participation of radiation-induced radical ions SO 3 - in formation of post-radiation SO 2 - .

  16. Metal ion binding with dehydroannulenes – Plausible two ...

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. Theoretical investigations have been carried out at B3LYP/6-311++G** level of theory to study the binding interaction of various metal ions, Li+, Na+ and K+ with dehydroannulene systems. The present study reveals that alkali metal ions bind strongly to dehydroannulenes and the passage through the central.

  17. Studies on two calcium-binding proteins from squid optic lobe

    International Nuclear Information System (INIS)

    Sheldon, A.

    1988-01-01

    Investigations focused on the physicochemical and functional properties of squid calcium-binding protein (SCaBP) and squid calmodulin (SCaM). The physiochemical studies included characterization of Ca 2+ - and Mg 2+ -binding properties, and the effects of metal ion-binding on protein conformation. These studies were performed using various ionic conditions, including those physiological for the squid. Ca 2+ -binding by SCaBP, SCaM, and bovine brain calmodulin (BCaM) (for comparison) was measured by equilibrium dialysis. All three proteins bound 4 Ca 2+ per mol protein under each set of ionic conditions. Under conditions physiological for the squid, both the squid proteins bound Ca 2+ over a similar range of free Ca 2+ concentrations. Ca 2+ - and Mg 2+ -induced changes in the conformation of the proteins were studied by polyacrylamide gel electrophoresis, fluphenazine-Sepharose affinity chromatography, and ultraviolet absorption difference spectroscopy. The functional studies focused on the identification of squid optic lobe proteins which interacted with SCaBP and SCaM in a Ca 2+ - dependent manner. These proteins were identified by SCaBP- and SCaM-Sepharose affinity chromatography, an immunoblotting technique using a polyclonal anti-SCaBP antibody, and a 125 I-calmodulin overlay procedure

  18. Coprecipitation of alkali metal ions with calcium carbonate

    International Nuclear Information System (INIS)

    Okumura, Minoru; Kitano, Yasushi

    1986-01-01

    The coprecipitation of alkali metal ions Li + , Na + , K + and Rb + with calcium carbonate has been studied experimentally and the following results have been obtained: (1) Alkali metal ions are more easily coprecipitated with aragonite than with calcite. (2) The relationship between the amounts of alkali metal ions coprecipitated with aragonite and their ionic radii shows a parabolic curve with a peak located at Na + which has approximately the same ionic radius as Ca 2+ . (3) However, the amounts of alkali metal ions coprecipitated with calcite decrease with increasing ionic radius of alkali metals. (4) Our results support the hypothesis that (a) alkali metals are in interstitial positions in the crystal structure of calcite and do not substitute for Ca 2+ in the lattice, but (b) in aragonite, alkali metals substitute for Ca 2+ in the crystal structure. (5) Magnesium ions in the parent solution increase the amounts of alkali metal ions (Li + , Na + , K + and Rb + ) coprecipitated with calcite but decrease those with aragonite. (6) Sodium-bearing aragonite decreases the incorporation of other alkali metal ions (Li + , K + and Rb + ) into the aragonite. (author)

  19. Importance of diffuse metal ion binding to RNA.

    Science.gov (United States)

    Tan, Zhi-Jie; Chen, Shi-Jie

    2011-01-01

    RNAs are highly charged polyanionic molecules. RNA structure and function are strongly correlated with the ionic condition of the solution. The primary focus of this article is on the role of diffusive ions in RNA folding. Due to the long-range nature of electrostatic interactions, the diffuse ions can contribute significantly to RNA structural stability and folding kinetics. We present an overview of the experimental findings as well as the theoretical developments on the diffuse ion effects in RNA folding. This review places heavy emphasis on the effect of magnesium ions. Magnesium ions play a highly efficient role in stabilizing RNA tertiary structures and promoting tertiary structural folding. The highly efficient role goes beyond the mean-field effect such as the ionic strength. In addition to the effects of specific ion binding and ion dehydration, ion-ion correlation for the diffuse ions can contribute to the efficient role of the multivalent ions such as the magnesium ions in RNA folding.

  20. Calcium-permeable ion channels in the kidney

    Science.gov (United States)

    Zhou, Yiming

    2016-01-01

    Calcium ions (Ca2+) are crucial for a variety of cellular functions. The extracellular and intracellular Ca2+ concentrations are thus tightly regulated to maintain Ca2+ homeostasis. The kidney, one of the major organs of the excretory system, regulates Ca2+ homeostasis by filtration and reabsorption. Approximately 60% of the Ca2+ in plasma is filtered, and 99% of that is reabsorbed by the kidney tubules. Ca2+ is also a critical signaling molecule in kidney development, in all kidney cellular functions, and in the emergence of kidney diseases. Recently, studies using genetic and molecular biological approaches have identified several Ca2+-permeable ion channel families as important regulators of Ca2+ homeostasis in kidney. These ion channel families include transient receptor potential channels (TRP), voltage-gated calcium channels, and others. In this review, we provide a brief and systematic summary of the expression, function, and pathological contribution for each of these Ca2+-permeable ion channels. Moreover, we discuss their potential as future therapeutic targets. PMID:27029425

  1. Calcium Binding by Ro 60 Multiple Antigenic Peptides on PVDF Membrane.

    Science.gov (United States)

    Kurien, Biji T; Bachmann, Michael P

    2015-01-01

    Antibodies directed against ribonucleoprotein (RNP) particles are observed in systemic lupus erythematosus. Ro RNP particle is one such target. It is composed of a 60 kDa protein (Ro 60 or SS-A) that is non-covalently associated with at least one of the four short uridine-rich RNAs (the hY RNAs). Previously, we showed that multiple antigenic peptides (MAPs) made from the sequence of the Ro 60 autoantigen could be used, using double-immunodiffusion studies, enzyme-linked immunosorbant assay, affinity chromatography, and surface plasmon resonance, to show intramolecular and intermolecular protein-protein interaction within the Ro 60 RNP particle. We also observed that calcium is important in mediating this interaction. We hypothesized, therefore, that 60 kDa Ro is a calcium-binding protein. To investigate this, we electrophoresed 60 kDa Ro MAPs, transferred them to PVDF membrane, and assayed calcium binding using the Quin-2 system. Several Ro 60 MAPs were found to bind calcium using this assay, as well as bovine serum albumin, another calcium-binding protein. However, a MAP constructed from the Sm autoantigen did not bind to calcium. These data, along with our observation regarding the involvement of calcium in protein-protein interaction occurring between Ro 60 antigen and Ro 60 MAPs, makes us propose that Ro 60 antigen is a calcium-binding protein.

  2. FhCaBP2: a Fasciola hepatica calcium-binding protein with EF-hand and dynein light chain domains.

    Science.gov (United States)

    Thomas, Charlotte M; Timson, David J

    2015-09-01

    FhCaBP2 is a Fasciola hepatica protein which belongs to a family of helminth calcium-binding proteins which combine an N-terminal domain containing two EF-hand motifs and a C-terminal dynein light chain-like (DLC-like) domain. Its predicted structure showed two globular domains joined by a flexible linker. Recombinant FhCaBP2 interacted reversibly with calcium and manganese ions, but not with magnesium, barium, strontium, copper (II), colbalt (II), iron (II), nickel, lead or potassium ions. Cadmium (II) ions appeared to bind non-site-specifically and destabilize the protein. Interaction with either calcium or magnesium ions results in a conformational change in which the protein's surface becomes more hydrophobic. The EF-hand domain alone was able to interact with calcium and manganese ions; the DLC-like domain was not. Alteration of a residue (Asp-58 to Ala) in the second EF-hand motif in this domain abolished ion-binding activity. This suggests that the second EF-hand is the one responsible for ion-binding. FhCaBP2 homodimerizes and the extent of dimerization was not affected by calcium ions or by the aspartate to alanine substitution in the second EF-hand. The isolated EF-hand and DLC-like domains are both capable of homodimerization. FhCaBP2 interacted with the calmodulin antagonists trifluoperazine, chlorpromazine, thiamylal and W7. Interestingly, while chlorpromazine and thiamylal interacted with the EF-hand domain (as expected), trifluoperazine and W7 bound to the DLC-like domain. Overall, FhCaBP2 has distinct biochemical properties compared with other members of this protein family from Fasciola hepatica, a fact which supports the hypothesis that these proteins have different physiological roles.

  3. Biophysical characterization and functional studies on calbindin-D28K: A vitamin D-induced calcium-binding protein

    International Nuclear Information System (INIS)

    Leathers, V.L.

    1989-01-01

    Vitamin D dependent calcium binding protein, or calbindin-D, is the principal protein induced in the intestine in response to the steroid hormone 1,25(OH) 2 -vitamin D 3 . A definitive role for calbindin-D in vitamin D 3 mediated biological responses remains unclear. Biophysical and functional studies on chick intestinal calbindin-D 28K (CaBP) were initiated so that some insight might be gained into its relevance to the process of intestinal calcium transport. Calbindin-D belongs to a class of high affinity calcium binding proteins which includes calmodulin, parvalbumin and troponin C. The Ca 2+ binding stoichiometry and binding constants for calbindin-D 28K were quantitated by Quin 2 titration analysis. The protein was found to bind 5-6 Ca 2+ ions with a K D on the order of 10 -8 , in agreement with the 6 domains identified from the amino acid sequence. A slow Ca 2+ exchange rate (80 s -1 ) as assessed by 43 Ca NMR and extensive calcium dependent conformational changes in 1 H NMR spectra were also observed. Functional studies on chick intestinal CaBP were carried out by two different methods. Interactions between CaBP and intestinal cellular components were assessed via photoaffinity labeling techniques. Specific calcium dependent complexes for CaBP were identified with bovine intestinal alkaline phosphatase and brush border membrane proteins of 60 and 150 kD. CaBP was also found to co-migrate with the alkaline phosphatase activity of chick intestinal brush border membranes as evaluated by gel filtration chromatography. The second procedure for evaluating CaBP functionality has involved the quantitation of CaBP association with vesicular transport components as assessed by ELISA. CaBP, immunoreactivity was observed in purified lysosomes, microsomes and microtubules

  4. Structure-Functional Basis of Ion Transport in Sodium–Calcium Exchanger (NCX Proteins

    Directory of Open Access Journals (Sweden)

    Moshe Giladi

    2016-11-01

    Full Text Available The membrane-bound sodium–calcium exchanger (NCX proteins shape Ca2+ homeostasis in many cell types, thus participating in a wide range of physiological and pathological processes. Determination of the crystal structure of an archaeal NCX (NCX_Mj paved the way for a thorough and systematic investigation of ion transport mechanisms in NCX proteins. Here, we review the data gathered from the X-ray crystallography, molecular dynamics simulations, hydrogen–deuterium exchange mass-spectrometry (HDX-MS, and ion-flux analyses of mutants. Strikingly, the apo NCX_Mj protein exhibits characteristic patterns in the local backbone dynamics at particular helix segments, thereby possessing characteristic HDX profiles, suggesting structure-dynamic preorganization (geometric arrangements of catalytic residues before the transition state of conserved α1 and α2 repeats at ion-coordinating residues involved in transport activities. Moreover, dynamic preorganization of local structural entities in the apo protein predefines the status of ion-occlusion and transition states, even though Na+ or Ca2+ binding modifies the preceding backbone dynamics nearby functionally important residues. Future challenges include resolving the structural-dynamic determinants governing the ion selectivity, functional asymmetry and ion-induced alternating access. Taking into account the structural similarities of NCX_Mj with the other proteins belonging to the Ca2+/cation exchanger superfamily, the recent findings can significantly improve our understanding of ion transport mechanisms in NCX and similar proteins.

  5. Variations in Calcium and Alginate Ions Concentration in Relation to the Properties of Calcium Alginate Nanoparticles

    Directory of Open Access Journals (Sweden)

    Hamed Daemi

    2013-05-01

    Full Text Available Alginate belongs to a group of natural polymers called polysaccharides. They have carboxylic functional groups beside hydroxyls which are common in all polysaccharides. These materials show interesting properties due to theirfunctional groups. One of these properties is the ability of this polymer as a suitable carrier of protecting and transferring drugs and biomolecules. The particle sizes of these polymers are very important for their applications, so different techniques were used for preparation of these materials. In this way polymeric nanoparticles of calcium alginate which are excellent carriers in drug delivery systems were prepared by addition of calcium chloride solution to dilute solution of sodium alginate. Investigation of the size and distribution of nanoparticles were analyzed by SEM method. The concentration effects of both alginate and calcium ions on the size and distribution of  nanoparticles were studied in this research. Results showed that the size of nanoparticles obviously decreased with decreasing polymeric alginate concentration because of lower active sites in polymer chain. On the other hand, thesize and distribution of nanoparticles are significantly improved with increase of calcium cation concentrations. The mean particle size 40-70 nm and spherical shape are the main characteristics of the prepared nanoparticles.

  6. Location and nature of calcium-binding sites in salivary acidic proline-rich phosphoproteins

    International Nuclear Information System (INIS)

    Bennick, A.; McLaughlin, A.C.; Grey, A.A.; Madapallimattam, G.

    1981-01-01

    The location of the calcium-binding sites in the human acidic proline-rich proteins, salivary proteins A and C, was determined by equilibrium dialysis of the tryptic peptides with buffers containing 45 Ca. All the calcium-binding sites are located in the NH 2 -terminal tryptic peptide (TX peptide). The nature of the calcium binding sites in the TX peptide and native salivary proteins A and C, as well as dephosphorylated proteins was compared. Two types of sites can be distinguished in peptide TX. Type I sites have an apparent dissociation constant (K) of 38 μM and are responsible for the binding of 2.6 mol of Ca/mol of peptide. The corresponding figures for Type II sites are 780 μM and 5.3 mol of Ca/mol of peptide. In the native proteins, the amount of calcium bound at the type II sites decreases to 3.9 mol of Ca/mol of proteins A and C and K increases to 1100 μM. The amount of calcium bound at type I sites decreases to 1.5 mol/mol of protein A and 0.6 mol/mol of protein C, but there is no change in K. Dephosphorylation affects the calcium binding at both types of sites. The experiments indicate that the COOH-terminal parts of the native proteins affect the number and the nature of the protein calcium-binding sites. Proton and phosphorous NMR data demonstrate that β-COOH in aspartic acid, as well as phosphoserine, are part of the calcium-binding sites. The difference in calcium binding to salivary proteins A and C may be due at least partially to differences in the environment of one or more aspartic acids

  7. Structural Insight into the Ion-Exchange Mechanism of the Sodium/Calcium Exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Jun; Li, Hua; Zeng, Weizhong; Sauer, David B.; Belmares, Ricardo; Jiang, Youxing (UTSMC)

    2012-06-19

    Sodium/calcium (Na{sup +}/Ca{sup 2+}) exchangers (NCX) are membrane transporters that play an essential role in maintaining the homeostasis of cytosolic Ca{sup 2+} for cell signaling. We demonstrated the Na{sup +}/Ca{sup 2+}-exchange function of an NCX from Methanococcus jannaschii (NCX{_}Mj) and report its 1.9 angstrom crystal structure in an outward-facing conformation. Containing 10 transmembrane helices, the two halves of NCX{_}Mj share a similar structure with opposite orientation. Four ion-binding sites cluster at the center of the protein: one specific for Ca{sup 2+} and three that likely bind Na{sup +}. Two passageways allow for Na{sup +} and Ca{sup 2+} access to the central ion-binding sites from the extracellular side. Based on the symmetry of NCX{_}Mj and its ability to catalyze bidirectional ion-exchange reactions, we propose a structure model for the inward-facing NCX{_}Mj.

  8. Calcium isotope fractionation in ion-exchange chromatography

    International Nuclear Information System (INIS)

    Russell, W.A.; Papanastassiou, D.A.

    1978-01-01

    Significant fractionation of the isotopes of calcium has been observed during elution through short ion-exchange columns packed with Dowex 50W-X8 resin. A double isotopic tracer was used to provide correction for instrumental fractionation effects. The absolute 40 Ca/ 44 Ca ratio is determined by this method to 0.05% and provides a measure of the fractionation of all Ca isotopes. It is found that the lighter isotopes are preferentially retained by the resin, with variations in 40 Ca/ 44 Ca between the first and last fractions of up to 1.1%. An estimate of the separation factor between batch solute and resin gives epsilon = 2.1 x 10 -4 . Details of the chemical or physical mechanisms causing isotope fractionation of Li, Na, Ca, and other elements during ion-exchange chromatography are not yet clear

  9. Neutrophils and the calcium-binding protein MRP-14 mediate carrageenan-induced antinociception in mice

    Directory of Open Access Journals (Sweden)

    Rosana L. Pagano

    2002-01-01

    Full Text Available Background: We have previously shown that the calcium-binding protein MRP-14 secreted by neutrophils mediates the antinociceptive response in an acute inflammatory model induced by the intraperitoneal injection of glycogen in mice.

  10. Identification and quantification of calcium-binding proteins in squid axoplasm

    International Nuclear Information System (INIS)

    Krinks, M.H.; Klee, C.B.; Pant, H.C.; Gainer, H.

    1988-01-01

    The identities and quantities of calcium-binding proteins were determined in axoplasm isolated from the squid giant axon. 45 Ca-binding assays on nitrocellulose filters containing axoplasm proteins separated by SDS-polyacrylamide electrophoresis revealed 4 major calcium-binding bands. These included the high-molecular-weight (Mr greater than 330 and 220 X 10(3] neurofilament proteins, an unidentified protein band that migrated around Mr 55,000, and a diverse group of proteins that migrated together around Mr 17,000. The low-molecular-weight (Mr 17,000) calcium-binding proteins could be resolved into calmodulin (ca. 120 mumol/kg axoplasm), 2 other Mr 17,000 calcium-binding proteins, and a small amount of calcineurin B. It is estimated that these calcium-binding proteins in squid axoplasm could theoretically bind about 1 mmol Ca 2+ /kg axoplasm. 125 I-Calmodulin overlay and Western blot analyses disclosed a number of calmodulin-binding proteins in axoplasm. These included fodrin, calcineurin A, and Ca 2+ /CaM protein kinase II subunits

  11. The effect of calcium ions on adhesion and competitive exclusion of Lactobacillus ssp. and E. coli O138

    DEFF Research Database (Denmark)

    Larsen, Nadja; Nissen, Peter; Willats, William G.T.

    2007-01-01

    that bacteria may share the same binding sites for attachment to intestinal cells. Furthermore, it was revealed that calcium ions significantly increased the binding of tested lactobacilli to IPEC-J2 cells; and therefore, added calcium may be useful in enhancing the adhesion of normally weakly adhesive...... probiotic cultures. In contrast, no significant change in adhesion of lactobacilli was observed in the presence of Mg and Zn ions. Displacement assays performed with pathogenic E. coli O138 showed that all tested Lactobacillus strains reduced the attachment of E. coli O138 to IPEC-J2 by more than 2-fold...

  12. Calcium binding to low molecular weight compounds and health promoting products

    DEFF Research Database (Denmark)

    Vavrusova, Martina

    food. Therefore, an understanding of the basic chemistry of calcium binding to low molecular weight compounds can contribute to a general knowledge about calcium bioavailability and also to product improvement. Calcium precipitation with palmitate was described by a first-order reaction for conditions...... only slowly precipitated after a lag phase. On the other hand, the slow dissolution of calcium D-gluconate by sodium L-lactate in aqueous solution with the reverse lactate/gluconate ratio did not result in a similar solution since fast precipitation prevented formation of a homogenous solution....

  13. Porous polymer film calcium ion chemical sensor and method of using the same

    Science.gov (United States)

    Porter, M.D.; Chau, L.K.

    1991-02-12

    A method of measuring calcium ions is disclosed wherein a calcium sensitive reagent, calcichrome, is immobilized on a porous polymer film. The reaction of the calcium sensitive reagent to the Ca(II) is then measured and concentration determined as a function of the reaction. 1 figure.

  14. Structure and calcium binding activity of LipL32, the major surface antigen of pathogenic Leptospira sp

    International Nuclear Information System (INIS)

    Hauk, Pricila; Roman-Ramos, Henrique; Ho, Paulo Lee; Guzzo, Cristiane R.; Farah, Chuck S.

    2009-01-01

    Leptospirosis, caused by the spirochaete Leptospira is an important emerging infectious disease. LipL32 is the major exposed outer membrane protein found exclusively in pathogenic leptospira. It is highly immunogenic and has been shown to bind to host extracellular matrix components, including collagens, fibronectin and laminin. In this work we crystallized recombinant LipL32 protein and determined its structure to 2.25 A resolution. Initial phases were determined using the multi-wavelength anomalous dispersion technique with data collected from selenomethionine-containing crystals at the MX2 beamline at the LNLS. The LipL32 monomer is made of a jelly-roll fold core from which protrude several peripheral secondary structures. Some structural features suggested that LipL32 could bind Ca 2+ ions and indeed, spectroscopic data (circular (dichroism. intrinsic tryptophan fluorescence and extrinsic 1-amino-2-anaphthol-4-sulfonic acid fluorescence) confirmed the calcium binding properties of LipL32. (author)

  15. Calcium binding to low molecular weight compounds and health promoting products

    DEFF Research Database (Denmark)

    Vavrusova, Martina

    of excess calcium in neutral aqueous solutions with a stoichiometry Ca:Pal lower than 1:2. Increasing pH during aging of the precipitate and solubility product determination lead to a suggestion of an initial precipitation of calcium hydroxy palmitate as a possible precursor phase. The binding of calcium...... to acidic amino acids and dipeptides was also investigated. It was found that aspartate binds calcium stronger than glutamate. This was confirmed by electrochemical determination of the association constants for aqueous solutions at ionic strength 0.20 and 1.0. The mixed dipeptides Asp/Glu showed additive...... solutions clearly indicated a 1:1 stoichiometry for the complex formation as determined electrochemically and also by the iodometric titration for both ionic strengths of 0.20 and 1.0 at 25 °C. Therefore, the increased solubility in the mixed solutions of calcium hydroxycarboxylates was due to complex...

  16. Distribution of calcium-binding proteins in the chick visual system

    Directory of Open Access Journals (Sweden)

    C.P. Pfeiffer

    1997-11-01

    Full Text Available The calcium-binding proteins calbindin (CB, calretinin (CR, and parvalbumin (PV have been extensively studied over the last decade since they appear to be important as buffers of intracellular calcium. In the present study we investigated the distribution of these proteins in the chick visual system by means of conventional immunocytochemistry. The results indicated that CB, CR, and PV are widely distributed in retinorecipient areas of the chick brain. In some regions, all three calcium-binding proteins were present at different intensities and often in different neurons such as in the dorsolateral thalamic complex. In other areas, such as the nucleus geniculatus lateralis ventralis, only CB and CR were detected, whereas PV was absent. These results show that these three calcium-binding proteins are differentially distributed in the visual system of the chick, with varying degrees of co-localization

  17. Calcium ions affect the hepatitis B virus core assembly

    International Nuclear Information System (INIS)

    Choi, Yongwook; Gyoo Park, Sung; Yoo, Jun-hi; Jung, Guhung

    2005-01-01

    Previous report showed that cytosolic Ca 2+ induced by hepatitis B virus X protein (HBx) promotes HBV replication. In this study, in vitro experiments showed that (i) HBV core assembly in vitro was promoted by Ca 2+ through the sucrose density gradient and the analytical ultracentrifuge analysis. Also (ii) transmission electron microscope analysis demonstrated these assembled HBV core particles were the capsids. Ex vivo experiments showed that the treatment of BAPTA-AM and cyclosporine A (CsA) reduced HBV capsids in the transfected HepG2 cells. In addition to that, the treatment of Thapsigargin (TG) increased HBV capsids in the transfected HepG2 cells. Furthermore, we investigated the increased HBV core assembly by HBx. The results show that the increased cytosolic calcium ions by HBx promote the HBV core assembly

  18. Randomized crossover study comparing the phosphate-binding efficacy of calcium ketoglutarate versus calcium carbonate in patients on chronic hemodialysis

    DEFF Research Database (Denmark)

    Bro, S; Rasmussen, R A; Handberg, J

    1998-01-01

    The objective of the study was to evaluate the phosphate-binding efficacy, side effects, and cost of therapy of calcium ketoglutarate granulate as compared with calcium carbonate tablets in patients on chronic hemodialysis. The study design used was a randomized, crossover open trial, and the main...... calcium concentration of 1.25 mmol/L and a fixed alfacalcidol dose for at least 2 months. All had previously tolerated therapy with calcium carbonate. Of the 19 patients included, 10 completed both treatment arms. After 12 weeks of therapy, the mean (+/-SEM) plasma ionized calcium level was significantly...... lower in the ketoglutarate arm compared with the calcium carbonate arm (4.8+/-0.1 mg/dL v 5.2+/-0.1 mg/dL; P = 0.004), whereas the mean plasma phosphate (4.5+/-0.3 mg/dL v 5.1+/-0.1 mg/dL) and PTH levels (266+/-125 pg/mL v 301+/-148 pg/mL) did not differ significantly between the two treatment arms...

  19. Determination of calcium and magnesium in nuclear grade alumina by ion chromatography technique

    International Nuclear Information System (INIS)

    Hespanhol, E.C.B.; Pires, M.A.F.; Atalla, L.T.

    1987-07-01

    A simple method for solubilization of alumina and separation of magnesium and calcium from alumina matrix was developed by initial coprecipitation of those elements with iron(III) hydroxide. Calcium and magnesium were later separated from iron chloride anionic complex in a Dowex 1-X 10 anionic exchange resin. The ion chromatography tecnnique was employed for the analysis of calcium and magnesium. One hundred percent recovery for calcium and magnesium was obtained in their separation from alumina. A precision of 6% and 10% for magnesium and calcium, respectively, was obtained in alumina samples analysis which contain less than 0,02% of magnesium and less than 0,08% of calcium. (Author) [pt

  20. Calcium phosphate formation in gelatin matrix using free ion precursors of Ca2+ and phosphate ions.

    Science.gov (United States)

    Chang, Myung Chul; DeLong, Ralph

    2009-02-01

    Hydroxyapatite (HAp)/gelatin (GEL) nanocomposite has been developed as a bone substitute. The nanocomposite formation in the GEL matrix is greatly affected by the reaction between Ca(2+) and phosphate ions. The mineralization of GEL macromolecules was investigated through a co-precipitation of calcium phosphates (Ca-P) by using free ions of Ca(2+) and phosphate ions, Pi. The purpose of this study was to prepare a dense HAp/GEL nanocomposite through a free ion production process. Free ionic calcium, Ca(2+), was produced through electrodialysis process using a cation membrane (CMV). Triprotic acid ions were diffused through an anion membrane (AMV) from an aqueous solution of H(3)PO(4). The HAp/GEL nanocomposite was prepared by the co-precipitation process. As a reference material for comparison, Ca(OH)(2) and H(3)PO(4) were used for the preparation of a HAp/GEL nanocomposite. The dense compact body of dried Ca-P/GEL nanocomposite was obtained through the fine chemical reaction of Ca(2+) and Pi. The free calcium ion Ca(2+), diffused from the CMV of the cation reactor greatly affected the formation of Ca-P phase. Phosphate ion species diffused through the AMV in the anion reactor definitely influenced the reaction with Ca(2+). For the formation of the Ca-P phase in the GEL matrix, the organic-inorganic interaction was analyzed using FT-IR. The crystal growth of HAp in the GEL matrix increased with the increase of GEL from XRD, FT-IR and TEM. The mineralization reaction in GEL macromolecules was critically influenced by the free ions of Ca(2+) and inorganic phosphate ions, Pi. The interaction between Ca(2+) and Pi in the GEL matrix was very fine compared to the HAp/GEL nanocomposite prepared from Ca(OH)(2) and H(3)PO(4) with the GEL. The dense compact body of HAp/GEL nanocomposite was obtained for an artificial bone application.

  1. Evaluation of pH, calcium ion release and antimicrobial activity of a new calcium aluminate cement

    Directory of Open Access Journals (Sweden)

    Fernanda de Carvalho Panzeri Pires-de-Souza

    2013-07-01

    Full Text Available This study evaluated the pH, calcium ion release and antimicrobial activity of EndoBinder (EB, containing different radiopacifiers: bismuth oxide (Bi2O3, zinc oxide (ZnO or zirconium oxide (ZrO2, in comparison to MTA. For pH and calcium ion release tests, 5 specimens per group (n = 5 were immersed into 10 mL of distilled and deionized water at 37°C. After 2, 4, 12, 24, 48 h; 7, 14 and 28 days, the pH was measured and calcium ion release quantified in an atomic absorption spectrophotometer. For antimicrobial activity, the cements were tested against S. aureus, E. coli, E. faecalis and C. albicans, in triplicate. MTA presented higher values for pH and calcium ion release than the other groups, however, with no statistically significant difference after 28 days (p > 0.05; and the largest inhibition halos for all strains, with no significant difference (E. coli and E. faecalis for pure EB and EB + Bi2O3 (p > 0.05. EB presented similar performance to that of MTA as regards pH and calcium ion release; however, when ZnO and ZrO2 were used, EB did not present antimicrobial activity against some strains.

  2. Characterization of P2X4 receptor agonists and antagonists by calcium influx and radioligand binding studies.

    Science.gov (United States)

    Abdelrahman, Aliaa; Namasivayam, Vigneshwaran; Hinz, Sonja; Schiedel, Anke C; Köse, Meryem; Burton, Maggi; El-Tayeb, Ali; Gillard, Michel; Bajorath, Jürgen; de Ryck, Marc; Müller, Christa E

    2017-02-01

    Antagonists for ATP-activated P2X4 ion channel receptors are currently in the focus as novel drug targets, in particular for the treatment of neuropathic and inflammatory pain. We stably expressed the human, rat and mouse P2X4 receptors in 1321N1 astrocytoma cells, which is devoid of functional nucleotide receptors, by retroviral transfection, and established monoclonal cell lines. Calcium flux assay conditions were optimized for high-throughput screening resulting in a Z'-factor of >0.8. The application of ready-to-use frozen cells did not negatively affect the results of the calcium assays, which is of great advantage for the screening of compound libraries. Species differences were observed, the rat P2X4 receptor being particularly insensitive to many ATP derivatives. Membrane preparations of the cell lines showed high levels of specific [ 35 S]ATPγS binding with low nonspecific binding (antagonist TNP-ATP displaced [ 35 S]ATPγS from its binding site at human P2X4 receptors, the non-nucleotidic antagonists paroxetine and 5-BDBD did not compete with radioligand binding and were therefore characterized as allosteric antagonists. Homology modeling was applied to find an explanation for the observed species differences. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Characterization of [125I]omega-conotoxin binding to brain N calcium channels and (-)[3H] desmethoxyverapamil binding to novel calcium channels in osteoblast-like osteosarcoma cells

    International Nuclear Information System (INIS)

    Wagner, J.A.

    1987-01-01

    This dissertation provides molecular evidence for a diversity of Ca 2+ channels in neuronal and non-neuronal tissues. First, I demonstrated specific, reversible, saturable binding sites for omega [ 125 I]conotoxin GVIA (omega[ 125 I]CTX) in rat brain and rabbit sympathetic ganglion. Omega [ 125 I]CTX binding has a unique pharmacology, ion selectivity, and anatomical distribution in rat brain. Omega [ 125 I]CTX binding was solubilized, retaining an appropriate pharmacology and ion selectivity. Omega[ 125 I]CTX binding may be associated with a Ca 2+ channel because the K/sub D/ of omega [ 125 I]CTX is similar to the IC 50 of inhibition of depolarization-induced 45 Ca 2+ flux into rat brain synaptosomes. Specific (-)[ 3 H]desmethoxyverapamil ((-)[ 3 H]DMV) binding sites were demonstrated on osteoblast-like osteosarcoma cell membranes

  4. The co-effect of collagen and magnesium ions on calcium carbonate biomineralization

    International Nuclear Information System (INIS)

    Jiao Yunfeng; Feng Qingling; Li Xiaoming

    2006-01-01

    The process of calcium carbonate biomineralization in the solution containing collagen and magnesium ions was studied in this paper. The results were characterized by using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effect rules were obtained by the cooperation of collagen and magnesium ions in different concentration. The experiment results showed that in the presence of both collagen and magnesium ions, aragonite and vaterite were precipitated at low Mg/Ca ion concentration ratio, while only aragonite with regular spherical morphology was precipitated at high Mg/Ca ion concentration ratio. It indicated that collagen has a promotional effect on magnesium ions in controlling the polymorph of calcium carbonate crystal. A much wider range of calcium carbonate morphologies was observed in the presence of both collagen and magnesium ions. The experiments suggested that collagen acts in combination with magnesium ions to inhibit calcite crystal growth, while favoring the formation of aragonite crystals

  5. Tight junction regulates epidermal calcium ion gradient and differentiation

    International Nuclear Information System (INIS)

    Kurasawa, Masumi; Maeda, Tetsuo; Oba, Ai; Yamamoto, Takuya; Sasaki, Hiroyuki

    2011-01-01

    Research highlights: → We disrupted epidermal tight junction barrier in reconstructed epidermis. → It altered Ca 2+ distribution and consequentially differentiation state as well. → Tight junction should affect epidermal homeostasis by maintaining Ca 2+ gradient. -- Abstract: It is well known that calcium ions (Ca 2+ ) induce keratinocyte differentiation. Ca 2+ distributes to form a vertical gradient that peaks at the stratum granulosum. It is thought that the stratum corneum (SC) forms the Ca 2+ gradient since it is considered the only permeability barrier in the skin. However, the epidermal tight junction (TJ) in the granulosum has recently been suggested to restrict molecular movement to assist the SC as a secondary barrier. The objective of this study was to clarify the contribution of the TJ to Ca 2+ gradient and epidermal differentiation in reconstructed human epidermis. When the epidermal TJ barrier was disrupted by sodium caprate treatment, Ca 2+ flux increased and the gradient changed in ion-capture cytochemistry images. Alterations of ultrastructures and proliferation/differentiation markers revealed that both hyperproliferation and precocious differentiation occurred regionally in the epidermis. These results suggest that the TJ plays a crucial role in maintaining epidermal homeostasis by controlling the Ca 2+ gradient.

  6. Identification of calcium-binding proteins in human platelets

    International Nuclear Information System (INIS)

    Brumley, L.M.; Wallace, R.W.

    1986-01-01

    In human platelets, intracellular Ca 2+ is a second messenger for platelet agonists. Two targets for the Ca 2+ signal are calmodulin and the C-,inase; however, other Ca 2+ -binding proteins may also play a role in platelet function. The Western blotting technique of Maruyama et al., which utilizes 45 Ca 2+ to detect Ca 2+ -binding proteins, has been used to identify numerous platelet Ca 2+ -binding proteins ranging in molecular weight from 165K to 15K. The greatest quantity of 45 Ca 2+ was bound to a 165 kilodalton protein which has been identified as thrombospondin based upon its release from thrombin-stimulated platelets and its comigration on SDS gels with purified thrombospondin. Two other major sites for 45 Ca 2+ -binding correspond to proteins of 120K and 108K which are present only in the platelet particulate fraction; they have been identified as glycoproteins IIb and IIIa based upon their labeling by 125 I-concanavalin A. Two proteins with molecular weights of 20K and 15K bound much less 45 Ca 2+ and correspond on SDS gels to calmodulin and subunit B of the calmodulin-dependent phosphatase. A number of other, yet to be identified, Ca 2+ -binding proteins were also detected. These data indicate that human platelets contain numerous Ca 2+ -binding proteins and that Western blotting techniques utilizing 45 Ca 2+ may be useful as an assay system in future attempts to purify platelet Ca 2+ -binding proteins

  7. Aptamer-Conjugated Calcium Phosphate Nanoparticles for Reducing Diabetes Risk via Retinol Binding Protein 4 Inhibition.

    Science.gov (United States)

    Torabi, Raheleh; Ghourchian, Hedayatollah; Amanlou, Massoud; Pasalar, Parvin

    2017-06-01

    Inhibition of the binding of retinol to its carrier, retinol binding protein 4, is a new strategy for treating type 2 diabetes; for this purpose, we have provided an aptamer-functionalized multishell calcium phosphate nanoparticle. First, calcium phosphate nanoparticles were synthesized and conjugated to the aptamer. The cytotoxicity of nanoparticles releases the process of aptamer from nanoparticles and their inhibition function of binding retinol to retinol binding protein 4. After synthesizing and characterizing the multishell calcium phosphate nanoparticles and observing the noncytotoxicity of conjugate, the optimum time (48 hours) and the pH (7.4) for releasing the aptamer from the nanoparticles was determined. The half-maximum inhibitory concentration (IC 50 ) value for inhibition of retinol binding to retinol binding protein 4 was 210 femtomolar (fmol). The results revealed that the aptamer could prevent connection between retinol and retinol binding protein 4 at a very low IC 50 value (210 fmol) compared to other reported inhibitors. It seems that this aptamer could be used as an efficient candidate not only for decreasing the insulin resistance in type 2 diabetes, but also for inhibiting the other retinol binding protein 4-related diseases. Copyright © 2017 Diabetes Canada. Published by Elsevier Inc. All rights reserved.

  8. Metal ion binding with dehydroannulenes – Plausible two ...

    Indian Academy of Sciences (India)

    WINTEC

    has highest interaction energy of –50∙6 kcal/mol at. B3LYP/6-311++G** level and is 128∙0 kcal/mol more than 1′-K+ complex. Understandably, the binding energy of metal complexes decreases with increase in the size of the metal ion, in accordance with ear- lier results.16,21. Placement of the metal ions at the centroid of ...

  9. High Affinity Binding of Indium and Ruthenium Ions by Gastrins.

    Directory of Open Access Journals (Sweden)

    Graham S Baldwin

    Full Text Available The peptide hormone gastrin binds two ferric ions with high affinity, and iron binding is essential for the biological activity of non-amidated forms of the hormone. Since gastrins act as growth factors in gastrointestinal cancers, and as peptides labelled with Ga and In isotopes are increasingly used for cancer diagnosis, the ability of gastrins to bind other metal ions was investigated systematically by absorption spectroscopy. The coordination structures of the complexes were characterized by extended X-ray absorption fine structure (EXAFS spectroscopy. Changes in the absorption of gastrin in the presence of increasing concentrations of Ga3+ were fitted by a 2 site model with dissociation constants (Kd of 3.3 x 10-7 and 1.1 x 10-6 M. Although the absorption of gastrin did not change upon the addition of In3+ ions, the changes in absorbance on Fe3+ ion binding in the presence of indium ions were fitted by a 2 site model with Kd values for In3+ of 6.5 x 10-15 and 1.7 x 10-7 M. Similar results were obtained with Ru3+ ions, although the Kd values for Ru3+ of 2.6 x 10-13 and 1.2 x 10-5 M were slightly larger than observed for In3+. The structures determined by EXAFS all had metal:gastrin stoichiometries of 2:1 but, while the metal ions in the Fe, Ga and In complexes were bridged by a carboxylate and an oxygen with a metal-metal separation of 3.0-3.3 Å, the Ru complex clearly demonstrated a short range Ru-Ru separation, which was significantly shorter, at 2.4 Å, indicative of a metal-metal bond. We conclude that gastrin selectively binds two In3+ or Ru3+ ions, and that the affinity of the first site for In3+ or Ru3+ ions is higher than for ferric ions. Some of the metal ion-gastrin complexes may be useful for cancer diagnosis and therapy.

  10. Molecular dynamics study of the effect of calcium ions on the monolayer of SDC and SDSn surfactants at the vapor/liquid interface.

    Science.gov (United States)

    Yan, Hui; Guo, Xin-Li; Yuan, Shi-Ling; Liu, Cheng-Bu

    2011-05-17

    The effect of Ca(2+) ions on the hydration shell of sodium dodecyl carboxylate (SDC) and sodium dodecyl sulfonate (SDSn) monolayer at vapor/liquid interfaces was studied using molecular dynamics simulations. For each surfactant, two different surface concentrations were used to perform the simulations, and the aggregation morphologies and structural details have been reported. The results showed that the aggregation structures relate to both the surface coverage and the calcium ions. The divalent ions can screen the interaction between the polar head and Na(+) ions. Thus, Ca(2+) ions locate near the vapor/liquid interface to bind to the headgroup, making the aggregations much more compact via the salt bridge. The potential of mean force (PMF) between Ca(2+) and the headgroups shows that the interaction is decided by a stabilizing solvent-separated minimum in the PMF. To bind to the headgroup, Ca(2+) should overcome the energy barrier. Among contributions to the PMF, the major repulsive interaction was due to the rearrangement of the hydration shell after the calcium ions entered into the hydration shell of the headgroup. The PMFs between the headgroup and Ca(2+) in the SDSn systems showed higher energy barriers than those in the SDC systems. This result indicated that SDSn binds the divalent ions with more difficulty compared with SDC, so the ions have a strong effect on the hydration shell of SDC. That is why sulfonate surfactants have better efficiency in salt solutions with Ca(2+) ions for enhanced oil recovery.

  11. Evolution and functional diversity of the Calcium Binding Proteins (CaBPs

    Directory of Open Access Journals (Sweden)

    Lee P Haynes

    2012-02-01

    Full Text Available The mammalian central nervous system (CNS exhibits a remarkable ability to process, store and transfer information. Key to these activities is the use of highly regulated and unique patterns of calcium signals encoded by calcium channels and decoded by families of specific calcium-sensing proteins. The largest family of eukaryotic calcium sensors are those related to the small EF-hand containing protein calmodulin (CaM. In order to maximise the usefulness of calcium as a signalling species and to permit the evolution and fine tuning of the mammalian CNS, families of related proteins have arisen that exhibit characteristic calcium binding properties and tissue-, cellular- and sub-cellular distribution profiles. The Calcium Binding Proteins (CaBPs represent one such family of vertebrate specific calmodulin like proteins that have emerged in recent years as important regulators of essential neuronal target proteins. Bioinformatic analyses indicate that the CaBPs consist of two subfamilies and that the ancestral members of these are CaBP1 and CaBP8. The CaBPs have distinct intracellular localisations based on different targeting mechanisms including a novel type-II transmembrane domain in CaBPs 7 and 8. Recent work has led to the identification of new target interactions and possible functions for the CaBPs suggesting that they have multiple physiological roles with relevance for the normal functioning of the CNS.

  12. Expression of the high capacity calcium-binding domain of calreticulin increases bioavailable calcium stores in plants

    Science.gov (United States)

    Wyatt, Sarah E.; Tsou, Pei-Lan; Robertson, Dominique; Brown, C. S. (Principal Investigator)

    2002-01-01

    Modulation of cytosolic calcium levels in both plants and animals is achieved by a system of Ca2+-transport and storage pathways that include Ca2+ buffering proteins in the lumen of intracellular compartments. To date, most research has focused on the role of transporters in regulating cytosolic calcium. We used a reverse genetics approach to modulate calcium stores in the lumen of the endoplasmic reticulum. Our goals were two-fold: to use the low affinity, high capacity Ca2+ binding characteristics of the C-domain of calreticulin to selectively increase Ca2+ storage in the endoplasmic reticulum, and to determine if those alterations affected plant physiological responses to stress. The C-domain of calreticulin is a highly acidic region that binds 20-50 moles of Ca2+ per mole of protein and has been shown to be the major site of Ca2+ storage within the endoplasmic reticulum of plant cells. A 377-bp fragment encoding the C-domain and ER retention signal from the maize calreticulin gene was fused to a gene for the green fluorescent protein and expressed in Arabidopsis under the control of a heat shock promoter. Following induction on normal medium, the C-domain transformants showed delayed loss of chlorophyll after transfer to calcium depleted medium when compared to seedlings transformed with green fluorescent protein alone. Total calcium measurements showed a 9-35% increase for induced C-domain transformants compared to controls. The data suggest that ectopic expression of the calreticulin C-domain increases Ca2+ stores, and that this Ca2+ reserve can be used by the plant in times of stress.

  13. Europium ion as a probe for binding sites to carrageenans

    International Nuclear Information System (INIS)

    Ramos, Ana P.; Goncalves, Rogeria R.; Serra, Osvaldo A.; Zaniquelli, Maria Elisabete D.; Wong, Kenneth

    2007-01-01

    Carrageenans, sulfated polysaccharides extracted from red algae, present a coil-helix transition and helix aggregation dependence on the type and concentration of counterions. In this study, we focus attention on a mixed valence counterion system: Eu 3+ /Na + or K + with different gel-forming carrageenans: kappa, iota, and kappa-2. Results of stationary and time-dependent luminescence showed to be a suitable tool to probe ion binding to both the negatively charged sulfate group and the hydroxyl groups present in the biopolymer. For lower europium ion concentrations, a single longer decay emission lifetime was detected, which was attributed to the binding of europium ion to the carrageenan sulfate groups. An additional decay ascribed to europium binding to hydroxyl groups was observed above a threshold concentration, and this decay was dependent on the carrageenan charge density. Symmetry of the europium ion microenvironment was estimated by the ratio between the intensities of its emission bands, which has been shown to depend on the concentration of europium ions and on the specificity of the monovalent counterion bound to the carrageenan

  14. Evaluation of calcium ion release and change in pH on combining calcium hydroxide with different vehicles

    Directory of Open Access Journals (Sweden)

    Charu Grover

    2014-01-01

    Full Text Available Introduction: Intracanal medicaments have traditionally been used in endodontics to disinfect root canals between appointments. Calcium hydroxide is widely used as an intracanal medicament for disinfection and to promote periapical healing. It is stable for long periods, harmless to the body, and bactericidal in a limited area. The efficacy of calcium hydroxide as a disinfectant is dependent on the availability of the hydroxyl ions in the solution that depends on the vehicle in which the calcium hydroxide is carried. In general, three types of vehicles are used: Aqueous, viscous or oily. Some in vitro studies have shown that the type of vehicle has a direct relationship with the concentration and the velocity of ionic liberation as well as with the antibacterial action when the paste is carried into a contaminated area. Aim of the Study: To evaluate the calcium ion release and measure the change in pH of the environment that occurred when calcium hydroxide was combined with different vehicles (distilled water, propylene glycol, calcium hydroxide containing gutta-percha points and chitosan over different time periods. Materials and Methods: Forty single rooted mandibular first premolar teeth were decoronated for this study. Working length was established and the root canals were enlarged and irrigation accomplished with 2 ml of NaOCl solution after every file. The teeth were then randomly divided into four groups. The canals were then packed with different preparations of calcium hydroxide using the following vehicles-distilled water, propylene glycol, gutta-percha points and chitosan. Calcium ion release in different groups was analyzed using an ultraviolet spectrophotometer at 220 nm. The change in pH of was determined using a pH meter. Results were statistically evaluated using one-way ANOVA test. Result: For calcium ion release, Group 2 showed cumulative drug release of 81.97% at the end of 15 days, whereas Group 1, 3 and 4 showed a release

  15. Adsorption efficiencies of calcium (II ion and iron (II ion on activated carbon obtained from pericarp of rubber fruit

    Directory of Open Access Journals (Sweden)

    Orawan Sirichote

    2008-03-01

    Full Text Available Determination of adsorption efficiencies of activated carbon from pericarp of rubber fruit for calcium (II ion and iron (II ion has been performed by flowing the solutions of these ions through a column of activated carbon. The weights of activated carbon in 500 mL buret column (diameter 3.2 cm for flowing calcium (II ion and iron (II ion solutions were 15 g and 10 g, respectively. The initial concentration of calcium ion was prepared to be about eight times more diluted than the true concentration found in the groundwater from the lower part of southern Thailand. Calcium (II ion concentrations were analysed by EDTA titration and its initial concentration was found to be 23.55 ppm. With a flow rate of 26 mL/min, the adsorption efficiency was 11.4 % with passed through volume 4.75 L. Iron (II ion concentrations were analysed by spectrophotometric method; its initial concentration was found to be 1.5565 ppm. At a flow rate of 22 mL/min, the adsorption efficiency was 0.42 % with passed through volume of 34.0 L.

  16. A First Principles Molecular Dynamics Study Of Calcium Ion In Water

    Energy Technology Data Exchange (ETDEWEB)

    Lightstone, F; Schwegler, E; Allesch, M; Gygi, F; Galli, G

    2005-01-28

    In this work we report on Car-Parrinello simulations of the divalent calcium ion in water, aimed at understanding the structure of the hydration shell and at comparing theoretical results with a series of recent experiments. Our paper shows some of the progress in the investigation of aqueous solutions brought about by the advent of ab initio molecular dynamics and highlights the importance of accessing subtle details of ion-water interactions from first-principles. Calcium plays a vital role in many biological systems, including signal transduction, blood clotting and cell division. In particular, calcium ions are known to interact strongly with proteins as they tend to bind well to both negatively charged (e.g. in aspartate and glutamate) and uncharged oxygens (e.g. in main-chain carbonyls). The ability of calcium to coordinate multiple ligands (from 6 to 8 oxygen atoms) with an asymmetric coordination shell enables it to cross-link different segments of a protein and induce large conformational changes. The great biochemical importance of the calcium ion has led to a number of studies to determine its hydration shell and its preferred coordination number in water. Experimental studies have used a variety of techniques, including XRD, EXAFS, and neutron diffraction to elucidate the coordination of Ca{sup 2+} in water. The range of coordination numbers (n{sub C}) inferred by X-ray diffraction studies varies from 6 to 8, and is consistent with that reported in EXAFS experiments (8 and 7.2). A wider range of values (6 to 10) was found in early neutron diffraction studies, depending on concentration, while a more recent measurement by Badyal, et al. reports a value close to 7. In addition to experimental measurements, many theoretical studies have been carried out to investigate the solvation of Ca{sup 2+} in water and have also reported a wide range of coordination numbers. Most of the classical molecular dynamics (MD) and QM/MM simulations report n{sub C} in the

  17. Influence of calcium depletion on iron-binding properties of milk.

    Science.gov (United States)

    Mittal, V A; Ellis, A; Ye, A; Das, S; Singh, H

    2015-04-01

    We investigated the effects of calcium depletion on the binding of iron in milk. A weakly acidic cation-exchange resin was used to remove 3 different levels (18-22, 50-55, and 68-72%) of calcium from milk. Five levels of iron (5, 10, 15, 20, and 25 mM) were added to each of these calcium-depleted milks (CDM) and the resultant milks were analyzed for particle size, microstructure, and the distribution of protein and minerals between the colloidal and soluble phases. The depletion of calcium affected the distribution of protein and minerals in normal milk. Iron added to normal milk and low-CDM (~20% calcium depletion) bound mainly to the colloidal phase (material sedimented at 100,000 × g for 1 h at 20 °C), with little effect on the integrity of the casein micelles. Depletion of ~70% of the calcium from milk resulted in almost complete disintegration of the casein micelles, as indicated by all the protein remaining in the soluble phase upon ultracentrifugation. Addition of up to ~20 mM iron to high CDM resulted in the formation of small fibrous structures that remained in the soluble phase of milk. It appeared that the iron bound to soluble (nonsedimentable) caseins in high-CDM. We observed a decrease in the aqueous phosphorus content of all milks upon iron addition, irrespective of their calcium content. We considered the interaction between aqueous phosphorus and added iron to be responsible for the high iron-binding capacity of the proteins in milk. The soluble protein-iron complexes formed in high-CDM (~70% calcium depletion) could be used as an effective iron fortificant for a range of food products because of their good solubility characteristics. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  18. Calcium-dependent binding of Myc to calmodulin

    Science.gov (United States)

    Raffeiner, Philipp; Schraffl, Andrea; Schwarz, Thomas; Röck, Ruth; Ledolter, Karin; Hartl, Markus; Konrat, Robert; Stefan, Eduard; Bister, Klaus

    2017-01-01

    The bHLH-LZ (basic region/helix-loop-helix/leucine zipper) oncoprotein Myc and the bHLH-LZ protein Max form a binary transcription factor complex controlling fundamental cellular processes. Deregulated Myc expression leads to neoplastic transformation and is a hallmark of most human cancers. The dynamics of Myc transcription factor activity are post-translationally coordinated by defined protein-protein interactions. Here, we present evidence for a second messenger controlled physical interaction between the Ca2+ sensor calmodulin (CaM) and all Myc variants (v-Myc, c-Myc, N-Myc, and L-Myc). The predominantly cytoplasmic Myc:CaM interaction is Ca2+-dependent, and the binding site maps to the conserved bHLH domain of Myc. Ca2+-loaded CaM binds the monomeric and intrinsically disordered Myc protein with high affinity, whereas Myc:Max heterodimers show less, and Max homodimers no affinity for CaM. NMR spectroscopic analyses using alternating mixtures of 15N-labeled and unlabeled preparations of CaM and a monomeric Myc fragment containing the bHLH-LZ domain corroborate the biochemical results on the Myc:CaM interaction and confirm the interaction site mapping. In electrophoretic mobility shift assays, addition of CaM does not affect high-affinity DNA-binding of Myc:Max heterodimers. However, cell-based reporter analyses and cell transformation assays suggest that increasing CaM levels enhance Myc transcriptional and oncogenic activities. Our results point to a possible involvement of Ca2+ sensing CaM in the fine-tuning of Myc function. PMID:27926480

  19. Subcellular distribution of calcium-binding proteins and a calcium-ATPase in canine pancreas

    International Nuclear Information System (INIS)

    Nigam, S.K.; Towers, T.

    1990-01-01

    Using a 45Ca blot-overlay assay, we monitored the subcellular fractionation pattern of several Ca binding proteins of apparent molecular masses 94, 61, and 59 kD. These proteins also appeared to stain blue with Stains-All. Additionally, using a monoclonal antiserum raised against canine cardiac sarcoplasmic reticulum Ca-ATPase, we examined the subcellular distribution of a canine pancreatic 110-kD protein recognized by this antiserum. This protein had the same electrophoretic mobility as the cardiac protein against which the antiserum was raised. The three Ca binding proteins and the Ca-ATPase cofractionated into the rough microsomal fraction (RM), previously shown to consist of highly purified RER, in a pattern highly similar to that of the RER marker, ribophorin I. To provide further evidence for an RER localization, native RM were subjected to isopycnic flotation in sucrose gradients. The Ca binding proteins and the Ca-ATPase were found in dense fractions, along with ribophorin I. When RM were stripped of ribosomes with puromycin/high salt, the Ca binding proteins and the Ca-ATPase exhibited a shift to less dense fractions, as did ribophorin I. We conclude that, in pancreas, the Ca binding proteins and Ca-ATPase we detect are localized to the RER (conceivably a subcompartment of the RER) or, possibly, a structure intimately associated with the RER

  20. Assessment of ion diffusion from a calcium hydroxide-propolis paste through dentin

    Directory of Open Access Journals (Sweden)

    Janaina Corazza Montero

    2012-08-01

    Full Text Available This study evaluated the ability of ions from a non-alcoholic calcium hydroxide-propolis paste to diffuse through dentinal tubules. Thirty-six single-rooted bovine teeth were used. The tooth crowns were removed, and the root canals were instrumented and divided into 3 groups: Group 1 - calcium hydroxide-propylene glycol paste; Group 2 - calcium hydroxide-saline solution paste; Group 3 - calcium hydroxide-propolis paste. After the root canal dressings were applied, the teeth were sealed and placed in containers with deionized water. The pH of the water was measured after 3, 24, 72 and 168 hours to determine the diffusion of calcium hydroxide ions through the dentinal tubules. All of the pastes studied promoted the diffusion of calcium hydroxide ions through the dentinal tubules. Associating propolis to calcium hydroxide resulted in a pH increase, which occurred with greater intensity after 72 hours. The calcium hydroxide-propolis paste was able to diffuse in dentin.

  1. Phosphorylation of SOS3-LIKE CALCIUM BINDING PROTEIN8 by SOS2 protein kinase stabilizes their protein complex and regulates salt tolerance in Arabidopsis.

    Science.gov (United States)

    Lin, Huixin; Yang, Yongqing; Quan, Ruidang; Mendoza, Imelda; Wu, Yisheng; Du, Wenming; Zhao, Shuangshuang; Schumaker, Karen S; Pardo, José M; Guo, Yan

    2009-05-01

    The Salt Overly Sensitive (SOS) pathway plays an important role in the regulation of Na+/K+ ion homeostasis and salt tolerance in Arabidopsis thaliana. Previously, we reported that the calcium binding proteins SOS3 and SOS3-LIKE CALCIUM BINDING PROTEIN8 (SCaBP8) nonredundantly activate the protein kinase SOS2. Here, we show that SOS2 phosphorylates SCaBP8 at its C terminus but does not phosphorylate SOS3. In vitro, SOS2 phosphorylation of SCaBP8 was enhanced by the bimolecular interaction of SOS2 and SCaBP8 and did not require calcium ions. In vivo, this phosphorylation was induced by salt stress, occurred at the membrane, stabilized the SCaBP8-SOS2 interaction, and enhanced plasma membrane Na+/H+ exchange activity. When a Ser at position 237 in the SCaBP8 protein (the SOS2 phosphorylation target) was mutated to Ala, SCaBP8 was no longer phosphorylated by SOS2 and the mutant protein could not fully rescue the salt-sensitive phenotype of the scabp8 mutant. By contrast, when Ser-237 was mutated to Asp to mimic the charge of a phosphorylated Ser residue, the mutant protein rescued the scabp8 salt sensitivity. These data demonstrate that calcium sensor phosphorylation is a critical component of SOS pathway regulation of salt tolerance in Arabidopsis.

  2. Evaluation of a novel method for measurement of intracellular calcium ion concentration in fission yeast.

    Science.gov (United States)

    Ogata, Fumihiko; Satoh, Ryosuke; Kita, Ayako; Sugiura, Reiko; Kawasaki, Naohito

    2017-01-01

    The distribution of metal and metalloid species in each of the cell compartments is termed as "metallome". It is important to elucidate the molecular mechanism underlying the beneficial or toxic effects exerted by a given metal or metalloid on human health. Therefore, we developed a method to measure intracellular metal ion concentration (particularly, intracellular calcium ion) in fission yeast. We evaluated the effects of nitric acid (HNO 3 ), zymolyase, and westase treatment on cytolysis in fission yeast. Moreover, we evaluated the changes in the intracellular calcium ion concentration in fission yeast in response to treatment with/without micafungin. The fission yeast undergoes lysis when treated with 60% HNO 3 , which is simpler and cheaper compared to the other treatments. Additionally, the intracellular calcium ion concentration in 60% HNO 3 -treated fission yeast was determined by inductively coupled plasma atomic emission spectrometry. This study yields significant information pertaining to measurement of the intracellular calcium ion concentration in fission yeast, which is useful for elucidating the physiological or pathological functions of calcium ion in the biological systems. This study is the first step to obtain perspective view on the effect of the metallome in biological systems.

  3. Enhancing effect of calcium and vanadium ions on thermal stability of bromoperoxidase from Corallina pilulifera.

    Science.gov (United States)

    Garcia-Rodriguez, Esther; Ohshiro, Takashi; Aibara, Toshiaki; Izumi, Yoshikazu; Littlechild, Jennifer

    2005-05-01

    Bromoperoxidase from the macro-alga Corallina pilulifera is an enzyme that possesses vanadate in the catalytic center, and shows a significant thermostability and stability toward organic solvents. The structural analysis of the recombinant enzyme overexpressed in yeast revealed that it contains one calcium atom per subunit. This has been confirmed by inductively coupled plasma emission spectrometry experiments. The study of the effect of metal ions on the apo-enzyme stability has shown that the calcium ion significantly increased the enzyme stability. In addition, vanadate also increased the thermostability and strontium and magnesium ions had similar effects as calcium. The holo-enzyme shows high stability in a range of organic solvents. The effect of the different ions and solvents on the structure of the enzyme has been studied by circular dichroism experiments. The high stability of the enzyme in the presence of organic solvents is useful for its application as a biocatalyst.

  4. Analysis of Perforin Assembly by Quartz Crystal Microbalance Reveals a Role for Cholesterol and Calcium-independent Membrane Binding*

    Science.gov (United States)

    Stewart, Sarah E.; Bird, Catherina H.; Tabor, Rico F.; D'Angelo, Michael E.; Piantavigna, Stefania; Whisstock, James C.; Trapani, Joseph A.; Martin, Lisandra L.; Bird, Phillip I.

    2015-01-01

    Perforin is an essential component in the cytotoxic lymphocyte-mediated cell death pathway. The traditional view holds that perforin monomers assemble into pores in the target cell membrane via a calcium-dependent process and facilitate translocation of cytotoxic proteases into the cytoplasm to induce apoptosis. Although many studies have examined the structure and role of perforin, the mechanics of pore assembly and granzyme delivery remain unclear. Here we have employed quartz crystal microbalance with dissipation monitoring (QCM-D) to investigate binding and assembly of perforin on lipid membranes, and show that perforin monomers bind to the membrane in a cooperative manner. We also found that cholesterol influences perforin binding and activity on intact cells and model membranes. Finally, contrary to current thinking, perforin efficiently binds membranes in the absence of calcium. When calcium is added to perforin already on the membrane, the QCM-D response changes significantly, indicating that perforin becomes membranolytic only after calcium binding. PMID:26542805

  5. Preparation of an ultra fast binding cement from calcium silicate-based mixed oxide nanoparticles.

    Science.gov (United States)

    Halim, S C; Brunner, T J; Grass, R N; Bohner, M; Stark, W J

    2007-10-03

    Building construction takes time, in part because the binding process of cement is based on the slow re-crystallization and precipitation of calcium silicate species. Since the material's reactivity is surface area limited, a reduction in particle size of Portland cements has been used to prepare faster binding formulations. The present work investigates a new and direct, one-step preparation of calcium silicate-based nanoparticles of a typical Portland cement composition by flame spray synthesis. Isothermal calorimetry revealed that the hardening of this new nano-cement corroborated a more than tenfold increase of initial reactivity with different reaction kinetics if compared to conventionally prepared cements. At present, the unfavourably high porosity of nano-cements, however, underlines the need for additional improvements of chemical composition and formulation to make these highly reactive materials applicable to modern construction work, where load-bearing strength is of importance.

  6. Repair of Nerve Cell Membrance Damage by Calcium-Dependent, Membrane-Binding Proteins

    Science.gov (United States)

    2013-09-01

    disease amyloid beta protein forms calcium channels in bilayer membranes: blockade by tromethamine and aluminum , Proc Natl Acad Sci U S A 90 (1993) 567... coagulation cascade in blood and the chaperoning of membrane interactions inside cells.4 Common to these diverse functions is the ability to bind...are quickly resolved restoring the permeability barrier. In vivo, such a transient breakdown of the membrane might constitute a significant initial cost

  7. The Calcium-Binding Activity of a Vacuole-Associated, Dehydrin-Like Protein Is Regulated by Phosphorylation1

    Science.gov (United States)

    Heyen, Bruce J.; Alsheikh, Muath K.; Smith, Elizabeth A.; Torvik, Carl F.; Seals, Darren F.; Randall, Stephen K.

    2002-01-01

    A vacuole membrane-associated calcium-binding protein with an apparent mass of 45 kD was purified from celery (Apium graveolens). This protein, VCaB45, is enriched in highly vacuolate tissues and is located within the lumen of vacuoles. Antigenically related proteins are present in many dicotyledonous plants. VCaB45 contains significant amino acid identity with the dehydrin family signature motif, is antigenically related to dehydrins, and has a variety of biochemical properties similar to dehydrins. VCaB45 migrates anomalously in sodium dodecyl sulfate-polyacrylamide gel electrophoresis having an apparent molecular mass of 45 kD. The true mass as determined by matrix-assisted laser-desorption ionization time of flight was 16.45 kD. VCaB45 has two characteristic dissociation constants for calcium of 0.22 ± 0.142 mm and 0.64 ± 0.08 mm, and has an estimated 24.7 ± 11.7 calcium-binding sites per protein. The calcium-binding properties of VCaB45 are modulated by phosphorylation; the phosphorylated protein binds up to 100-fold more calcium than the dephosphorylated protein. VCaB45 is an “in vitro” substrate of casein kinase II (a ubiquitous eukaryotic kinase), the phosphorylation resulting in a partial activation of calcium-binding activity. The vacuole localization, calcium binding, and phosphorylation of VCaB45 suggest potential functions. PMID:12376635

  8. Structure and calcium binding activity of LipL32, the major surface antigen of pathogenic Leptospira sp

    Energy Technology Data Exchange (ETDEWEB)

    Hauk, Pricila; Roman-Ramos, Henrique; Ho, Paulo Lee [Instituto Butantan, Sao Paulo, SP (Brazil). Centro de Biotecnologia; Guzzo, Cristiane R.; Farah, Chuck S. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Quimica. Dept. de Bioquimica

    2009-07-01

    Leptospirosis, caused by the spirochaete Leptospira is an important emerging infectious disease. LipL32 is the major exposed outer membrane protein found exclusively in pathogenic leptospira. It is highly immunogenic and has been shown to bind to host extracellular matrix components, including collagens, fibronectin and laminin. In this work we crystallized recombinant LipL32 protein and determined its structure to 2.25 A resolution. Initial phases were determined using the multi-wavelength anomalous dispersion technique with data collected from selenomethionine-containing crystals at the MX2 beamline at the LNLS. The LipL32 monomer is made of a jelly-roll fold core from which protrude several peripheral secondary structures. Some structural features suggested that LipL32 could bind Ca{sup 2+} ions and indeed, spectroscopic data (circular (dichroism. intrinsic tryptophan fluorescence and extrinsic 1-amino-2-anaphthol-4-sulfonic acid fluorescence) confirmed the calcium binding properties of LipL32. (author)

  9. Selectivity coefficients of ion-selective magnesium electrodes used for simultaneous determination of magnesium and calcium ions.

    Science.gov (United States)

    Maj-Zurawska, Magdalena; Lewenstam, Andrzej

    2011-12-15

    Membrane ion-selective magnesium electrodes are commonly used to determine ionized magnesium concentration in blood serum and intracellular fluid by potentiometric clinical analyzers. The selectivity of these electrodes against calcium ion is typically insufficient to avoid calcium interference in blood serum analysis. For this reason the selectivity coefficient for calcium ion has to be studied to make possible any mathematical corrections for calcium ion influence. Existing methods relate to the thermodynamic concept of ISE response which suggest a single constant value of the selectivity coefficient and slope that are stable over the concentration ranges of calcium and magnesium ions in the samples. Unfortunately, this rarely happens, and we rather observe dependences on solution and membrane composition, readout time, matrices (anticoagulant, vial coats) that justify usage of apparent selectivities and slopes. To get the practical insight into the response of magnesium ion-selective electrodes a novel method for estimating the selectivity coefficients and the slope of the electrode characteristics is proposed. This method is an effective starting point for selecting electrodes and designing transient signal software in a potentiometric clinical analyzer. The method allows obtaining the ionized magnesium concentration in blood serum with minimal possible error by addressing the assessed targets, i.e. apparent selectivity and slope. The method is based on computer simulation and on the Nicolsky-Eisenman equation. Usually only a few iterations are needed to obtain stable congruent results. The method presented is particularly useful in conditions where is not possible to obtain calibration curve, which is typical for clinical analyzer where at most three point calibration is performed. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Immobilization of calcium and phosphate ions improves the osteoconductivity of titanium implants

    International Nuclear Information System (INIS)

    Sunarso; Toita, Riki; Tsuru, Kanji; Ishikawa, Kunio

    2016-01-01

    In this work, to elevate weak osteoconductivity of titanium (Ti) implant, we prepared a Ti implant having both calcium and phosphate ions on its surface. To modify calcium and phosphate ions onto Ti, phosphate ions were first immobilized by treating the Ti with a NaH 2 PO 4 solution, followed by CaCl 2 treatment to immobilize calcium ions, which created the calcium and phosphate ions-modified Ti (Ca-P-Ti). X-ray photoelectron spectroscopy and thin-layer X-ray diffraction measurement confirmed that both phosphate and calcium ions were co-immobilized onto the Ti surface on the molecular level. Three-hour after seeding MC3T3-E1 murine pre-osteoblast cells on substrates, cell number on Ca-P-Ti was much larger than that of Ti and phosphate-modified Ti (P-Ti), but was similar to that of calcium-modified Ti (Ca-Ti). Also, MC3T3-E1 cells on Ca-P-Ti expressed larger amount of vinculin, a focal adhesion protein, than those on other substrates, probably resulting in larger cell size as well as greater cell proliferation on Ca-P-Ti than those on other substrates. Alkaline phosphatase activity of cells on Ca-P-Ti was greater than those on Ti and P-Ti, but was almost comparable to that of Ca-Ti. Moreover, the largest amount of bone-like nodule formation was observed on Ca-P-Ti. These results provide evidence that calcium and phosphate ions-co-immobilization onto Ti increased the osteoconductivity of Ti by stimulating the responses of pre-osteoblast cells. This simple modification would be promising technique for bone tissue implant including dental and orthopedic implants. - Highlights: • Phosphate and calcium ions have been successfully co-immobilize on Ti surface. • Co-immobilization of Ca and phosphate ions (Ca-P-Ti) did not alter the original surface morphology. • Ca-P-Ti significantly improved initial MC3T3-E1 cell adhesion. • Ca-P-Ti demonstrated remarkable cell proliferation, differentiation and mineralization. • Overall, Ca-P-Ti would be a promising bone

  11. Identification of a novel calcium binding motif based on the detection of sequence insertions in the animal peroxidase domain of bacterial proteins.

    Directory of Open Access Journals (Sweden)

    Saray Santamaría-Hernando

    Full Text Available Proteins of the animal heme peroxidase (ANP superfamily differ greatly in size since they have either one or two catalytic domains that match profile PS50292. The orf PP_2561 of Pseudomonas putida KT2440 that we have called PepA encodes a two-domain ANP. The alignment of these domains with those of PepA homologues revealed a variable number of insertions with the consensus G-x-D-G-x-x-[GN]-[TN]-x-D-D. This motif has also been detected in the structure of pseudopilin (pdb 3G20, where it was found to be involved in Ca(2+ coordination although a sequence analysis did not reveal the presence of any known calcium binding motifs in this protein. Isothermal titration calorimetry revealed that a peptide containing this consensus motif bound specifically calcium ions with affinities ranging between 33-79 µM depending on the pH. Microcalorimetric titrations of the purified N-terminal ANP-like domain of PepA revealed Ca(2+ binding with a K(D of 12 µM and stoichiometry of 1.25 calcium ions per protein monomer. This domain exhibited peroxidase activity after its reconstitution with heme. These data led to the definition of a novel calcium binding motif that we have termed PERCAL and which was abundantly present in animal peroxidase-like domains of bacterial proteins. Bacterial heme peroxidases thus possess two different types of calcium binding motifs, namely PERCAL and the related hemolysin type calcium binding motif, with the latter being located outside the catalytic domains and in their C-terminal end. A phylogenetic tree of ANP-like catalytic domains of bacterial proteins with PERCAL motifs, including single domain peroxidases, was divided into two major clusters, representing domains with and without PERCAL motif containing insertions. We have verified that the recently reported classification of bacterial heme peroxidases in two families (cd09819 and cd09821 is unrelated to these insertions. Sequences matching PERCAL were detected in all kingdoms of

  12. Investigation into the role of NaOH and calcium ions in the synthesis of calcium phosphate nanoshells

    Directory of Open Access Journals (Sweden)

    C. H. Yeo

    2012-03-01

    Full Text Available Calcium phosphate (CaP nanoshells were prepared using negatively charged liposomes (1,2-dioleoyl-sn-glycero-3-phosphate sodium salt (DOPA as a template by base titration synthesis at various concentrations of NaOH and calcium ions. The elemental composition, morphology, particle size, particle size distribution and zeta potential of the products were determined via various characterisation techniques, such as energy-dispersive X-ray spectrometry (EDX, transmission electron microscopy (TEM, dynamic light scattering (DLS, laser Doppler velocimetry (LDV and Fourier transform infrared spectroscopy (FTIR. The best results showed that stable spherical CaP nanoshells with a mean particle size of 197.5 ± 5.8 nm and a zeta potential of -34.5 ± 0.6 mV were successfully formed when 0.100 M sodium hydroxide (NaOH and 0.100 M calcium ions were used. Moreover, an optimal pH of 10.52 and a final Ca/P molar ratio of 0.97 were achieved under these conditions.

  13. Chirality-induced conformational preferences in peptide-metal ion binding revealed by IR spectroscopy

    NARCIS (Netherlands)

    Dunbar, R.C.; Steill, J.D.; Oomens, J.

    2011-01-01

    Chirality reversal of a residue in a peptide can change its mode of binding to a metal ion, as shown here experimentally by gas-phase IR spectroscopy of peptide−metal ion complexes. The binding conformations of Li+, Na+, and H+ with the ll and dl stereoisomers of PhePhe were compared through IR ion

  14. Chirality-Induced Conformational Preferences in Peptide-Metal Ion Binding Revealed by IR Spectroscopy

    NARCIS (Netherlands)

    Dunbar, R. C.; Steill, J. D.; Oomens, J.

    2011-01-01

    Chirality reversal of a residue in a peptide can change its mode of binding to a metal ion, as shown here experimentally by gas-phase IR spectroscopy of peptide metal ion complexes. The binding conformations of Li+, Na+, and H+ with the LL and DL stereoisomers of PhePhe were compared through IR ion

  15. Site I Inactivation Impacts Calmodulin Calcium Binding and Activation of Bordetella pertussis Adenylate Cyclase Toxin.

    Science.gov (United States)

    Johns, Christian W; Finley, Natosha L

    2017-11-30

    Site I inactivation of calmodulin (CaM) was used to examine the importance of aspartic acid 22 at position 3 in CaM calcium binding, protein folding, and activation of the Bordetella pertussis adenylate cyclase toxin domain (CyaA-ACD). NMR calcium titration experiments showed that site I in the CaM mutant (D22A) remained largely unperturbed, while sites II, III, and IV exhibited calcium-induced conformational changes similar to wild-type CaM (CaMWt). Circular dichroism analyses revealed that D22A had comparable α -helical content to CaMWt, and only modest differences in α -helical composition were detected between CaMWt-CyaA-ACD and D22A-CyaA-ACD complexes. However, the thermal stability of the D22A-CyaA-ACD complex was reduced, as compared to the CaMWt-CyaA-ACD complex. Moreover, CaM-dependent activity of CyaA-ACD decreased 87% in the presence of D22A. Taken together, our findings provide evidence that D22A engages CyaA-ACD, likely through C -terminal mediated binding, and that site I inactivation exerts functional effects through the modification of stabilizing interactions that occur between N -terminal CaM and CyaA-ACD.

  16. Calcium-dependent and calcium-independent signals in the conglutinin-binding assay (KgBa) for immune complexes. Influence of anti-collagen-antibodies

    DEFF Research Database (Denmark)

    Holmskov, U; Haas, Henning de; Teisner, B

    1992-01-01

    G to solid phase bovine conglutinin was also observed to a variable degree in normal and pathological sera. However, in this situation the IgG binding was largely calcium-independent, was not inhibited by GlcNAc and did not decrease after prolonged incubation of the serum at 37 degrees C. The reactive Ig...... been "solubilized" (i.e., complement treated by incubation with serum) was employed as a reference. The binding of the complement-reacted IgG to solid phase conglutinin was found to be calcium-dependent and inhibitable with N-acetyl-D-glucosamine (GlcNAc). Prolonged incubation (4 days) of aggregated Ig...

  17. Response of wheat plants to sodium and calcium ion interaction under saline environment

    International Nuclear Information System (INIS)

    Zaman, B.; Niazi, B.H.; Athar, M.; Ahmad, M.

    2005-01-01

    Wheat being a glycophyte crop, responds differently to saline-sodic soil environmental conditions. The application of calcium is multidimensional with respect to sodium ion and plant part response. This study was conducted to record the response of shoot and root to sodium and calcium interaction under saline environment. Wheat seed of variety Punjab 85 were raised in quartz sand. Later on the seedlings were transplanted to pots containing Hoagland's nutrient solution along with NaCl at 0 mM. and 50 mM. Calcium was applied as CaSO 4 2H O at 3m M. and 6 mM. Under saline conditions shoot showed positive response to sodium ion in the presence of higher calcium. Relative water contents were higher in the root system at 6 mM of CaSO 4 .2H 2 O under saline condition. Growth responses to potassium and Magnesium in the presence of sodium induced salinity with calcium ion interaction remained variable

  18. Assessment of diffusion of hydroxyl and calcium ions of root canal filling materials in primary teeth.

    Science.gov (United States)

    Ximenes, Marcos; Cardoso, Mariane

    2012-01-01

    The purpose of this study was to evaluate the diffusion of hydroxyl (OH-) and calcium (Ca+2) of 2 intracanal calcium hydroxide-based medications through the root dentin and cementum of primary teeth. Forty roots were selected and a single operator instrumented the canals. The irrigation was performed with a 1% sodium hypochlorite solution, and a final irrigation used 17% ethylenediaminetetraacetic acid solution. The teeth were divided into 3 groups: (1) group 1 (N=15)- thickened calcium hydroxide paste blended with propylene glycol paste; (2) group 2 (N=15)-Calen; and (3) group 3 (N=10)-no medication. Diffusion of the OH-ions was determined using a digital pH meter, and diffusion of Ca+2 ions was determined through atomic absorption spectrometry at baseline, 24 hours, 7 days, 15 days, and 30 days later. Two-way analysis of variance and Tukey's test revealed that Group 1 achieved significantly higher pH values (P<.01), followed by Groups 2 and 3. There was a statistically significant difference between groups (P<.01) in the amount of Ca+2 ions released; group 1 had the highest diffusion values, followed by group 2, both with peak diffusion at 7 days. Thickened calcium hydroxide paste blended with propylene glycol paste achieved the greatest diffusion of hydroxyl and calcium through the dentin and cementum of primary teeth.

  19. Insights into the activation mechanism of calcium ions on the sericite surface: A combined experimental and computational study

    Science.gov (United States)

    Hu, Yuehua; He, Jianyong; Zhang, Chenhu; Zhang, Chenyang; Sun, Wei; Zhao, Dongbo; Chen, Pan; Han, Haisheng; Gao, Zhiyong; Liu, Runqing; Wang, Li

    2018-01-01

    The adsorption behaviors and the activation mechanism of calcium ions (Ca2+) on sericite surface have been investigated by Zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR), Micro-flotation tests and First principle calculations. Zeta potential tests results show that the sericite surface potential increases due to the adsorption of calcium ions on the surface. Micro-flotation tests demonstrate that sericite recovery remarkably rise by 10% due to the calcium ions activation on sericite surface. However, the characteristic adsorption bands of calcium oleate do not appear in the FT-IR spectrum, suggesting that oleate ions just physically adsorb on the sericite surface. The first principle calculations based on the density functional theory (DFT) further reveals the microscopic adsorption mechanism of calcium ions on the sericite surface before and after hydration.

  20. Modulation of calcium oxalate monohydrate crystallization by citrate through selective binding to atomic steps

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, S R; Wierzbicki, A; Salter, E A; Zepeda, S; Orme, C A; Hoyer, J R; Nancollas, G H; Cody, A M; De Yoreo, J J

    2004-10-19

    The majority of human kidney stones are composed primarily of calcium oxalate monohydrate (COM) crystals. Thus, determining the molecular mechanisms by which urinary constituents modulate calcium oxalate crystallization is crucial for understanding and controlling urolithiassis in humans. A comprehensive molecular-scale view of COM shape modification by citrate, a common urinary constituent, obtained through a combination of in situ atomic force microscopy (AFM) and molecular modeling is now presented. We show that citrate strongly influences the growth morphology and kinetics on the (-101) face but has much lower effect on the (010) face. Moreover, binding energy calculations show that the strength of the citrate-COM interaction is much greater at steps than on terraces and is highly step-specific. The maximum binding energy, -166.5 kJ {center_dot} mol{sup -1}, occurs for the [101] step on the (-101) face. In contrast, the value is only -56.9 kJ {center_dot} mol-1 for the [012] step on the (010) face. The binding energies on the (-101) and (010) terraces are also much smaller, -65.4 and -48.9 kJ {center_dot} mol{sup -1} respectively. All other binding energies lie between these extremes. This high selectivity leads to preferential binding of citrate to the acute [101] atomic steps on the (-101) face. The strong citrate-step interactions on this face leads to pinning of all steps, but the anisotropy in interaction strength results in anisotropic reductions in step kinetics. These anisotropic changes in step kinetics are, in turn, responsible for changes in the shape of macroscopic COM crystals. Thus, the molecular scale growth morphology and the bulk crystal habit in the presence of citrate are similar, and the predictions of molecular simulations are fully consistent with the experimental observations.

  1. Aqueous solutions of calcium ions: hydration numbers and the effect of temperature.

    Science.gov (United States)

    Zavitsas, Andreas A

    2005-11-03

    Hydration numbers of calcium ions are determined from extensive measurements of colligative properties of water solutions of calcium salts. The hydration numbers reported refer to the average number of water molecules that are bound sufficiently strongly to calcium ions so as to be removed from the solvent and become part of the solute. Contrary to common descriptions of deviations from ideal behavior for concentrated solutions, ideal behavior is demonstrated when mole fractions are calculated by taking account of such bound water. Measurements over wide concentration and temperature ranges are used to obtain the effect of temperature on the average hydration number of Ca(2+). Freezing point depression measurements yield a hydration number of 12.0 +/- 0.8. Boiling point elevations yield 6.7 +/- 0.6. Consistent with this, vapor pressure measurements from 0 to 200 degrees C show a gradual decrease in hydration number with increasing temperature, with a value of 5.0 at 200 degrees C.

  2. NALCN ion channels have alternative selectivity filters resembling calcium channels or sodium channels

    NARCIS (Netherlands)

    Senatore, A.; Monteil, A.; van Minnen, J.; Smit, A.B.; Spafford, J.D.

    2013-01-01

    NALCN is a member of the family of ion channels with four homologous, repeat domains that include voltage-gated calcium and sodium channels. NALCN is a highly conserved gene from simple, extant multicellular organisms without nervous systems such as sponges and placozoans and mostly remains a single

  3. Analysis of the effects of cerium on calcium ion in the protoplasts of ...

    African Journals Online (AJOL)

    Administrator

    2011-09-12

    Sep 12, 2011 ... The laser-scanning confocal microscopy has become a routine technique and indispensable tool for cell biological studies. In this study, the probe Fluo-3 AM was used to research the instantaneous changes of calcium ion (Ca2+) in the protoplasts of Arabidopsis thaliana. The laser-scanning mode of.

  4. Analysis of the effects of cerium on calcium ion in the protoplasts of ...

    African Journals Online (AJOL)

    The laser-scanning confocal microscopy has become a routine technique and indispensable tool for cell biological studies. In this study, the probe Fluo-3 AM was used to research the instantaneous changes of calcium ion (Ca2+) in the protoplasts of Arabidopsis thaliana. The laser-scanning mode of confocal microscope is ...

  5. Actin filaments as the fast pathways for calcium ions involved in ...

    Indian Academy of Sciences (India)

    We investigated the polyelectrolyte properties of actin filaments which are in interaction with myosin motors, basic participants in mechano-electrical transduction in the stereocilia of the inner ear. Here, we elaborated a model in which actin filaments play the role of guides or pathways for localized flow of calcium ions.

  6. Actin filaments as the fast pathways for calcium ions involved in ...

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Journal of Biosciences; Volume 40; Issue 3. Actin filaments as the fast pathways for calcium ions involved in auditory processes. Miljko V Sataric Dalibor L Sekulic Bogdan M Sataric. Articles Volume 40 Issue 3 September 2015 pp 549- ...

  7. Contactless Stimulation and Control of Biomimetic Nanotubes by Calcium Ion Gradients.

    Science.gov (United States)

    Kirejev, Vladimir; Ali Doosti, Baharan; Shaali, Mehrnaz; Jeffries, Gavin D M; Lobovkina, Tatsiana

    2018-04-17

    Membrane tubular structures are important communication pathways between cells and cellular compartments. Studying these structures in their native environment is challenging, due to the complexity of membranes and varying chemical conditions within and outside of the cells. This work demonstrates that a calcium ion gradient, applied to a synthetic lipid nanotube, triggers lipid flow directed toward the application site, resulting in the formation of a bulge aggregate. This bulge can be translated in a contactless manner by moving a calcium ion source along the lipid nanotube. Furthermore, entrapment of polystyrene nanobeads within the bulge does not tamper the bulge movement and allows transporting of the nanoparticle cargo along the lipid nanotube. In addition to the synthetic lipid nanotubes, the response of cell plasma membrane tethers to local calcium ion stimulation is investigated. The directed membrane transport in these tethers is observed, but with slower kinetics in comparison to the synthetic lipid nanotubes. The findings of this work demonstrate a novel and contactless mode of transport in lipid nanotubes, guided by local exposure to calcium ions. The observed lipid nanotube behavior can advance the current understanding of the cell membrane tubular structures, which are constantly reshaped during dynamic cellular processes. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Enhanced osteogenic activity of poly ether ether ketone using calcium plasma immersion ion implantation.

    Science.gov (United States)

    Lu, Tao; Qian, Shi; Meng, Fanhao; Ning, Congqin; Liu, Xuanyong

    2016-06-01

    As a promising implantable material, poly ether ether ketone (PEEK) possesses similar elastic modulus to that of cortical bones yet suffers from bio-inertness and poor osteogenic properties, which limits its application as orthopedic implants. In this work, calcium is introduced onto PEEK surface using calcium plasma immersion ion implantation (Ca-PIII). The results obtained from scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) confirm the modified layer with varying contents of calcium are formed on PEEK surfaces. Water contact angle measurements reveal the increasing hydrophobicity of both Ca-PIII treated surfaces. In vitro cell adhesion, viability assay, alkaline phosphatase activity and collagen secretion analyses disclose improved the adhesion, proliferation, and osteo-differentiation of rat bone mesenchymal stem cells (bMSCs) on Ca-PIII treated surfaces. The obtained results indicate that PEEK surface with enhanced osteogenic activity can be produced by calcium incorporation. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Calcium

    Science.gov (United States)

    ... absorb calcium as well. Sufficient calcium intake from food, and supplements if needed, can slow the rate of bone loss. Women of childbearing ... calcium absorption. People who eat a variety of foods don't have to consider ... include consumption of alcohol- and caffeine-containing beverages as well ...

  10. Structural Changes in the Lectin Domain of CD23, the Low-Affinity IgE Receptor, upon Calcium Binding

    Energy Technology Data Exchange (ETDEWEB)

    Wurzburg, Beth A.; Tarchevskaya, Svetlana S.; Jardetzky, Theodore S. (NWU)

    2010-03-08

    CD23, the low-affinity receptor for IgE (Fc{var_epsilon}RII), regulates IgE synthesis and also mediates IgE-dependent antigen transport and processing. CD23 is a unique Fc receptor belonging to the C-type lectin-like domain superfamily and binds IgE in an unusual, non-lectin-like manner, requiring calcium but not carbohydrate. We have solved the high-resolution crystal structures of the human CD23 lectin domain in the presence and absence of Ca{sup 2+}. The crystal structures differ significantly from a previously determined NMR structure and show that calcium binding occurs at the principal binding site, but not at an auxiliary site that appears to be absent in human CD23. Conformational differences between the apo and Ca{sup 2+} bound structures suggest how IgE-Fc binding can be both calcium-dependent and carbohydrate-independent.

  11. Dissecting electrostatic screening, specific ion binding, and ligand binding in an energetic model for glycine riboswitch folding

    Energy Technology Data Exchange (ETDEWEB)

    Lipfert, Jan; Sim, Adelene Y.L.; Herschlag, Daniel; Doniach, Sebastian (Stanford)

    2010-09-17

    Riboswitches are gene-regulating RNAs that are usually found in the 5{prime}-untranslated regions of messenger RNA. As the sugar-phosphate backbone of RNA is highly negatively charged, the folding and ligand-binding interactions of riboswitches are strongly dependent on the presence of cations. Using small angle X-ray scattering (SAXS) and hydroxyl radical footprinting, we examined the cation dependence of the different folding stages of the glycine-binding riboswitch from Vibrio cholerae. We found that the partial folding of the tandem aptamer of this riboswitch in the absence of glycine is supported by all tested mono- and divalent ions, suggesting that this transition is mediated by nonspecific electrostatic screening. Poisson-Boltzmann calculations using SAXS-derived low-resolution structural models allowed us to perform an energetic dissection of this process. The results showed that a model with a constant favorable contribution to folding that is opposed by an unfavorable electrostatic term that varies with ion concentration and valency provides a reasonable quantitative description of the observed folding behavior. Glycine binding, on the other hand, requires specific divalent ions binding based on the observation that Mg{sup 2+}, Ca{sup 2+}, and Mn{sup 2+} facilitated glycine binding, whereas other divalent cations did not. The results provide a case study of how ion-dependent electrostatic relaxation, specific ion binding, and ligand binding can be coupled to shape the energetic landscape of a riboswitch and can begin to be quantitatively dissected.

  12. Analysis of the interaction between Bacillus coagulans and Bacillus thuringiensis S-layers and calcium ions by XRD, light microscopy, and FTIR.

    Science.gov (United States)

    Babolmorad, Ghazal; Emtiazi, Giti; Emamzadeh, Rahman

    2014-05-01

    S-layer is a self-assemble regularly crystalline surface that covers major cell wall component of many bacteria and archaea and exhibits a high metal-binding capacity. We have studied the effect of the calcium ions and type of solid support (glass or mica) on the structure of the S-layers from Bacillus coagulans HN-68 and Bacillus thuringiensis MH14 upon simple methods based on light microscopy and AFM. Furthermore, the Fourier transform infrared spectroscopy (FTIR) study is indicated that the calcium-S-layer interaction occurred mainly through the carboxylate groups of the side chains of aspartic acid (Asp) and glutamic acid (Glu) and nitrogen atoms of Lys, Asn, and histidine (His) amino acids and N-H groups of the peptide backbone. Studied FTIR revealed that inner faces of S-layer are mainly negative, and outer faces of S-layer are mainly positive. Probably, calcium ions with positive charges bound to the carboxyl groups of Glu and Asp. Accordingly, calcium ions are anchored in the space between the inner faces of S-layer with negative charge and the surface of mica with negative charge. This leads to regular arrangement of the S-layer subunits.

  13. Calcium tolerance and ion uptake of Egyptian lupin landraces on ...

    African Journals Online (AJOL)

    To establish the cause of poor growth of white lupin (Lupinus albus L.) in the presence of high CaCO3 and identify tolerant accessions a field and a pot experiment was conducted. In the field 100 accessions of Egyptian landraces were tested in West Delta (20-26 % CaCO3). Ion uptake ( N, Fe, Mn and Ca) was determined ...

  14. A role for calcium in the regulation of ATP-binding cassette, sub-family C, member 3 (ABCC3) gene expression in a model of epidermal growth factor-mediated breast cancer epithelial-mesenchymal transition.

    Science.gov (United States)

    Stewart, Teneale A; Azimi, Iman; Thompson, Erik W; Roberts-Thomson, Sarah J; Monteith, Gregory R

    2015-03-13

    Epithelial-mesenchymal transition (EMT), a process implicated in cancer metastasis, is associated with the transcriptional regulation of members of the ATP-binding cassette superfamily of efflux pumps, and drug resistance in breast cancer cells. Epidermal growth factor (EGF)-induced EMT in MDA-MB-468 breast cancer cells is calcium signal dependent. In this study induction of EMT was shown to result in the transcriptional up-regulation of ATP-binding cassette, subfamily C, member 3 (ABCC3), a member of the ABC transporter superfamily, which has a recognized role in multidrug resistance. Buffering of cytosolic free calcium inhibited EGF-mediated ABCC3 increases, indicating a calcium-dependent mode of regulation. Silencing of TRPM7 (an ion channel involved in EMT associated vimentin induction) did not inhibit ABCC3 up-regulation. Silencing of the store operated calcium entry (SOCE) pathway components ORAI1 and STIM1 also did not alter ABCC3 induction by EGF. However, the calcium permeable ion channel transient receptor potential cation channel, subfamily C, member 1 (TRPC1) appears to contribute to the regulation of both basal and EGF-induced ABCC3 mRNA. Improved understanding of the relationship between calcium signaling, EMT and the regulation of genes important in therapeutic resistance may help identify novel therapeutic targets for breast cancer. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Structural insights into binding of STAC proteins to voltage-gated calcium channels

    Science.gov (United States)

    Wong King Yuen, Siobhan M.; Campiglio, Marta; Tung, Ching-Chieh

    2017-01-01

    Excitation–contraction (EC) coupling in skeletal muscle requires functional and mechanical coupling between L-type voltage-gated calcium channels (CaV1.1) and the ryanodine receptor (RyR1). Recently, STAC3 was identified as an essential protein for EC coupling and is part of a group of three proteins that can bind and modulate L-type voltage-gated calcium channels. Here, we report crystal structures of tandem-SH3 domains of different STAC isoforms up to 1.2-Å resolution. These form a rigid interaction through a conserved interdomain interface. We identify the linker connecting transmembrane repeats II and III in two different CaV isoforms as a binding site for the SH3 domains and report a crystal structure of the complex with the STAC2 isoform. The interaction site includes the location for a disease variant in STAC3 that has been linked to Native American myopathy (NAM). Introducing the mutation does not cause misfolding of the SH3 domains, but abolishes the interaction. Disruption of the interaction via mutations in the II–III loop perturbs skeletal muscle EC coupling, but preserves the ability of STAC3 to slow down inactivation of CaV1.2. PMID:29078335

  16. Characterization of ion distributions near the surface of sodium-containing and sodium-depleted calcium aluminosilicate glass melts

    International Nuclear Information System (INIS)

    Corrales, Louis R.; Du, Jincheng

    2006-01-01

    The distribution of cation and anion components of sodium containing calcium aluminosilicate glass was studied by classical molecular dynamics simulations in a high temperature melt in the bulk and at the vacuum-melt interface. A significant redistribution of the sodium and non-bridging oxygen ions was observed. Subsequently, a sodium depleted calcium aluminosilicate glass melt was simulated to determine the sensitivity of the redistribution of ions near the vacuum-melt interface to the presence of sodium ions. It is found that the thermodynamic equilibrium condition near a surface favors the enrichment of non-bridging oxygen ions that is closely associated with enrichment of the sodium ions

  17. Generic NICA-Donnan model parameters for metal-ion binding by humic substances

    NARCIS (Netherlands)

    Milne, C.J.; Kinniburgh, D.G.; Riemsdijk, van W.H.; Tipping, E.

    2003-01-01

    A total of 171 datasets of literature and experimental data for metal-ion binding by fulvic and humic acids have been digitized and re-analyzed using the NICA-Donnan model. Generic parameter values have been derived that can be used for modeling in the absence of specific metal-ion binding

  18. Rechargeable calcium phosphate orthodontic cement with sustained ion release and re-release

    Science.gov (United States)

    Zhang, Ling; Weir, Michael D.; Chow, Laurence C.; Reynolds, Mark A.; Xu, Hockin H. K.

    2016-11-01

    White spot lesions (WSL) due to enamel demineralization are major complications for orthodontic treatments. Calcium phosphate (CaP) dental resins with Ca and P ion releases are promising for remineralization. However, previous Ca and P releases lasted for only weeks. Experimental orthodontic cements were developed using pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA) at mass ratio of 1:1 (PE); and PE plus 10% of 2-hydroxyethyl methacrylate (HEMA) and 5% of bisphenol A glycidyl dimethacrylate (BisGMA) (PEHB). Particles of amorphous calcium phosphate (ACP) were incorporated into PE and PEHB at 40% filler level. Specimens were tested for bracket-enamel shear bond strength, water sorption, CaP release, and ion recharge and re-release. PEHB+40ACP had higher bracket-enamel bond strength and ion release and rechargeability than PE+40ACP. ACP incorporation into the novel orthodontic cement did not adversely affect the bracket-enamel bond strength. Ion release and re-release from the novel ACP orthodontic cement indicated favorable release and re-release patterns. The recharged orthodontic cement could release CaP ions continuously for four weeks without further recharge. Novel rechargeable orthodontic cement containing ACP was developed with a high bracket-enamel bond strength and the ability to be repeatedly recharged to maintain long-term high levels of CaP ion releases.

  19. Calcium-protein interactions in the extracellular environment: calcium binding, activation, and immunolocalization of a collagenase/gelatinase activity expressed in the sea urchin embryo.

    Science.gov (United States)

    Mayne, J; Robinson, J J

    1998-12-15

    We have purified and characterized a collagenase/gelatinase activity expressed during sea urchin embryonic development. The native molecular mass was determined to be 160 kDa, while gelatin substrate gel zymography revealed an active species of 41 kDa, suggesting that the native enzyme is a tetramer of active subunits. Incubation in the presence of EGTA resulted in nearly complete loss of activity and this effect could be reversed by calcium. Calcium-induced reactivation appeared to be cooperative and occurred with an apparent kd value of 3.7 mM. Two modes of calcium binding to the 41-kDa subunit were detected; up to 80 moles of calcium bound with a kd value of 0.5 mM, while an additional 120 moles bound with a kd value of 5 mM. Amino acid analysis revealed a carboxy plus carboxyamide content of 24.3 mol/100 mol, indicating the availability of substantial numbers of weak Ca2+-binding sites. Calcium binding did not result in either secondary or quaternary structural changes in the collagenase/gelatinase, suggesting that Ca2+ may facilitate activation through directly mediating the binding of substrate to the enzyme. The collagenase/gelatinase activity was detected in blastocoelic fluid and in the hyalin fraction dissociated from 1-h-old embryos. Immunolocalization studies revealed two storage compartments in the egg; cortical granules and small granules/vesicles dispersed throughout the cytoplasm. After fertilization, the antigen was detected in both the apical and basal extracellular matrices, the hyaline layer, and basal lamina, respectively.

  20. Calcium

    Science.gov (United States)

    ... and blood vessels contract and expand, to secrete hormones and enzymes and to send messages through the nervous system. It is important to get plenty of calcium in the foods you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with ...

  1. Highly Stable Aqueous Zinc-ion Storage Using Layered Calcium Vanadium Oxide Bronze Cathode

    KAUST Repository

    Xia, Chuan

    2018-02-12

    Cost-effective aqueous rechargeable batteries are attractive alternatives to non-aqueous cells for stationary grid energy storage. Among different aqueous cells, zinc-ion batteries (ZIBs), based on Zn2+ intercalation chemistry, stand out as they can employ high-capacity Zn metal as anode material. Herein, we report a layered calcium vanadium oxide bronze as cathode material for aqueous Zn batteries. For the storage of Zn2+ ions in aqueous electrolyte, we demonstrate that calcium based bronze structure can deliver a high capacity of 340 mAh g-1 at 0.2 C, good rate capability and very long cycling life (96% retention after 3000 cycles at 80 C). Further, we investigate the Zn2+ storage mechanism, and the corresponding electrochemical kinetics in this bronze cathode. Finally, we show that our Zn cell delivers an energy density of 267 Wh kg-1 at a power density of 53.4 W kg-1.

  2. IBiSA_Tools: A Computational Toolkit for Ion-Binding State Analysis in Molecular Dynamics Trajectories of Ion Channels.

    Science.gov (United States)

    Kasahara, Kota; Kinoshita, Kengo

    2016-01-01

    Ion conduction mechanisms of ion channels are a long-standing conundrum. Although the molecular dynamics (MD) method has been extensively used to simulate ion conduction dynamics at the atomic level, analysis and interpretation of MD results are not straightforward due to complexity of the dynamics. In our previous reports, we proposed an analytical method called ion-binding state analysis to scrutinize and summarize ion conduction mechanisms by taking advantage of a variety of analytical protocols, e.g., the complex network analysis, sequence alignment, and hierarchical clustering. This approach effectively revealed the ion conduction mechanisms and their dependence on the conditions, i.e., ion concentration and membrane voltage. Here, we present an easy-to-use computational toolkit for ion-binding state analysis, called IBiSA_tools. This toolkit consists of a C++ program and a series of Python and R scripts. From the trajectory file of MD simulations and a structure file, users can generate several images and statistics of ion conduction processes. A complex network named ion-binding state graph is generated in a standard graph format (graph modeling language; GML), which can be visualized by standard network analyzers such as Cytoscape. As a tutorial, a trajectory of a 50 ns MD simulation of the Kv1.2 channel is also distributed with the toolkit. Users can trace the entire process of ion-binding state analysis step by step. The novel method for analysis of ion conduction mechanisms of ion channels can be easily used by means of IBiSA_tools. This software is distributed under an open source license at the following URL: http://www.ritsumei.ac.jp/~ktkshr/ibisa_tools/.

  3. Effect of Sr2+AND Mg2+ IONS on electrochemical deposition of calcium phosphates

    Energy Technology Data Exchange (ETDEWEB)

    Correia, M.B.; Gualberto Junior, J.P.; Macedo, M.C.S.S.; Resende, C.X.; Santos, E.A. [Universidade Federal de Sergipe (UFS), SE (Brazil)

    2014-07-01

    The incorporation of Sr2+ and Mg2+ ions into apatite favors the mineralization process of the bone, besides it to prevent the osteoporosis. In this work, it was evaluated the individual effect of Sr2+ and Mg2+ ions in the electrochemical deposition process of calcium phosphate on metallic substrate. The electrodeposition was performed using a conventional three- electrode cell. The titanium sheets were immersed in the electrolyte containing Ca(NO3)2 and NH4H2PO4 and a potential of -0. 8 V was applied. The coatings were characterized by SEM and XRD. By XRD analysis was possible to identify octacalcium phosphate in the control sample. However, after the addition of Mg2+ ions the OCP becomes the secondary phase while the brushite showed as majoritary phase. On the other hand, the incorporation of Sr2+ ions stabilized the OCP phase. (author)

  4. Studies on the Binding of Lead and Zinc Ions by Modified Cellulosic ...

    African Journals Online (AJOL)

    substrate contact time, the metal ion concentration, the metal ion type and the substrate type. The amount of these ions absorbed varies with the cellulosic material and in the order Pb (II) > Zn (II). It is shown that the cellulosic materials could bind ...

  5. Biosensor and chemical sensor probes for calcium and other metal ions

    Science.gov (United States)

    Vo-Dinh, Tuan; Viallet, Pierre

    1996-01-01

    The present invention relates to chemical sensor and biosensor probes for measuring low concentration of metals and metal ions in complex samples such as biological fluids, living cells, and environmental samples. More particularly the present invention relates to a gel-based Indo-1 and Fura-2 chemical sensor probes for the measurement of low concentrations of calcium, cadmium, magnesium and the like. Also disclosed is a detector device using the sensors of the present invention.

  6. A short introduction to the new principle of binding ration calcium with sodium zeolite

    DEFF Research Database (Denmark)

    Jørgensen, R J; Bjerrum, M J; Classen, H

    2003-01-01

    This paper summarise the development of the new principle of preventing parturient hypocalcaemia by reducing the bioavailability of ration calcium with calcium binders, based on the idea that a negative calcium balance would stimulate natural defence mechanisms against threatening hypocalcaemia. ...

  7. In vitro phosphate-binding ability of calcium-based agents is augmented by co-administration of activated charcoal.

    Science.gov (United States)

    Jia, Meng; Cheng, Xu-Yang; Zuo, Li

    2013-06-01

    Calcium carbonate is widely used as a phosphate binder in patients on maintenance hemodialysis. An unwanted side effect of calcium carbonate is hypercalcemia and vascular calcification. Oral activated charcoal (AC) is a non-selective and highly effective adsorbent. We hypothesized that AC augments the phosphate binding capacity of calcium-based agents. We performed an in vitro study to test this hypothesis. Simulated gastric fluid and intestinal fluid were prepared with a phosphate concentration of 10 mmol/l. Different dosages of calcium chloride (0.083 g, 0.167 g, and 0.250 g), AC (0.15 g, 0.30 g, and 0.45 g) or a combination of both were added to either gastric or intestinal fluid for phosphate binding. After a reaction time of 2 hours, phosphate concentrations in the supernatant were measured, and absolute reduction and percent reduction of phosphate were calculated. The phosphate-binding abilities of calcium chloride, AC, and a combination of both were compared. In simulated intestinal fluid there was no significant difference in the percent reduction of phosphate concentrations among the different calcium chloride concentration groups (28.90 ± 2.04 vs. 33.33 ± 3.90 vs. 31.86 ± 5.23) and there was still no significant difference in phosphate concentrations among the different AC groups (3.33 ± 0.08 vs. 3.26 ± 0.01 vs. 3.36 ± 0.11). In simulated gastric fluid phosphate concentrations at each of the time points (before the reaction, 1 hour after calcium chloride was added, and 2 hours after AC was added) were not significantly different. In simulated intestinal fluid the percent decrease in phosphate concentration in the calcium chloride + AC group was significantly higher than that in the calcium chloride group (48.23 ± 5.55 vs. 30.72 ± 6.11). AC alone had no phosphate-binding ability in either gastric or intestinal fluid. The phosphate-binding ability of calcium chloride was improved by AC in intestinal fluid.

  8. Neutralizing mutations of carboxylates that bind metal 2 in T5 flap endonuclease result in an enzyme that still requires two metal ions.

    Science.gov (United States)

    Tomlinson, Christopher G; Syson, Karl; Sengerová, Blanka; Atack, John M; Sayers, Jon R; Swanson, Linda; Tainer, John A; Williams, Nicholas H; Grasby, Jane A

    2011-09-02

    Flap endonucleases (FENs) are divalent metal ion-dependent phosphodiesterases. Metallonucleases are often assigned a "two-metal ion mechanism" where both metals contact the scissile phosphate diester. The spacing of the two metal ions observed in T5FEN structures appears to preclude this mechanism. However, the overall reaction catalyzed by wild type (WT) T5FEN requires three Mg(2+) ions, implying that a third ion is needed during catalysis, and so a two-metal ion mechanism remains possible. To investigate the positions of the ions required for chemistry, a mutant T5FEN was studied where metal 2 (M2) ligands are altered to eliminate this binding site. In contrast to WT T5FEN, the overall reaction catalyzed by D201I/D204S required two ions, but over the concentration range of Mg(2+) tested, maximal rate data were fitted to a single binding isotherm. Calcium ions do not support FEN catalysis and inhibit the reactions supported by viable metal cofactors. To establish participation of ions in stabilization of enzyme-substrate complexes, dissociation constants of WT and D201I/D204S-substrate complexes were studied as a function of [Ca(2+)]. At pH 9.3 (maximal rate conditions), Ca(2+) substantially stabilized both complexes. Inhibition of viable cofactor supported reactions of WT, and D201I/D204S T5FENs was biphasic with respect to Ca(2+) and ultimately dependent on 1/[Ca(2+)](2). By varying the concentration of viable metal cofactor, Ca(2+) ions were shown to inhibit competitively displacing two catalytic ions. Combined analyses imply that M2 is not involved in chemical catalysis but plays a role in substrate binding, and thus a two-metal ion mechanism is plausible.

  9. Neutralizing Mutations of Carboxylates That Bind Metal 2 in T5 Flap Endonuclease Result in an Enzyme That Still Requires Two Metal Ions*

    Science.gov (United States)

    Tomlinson, Christopher G.; Syson, Karl; Sengerová, Blanka; Atack, John M.; Sayers, Jon R.; Swanson, Linda; Tainer, John A.; Williams, Nicholas H.; Grasby, Jane A.

    2011-01-01

    Flap endonucleases (FENs) are divalent metal ion-dependent phosphodiesterases. Metallonucleases are often assigned a “two-metal ion mechanism” where both metals contact the scissile phosphate diester. The spacing of the two metal ions observed in T5FEN structures appears to preclude this mechanism. However, the overall reaction catalyzed by wild type (WT) T5FEN requires three Mg2+ ions, implying that a third ion is needed during catalysis, and so a two-metal ion mechanism remains possible. To investigate the positions of the ions required for chemistry, a mutant T5FEN was studied where metal 2 (M2) ligands are altered to eliminate this binding site. In contrast to WT T5FEN, the overall reaction catalyzed by D201I/D204S required two ions, but over the concentration range of Mg2+ tested, maximal rate data were fitted to a single binding isotherm. Calcium ions do not support FEN catalysis and inhibit the reactions supported by viable metal cofactors. To establish participation of ions in stabilization of enzyme-substrate complexes, dissociation constants of WT and D201I/D204S-substrate complexes were studied as a function of [Ca2+]. At pH 9.3 (maximal rate conditions), Ca2+ substantially stabilized both complexes. Inhibition of viable cofactor supported reactions of WT, and D201I/D204S T5FENs was biphasic with respect to Ca2+ and ultimately dependent on 1/[Ca2+]2. By varying the concentration of viable metal cofactor, Ca2+ ions were shown to inhibit competitively displacing two catalytic ions. Combined analyses imply that M2 is not involved in chemical catalysis but plays a role in substrate binding, and thus a two-metal ion mechanism is plausible. PMID:21734257

  10. Localisation of calcium-binding proteins in ram spermatozoa using the immunofluorescence technique

    International Nuclear Information System (INIS)

    Sabrina Sukardi; Watson, P.F.

    2000-01-01

    Localization of two calcium-binding proteins (proteins A and B) believed to be involve in membrane fusion on whole spermatozoa were carried out in two stages; before and after the acrosome reaction, the reaction being a prerequisite to fertilization. Determination of the acrosome reaction and sperm viability is carried out using fluorescent dyes i.e., FITC-conjugated Pisum sativum agglutinin (PSA) and propidium iodide (PI) respectively. Polyclonal antibodies were raised in rabbits. Ejaculated semen was diluted in buffer and loaded into tubes. Acrosome reaction was induced with calcium ionophore A23187 at 390 degree C. PI was added to the sub-samples at time 0 and 45 minutes. Excess PI, ionophore and seminal plasma was filtered out with a syringe. Smears were made on slides and air-dried. The cells were pemeabilised with ethanol and rinsed in PBS. Batch 1 slides were incubated with FITC-PSA in the dark while batch H slides were incubated in 1% sheep serum. Batch II slides were then rinsed in PBS twice and incubated in both antiserum and pre-immune serum (negative control). These slides were then incubated in FITC-conjugated secondary antibody (anti-rabbit IgG) and kept in the dark. After final washing and mounted, both batches of slides were viewed immediately using fluorescence microscope. Results obtained before acrosome reaction showed localization of both antibodies to the whole sperm head, along the midpiece and tail. The acrosomes were also intact and cells were viable. After the acrosome reaction, localization of both antibodies were observed at the post-acrosomal region, midpiece, tail and the equatorial segment with no binding to the acrosome. Cells were mainly acrosome-reacted and dying. No binding was observed with pre-immune serum. Results indicate that the antigens were present in the acrosome and the change in binding suggests that the antigens have been redistributed after commencement of the acrosome reaction. The findings suggest that the proteins

  11. Calcium-binding proteins in the laterodorsal thalamic nucleus during development of the guinea pig.

    Science.gov (United States)

    Zakowski, Witold; Bogus-Nowakowska, Krystyna; Wasilewska, Barbara; Hermanowicz, Beata; Robak, Anna

    2014-11-01

    The laterodorsal thalamic nucleus (LD) is often treated as a part of the anterior thalamic nuclei (ATN) because of its location and similar connectivity. Our previous studies have shown that distribution of three calcium-binding proteins, i.e. calbindin D28k (CB), calretinin (CR) and parvalbumin (PV), changes within the ATN during development of the guinea pig. The aim of this study is to examine the immunoreactivity pattern of these proteins in the LD in the guinea pig ontogeny. Brains from animals ranging from 40th embryonic day to 80th postnatal day were used in the study. Two methods were applied: a single-labelling immunoenzymatic method and double-labelling immunofluorescence. No changes of the distribution pattern of the substances were observed throughout the examined developmental stages. CB and CR were the most abundantly expressed proteins in perikarya of the LD. Numerous CB- and CR-immunoreactive cell bodies were found throughout the whole extent of the nucleus. In most of these cell bodies both proteins colocalized vastly. The highest immunoreactivity of the perikarya containing CB and CR was observed in the mediodorsal part of the LD and in its rostral portion. In regard to PV, single cell bodies were observed mostly in the dorsal part of the nucleus. PV did not colocalize with the other proteins. In summary, all the studied calcium-binding proteins were already present in the LD at prenatal developmental stages and the pattern of distribution remained virtually constant until adulthood. Thus, the LD differs considerably from the ATN in an aspect of neurochemical cell differentiation. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Ion Association versus Ion Interaction Models in Examining Electrolyte Solutions: Application to Calcium Hydroxide Solubility Equilibrium

    Science.gov (United States)

    Menéndez, M. Isabel; Borge, Javier

    2014-01-01

    The heterogeneous equilibrium of the solubility of calcium hydroxide in water is used to predict both its solubility product from solubility and solubility values from solubility product when inert salts, in any concentration, are present. Accepting the necessity of including activity coefficients to treat the saturated solution of calcium…

  13. Calcium binding by human erythrocyte membranes. Significance of carboxyl, amino and thiol groups.

    Science.gov (United States)

    Forstner, J; Manery, J F

    1971-11-01

    1. The role of the ionized carboxyl groups of proteins of the erythrocyte membrane as Ca(2+) receptor sites was investigated. A water-soluble carbodi-imide [1-cyclohexyl-3-(2-morpholinoethyl)carbodi-imide methotoluene-p-sulphonate], referred to as carbodi-imide reagent, and glycine methyl ester were used to modify the free carboxyl groups of the membrane. The degree of modification was estimated from amino acid analyses, which showed the amount of glycine incorporated. As the concentration of carbodi-imide reagent was raised (0.1-0.4m) incorporation of glycine increased and Ca(2+) binding decreased by about 77%. At 0.4m-carbodi-imide reagent all of the binding of Ca(2+) to protein was abolished and it was estimated that about 37% of the side-chain carboxyl groups of aspartic acid plus glutamic acid had been blocked by glycine. 2. Acetylation of all of the free amino groups was achieved by incubating the erythrocyte ;ghosts' at pH10.3 with acetic anhydride (10-15mg/10mg of ;ghost' protein). Acetylation increased by 1.5-fold the capacity of the ;ghost' to bind Ca(2+), indicating that the remaining carboxyl groups of aspartic acid and glutamic acid were made available for Ca(2+) binding by this procedure. These findings support the concept that in normal ;ghosts', at pH7.4, Ca(2+) binding to free carboxyl groups is partially hindered by the presence of charged amino groups. 3. Treatment of ;ghosts' with N-acetylneuraminidase, which removed 94% of sialic acid residues, and treatment with 1mm-p-chloromercuribenzoate did not alter Ca(2+) binding. The major effect of 5.8mm-p-chloromercuribenzoate upon ;ghosts' was to cause a solubilization of a calcium-membrane complex, which included about one-third of the ;ghost' protein. The molar ratio of Ca(2+): protein in the solubilized material was the same as that in the intact (untreated) ;ghosts'.

  14. Evolution of blood magnesium and phosphorus ion levels following thyroidectomy and correlation with total calcium values

    Directory of Open Access Journals (Sweden)

    Alexandre de Andrade Sousa

    Full Text Available CONTEXT AND OBJECTIVE: Magnesium ion concentration is directly related and phosphorus ion concentration is inversely related to calcemia. The aim of this study was to evaluate the evolution of magnesium and phosphorus ion levels in patients undergoing thyroidectomy and correlate these with changes to calcium concentration. DESIGN AND SETTING: Prospective study at the Alpha Institute of Gastroenterology, Hospital das Clínicas, Universidade Federal de Minas Gerais. METHODS: The study included 333 patients, of both genders and mean age 45 ± 15 years, who underwent thyroidectomy between 2000 and 2005. Total calcium, phosphorus and magnesium were measured in the blood preoperatively and 24 and 48 hours postoperatively. Ionic changes were evaluated according to the presence or absence of postoperative hypocalcemia. RESULTS: There were statistically significant drops in blood phosphorus levels 24 and 48 hours after thyroidectomy, compared with preoperative values, in the patients without hypocalcemia. In the patients who developed hypocalcemia, there was a significant drop in plasma phosphorus on the first postoperative day and an increase (also statistically significant on the second day, in relation to preoperative phosphorus levels. A significant drop in postoperative magnesium was also observed on the first and second days after thyroidectomy in the patients with hypocalcemia, in relation to preoperative levels. In the patients without hypocalcemia, the drop in magnesium was significant on the first day, but there was no difference on the second day. CONCLUSION: Despite the postoperative changes, neither magnesium nor phosphorus ion levels had any role in post-thyroidectomy calcemia.

  15. The calcium binding protein ALG-2 binds and stabilizes Scotin, a p53-inducible gene product localized at the endoplasmic reticulum membrane

    DEFF Research Database (Denmark)

    Draeby, Ingrid; Woods, Yvonne L; la Cour, Jonas Marstrand

    2007-01-01

    101, respectively. An in vitro synthesized C-terminal fragment of Scotin bound specifically to immobilized recombinant ALG-2 and tagged ALG-2 and Scotin were shown by immunoprecipitation to interact in MCF7 and U2OS cell lines. Furthermore ALG-2 bound to endogenous Scotin in extracts from mouse NIH3T3...... cells. Overexpression of ALG-2 led to accumulation of Scotin in MCF7 and H1299 cells. In vitro and in vivo binding of ALG-2 to Scotin was demonstrated to be strictly calcium dependent indicating a role of this interaction in calcium signaling pathways....

  16. short communication binding of nickel and zinc ions with activated ...

    African Journals Online (AJOL)

    a

    Equilibrium sorption of nickel and zinc ions by the activated carbon was studied using a range of metal ion concentrations. The sorption data was observed to have an adequate fit for the. Langmuir isotherm equation. The level of metal ion uptake was found to be of the order: Ni2+ >. Zn2+. The difference in the removal ...

  17. UCP3 is associated with Hax-1 in mitochondria in the presence of calcium ion

    International Nuclear Information System (INIS)

    Hirasaka, Katsuya; Mills, Edward M.; Haruna, Marie; Bando, Aki; Ikeda, Chika; Abe, Tomoki; Kohno, Shohei; Nowinski, Sara M.; Lago, Cory U.; Akagi, Ken-ichi; Tochio, Hidehito; Ohno, Ayako; Teshima-Kondo, Shigetada; Okumura, Yuushi; Nikawa, Takeshi

    2016-01-01

    Uncoupling protein 3 (UCP3) is known to regulate energy dissipation, proton leakage, fatty acid oxidation, and oxidative stress. To identify the putative protein regulators of UCP3, we performed yeast two-hybrid screens. Here we report that UCP3 interacted with HS-1 associated protein X-1 (Hax-1), an anti-apoptotic protein that was localized in the mitochondria, and is involved in cellular responses to Ca 2+ . The hydrophilic sequences within loop 2, and the matrix-localized hydrophilic domain of mouse UCP3, were necessary for binding to Hax-1 at the C-terminal domain, adjacent to the mitochondrial inner membrane. Interestingly, interaction of these proteins occurred in a calcium-dependent manner. Moreover, the NMR spectrum of the C-terminal domain of Hax-1 was dramatically changed by removal of Ca 2+ , suggesting that the C-terminal domain of Hax-1 underwent a Ca 2+ -induced conformational change. In the Ca 2+ -free state, the C-terminal Hax-1 tended to unfold, suggesting that Ca 2+ binding may induce protein folding of the Hax-1 C-terminus. These results suggested that the UCP3-Hax-1 complex may regulate mitochondrial functional changes caused by mitochondrial Ca 2+ . - Highlights: • UCP3 interacts with Hax-1. • The interaction of UCP3 and Hax-1 occurs in a calcium-dependent manner. • The C-terminal domain of Hax-1 undergoes a calcium-induced conformational change.

  18. The role of solvation in the binding selectivity of the L-type calcium channel.

    Science.gov (United States)

    Boda, Dezső; Henderson, Douglas; Gillespie, Dirk

    2013-08-07

    We present grand canonical Monte Carlo simulation results for a reduced model of the L-type calcium channel. While charged residues of the protein amino acids in the selectivity filter are treated explicitly, most of the degrees of freedom (including the rest of the protein and the solvent) are represented by their dielectric response, i.e., dielectric continua. The new aspect of this paper is that the dielectric coefficient in the channel is different from that in the baths. The ions entering the channel, thus, cross a dielectric boundary at the entrance of the channel. Simulating this case has been made possible by our recent methodological development [D. Boda, D. Henderson, B. Eisenberg, and D. Gillespie, J. Chem. Phys. 135, 064105 (2011)]. Our main focus is on the effect of solvation energy (represented by the Born energy) on monovalent vs. divalent ion selectivity in the channel. We find no significant change in selectivity by changing the dielectric coefficient in the channel because the larger solvation penalty is counterbalanced by the enhanced Coulomb attraction inside the channel as soon as we use the Born radii (fitted to experimental hydration energies) to compute the solvation penalty from the Born equation.

  19. Diffusion of hydroxyl ions from calcium hydroxide and Aloe vera pastes.

    Science.gov (United States)

    Batista, Victor Eduardo de Souza; Olian, Douglas Dáquila; Mori, Graziela Garrido

    2014-01-01

    This study evaluated the diffusion through the dentinal tubules of hydroxyl ions from different calcium hydroxide (CH) pastes containing Aloe vera. Sixty single-rooted bovine teeth were used. The tooth crowns were removed, the root canals were instrumented and the specimens were assigned to 4 groups (n=15) according to the intracanal medication: Group CH/S - CH powder and saline paste; Group CH/P - CH powder and propylene glycol paste; Group CH/A - calcium hydroxide powder and Aloe vera gel paste; Group CH/A/P - CH powder, Aloe vera powder and propylene glycol paste. After placement of the root canal dressings, the teeth were sealed coronally and apically with a two-step epoxy adhesive. The teeth were placed in identified flasks containing deionized water and stored in an oven with 100% humidity at 37 °C. After 3 h, 24 h, 72 h, 7 days, 15 days and 30 days, the deionized water in the flasks was collected and its pH was measured by a pH meter. The obtained data were subjected to statistical analysis at a significance level of 5%. The results demonstrated that all pastes provided diffusion of hydroxyl ions through the dentinal tubules. The combination of Aloe vera and CH (group CH/A) provided a constant release of calcium ions. Group CH/A/P showed the highest pH at 24 and 72 h. In conclusion, the experimental pastes containing Aloe vera were able to enable the diffusion of hydroxyl ions through the dentinal tubules.

  20. Atypical calcium regulation of the PKD2-L1 polycystin ion channel.

    Science.gov (United States)

    DeCaen, Paul G; Liu, Xiaowen; Abiria, Sunday; Clapham, David E

    2016-06-27

    Native PKD2-L1 channel subunits are present in primary cilia and other restricted cellular spaces. Here we investigate the mechanism for the channel's unusual regulation by external calcium, and rationalize this behavior to its specialized function. We report that the human PKD2-L1 selectivity filter is partially selective to calcium ions (Ca(2+)) moving into the cell, but blocked by high internal Ca(2+)concentrations, a unique feature of this transient receptor potential (TRP) channel family member. Surprisingly, we find that the C-terminal EF-hands and coiled-coil domains do not contribute to PKD2-L1 Ca(2+)-induced potentiation and inactivation. We propose a model in which prolonged channel activity results in calcium accumulation, triggering outward-moving Ca(2+) ions to block PKD2-L1 in a high-affinity interaction with the innermost acidic residue (D523) of the selectivity filter and subsequent long-term channel inactivation. This response rectifies Ca(2+) flow, enabling Ca(2+) to enter but not leave small compartments such as the cilium.

  1. Calcium-dependent displacement of haloperidol-sensitive sigma receptor binding in rat hippocampal slices following tissue depolarization.

    Science.gov (United States)

    Neumaier, J F; Chavkin, C

    1989-10-23

    To evaluate the possible existence of an endogenous ligand for the haloperidol-sensitive sigma receptor, we developed an in vitro competition assay to measure endogenous ligand release. Depolarization of in vitro hippocampal slices by either veratridine or potassium reduced [3H]ditolylguanidine binding in a calcium-dependent and transient manner. None of the drugs or iron substitutions directly affected [3H]ditolylguanidine binding to rat brain membranes. Veratridine-induced depolarization also reduced the binding of [3H](+)3-(3-hydroxyphenyl)-N-(1-propyl)piperidine, another sigma radioligand, in a calcium-dependent manner. Radioligand displacement was not associated with alteration in sigma receptor dissociation kinetics or receptor degradation in the hippocampal slice. In contrast, KC1 depolarization had no effect on [3H]ditolyguanidine binding to sigma receptors in liver slices. The results suggest that a calcium-dependent, depolarization-induced reduction in sigma receptor binding may have been caused by the release of an endogenous sigma ligand in rat hippocampal tissue.

  2. Calculated distortions induced by metal-ion binding to simple oligonucleotide systems: Implications for toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Turner, J.E.; Hingerty, B.E.; England, M.W.; Jacobson, K.B.

    1990-01-01

    We have previously published detailed results of calculations of the binding of the metal ions, Cd{sup 2+} and Ca{sup 2+}, to the dinucleoside monophosphate GpC in water. These ions, which have the same charge and radius, differ enormously in their toxicity to man and other biological systems. Our calculations showed contrasting behavior in the binding of these two metal ions to GpC. We suggest the hypothesis that structural distortions calculated for metal ions binding to simple nucleic-acid systems might serve as a indicator of an ion's potential ability to alter molecular activity and hence to be toxic to an organism. Furthermore, the degree of distortion might be correlated with the degree of toxicity as measured by some suitable criteria. The present paper reports the results of binding calculations for a number of other metal ions, of different valence states, with several dinucleoside monophosphates in water. A general trend of distortion with the type of binding of the metal ions is found. We are seeking quantitative measures of distortion to correlate with indicators of acute toxicity that we have measured for 24 metal ions using mice, Drosophila, and CHO cells. 3 refs., 3 figs.

  3. The ability of AIF-1 to activate human vascular smooth muscle cells is lost by mutations in the EF-hand calcium-binding region

    International Nuclear Information System (INIS)

    Autieri, Michael V.; Chen Xing

    2005-01-01

    Allograft Inflammatory Factor-1 (AIF-1) is a cytoplasmic calcium-binding protein expressed in vascular smooth muscle cells (VSMC) in response to injury or cytokine stimulation. AIF-1 contains a partially conserved EF-hand calcium-binding domain, and participates in VSMC activation by activation of Rac1 and induction of Granulocyte-Colony Stimulating Factor (G-CSF) expression; however, the mechanism whereby AIF-1 mediates these effects is presently uncharacterized. To determine if calcium binding plays a functional role in AIF-1 activity, a single site-specific mutation was made in the EF-hand calcium-binding domain to abrogate binding of calcium (AIF-1ΔA), which was confirmed by calcium overlay. Functionally, similar to wild-type AIF-1, AIF-1ΔA was able to polymerize F-actin in vitro. However, in contrast to wild-type AIF-1, over-expression of AIF-1ΔA was unable to increase migration or proliferation of primary human VSMC. Further, it was unable to activate Rac1, or induce G-CSF expression to the degree as wild-type AIF-1. Taken together, modification of the wild-type EF-hand domain and native calcium-binding activity results in a loss of AIF-1 function. We conclude that appropriate calcium-binding potential is critical in AIF-1-mediated effects on VSMC pathophysiology, and that AIF-1 activity is mediated by Rac1 activation and G-CSF expression

  4. The Effects of Calcium Ions on the Flotation of Sillimanite Using Dodecylammonium Chloride

    Directory of Open Access Journals (Sweden)

    Zhijie Chen

    2017-02-01

    Full Text Available The effects of Ca2+ ions on the flotation of sillimanite using dodecylammonium chloride as a collector were investigated by micro-flotation tests, zeta potential measurements, solution chemistry analysis and molecular dynamics (MD simulation. The micro-flotation results indicated that Ca2+ ions remarkably inhibit the flotation of sillimanite in the pH range of 2.0–9.0. The point of zero charge (PZC of sillimanite changed from 5.4 to 6.1 with the addition of Ca2+ ions. Meanwhile, the calculated concentration of RNH3+ in the sillimanite interface layer decreased in the presence of Ca2+ ions. The results of MD simulation revealed that Ca2+ ions have strong binding energy with the sillimanite (010 surface, and the binding energy of RNH3+ with sillimanite (010 surface reduced in the presence of Ca2+ ions. The conclusions drawn from the computations are in good agreement with the experimental results.

  5. Hydrogen-Deuterium Exchange Mass Spectrometry Reveals Calcium Binding Properties and Allosteric Regulation of Downstream Regulatory Element Antagonist Modulator (DREAM).

    Science.gov (United States)

    Zhang, Jun; Li, Jing; Craig, Theodore A; Kumar, Rajiv; Gross, Michael L

    2017-07-18

    Downstream regulatory element antagonist modulator (DREAM) is an EF-hand Ca 2+ -binding protein that also binds to a specific DNA sequence, downstream regulatory elements (DRE), and thereby regulates transcription in a calcium-dependent fashion. DREAM binds to DRE in the absence of Ca 2+ but detaches from DRE under Ca 2+ stimulation, allowing gene expression. The Ca 2+ binding properties of DREAM and the consequences of the binding on protein structure are key to understanding the function of DREAM. Here we describe the application of hydrogen-deuterium exchange mass spectrometry (HDX-MS) and site-directed mutagenesis to investigate the Ca 2+ binding properties and the subsequent conformational changes of full-length DREAM. We demonstrate that all EF-hands undergo large conformation changes upon calcium binding even though the EF-1 hand is not capable of binding to Ca 2+ . Moreover, EF-2 is a lower-affinity site compared to EF-3 and -4 hands. Comparison of HDX profiles between wild-type DREAM and two EF-1 mutated constructs illustrates that the conformational changes in the EF-1 hand are induced by long-range structural interactions. HDX analyses also reveal a conformational change in an N-terminal leucine-charged residue-rich domain (LCD) remote from Ca 2+ -binding EF-hands. This LCD domain is responsible for the direct interaction between DREAM and cAMP response element-binding protein (CREB) and regulates the recruitment of the co-activator, CREB-binding protein. These long-range interactions strongly suggest how conformational changes transmit the Ca 2+ signal to CREB-mediated gene transcription.

  6. Mineralization Process of Biocemented Sand and Impact of Bacteria and Calcium Ions Concentrations on Crystal Morphology

    Directory of Open Access Journals (Sweden)

    Guobin Xu

    2017-01-01

    Full Text Available Microbial-induced calcite precipitation (MICP is a sustainable technique used to improve sandy soil. Analysis of the mineralization process, as well as different bacterial suspensions and calcium concentrations on the crystal morphology, revealed that the mineralization process included four stages: self-organised hydrolysis of microorganisms, molecular recognition and interface interaction, growth modulation, and epitaxial growth. By increasing bacterial suspensions and calcium concentrations, the crystal morphology changed from hexahedron to oblique polyhedron to ellipsoid; the best crystal structure occurs at OD600 = 1.0 and [Ca2+] = 0.75 mol/l. It should be noted that interfacial hydrogen bonding is the main force that binds the loose sand particles. These results will help in understanding the mechanism of MICP.

  7. Modeling strontium-cesium-calcium-magnesium-sodium ion exchange equilibria on chabazite with the Wilson equation

    International Nuclear Information System (INIS)

    Perona, J.J.

    1992-01-01

    Chabazite zeolites are used at ORNL for decontamination of wastewaters containing 90 Sr and 137 Cs. Treatability studies have shown that chabazite can remove trace amounts of these nuclides from wastewaters containing much higher concentrations of calcium and magnesium. The design of ion exchange columns for multicomponent systems requires a method for predicting multicomponent equilibria from binary or ternary experiments, since the number of experiments required for an empirical equilibrium model is generally not feasible. Binary interaction parameters for the Wilson equation were used to predict solid-phase activity coefficients for the five-component system, and the sum of squares of deviations between experimental and predicted solution concentrations for the data points available was calculated. The average deviation per data point for the five-component system was about the same as for the calcium-magnesium-sodium ternary system

  8. Corrosion control of galvanized steel using a phosphate/calcium ion inhibitor mixture

    International Nuclear Information System (INIS)

    Zin, I.M.; Lyon, S.B.; Pokhmurskii, V.I.

    2003-01-01

    The corrosion inhibition of galvanized steel was studied in artificial acid rain solution using extracts of pigments normally used in organic coatings for corrosion control. It was established that a combination of zinc phosphate/molybdate and calcium ion exchange silica has a significant synergetic anticorrosion effect in the acid rain solution compared to the pigments used alone. Further, the charge transfer resistance of galvanized steel in acid rain solution saturated by the above pigment blend approaches that of strontium chromate in artificial acid rain solution. Use of the pigment blend was found to lead to development of a protective film, which is thought to be a complex mixture of calcium phosphates and zinc phosphate

  9. Organometallics and quaternary ammonium salts affect calcium ion desorption from lecithin liposome membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kral, T.E.; Kuczera, J.; Przestalski, S. [Dept. of Physics and Biophysics, Agricultural Univ., Wroclaw (Poland)

    2001-06-01

    The objective of the present work was to compare the effects of groups of tin and lead organometallic compounds and their mixtures with amphiphilic quaternary ammonium salts (QAS) on the process of calcium ion desorption from lecithin liposome membranes, as dependent on the properties of the hydrophilic and hydrophobic parts of QAS. In the investigations the method of radioactive labels was applied. Synergism and antagonism in the action of both groups of compounds were found. The effectiveness of the cooperation depended more on chain length of QAS compounds than on the size and polarity of their hydrophobic parts. The most effective of all compounds studied was a the mixture of benzyldimethylammonium chloride in a mixture with tripropyltin. Since the rate of calcium desorption proved to be a good measure of efficacy of biologically active surfactants, it seems that the conclusions reached in this paper may be useful for choosing compounds which are able to decontaminate the environment polluted with heavy metals. (orig.)

  10. Accumulation of calcium in the centre of leaves of coriander (Coriandrum sativum L.) is due to an uncoupling of water and ion transport.

    Science.gov (United States)

    Kerton, Matt; Newbury, H John; Hand, David; Pritchard, Jeremy

    2009-01-01

    The aim of this study is to understand the parameters regulating calcium ion distribution in leaves. Accumulation of ions in leaf tissue is in part dependent on import from the xylem. This import via the transpiration stream is more important for ions such as calcium that are xylem but not phloem mobile and cannot therefore be retranslocated. Accumulation of calcium was measured on bulk coriander leaf tissue (Coriandrum sativum L. cv. Lemon) using ion chromatography and calcium uptake was visualized using phosphor-images of (45)Ca(2+). Leaves of plants grown in hydroponics had elevated calcium in the centre of the leaf compared with the leaf margin, while K(+) was distributed homogeneously over the leaf. This calcium was shown to be localised to the mesophyll vacuoles using EDAX. Stomatal density and evapotranspiration (water loss per unit area of leaf) were equal at inner and outer sections of the leaf. Unequal ion distribution but uniformity of water loss suggested that there was a difference in the extent of uncoupling of calcium and water transport between the inner and outer leaf. Since isolated tissue from the inner and outer leaf were able to accumulate similar amounts of calcium, it is proposed that the spatial variation of leaf calcium concentration is due to differential ion delivery to the two regions rather than tissue/cell-specific differences in ion uptake capacity. There was a positive correlation between whole leaf calcium concentration and the difference in calcium concentration between inner and outer leaf tissue. Exposing the plants to increased humidity reduced transpiration and calcium delivery to the leaf and abolished this spatial variation of calcium concentration. Mechanisms of calcium delivery to leaves are discussed. An understanding of calcium delivery and distribution within coriander will inform strategies to reduce the incidence of calcium-related syndromes such as tip-burn and provides a robust model for the transport of ions and

  11. Effects of soil salinity on the content, composition, and ion binding capacity of glomalin-related soil protein (GRSP).

    Science.gov (United States)

    Zhang, Zhonghua; Wang, Qiong; Wang, Hua; Nie, Siming; Liang, Zhengwei

    2017-03-01

    Soil aggregation, an ecosystem function correlated with the concentration of glomalin-related soil protein (GRSP), is highly disturbed in saline soil. However, few studies have focused on differences in amount, composition, and ion binding capacity of GRSP in typical sodic-saline soils. In this study, a field study was performed in Songnen Plain. Combined indicators of soil salinity (Q value) were significant negatively correlated with GRSP concentration by Principal Component Analysis. Multiple linear regression models showed that soil salinity might account for 46%, 25% and 44% variation in total GRSP (T-GRSP), easily-extractable GRSP (EE-GRSP) and difficultly-extractable GRSP (DE-GRSP), respectively. Soil bulk density had most important impact on GRSP concentration, followed by the pH, soil EC had the weak influence. Comparative analysis was carried out between low-salinity and high-salinity soil. Purified T-GRSP of high-saline soil contained higher N content (13.13%), lower C content (43.41%) and lower functional groups relative content (e.g. CO and SiOSi). Purified T-GRSP of high-salinity soil had a greater binding capacity with calcium and phosphorus, the binding capacity could compensate the GRSP loss about 29.8% and 14.1%, respectively. Our findings suggested that sodic salinization of the soil led to a decrease in GRSP concentration and a change in the component percentages. This change in composition might be related to adaptation of fungi-plant systems to varied environments. The calcium and phosphorus binding capacity had a positive dependent of soil salinization, which was possible to develop ecological management or recovery technology in the future. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. NALCN ion channels have alternative selectivity filters resembling calcium channels or sodium channels.

    Directory of Open Access Journals (Sweden)

    Adriano Senatore

    Full Text Available NALCN is a member of the family of ion channels with four homologous, repeat domains that include voltage-gated calcium and sodium channels. NALCN is a highly conserved gene from simple, extant multicellular organisms without nervous systems such as sponges and placozoans and mostly remains a single gene compared to the calcium and sodium channels which diversified into twenty genes in humans. The single NALCN gene has alternatively-spliced exons at exons 15 or exon 31 that splices in novel selectivity filter residues that resemble calcium channels (EEEE or sodium channels (EKEE or EEKE. NALCN channels with alternative calcium, (EEEE and sodium, (EKEE or EEKE -selective pores are conserved in simple bilaterally symmetrical animals like flatworms to non-chordate deuterostomes. The single NALCN gene is limited as a sodium channel with a lysine (K-containing pore in vertebrates, but originally NALCN was a calcium-like channel, and evolved to operate as both a calcium channel and sodium channel for different roles in many invertebrates. Expression patterns of NALCN-EKEE in pond snail, Lymnaea stagnalis suggest roles for NALCN in secretion, with an abundant expression in brain, and an up-regulation in secretory organs of sexually-mature adults such as albumen gland and prostate. NALCN-EEEE is equally abundant as NALCN-EKEE in snails, but is greater expressed in heart and other muscle tissue, and 50% less expressed in the brain than NALCN-EKEE. Transfected snail NALCN-EEEE and NALCN-EKEE channel isoforms express in HEK-293T cells. We were not able to distinguish potential NALCN currents from background, non-selective leak conductances in HEK293T cells. Native leak currents without expressing NALCN genes in HEK-293T cells are NMDG(+ impermeant and blockable with 10 µM Gd(3+ ions and are indistinguishable from the hallmark currents ascribed to mammalian NALCN currents expressed in vitro by Lu et al. in Cell. 2007 Apr 20;129(2:371-83.

  13. Molecular mechanism of ATP binding and ion channel activation in P2X receptors

    Energy Technology Data Exchange (ETDEWEB)

    Hattori, Motoyuki; Gouaux, Eric (Oregon HSU)

    2012-10-24

    P2X receptors are trimeric ATP-activated ion channels permeable to Na{sup +}, K{sup +} and Ca{sup 2+}. The seven P2X receptor subtypes are implicated in physiological processes that include modulation of synaptic transmission, contraction of smooth muscle, secretion of chemical transmitters and regulation of immune responses. Despite the importance of P2X receptors in cellular physiology, the three-dimensional composition of the ATP-binding site, the structural mechanism of ATP-dependent ion channel gating and the architecture of the open ion channel pore are unknown. Here we report the crystal structure of the zebrafish P2X4 receptor in complex with ATP and a new structure of the apo receptor. The agonist-bound structure reveals a previously unseen ATP-binding motif and an open ion channel pore. ATP binding induces cleft closure of the nucleotide-binding pocket, flexing of the lower body {beta}-sheet and a radial expansion of the extracellular vestibule. The structural widening of the extracellular vestibule is directly coupled to the opening of the ion channel pore by way of an iris-like expansion of the transmembrane helices. The structural delineation of the ATP-binding site and the ion channel pore, together with the conformational changes associated with ion channel gating, will stimulate development of new pharmacological agents.

  14. Randomized crossover study comparing the phosphate-binding efficacy of calcium ketoglutarate versus calcium carbonate in patients on chronic hemodialysis

    DEFF Research Database (Denmark)

    Bro, S; Rasmussen, R A; Handberg, J

    1998-01-01

    , diarrhea, general uneasiness), whereas the remaining 12 patients did not experience any side effects at all. The five patients with calcium ketoglutarate intolerance all had pre-existing gastrointestinal symptoms; four of them had received treatment with cimetidine or omeprazol before inclusion...

  15. Metal binding by food components

    DEFF Research Database (Denmark)

    Tang, Ning

    For calcium binding: Electrochemical method (calcium ion selective electrode) combined with quantum mechanical calculations (density functional theory) were used to investigate the calcium binding affinity of the amino acids and small glycine peptides. The effects of the ionic strength and p......, synergistic effect in calcium binding was found for the small glycine peptide rather than amino acids mixtures with the enhanced driving force up to -6 kJ/mol. Such study provides useful information for the future development of calcium supplements. For zinc binding: Isothermal titration calorimetry...... titration calorimetry and quantum mechanical calculations. This is due to the zinc binding affinity of the relatively softer ligands (investigated food components) will become much stronger than citrate or phytate when they present together in aqueous solution. This mechanism indicates these food components...

  16. short communication binding of nickel and zinc ions with activated ...

    African Journals Online (AJOL)

    a

    ABSTRACT. Activated carbon was prepared from sugar cane fibre by carbonizing at 500 oC for 30 minutes. ... Equilibrium sorption of nickel and zinc ions by the activated carbon was studied using a range of metal ion .... which means that limited sorption cycles will be required in the treatment of waste water containing the ...

  17. Deciphering ligand specificity of a Clostridium thermocellum family 35 carbohydrate binding module (CtCBM35 for gluco- and galacto- substituted mannans and its calcium induced stability.

    Directory of Open Access Journals (Sweden)

    Arabinda Ghosh

    Full Text Available This study investigated the role of CBM35 from Clostridium thermocellum (CtCBM35 in polysaccharide recognition. CtCBM35 was cloned into pET28a (+ vector with an engineered His6 tag and expressed in Escherichia coli BL21 (DE3 cells. A homogenous 15 kDa protein was purified by immobilized metal ion chromatography (IMAC. Ligand binding analysis of CtCBM35 was carried out by affinity electrophoresis using various soluble ligands. CtCBM35 showed a manno-configured ligand specific binding displaying significant association with konjac glucomannan (Ka = 14.3×10(4 M(-1, carob galactomannan (Ka = 12.4×10(4 M(-1 and negligible association (Ka = 12 µM(-1 with insoluble mannan. Binding of CtCBM35 with polysaccharides which was calcium dependent exhibited two fold higher association in presence of 10 mM Ca(2+ ion with konjac glucomannan (Ka = 41×10(4 M(-1 and carob galactomannan (Ka = 30×10(4 M(-1. The polysaccharide binding was further investigated by fluorescence spectrophotometric studies. On binding with carob galactomannan and konjac glucomannan the conformation of CtCBM35 changed significantly with regular 21 nm peak shifts towards lower quantum yield. The degree of association (K a with konjac glucomannan and carob galactomannan, 14.3×10(4 M(-1 and 11.4×10(4 M(-1, respectively, corroborated the findings from affinity electrophoresis. The association of CtCBM35with konjac glucomannan led to higher free energy of binding (ΔG -25 kJ mole(-1 as compared to carob galactomannan (ΔG -22 kJ mole(-1. On binding CtCBM35 with konjac glucomannan and carob galactomannan the hydrodynamic radius (RH as analysed by dynamic light scattering (DLS study, increased to 8 nm and 6 nm, respectively, from 4.25 nm in absence of ligand. The presence of 10 mM Ca(2+ ions imparted stiffer orientation of CtCBM35 particles with increased RH of 4.52 nm. Due to such stiffer orientation CtCBM35 became more thermostable and its melting temperature was

  18. Solvation of calcium ion in methanol: Comparison of diffraction studies and molecular dynamics simulation

    International Nuclear Information System (INIS)

    Megyes, Tuende; Balint, Szabolcs; Bako, Imre; Grosz, Tamas; Radnai, Tamas; Palinkas, Gabor

    2006-01-01

    Molecular dynamics simulation and diffraction (X-ray and neutron) studies were compared on 1 and 2 M methanol solutions of calcium chloride with aiming at the determination of the solution structures. Beyond that, the capabilities of the methods to describe solution structure are discussed. It has been found that diffraction methods are performing very well in determination of Ca 2+ -O distances (2.39 A in average). Further on, by applying the X-ray diffraction method ion pairs could be observed easily for higher concentrated solution, but for neutron diffraction study, the most adequate isotope substitution method has to be chosen with care in order to be able to detect ion pairs in solution. The results of molecular dynamic simulation were found to be in general accordance with the experimental findings. The smaller discrepancies between simulation and experimental results are coming from small differences in the ion-methanol and ion-ion distances, and they may be due to both the potential model applied in the simulation and to the experimental uncertainties

  19. Distribution and Morphology of Calcium-Binding Proteins Immunoreactive Neurons following Chronic Tungsten Multielectrode Implants.

    Directory of Open Access Journals (Sweden)

    Marco Aurelio M Freire

    Full Text Available The development of therapeutic approaches to improve the life quality of people suffering from different types of body paralysis is a current major medical challenge. Brain-machine interface (BMI can potentially help reestablishing lost sensory and motor functions, allowing patients to use their own brain activity to restore sensorimotor control of paralyzed body parts. Chronic implants of multielectrodes, employed to record neural activity directly from the brain parenchyma, constitute the fundamental component of a BMI. However, before this technique may be effectively available to human clinical trials, it is essential to characterize its long-term impact on the nervous tissue in animal models. In the present study we evaluated how chronic implanted tungsten microelectrode arrays impact the distribution and morphology of interneurons reactive to calcium-binding proteins calbindin (CB, calretinin (CR and parvalbumin (PV across the rat's motor cortex. Our results revealed that chronic microelectrode arrays were well tolerated by the nervous tissue, with recordings remaining viable for up to 6 months after implantation. Furthermore, neither the morphology nor the distribution of inhibitory neurons were broadly impacted. Moreover, restricted microglial activation was observed on the implanted sites. On the whole, our results confirm and expand the notion that tungsten multielectrodes can be deemed as a feasible candidate to future human BMI studies.

  20. Auditory hindbrain atrophy and anomalous calcium binding protein expression after neonatal exposure to monosodium glutamate.

    Science.gov (United States)

    Foran, Lindsey; Blackburn, Kaitlyn; Kulesza, Randy J

    2017-03-06

    Glutamate is the most abundant excitatory neurotransmitter in the central nervous system, and is stored and released by both neurons and astrocytes. Despite the important role of glutamate as a neurotransmitter, elevated extracellular glutamate can result in excitotoxicity and apoptosis. Monosodium glutamate (MSG) is a naturally occurring sodium salt of glutamic acid that is used as a flavor enhancer in many processed foods. Previous studies have shown that MSG administration during the early postnatal period results in neurodegenerative changes in several forebrain regions, characterized by neuronal loss and neuroendocrine abnormalities. Systemic delivery of MSG during the neonatal period and induction of glutamate neurotoxicity in the cochlea have both been shown to result in fewer neurons in the spiral ganglion. We hypothesized that an MSG-induced loss of neurons in the spiral ganglion would have a significant impact on the number of neurons in the cochlear nuclei and superior olivary complex (SOC). Indeed, we found that exposure to MSG from postnatal days 4 through 10 resulted in significantly fewer neurons in the cochlear nuclei and SOC and significant dysmorphology in surviving neurons. Moreover, we found that neonatal MSG exposure resulted in a significant decrease in the expression of both calretinin and calbindin. These results suggest that neonatal exposure to MSG interferes with early development of the auditory brainstem and impacts expression of calcium binding proteins, both of which may lead to diminished auditory function. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  1. Effects of Leaching Behavior of Calcium Ions on Compression and Durability of Cement-Based Materials with Mineral Admixtures

    Science.gov (United States)

    Cheng, An; Chao, Sao-Jeng; Lin, Wei-Ting

    2013-01-01

    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 reinforcing steel corrosion. This study investigates the effects of leaching behavior of calcium ions on the compression and durability of cement-based materials. Since the parameters influencing the leaching behavior of cement-based materials are unclear and diverse, this paper focuses on the influence of added mineral admixtures (fly ash, slag and silica fume) on the leaching behavior of calcium ions regarding compression and durability of cemented-based materials. Ammonium nitrate solution was used to accelerate the leaching process in this study. Scanning electron microscopy, X-ray diffraction analysis, and thermogravimetric analysis were employed to analyze and compare the cement-based material compositions prior to and after calcium ion leaching. The experimental results show that the mineral admixtures reduce calcium hydroxide quantity and refine pore structure through pozzolanic reaction, thus enhancing the compressive strength and durability of cement-based materials. PMID:28809247

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

    Science.gov (United States)

    Presečki, Ana Vrsalović; Blažević, Zvjezdana Findrik; Vasić-Rački, Durđa

    2013-11-01

    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.

  3. Aluminium and hydrogen ions inhibit a mechanosensory calcium-selective cation channel

    Science.gov (United States)

    Ding, J. P.; Pickard, B. G.

    1993-01-01

    The tension-dependent activity of mechanosensory calcium-selective cation channels in excised plasmalemmal patches from onion bulb scale epidermis is modulated by pH in the physiologically meaningful range between 4.5 and 7.2. It is rapidly lowered by lowering pH and rapidly raised by raising pH. Channel activity is effectively inhibited by low levels of aluminium ions and activity can be partially restored by washing for a few minutes. We suggest that under normal conditions the sensitivity of the mechanosensory channels to pH of the wall free space plays important roles in regulation of plant activities such as growth. We further suggest that, when levels of acid and aluminium ions in the soil solution are high, they might inhibit similar sensory channels in cells of the root tip, thus contributing critically to the acid soil syndrome.

  4. Combinatorial incorporation of fluoride and cobalt ions into calcium phosphates to stimulate osteogenesis and angiogenesis.

    Science.gov (United States)

    Birgani, Zeinab Tahmasebi; Gharraee, Nazli; Malhotra, Angad; van Blitterswijk, Clemens A; Habibovic, Pamela

    2016-02-29

    Bone healing requires two critical mechanisms, angiogenesis and osteogenesis. In order to improve bone graft substitutes, both mechanisms should be addressed simultaneously. While the individual effects of various bioinorganics have been studied, an understanding of the combinatorial effects is lacking. Cobalt and fluoride ions, in appropriate concentrations, are known to individually favor the vascularization and mineralization processes, respectively. This study investigated the potential of using a combination of fluoride and cobalt ions to simultaneously promote osteogenesis and angiogenesis in human mesenchymal stromal cells (hMSCs). Using a two-step biomimetic method, wells of tissue culture plates were coated with a calcium phosphate (CaP) layer without or with the incorporation of cobalt, fluoride, or both. In parallel, hMSCs were cultured on uncoated well plates, and cultured with cobalt and/or fluoride ions within the media. The results revealed that cobalt ions increased the expression of angiogenic markers, with the effects being stronger when the ions were added as a dissolved salt in cell medium as compared to incorporation into CaP. Cobalt ions generally suppressed the ALP activity, the expression of osteogenic genes, and the level of mineralization, regardless of delivery method. Fluoride ions, individually or in combination with cobalt, significantly increased the expression of many of the selected osteogenic markers, as well as mineral deposition. This study demonstrates an approach to simultaneously target the two essential mechanisms in bone healing: angiogenesis and osteogenesis. The incorporation of cobalt and fluoride into CaPs is a promising method to improve the biological performance of fully synthetic bone graft substitutes.

  5. Renal transport of bisphosphonates: accumulation by renal cortical slices enhanced by calcium phosphate ions

    Energy Technology Data Exchange (ETDEWEB)

    Troehler, U.; Bonjour, J.P.; Fleisch, H.

    1985-07-01

    Bisphosphonates have been recognized as useful therapeutic agents in metabolic bone disease. Earlier studies showed a net renal secretion of 1-hydroxy-ethylidene-1,1-bisphosphonate (HEBP). They suggested a renal cellular uptake of this compound. The authors further studied this concept by investigating the uptake in vitro of /sup 14/C-HEBP by rat renal cortex slices. HEBP was accumulated against a concentration gradient, a process that was dependent on time, temperature, and substrate concentration. Unlike that of /sup 3/H-p-aminohippurate, the uptake was not affected by change in medium Na+ or glucose and acetate concentration, or by anoxia and various metabolic inhibitors. It was, however, markedly increased by raising the medium calcium and inorganic phosphate concentration. Equilibrium dialysis with renal cortex homogenates suggests that HEBP binds to a cytosolic macromolecule through a process that exhibits saturability and calcium dependency. In conclusion, the results suggest that the bisphosphonate HEBP can penetrate kidney cells by a process that does not appear to be energy dependent, but is markedly influenced by the extracellular calcium-phosphate concentration.

  6. Ions in size-selected aqueous nanodrops: sequential water molecule binding energies and effects of water on ion fluorescence.

    Science.gov (United States)

    Donald, William A; Leib, Ryan D; Demireva, Maria; Williams, Evan R

    2011-11-23

    The effects of water on ion fluorescence were investigated, and average sequential water molecule binding energies to hydrated ions, M(z)(H(2)O)(n), at large cluster size were measured using ion nanocalorimetry. Upon 248-nm excitation, nanodrops with ~25 or more water molecules that contain either rhodamine 590(+), rhodamine 640(+), or Ce(3+) emit a photon with average energies of approximately 548, 590, and 348 nm, respectively. These values are very close to the emission maxima of the corresponding ions in solution, indicating that the photophysical properties of these ions in the nanodrops approach those of the fully hydrated ions at relatively small cluster size. As occurs in solution, these ions in nanodrops with 8 or more water molecules fluoresce with a quantum yield of ~1. Ce(3+) containing nanodrops that also contain OH(-) fluoresce, whereas those with NO(3)(-) do not. This indirect fluorescence detection method has the advantages of high sensitivity, and both the size of the nanodrops as well as their constituents can be carefully controlled. For ions that do not fluoresce in solution, such as protonated tryptophan, full internal conversion of the absorbed 248-nm photon occurs, and the average sequential water molecule binding energies to the hydrated ions can be accurately obtained at large cluster sizes. The average sequential water molecule binding energies for TrpH(+)(H(2)O)(n) and a doubly protonated tripeptide, [KYK + 2H](2+)(H(2)O)(n), approach asymptotic values of ~9.3 (n ≥ 11) and ~10.0 kcal/mol (n ≥ 25), respectively, consistent with a liquidlike structure of water in these nanodrops.

  7. Production and Characterization of Desmalonichrome Relative Binding Affinity for Uranyl Ions in Relation to Other Siderophores

    Energy Technology Data Exchange (ETDEWEB)

    Mo, Kai-For; Dai, Ziyu; Wunschel, David S.

    2016-06-24

    Siderophores are Fe binding secondary metabolites that have been investigated for their uranium binding properties. Much of the previous work has focused on characterizing hydroxamate types of siderophores, such as desferrioxamine B, for their uranyl binding affinity. Carboxylate forms of these metabolites hold potential to be more efficient chelators of uranyl, yet they have not been widely studied and are more difficult to obtain. Desmalonichrome is a carboxylate siderophore which is not commercially available and so was obtained from the ascomycete fungus Fusarium oxysporum cultivated under Fe depleted conditions. The relative affinity for uranyl binding of desmalonichrome was investigated using a competitive analysis of binding affinities between uranyl acetate and different concentrations of iron(III) chloride using electrospray ionization mass spectrometry (ESI-MS). In addition to desmalonichrome, three other siderophores, including two hydroxamates (desferrioxamine B and desferrichrome) and one carboxylate (desferrichrome A) were studied to understand their relative affinities for the uranyl ion at two pH values. The binding affinities of hydroxymate siderophores to uranyl ion were found to decrease to a greater degree at lower pH as the concentration of Fe (III) ion increases. On the other hand, lowering pH has little impact on the binding affinities between carboxylate siderophores and uranyl ion. Desmalonichrome was shown to have the greatest relative affinity for uranyl at any pH and Fe(III) concentration. These results suggest that acidic functional groups in the ligands are critical for strong chelation with uranium at lower pH.

  8. Absorption of calcium ions on oxidized graphene sheets and study its dynamic behavior by kinetic and isothermal models

    Directory of Open Access Journals (Sweden)

    Mahmoud Fathy

    2016-07-01

    Full Text Available Abstract Sorption of calcium ion from the hard underground water using novel oxidized graphene (GO sheets was studied in this paper. Physicochemical properties and microstructure of graphene sheets were investigated using Raman spectrometer, thermogravimetry analyzer, transmission electron microscope, scanning electron microscope. The kinetics adsorption of calcium on graphene oxide sheets was examined using Lagergren first and second orders. The results show that the Lagergren second-order was the best-fit model that suggests the conception process of calcium ion adsorption on the Go sheets. For isothermal studies, the Langmuir and Freundlich isotherm models were used at temperatures ranging between 283 and 313 K. Thermodynamic parameters resolved at 283, 298 and 313 K indicating that the GO adsorption was exothermic spontaneous process. Finally, the graphene sheets show high partiality toward calcium particles and it will be useful in softening and treatment of hard water.

  9. UCP3 is associated with Hax-1 in mitochondria in the presence of calcium ion

    Energy Technology Data Exchange (ETDEWEB)

    Hirasaka, Katsuya, E-mail: hirasaka@nagasaki-u.ac.jp [Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Nagasaki (Japan); Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima (Japan); Mills, Edward M. [Division of Pharmacology/Toxicology, University of Texas at Austin, Austin, TX (United States); Haruna, Marie; Bando, Aki; Ikeda, Chika; Abe, Tomoki [Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima (Japan); Kohno, Shohei; Nowinski, Sara M. [Division of Pharmacology/Toxicology, University of Texas at Austin, Austin, TX (United States); Lago, Cory U. [Translational Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD (United States); Akagi, Ken-ichi [Section of Laboratory Equipment, National Institute of Biomedical Innovation, Osaka (Japan); Tochio, Hidehito [Graduate School of Engineering, Kyoto University, Kyoto (Japan); Ohno, Ayako; Teshima-Kondo, Shigetada [Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima (Japan); Okumura, Yuushi [Department of Nutrition and Health, Sagami Woman' s University, Kanagawa (Japan); Nikawa, Takeshi [Department of Nutritional Physiology, Institute of Health Biosciences, University of Tokushima, Tokushima (Japan)

    2016-03-25

    Uncoupling protein 3 (UCP3) is known to regulate energy dissipation, proton leakage, fatty acid oxidation, and oxidative stress. To identify the putative protein regulators of UCP3, we performed yeast two-hybrid screens. Here we report that UCP3 interacted with HS-1 associated protein X-1 (Hax-1), an anti-apoptotic protein that was localized in the mitochondria, and is involved in cellular responses to Ca{sup 2+}. The hydrophilic sequences within loop 2, and the matrix-localized hydrophilic domain of mouse UCP3, were necessary for binding to Hax-1 at the C-terminal domain, adjacent to the mitochondrial inner membrane. Interestingly, interaction of these proteins occurred in a calcium-dependent manner. Moreover, the NMR spectrum of the C-terminal domain of Hax-1 was dramatically changed by removal of Ca{sup 2+}, suggesting that the C-terminal domain of Hax-1 underwent a Ca{sup 2+}-induced conformational change. In the Ca{sup 2+}-free state, the C-terminal Hax-1 tended to unfold, suggesting that Ca{sup 2+} binding may induce protein folding of the Hax-1 C-terminus. These results suggested that the UCP3-Hax-1 complex may regulate mitochondrial functional changes caused by mitochondrial Ca{sup 2+}. - Highlights: • UCP3 interacts with Hax-1. • The interaction of UCP3 and Hax-1 occurs in a calcium-dependent manner. • The C-terminal domain of Hax-1 undergoes a calcium-induced conformational change.

  10. Serum testosterone, sex hormone-binding globulin and total calcium levels predict the calcaneal speed of sound in men.

    Science.gov (United States)

    Chin, Kok-Yong; Soelaiman, Ima-Nirwana; Mohamed, Isa Naina; Ngah, Wan Zurinah Wan

    2012-08-01

    Variations in sex hormones and the calcium balance can influence bone health in men. The present study aimed to examine the relationship between the calcaneal speed of sound and biochemical determinants of bone mass, such as sex hormones, parathyroid hormones and serum calcium. Data from 549 subjects from the Malaysian Aging Male Study, which included Malay and Chinese men aged 20 years and older residing in the Klang Valley, were used for analysis. The subjects' calcaneal speed of sound was measured, and their blood was collected for biochemical analysis. Two sets of multiple regression models were generated for the total/bioavailable testosterone and estradiol to avoid multicollinearity. The multiple regression results revealed that bioavailable testosterone and serum total calcium were significant predictors of the calcaneal speed of sound in the adjusted model. After adjustment for ethnicity and body mass index, only bioavailable testosterone remained significant; the total serum calcium was marginally insignificant. In a separate model, the total testosterone and sex hormone-binding globulin were significant predictors, whereas the total serum calcium was marginally insignificant. After adjustment for ethnicity and body mass index (BMI), the significance persisted for total testosterone and SHBG. After further adjustment for age, none of the serum biochemical determinants was a significant predictor of the calcaneal speed of sound. There is a significant age-dependent relationship between the calcaneal speed of sound and total testosterone, bioavailable testosterone and sex hormone-binding globulin in Chinese and Malay men in Malaysia. The relationship between total serum calcium and calcaneal speed of sound is ethnicity-dependent.

  11. MeRNA: a Database of Metal Ion Binding Sites in RNAStructures

    Energy Technology Data Exchange (ETDEWEB)

    Stefan, Liliana R.; Zhang, Rui; Levitan, Aaron G.; Hendrix, DonnaF.; Brenner, Steven E.; Holbrook, Stephen R.

    2005-10-05

    Metal ions are essential for the folding of RNA into stable tertiary structures and for the catalytic activity of some RNA enzymes. To aid in the study of the roles of metal ions in RNA structural biology, we have created MeRNA (Metals in RNA), a comprehensive compilation of all metal binding sites identified in RNA three-dimensional structures available from the Protein Data Bank (PDB) and Nucleic Acid Database (NDB). Currently, our database contains information relating to binding of 9764 metal ions corresponding to 23 distinct elements; in 256 RNA structures. The metal ion locations were confirmed and ligands characterized using original literature references. MeRNA includes eight manually identified metal-ion binding motifs, which are described in the literature. MeRNA is searchable by PDB identifier, metal ion, method of structure determination, resolution and R-values for X-ray structure, and distance from metal to any RNA atom or to water. New structures with their respective binding motifs will be added to the database as they become available. The MeRNA database will further our understanding of the roles of metal ions in RNA folding and catalysis and have applications in structural and functional analysis, RNA design and engineering.

  12. Optical planar waveguide in sodium-doped calcium barium niobate crystals by carbon ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jin-Hua, E-mail: zhaojinhuazjh@gmail.com [School of Science, Shandong Jianzhu University, Jinan 250101 (China); Qin, Xi-Feng; Wang, Feng-Xiang; Fu, Gang; Wang, Hui-Lin [School of Science, Shandong Jianzhu University, Jinan 250101 (China); Wang, Xue-Lin [School of Physics, Key Laboratory of Particle Physics and Particle Irradiation, Ministry of Education, and State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China)

    2013-07-15

    There is great interest in niobate crystals which belong to the tetragonal tungsten bronze (TTB) families owing to their intriguing properties. As one representative of such crystals, CBN (calcium barium niobate) has attracted rapidly growing attention. Because it has a higher Curie temperature than SBN (strontium barium niobate), possesses outstanding ferroelectric and it possesses optical properties. In addition, doped with sodium, CBN will show a higher Curie temperature than pure CBN. We report on the fabrication and characterization of optical planar waveguide in x-cut sodium-doped calcium barium niobate crystal by using C ion implantation. The guided-mode properties at the wavelength of 633 and 1539 nm are investigated through prism-coupling measurements, respectively. By applying direct end-face coupling arrangement, the near-field optical intensity distribution of waveguide modes is measured at 633 nm. For comparison, the modal profile of the same guided mode is also numerically calculated by the finite difference beam-propagation method via computer software BeamPROP. The transmission spectra of the waveguide before and after ion implantation treatments were investigated also. Our experiment results reveal that the waveguide could propagate light with transverse magnetic polarized direction only and it is assumed that the polarization selectivity of CBN crystal may responsible for this phenomenon.

  13. Regulation of proteolysis in Bacillus subtilis: effects of calcium ions and energy poisons

    International Nuclear Information System (INIS)

    O'Hara, M.B.; Hageman, J.H.

    1987-01-01

    Bacillus subtilis cells carry out extensive intracellular proteolysis (k = 0.15-0.23/h) during sporulation. Protein degradation was measured in cells growing in chemically defined sporulation medium, by following the release of [ 14 C]-leucine from the cells during spore formation. Sodium arsenate, carbonyl cyanide 3-chlorophenyl hydrazone, and sodium azide strongly inhibited proteolysis without altering cell viability greatly, which suggested that bulk proteolysis in B. subtilis is energy dependent. The authors have tested the hypothesis that the energy requirement may be for pumping in Ca 2+ . When [Ca 2+ ] was -6 , rates of proteolysis in sporulating cells were reduced 4-8 times that in cells in calcium ion- sufficient medium. Further, omission of Ca 2+ from the medium prevented the increase in the activity of the major intracellular serine protease. However, the presence of energy poisons in the media at levels which inhibited proteolysis, had no detectable effect on the uptake of by cells [ 45 Ca]. The authors concluded that B. subtilis cells required both metabolic energy and calcium ions for normal proteolysis

  14. A Proposed Mechanism for the Thermal Denaturation of a Recombinant Bacillus Halmapalus Alpha-amylase - the Effect of Calcium Ions

    Science.gov (United States)

    Nielsen, Anders D.; Pusey, Marc L.; Fuglsang, Claus C.; Westh, Peter

    2003-01-01

    The thermal stability of a recombinant alpha-amylase from Bacillus halmapalus alpha-amylase (BHA) has been investigated using circular dichroism spectroscopy (CD) and differential scanning calorimetry (DSC). This alpha-amylase is homologous to other Bacillus alpha-amylases where previous crystallographic studies have identified the existence of 3 calcium binding sites in the structure. Denaturation of BHA is irreversible with a Tm of approximately 89 C, and DSC thermograms can be described using a one-step irreversible model. A 5 C increase in T(sub m) in the presence of 10 fold excess CaCl2 was observed. However, a concomitant increase in the tendency to aggregate was also observed. The presence of 30-40 fold excess calcium chelator (EDTA or EGTA) results in a large destabilization of BHA corresponding to about 40 C lower T(sub m), as determined by both CD and DSC. Ten fold excess EGTA reveals complex DSC thermograms corresponding to both reversible and irreversible transitions, which possibly originate from different populations of BHA:calcium complexes. The observations in the present study have, in combination with structural information of homologous alpha-amylases, provided the basis for the proposal of a simple denaturation mechanism of BHA. The proposed mechanism describes the irreversible thermal denaturation of different BHA:calcium complexes and the calcium binding equilibrium involved. Furthermore, the model accounts for a temperature induced reversible structural change associated with calcium binding.

  15. Influence of strontium for calcium substitution in bioactive glasses on degradation, ion release and apatite formation

    Science.gov (United States)

    Fredholm, Yann C.; Karpukhina, Natalia; Brauer, Delia S.; Jones, Julian R.; Law, Robert V.; Hill, Robert G.

    2012-01-01

    Bioactive glasses are able to bond to bone through the formation of hydroxy-carbonate apatite in body fluids while strontium (Sr)-releasing bioactive glasses are of interest for patients suffering from osteoporosis, as Sr was shown to increase bone formation both in vitro and in vivo. A melt-derived glass series (SiO2–P2O5–CaO–Na2O) with 0–100% of calcium (Ca) replaced by Sr on a molar base was prepared. pH change, ion release and apatite formation during immersion of glass powder in simulated body fluid and Tris buffer at 37°C over up to 8 h were investigated and showed that substituting Sr for Ca increased glass dissolution and ion release, an effect owing to an expansion of the glass network caused by the larger ionic radius of Sr ions compared with Ca. Sr release increased linearly with Sr substitution, and apatite formation was enhanced significantly in the fully Sr-substituted glass, which allowed for enhanced osteoblast attachment as well as proliferation and control of osteoblast and osteoclast activity as shown previously. Studying the composition–structure–property relationship in bioactive glasses enables us to successfully design next-generation biomaterials that combine the bone regenerative properties of bioactive glasses with the release of therapeutically active Sr ions. PMID:21993007

  16. The physical properties and ion release of CPP-ACP-modified calcium silicate-based cements.

    Science.gov (United States)

    Dawood, A E; Manton, D J; Parashos, P; Wong, Rhk; Palamara, Jea; Stanton, D P; Reynolds, E C

    2015-12-01

    This study investigated the physical properties and ion release of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP)-modified calcium silicate-based cements (CSCs) and compared the properties of a trial mineral trioxide aggregate (MTA) with two commercially available CSCs, Biodentine(™) and Angelus(®) MTA. The setting time, solubility, compressive strength and Vickers surface microhardness of the three CSCs incorporated with 0%, 0.5%, 1.0%, 2.0% and 3.0% (w/w) CPP-ACP were investigated. Release of calcium (Ca(2+) ), phosphate ions (Pi ) and pH of the test cements were measured after 24, 72, 168 and 336 h of storage. The addition of up to 1.0% CPP-ACP into Biodentine(™) and 0.5% into the other cements did not adversely affect their physical properties except for the setting time. The addition of 0.5% CPP-ACP increased Ca(2+) released from Biodentine(™) (after 168 and 336 h), Angelus(®) MTA (after 168 h) and the trial MTA (after 72 h). The addition of 1.0-3.0% CPP-ACP increased Ca(2+) and Pi released from all the cements. Biodentine(™) released more Ca(2+) particularly in the early stages and showed shorter setting time and higher mechanical properties than the other cements. The mechanical properties of Angelus(®) MTA and the trial MTA were similar. All the cements produced highly alkaline storage solutions. Up to 1.0% CPP-ACP in Biodentine(™) improves Ca(2+) and Pi release and 0.5% CPP-ACP in Angelus(®) MTA and the trial MTA improves Ca(2+) release without altering the mechanical properties and solubility. The addition of CPP-ACP into CSCs prolonged the setting time. © 2015 Australian Dental Association.

  17. Chemically modified carbon paste ion-selective electrodes for determination of atorvastatin calcium in pharmaceutical preparations

    Directory of Open Access Journals (Sweden)

    Salwa Fares Rassi

    2017-06-01

    Full Text Available A simple, rapid and sensitive method for the determination of atorvastatin calcium in pharmaceutical preparations using two modified carbon paste electrodes was developed. One electrode (sensor A is based on ion-pair of atorvastatin with 5,6-diaminouracil hydrochloride (ATS-DAUH and the other (sensor B is based on atorvastatin with picric acid (ATS-PC. Among three different solvent mediators tested, dioctylphthalate (DOPH exhibited a proper behavior including Nernstian slopes of the calibration curve at 58.76 ± 0.8 and 57.48±1 mV per decade for sensors A and B. The response times were 10 and 12 s, detection limits 1.3 × 10−6 and 2.2 × 10−6 M; the concentration range 2.5 × 10−6-7.9 × 10−2 M and 3.0 × 10−6 to 7.9 × 10−2 M respectively. The present electrodes show good discrimination of atorvastatin calcium from several inorganic, organic ions, sugars and some common excipients. The sensors were applied for the determination of atorvastatin calcium in pharmaceutical preparations using standard addition and the calibration curve methods. The results obtained were satisfactory with excellent percentage recovery comparable and sometimes better than those obtained by other routine methods for the assay. The proposed potentiometric methods offer the advantages of simplicity, accuracy, automation feasibility and applicability to turbid and colored sample solutions.

  18. Structure of the plasminogen kringle 4 binding calcium-free form of the C-type lectin-like domain of tetranectin

    DEFF Research Database (Denmark)

    Nielbo, Steen; Thomsen, Jens K; Graversen, Jonas Heilskov

    2004-01-01

    4). The structure of the calcium free-form of TN3 (apoTN3) has been determined by NMR. Compared to the structure of the calcium-bound form of TN3 (holoTN3), the core region of secondary structural elements is conserved, while large displacements occur in the loops involved in calcium or K4 binding......Tetranectin is a homotrimeric protein containing a C-type lectin-like domain. This domain (TN3) can bind calcium, but in the absence of calcium, the domain binds a number of kringle-type protein ligands. Two of the calcium-coordinating residues are also critical for binding plasminogen kringle 4 (K....... A conserved proline, which was found to be in the cis conformation in holoTN3, is in apoTN3 predominantly in the trans conformation. Backbone dynamics indicate that, in apoTN3 especially, two of the three calcium-binding loops and two of the three K4-binding residues exhibit increased flexibility, whereas...

  19. Uptake of CrO{sub 4}{sup 2-} ions by Fe-treated tri-calcium phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Serrano G, J.; Ramirez S, J. L.; Bonifacio M, J.; Granados C, F.; Badillo A, V. E., E-mail: juan.serrano@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2010-07-01

    CrO{sub 4}{sup 2-} ion adsorption of Fe-treated tri-calcium phosphate was studied by batch experiments as a function of contact time, initial concentration of metal ion and temperature. Adsorption results showed that at ph 5.5 and 1.0 x 10{sup -4} M chromium concentration the adsorption capacity of Fe-treated tri-calcium phosphate for CrO{sub 4}{sup 2-} ions was 7.10 x 10{sup -3} mmol/g. Chromium adsorption data on Fe-treated tri-calcium phosphate at various initial concentration fitted the Freundlich isotherm. By temperature studies the thermodynamic parameters {Delta}H{sup 0}, {Delta}G{sup 0} and {Delta}S{sup 0} were estimated and the obtained results showed that the adsorption reaction was endothermic and spontaneous. (Author)

  20. Structure of thrombospondin type 3 repeats in bacterial outer membrane protein A reveals its intra-repeat disulfide bond-dependent calcium-binding capability

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Shuyan; Sun, Cancan; Tan, Kemin; Ye, Sheng; Zhang, Rongguang

    2017-09-01

    Eukaryotic thrombospondin type 3 repeat (TT3R) is an efficient calcium ion (Ca2+) binding motif only found in mammalian thrombospondin family. TT3R has also been found in prokaryotic cellulase Cel5G, which was thought to forfeit the Ca2+-binding capability due to the formation of intra-repeat disulfide bonds, instead of the inter-repeat ones possessed by eukaryotic TT3Rs. In this study, we have identified an enormous number of prokaryotic TT3R-containing proteins belonging to several different protein families, including outer membrane protein A (OmpA), an important structural protein connecting the outer membrane and the periplasmic peptidoglycan layer in gram-negative bacteria. Here, we report the crystal structure of the periplasmic region of OmpA from Capnocytophaga gingivalis, which contains a linker region comprising five consecutive TT3Rs. The structure of OmpA-TT3R exhibits a well-ordered architecture organized around two tightly-coordinated Ca2+ and confirms the presence of abnormal intra-repeat disulfide bonds. Further mutagenesis studies showed that the Ca2+-binding capability of OmpA-TT3R is indeed dependent on the proper formation of intra-repeat disulfide bonds, which help to fix a conserved glycine residue at its proper position for Ca2+ coordination. Additionally, despite lacking inter repeat disulfide bonds, the interfaces between adjacent OmpA-TT3Rs are enhanced by both hydrophobic and conserved aromatic-proline interactions.

  1. NMR Structures and Dynamics in a Prohead RNA Loop that Binds Metal Ions.

    Science.gov (United States)

    Gu, Xiaobo; Park, Sun-Young; Tonelli, Marco; Cornilescu, Gabriel; Xia, Tianbing; Zhong, Dongping; Schroeder, Susan J

    2016-10-06

    Metal ions are critical for RNA structure and enzymatic activity. We present the structure of an asymmetric RNA loop that binds metal ions and has an essential function in a bacteriophage packaging motor. Prohead RNA is a noncoding RNA that is required for genome packaging activity in phi29-like bacteriophage. The loops in GA1 and phi29 bacteriophage share a conserved adenine that forms a base triple, although the structural context for the base triple differs. NMR relaxation studies and femtosecond time-resolved fluorescence spectroscopy reveal the dynamic behavior of the loop in the metal ion bound and unbound forms. The mechanism of metal ion binding appears to be an induced conformational change between two dynamic ensembles rather than a conformational capture mechanism. These results provide experimental benchmarks for computational models of RNA-metal ion interactions.

  2. The retention of calcium, barium, and strontium ions by a mollisol humic acid: Spectroscopic investigation

    Science.gov (United States)

    Oufqir, Sofia; Bloom, Paul R.; Torner, Brandy M.

    2014-05-01

    Humic substances have a major role in controlling the mobility and bioavailability of metallic ions in soils and natural waters. The alkaline earth metals, calcium, barium, and strontium, are broadly abundant in the crust of the earth, and Ca2+ ions are known to be important in the formation of structural aggregates in soils. Yet, direct spectroscopic evidence of how Ca, Ba, and Sr ions interact with soil organic matter, is minimal. To develop a deeper understanding of the interaction of the alkaline earth cations in soil, we studied the complexation behavior of strontium, barium and calcium by humic acid (HA) using solid-state 13C CP-MAS NMR, FTIR and extended x-ray absorption fine structure (EXAFS) spectroscopy. A HA sample was extracted from an agricultural mollisol (pH 6, 32.5% clay content, 3.7% organic carbon) located in southwestern Minnesota, USA, by the standard NaOH method. The HA sample was treated with chloride salts of Ca, Sr or Ba, then freeze-dried prior to spectroscopic measurements. The FTIR spectra, obtained using pressed KBr disks, and the 13C NMR spectra revealed spectral differences, stemming mainly from deprotonation reactions of the carboxylic and phenolic groups of the HA. The association of Ca, Ba, and Sr ions with the HA caused a marked FTIR shift of the carboxylate band, with the Ba shift being the most pronounced (HA 1604.7; HA-Ca 1595.1; HA-Sr 1597; HA-Ba 1579.6), which seems to imply that Ba is the strongest bound element. An NMR shift of the carbonyl peak at 171.8 ppm was also observed to 174.5 for Ca, 173.7 for Sr, and 174.4 for Ba confirming that these cations are behaving differently towards soil HA. The EXAFS spectra indicated back-scattering from oxygen atoms, in the first shell, for Ca, Sr, and Ba with varied coordination number. Our data prove that (1) the carboxylates and phenolates are the prevailing functional groups involved in the interactions between the extracted HA and alkali metal cations, (2) barium forms the

  3. Excited-state structural dynamics of a dual-emission calmodulin-green fluorescent protein sensor for calcium ion imaging.

    Science.gov (United States)

    Oscar, Breland G; Liu, Weimin; Zhao, Yongxin; Tang, Longteng; Wang, Yanli; Campbell, Robert E; Fang, Chong

    2014-07-15

    Fluorescent proteins (FPs) have played a pivotal role in bioimaging and advancing biomedicine. The versatile fluorescence from engineered, genetically encodable FP variants greatly enhances cellular imaging capabilities, which are dictated by excited-state structural dynamics of the embedded chromophore inside the protein pocket. Visualization of the molecular choreography of the photoexcited chromophore requires a spectroscopic technique capable of resolving atomic motions on the intrinsic timescale of femtosecond to picosecond. We use femtosecond stimulated Raman spectroscopy to study the excited-state conformational dynamics of a recently developed FP-calmodulin biosensor, GEM-GECO1, for calcium ion (Ca(2+)) sensing. This study reveals that, in the absence of Ca(2+), the dominant skeletal motion is a ∼ 170 cm(-1) phenol-ring in-plane rocking that facilitates excited-state proton transfer (ESPT) with a time constant of ∼ 30 ps (6 times slower than wild-type GFP) to reach the green fluorescent state. The functional relevance of the motion is corroborated by molecular dynamics simulations. Upon Ca(2+) binding, this in-plane rocking motion diminishes, and blue emission from a trapped photoexcited neutral chromophore dominates because ESPT is inhibited. Fluorescence properties of site-specific protein mutants lend further support to functional roles of key residues including proline 377 in modulating the H-bonding network and fluorescence outcome. These crucial structural dynamics insights will aid rational design in bioengineering to generate versatile, robust, and more sensitive optical sensors to detect Ca(2+) in physiologically relevant environments.

  4. Quercetagetin-Loaded Zein-Propylene Glycol Alginate Ternary Composite Particles Induced by Calcium Ions: Structure Characterization and Formation Mechanism.

    Science.gov (United States)

    Sun, Cuixia; Wei, Yang; Li, Ruirui; Dai, Lei; Gao, Yanxiang

    2017-05-17

    The complexation of zein and propylene glycol alginate (PGA) was confirmed to improve the entrapment efficiency and loading capacity of quercetagetin (Q) in our previous study. The present work focused on the influence and induction mechanism of calcium ions on structures of Q-loaded zein-PGA ternary composite particles. The incorporation of Ca 2+ resulted in the formation of aggregates with a large dimension between zein particles, led to obvious conformational, secondary, and tertiary structural changes of zein, and caused the disappearance of crystalline structure of zein. PGA exhibited a fine filamentous network structure and became much thicker and stronger in the presence of Ca 2+ . The presence of Q promoted the affinity and binding capacity of Ca 2+ to zein and PGA. An interwoven network structure with enhanced firmness and density was observed in Q-loaded zein-PGA composite particles, leading to improved thermal stability. Three potential mechanisms were proposed to explain the structural characteristics induced by Ca 2+ , including particle-particle collision for zein particles, chain-chain association for PGA molecules, and simultaneous cross-linking coupled with aggregating for Q-loaded zein-PGA composite particles.

  5. Protein kinase C interaction with calcium: a phospholipid-dependent process.

    LENUS (Irish Health Repository)

    Bazzi, M D

    1990-08-21

    The calcium-binding properties of calcium- and phospholipid-dependent protein kinase C (PKC) were investigated by equilibrium dialysis in the presence and the absence of phospholipids. Calcium binding to PKC displayed striking and unexpected behavior; the free proteins bound virtually no calcium at intracellular calcium concentrations and bound limited calcium (about 1 mol\\/mol of PKC) at 200 microM calcium. However, in the presence of membranes containing acidic phospholipids, PKC bound at least eight calcium ions per protein. The presence of 1 microM phorbol dibutyrate (PDBu) in the dialysis buffer had little effect on these calcium-binding properties. Analysis of PKC-calcium binding by gel filtration under equilibrium conditions gave similar results; only membrane-associated PKC bound significant amounts of calcium. Consequently, PKC is a member of what may be a large group of proteins that bind calcium in a phospholipid-dependent manner. The calcium concentrations needed to induce PKC-membrane binding were similar to those needed for calcium binding (about 40 microM calcium at the midpoint). However, the calcium concentration required for PKC-membrane binding was strongly influenced by the phosphatidylserine composition of the membranes. Membranes with higher percentages of phosphatidylserine required lower concentrations of calcium. These properties suggested that the calcium sites may be generated at the interface between PKC and the membrane. Calcium may function as a bridge between PKC and phospholipids. These studies also suggested that calcium-dependent PKC-membrane binding and PKC function could be regulated by a number of factors in addition to calcium levels and diacylglycerol content of the membrane.

  6. Characterization of Mn(II) ion binding to the amyloid-β peptide in Alzheimer's disease.

    Science.gov (United States)

    Wallin, Cecilia; Kulkarni, Yashraj S; Abelein, Axel; Jarvet, Jüri; Liao, Qinghua; Strodel, Birgit; Olsson, Lisa; Luo, Jinghui; Abrahams, Jan Pieter; Sholts, Sabrina B; Roos, Per M; Kamerlin, Shina C L; Gräslund, Astrid; Wärmländer, Sebastian K T S

    2016-12-01

    Growing evidence links neurodegenerative diseases to metal exposure. Aberrant metal ion concentrations have been noted in Alzheimer's disease (AD) brains, yet the role of metals in AD pathogenesis remains unresolved. A major factor in AD pathogenesis is considered to be aggregation of and amyloid formation by amyloid-β (Aβ) peptides. Previous studies have shown that Aβ displays specific binding to Cu(II) and Zn(II) ions, and such binding has been shown to modulate Aβ aggregation. Here, we use nuclear magnetic resonance (NMR) spectroscopy to show that Mn(II) ions also bind to the N-terminal part of the Aβ(1-40) peptide, with a weak binding affinity in the milli- to micromolar range. Circular dichroism (CD) spectroscopy, solid state atomic force microscopy (AFM), fluorescence spectroscopy, and molecular modeling suggest that the weak binding of Mn(II) to Aβ may not have a large effect on the peptide's aggregation into amyloid fibrils. However, identification of an additional metal ion displaying Aβ binding reveals more complex AD metal chemistry than has been previously considered in the literature. Copyright © 2016 Elsevier GmbH. All rights reserved.

  7. Quaternary Benzyltriethylammonium Ion Binding to the Na,K-ATPase: a Tool to Investigate Extracellular K+ Binding Reactions†

    Science.gov (United States)

    Peluffo, R. Daniel; González-Lebrero, Rodolfo M.; Kaufman, Sergio B.; Kortagere, Sandhya; Orban, Branly; Rossi, Rolando C.; Berlin, Joshua R.

    2009-01-01

    This study examined how the quaternary organic ammonium ion, benzyltriethylamine (BTEA), binds to the Na,K-ATPase to produce membrane potential (VM)-dependent inhibition and tested the prediction that such a VM-dependent inhibitor would display electrogenic binding kinetics. BTEA competitively inhibited K+ activation of Na,K-ATPase activity and steady-state 86Rb+ occlusion. The initial rate of 86Rb+ occlusion was decreased by BTEA to a similar degree whether it was added to the enzyme prior to or simultaneously with Rb+, a demonstration that BTEA inhibits the Na,K-ATPase without being occluded. Several BTEA structural analogues reversibly inhibited Na,K-pump current, but none blocked current in a VM-dependent manner except BTEA and its para-nitro derivative, pNBTEA. Under conditions that promoted electroneutral K+-K+ exchange by the Na,K-ATPase, step changes in VM elicited pNBTEA-activated ouabain-sensitive transient currents that had similarities to those produced with the K+ congener, Tl+. pNBTEA- and Tl+-dependent transient currents both displayed saturation of charge moved at extreme negative and positive VM, equivalence of charge moved during and after step changes in VM, and similar apparent valence. The rate constant (ktot) for Tl+-dependent transient current asymptotically approached a minimum value at positive VM. In contrast, ktot for pNBTEA-dependent transient current was a “U”-shaped function of VM with a minimum value near 0 mV. Homology models of the Na,K-ATPase alpha subunit suggested that quaternary amines can bind to two extracellularly-accessible sites, one of them located at K+ binding sites positioned between transmembrane helices 4, 5, and 6. Altogether, these data revealed important information about electrogenic ion binding reactions of the Na,K-ATPase that are not directly measurable during ion transport by this enzyme. PMID:19621894

  8. Vestibular nuclei characterized by calcium-binding protein immunoreactivity and tract tracing in Gekko gecko.

    Science.gov (United States)

    Song, Jing; Wang, Wenbo; Carr, Catherine E; Dai, Zhendong; Tang, Yezhong

    2013-02-01

    Immunohistochemical techniques were used to describe the distribution of the calcium binding proteins calretinin, calbindin and parvalbumin as well as synaptic vesicle protein 2 in the vestibular nuclei of the Tokay gecko (Gekko gecko). In addition, tract tracing was used to investigate connections between the vestibular nerves and brainstem nuclei. Seven vestibular nuclei were recognized: the nuclei cerebellaris lateralis (Cerl), vestibularis dorsolateralis (Vedl), ventrolateralis (Vevl), ventromedialis (Vevm), tangentialis (Vetg), ovalis (VeO) and descendens (Veds). Vestibular fibers entered the brainstem with the ascending branch projecting to Vedl and Cerl, the lateral descending branch to Veds, and the medial descending branch to ipsilateral Vevl. Cerl lay most rostral, in the cerebellar peduncle. Vedl, located rostrally, was ventral to the cerebellar peduncle, and consisted of loosely arranged multipolar and monopolar cells. Vevl was found at the level of the vestibular nerve root and contained conspicuously large cells and medium-sized cells. Veds is a large nucleus, the most rostral portion of which is situated lateral and ventral to Vevl, and occupies much of the dorsal brainstem extending caudally through the medulla. VeO is a spherically shaped cell group lateral to the auditory nucleus magnocellularis and dorsal to the caudal part of Vevl. Vevm and Vetg were small in the present study. Except for VeO, all other vestibular nuclei appear directly comparable to counterparts in other reptiles and birds based on their location, cytoarchitecture, and connections, indicating these are conserved features of the vestibular system. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Calcium-binding protein expression in peritoneal endometriosis-associated nerve fibres.

    Science.gov (United States)

    Barcena de Arellano, M L; Münch, S; Arnold, J; Helbig, S; Schneider, A; Mechsner, S

    2013-11-01

    Recent studies demonstrated the potential involvement of nerve fibres in the chronic inflammatory process of endometriosis. We aimed to characterize nerve fibres in the proximal and distal areas of the peritoneal endometriotic lesions in order to understand the chronic inflammatory process in endometriosis. Peritoneal endometriotic lesions (proximal area) (n = 17), the matching unaffected peritoneum (distal area) and healthy peritoneum of patients without endometriosis (n = 15) were analysed with the neuronal markers PGP 9.5, calbindin, calretinin and parvalbumin. Peritoneal fluids of women with and without endometriosis were used for Western blot analysis and for the neuronal growth assay. The protein expression of neuronal PC-12 cells incubated with peritoneal fluids was analysed. The overall nerve fibre density was significantly reduced in the distal area of the lesion when compared with the proximal area or with healthy peritoneum. The density of calbindin-, calretinin- and parvalbumin-positive nerve fibres was significantly increased in the endometriosis group. Calretinin expression was elevated in the peritoneal fluid of women with symptomatic endometriosis when compared with women with asymptomatic endometriosis. Furthermore, PC-12 cells incubated with peritoneal fluid of women with endometriosis showed a higher proliferation rate and a stronger neurite outgrowth than the control group. PC-12 cells incubated in peritoneal fluids of women with endometriosis expressed less calretinin but more calbindin than the control group. Calcium-binding proteins seem to be increased in endometriosis-associated nerve fibres and might play an important role in the chronic inflammatory condition and the pain pathogenesis of endometriosis. © 2013 European Federation of International Association for the Study of Pain Chapters.

  10. Morphological features of neurons containing calcium-binding proteins in the human striatum.

    Science.gov (United States)

    Prensa, L; Giménez-Amaya, J M; Parent, A

    1998-01-26

    An immunohistochemical approach was used to characterize the morphological phenotype of neurons containing the calcium-binding proteins calretinin (CR), parvalbumin (PV), or calbindin-D28k (CB) in the normal human striatum. The protein CR occurs in at least four morphologically distinct types of neurons. Apart from the numerous medium-sized aspiny interneurons and the less abundant giant aspiny interneurons, CR also labels some medium-sized spiny neurons morphologically identical to striatal projection neurons. This finding indicates that CR is not only confined to striatal interneurons but also may be involved in the function of certain projection neurons. Some small and peculiar bushy-like aspiny neurons also are enriched with CR. These neurons could correspond to the dwarf or neurogliform neurons first described by Ramón y Cajal (1911). Three types of PV-immunoreactive striatal neurons can be visualized in the human striatum: 1) the common medium-sized aspiny leptodendritic neurons, 2) some smaller and profusely arborized aspiny neurons, and 3) a few large and intensely stained neurons with conspicuously beaded and poorly branched dendrites. The protein CB labels virtually all medium-sized spiny projection neurons located in the striatal matrix but also identifies a small subset of large and more intensely immunostained aspiny neurons. The latter finding indicates that CB is not entirely confined to striatal projection neurons but also may play a role in local circuit neurons. These normative data should help our understanding of the chemical anatomy of the human striatum in both health and disease.

  11. Calcium binding to beta-2-microglobulin at physiological pH drives the occurrence of conformational changes which cause the protein to precipitate into amorphous forms that subsequently transform into amyloid aggregates.

    Directory of Open Access Journals (Sweden)

    Sukhdeep Kumar

    Full Text Available Using spectroscopic, calorimetric and microscopic methods, we demonstrate that calcium binds to beta-2-microglobulin (β2m under physiological conditions of pH and ionic strength, in biological buffers, causing a conformational change associated with the binding of up to four calcium atoms per β2m molecule, with a marked transformation of some random coil structure into beta sheet structure, and culminating in the aggregation of the protein at physiological (serum concentrations of calcium and β2m. We draw attention to the fact that the sequence of β2m contains several potential calcium-binding motifs of the DXD and DXDXD (or DXEXD varieties. We establish (a that the microscopic aggregation seen at physiological concentrations of β2m and calcium turns into actual turbidity and visible precipitation at higher concentrations of protein and β2m, (b that this initial aggregation/precipitation leads to the formation of amorphous aggregates, (c that the formation of the amorphous aggregates can be partially reversed through the addition of the divalent ion chelating agent, EDTA, and (d that upon incubation for a few weeks, the amorphous aggregates appear to support the formation of amyloid aggregates that bind to the dye, thioflavin T (ThT, resulting in increase in the dye's fluorescence. We speculate that β2m exists in the form of microscopic aggregates in vivo and that these don't progress to form larger amyloid aggregates because protein concentrations remain low under normal conditions of kidney function and β2m degradation. However, when kidney function is compromised and especially when dialysis is performed, β2m concentrations probably transiently rise to yield large aggregates that deposit in bone joints and transform into amyloids during dialysis related amyloidosis.

  12. Structural and luminescence properties of Mn2+ ions doped calcium zinc borophosphate glasses

    International Nuclear Information System (INIS)

    Wan, Ming Hua; Wong, Poh Sum; Hussin, Rosli; Lintang, Hendrik O.; Endud, Salasiah

    2014-01-01

    Highlights: • FT-IR revealed that the network structures are from borate and phosphate network. • The PL spectrum exhibits a green emission band at 582 nm ( 4 T 1g → 6 A 1g ). • As the concentration of Mn 2+ ions is increased, the emission band had been red shifted. • These glasses are found to have potential applications as luminescent optical materials. - Abstract: Calcium zinc borophosphate glasses (CaZnBP) doped with various concentrations of Mn 2+ ions and borate and phosphate as variable were prepared using conventional melt quenching technique. The structure of obtained glasses were examined by means of use: X-ray diffraction (XRD) and fourier transform infrared (FT-IR). XRD analysis confirmed amorphous nature of glass samples. The FT-IR spectra reveals the presence of both borate and phosphate vibrational modes in the prepared glasses. The doping of Mn 2+ ions (2–10 mol%) shows no significant changes in the main IR vibrational bands. Optical properties were studied by measuring the near infrared photoluminescence (PL) spectra. CaZnBP glasses exhibited intense green emission peak (582 nm) (tetrahedral symmetry), which is assigned to a transition from the upper 4 T 1g → 6 A 1g ground state of Mn 2+ ions. As the concentration of Mn 2+ ions increases, the emission band increases from 582 nm to 650 nm and exhibited a red light emission (octahedral symmetry). The decay curves of 4 T 1g level were examined for all concentrations and the measured lifetimes are found to depend strongly on Mn 2+ concentrations. From the emission characteristic parameters of 6 A 1g (S) level, it shows that the CaZnBP glasses could have potential applications as luminescent optical materials, visible lasers and fluorescent display devices

  13. The BRCA1 Tumor Suppressor Binds to Inositol 1,4,5-Trisphosphate Receptors to Stimulate Apoptotic Calcium Release*

    Science.gov (United States)

    Hedgepeth, Serena C.; Garcia, M. Iveth; Wagner, Larry E.; Rodriguez, Ana M.; Chintapalli, Sree V.; Snyder, Russell R.; Hankins, Gary D. V.; Henderson, Beric R.; Brodie, Kirsty M.; Yule, David I.; van Rossum, Damian B.; Boehning, Darren

    2015-01-01

    The inositol 1,4,5-trisphosphate receptor (IP3R) is a ubiquitously expressed endoplasmic reticulum (ER)-resident calcium channel. Calcium release mediated by IP3Rs influences many signaling pathways, including those regulating apoptosis. IP3R activity is regulated by protein-protein interactions, including binding to proto-oncogenes and tumor suppressors to regulate cell death. Here we show that the IP3R binds to the tumor suppressor BRCA1. BRCA1 binding directly sensitizes the IP3R to its ligand, IP3. BRCA1 is recruited to the ER during apoptosis in an IP3R-dependent manner, and, in addition, a pool of BRCA1 protein is constitutively associated with the ER under non-apoptotic conditions. This is likely mediated by a novel lipid binding activity of the first BRCA1 C terminus domain of BRCA1. These findings provide a mechanistic explanation by which BRCA1 can act as a proapoptotic protein. PMID:25645916

  14. Mutation/SNP analysis in EF-hand calcium binding domain of mitochondrial Ca[Formula: see text] uptake 1 gene in bipolar disorder patients.

    Science.gov (United States)

    Safari, Roghaiyeh; Salimi, Reza; Tunca, Zeliha; Ozerdem, Aysegul; Ceylan, Deniz; Sakizli, Meral

    2016-06-01

    Calcium signaling is important for synaptic plasticity, generation of brain rhythms, regulating neuronal excitability, data processing and cognition. Impairment in calcium homeostasis contributed to the development of psychiatric disorders such as bipolar disorder (BP). MCU is the most important calcium transporter in mitochondria inner membrane responsible for influx of Ca[Formula: see text]. MICU1 is linked with MCU and has two canonical EF hands that are vital for its activity and regulates MCU-mediated Ca[Formula: see text] influx. In the current study, we aimed to investigate the role of genetic alteration of EF hand calcium binding motifs of MICU1 on the development of BP. We examined patients with BP, first degree relatives of these patients and healthy volunteers for mutations and polymorphisms in EF hand calcium binding motifs of MICU1. The result showed no SNP/mutation in BP patients, in healthy subjects and in first degree relatives. Additionally, alignment of the EF hand calcium binding regions among species (Gallus-gallus, Canis-lupus-familiaris, Bos-taurus, Mus-musculus, Rattus-norvegicus, Pan-troglodytes, Homosapiens and Danio-rerio) showed exactly the same amino acids (DLNGDGEVDMEE and DCDGNGELSNKE) except in one of the calcium binding domain of Danio-rerio that there was only one difference; leucine instead of Methionine. Our results showed that the SNP on EF-hand Ca[Formula: see text] binding domains of MICU1 gene had no effect in phenotypic characters of BP patients.

  15. The C-terminal portion of BM-40 (SPARC/osteonectin) is an autonomously folding and crystallisable domain that binds calcium and collagen IV.

    Science.gov (United States)

    Maurer, P; Hohenadl, C; Hohenester, E; Göhring, W; Timpl, R; Engel, J

    1995-10-20

    The extracellular glycoprotein BM-40 consists of three domains, an acidic domain I, a follistatin (FS)-like domain II and a calcium-binding EC domain with an EF-hand related motif. BM-40 and several other related proteins (QR1, SC1/hevin, testican and tsc-36/FRP) are members of a novel modular protein family that share the FS domain followed by an EC domain. We have expressed this pair of FS and EC domains (mutant delta I) and the calcium-binding EC domain alone (mutant delta I, II) of human BM-40 as recombinant proteins in human 293 cells. Circular dichroism demonstrated that both mutants were obtained as folded proteins with a distinct three-dimensional conformation. In addition, mutant delta I, II could be readily crystallized and diffraction patterns with a resolution limit of 2.4 A resolution were obtained. Calcium binding to this fragment was ten times weaker (Kd = 0.8 microM) than for the wild-type protein. Identical reversible increases in alpha-helicity upon calcium binding were observed for the 150-residue long mutant delta I, II and for BM-40 (286 residues). A 26-residue synthetic peptide corresponding to the EF-hand related motif exhibited much weaker calcium binding. The apparent dissociation constant decreased with increasing peptide concentration (from Kd 2.4 mM at 1 microM, to Kd 0.3 mM at 100 microM peptide concentration) and calcium binding was accompanied by dimerization of the peptide. This suggests that for strong calcium binding the EF-hand related motif has to be embedded into a larger protein domain that can form an autonomously folding protein module. The EC domain was also shown by surface plasmon resonance assay to be responsible for calcium-dependent binding to collagen IV with an affinity (Kd = 19 microM) only sixfold lower than that of intact human BM-40.

  16. Evaluation of calcium (Ca2+) and hydroxide (OH-) ion diffusion rates of indirect pulp capping materials.

    Science.gov (United States)

    Kurun Aksoy, Merve; Tulga Oz, Firdevs; Orhan, Kaan

    2017-10-27

    The aim of this study was to evaluate and compare the calcium (Ca2+) and hydroxide (OH-) ion release of 4 artificially produced pulp capping materials (MTA, Biodentin, TheraCal LC, Calsimol) used for indirect pulp capping treatment. In total, 70 freshly extracted human third molar teeth were used for the study. Cavities of extracted teeth were prepared by round burs. The remaining dentin thickness (1 ± 0.3 mm) tissue was measured by a micrometer and cone beam computerized tomography. Indirect pulp capping was performed in the cavities using Calcimol, MTA, TheraCal LC and Biodentin. The leached Ca2+ were measured using optical emission spectrometry and the release of OH- ions using a pH meter. The measurements were performed after 24 hours, 7 days and 28 days in saline solution. Statistical analysis was performed using 1-way and 2-way analysis of variance (ANOVA) tests (ppulp capping because of their stimulation of hard tissue formation and ion-releasing ability.

  17. Exopolysaccharides regulate calcium flow in cariogenic biofilms.

    Directory of Open Access Journals (Sweden)

    Monika Astasov-Frauenhoffer

    Full Text Available Caries-associated biofilms induce loss of calcium from tooth surfaces in the presence of dietary carbohydrates. Exopolysaccharides (EPS provide a matrix scaffold and an abundance of primary binding sites within biofilms. The role of EPS in binding calcium in cariogenic biofilms is only partially understood. Thus, the aim of the present study is to investigate the relationship between the calcium dissolution rates and calcium tolerance of caries-associated bacteria and yeast as well as to examine the properties of EPS to quantify its binding affinity for dissolved calcium. Calcium dissolution was measured by dissolution zones on Pikovskaya's agar. Calcium tolerance was assessed by isothermal microcalorimetry (IMC by adding CaCl2 to the bacterial cultures. Acid-base titration and Fourier transform infrared (FTIR spectroscopy were used to identify possible functional groups responsible for calcium binding, which was assessed by isothermal titration calorimetry (ITC. Lactobacillus spp. and mutans streptococci demonstrated calcium dissolution in the presence of different carbohydrates. All strains that demonstrated high dissolution rates also revealed higher rates of calcium tolerance by IMC. In addition, acidic functional groups were predominantly identified as possible binding sites for calcium ions by acid-base titration and FTIR. Finally, ITC revealed EPS to have a higher binding affinity for calcium compared, for example, to lactic acid. In conclusion, this study illustrates the role of EPS in terms of the calcium tolerance of cariogenic microbiota by determining the ability of EPS to control free calcium concentrations within the biofilms as a self-regulating mode of action in the pathogenesis of dental caries.

  18. Calcium and initial surface binding phase of pinocytosis in Amoeba proteus

    Energy Technology Data Exchange (ETDEWEB)

    Prusch, R.D.

    1986-08-01

    The uptake of membrane-bound solute and external medium by bulk-phase pinocytosis in Amoeba proteus is influenced by the level of Ca/sup 2 +/ in the external medium. Increasing external Ca/sup 2 +/ to approx.10/sup -4/ M increases pinocytotic intensity, while increases in Ca/sup 2 +/ above this level decrease the intensity of pinocytosis. The initial interaction of pinocytotic inducers and Ca/sup +2/ at the surface of A moeba proteus was therefore examined. Alcain blue and Na/sup +/, both inducers of pinocytosis, differ in the manner with which they associate with the amoeba surface, suggesting the possibility of different pinocytosis-inducing sites on the amoeba surface. Low levels of external Ca/sup 2 +/ in the range of 3 x 10/sup -5/ to 4.5 x 10/sup -4/ M increase the amount of cationic inducer associated with the cell surface while, at the same time, decreasing anion association with the cell surface. It is suggested that Ca/sup 2 +/ influences ion association with the cell surface by controlling the availability of negative surface sites, which in turn influences pinocytotic intensity. Surface binding of Na/sup +/, Ca/sup 2 +/ and Cl/sup -/ was determined by adding /sup 22/Na, /sup 45/Ca or /sup 36/Cl.

  19. Silver ions increase plasma membrane permeability through modulation of intracellular calcium levels in tobacco BY-2 cells.

    Science.gov (United States)

    Klíma, Petr; Laňková, Martina; Vandenbussche, Filip; Van Der Straeten, Dominique; Petrášek, Jan

    2018-03-03

    Silver ions increase plasma membrane permeability for water and small organic compounds through their stimulatory effect on plasma membrane calcium channels, with subsequent modulation of intracellular calcium levels and ion homeostasis. The action of silver ions at the plant plasma membrane is largely connected with the inhibition of ethylene signalling thanks to the ability of silver ion to replace the copper cofactor in the ethylene receptor. A link coupling the action of silver ions and cellular auxin efflux has been suggested earlier by their possible direct interaction with auxin efflux carriers or by influencing plasma membrane permeability. Using tobacco BY-2 cells, we demonstrate here that besides a dramatic increase of efflux of synthetic auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and 1-naphthalene acetic acid (NAA), treatment with AgNO 3 resulted in enhanced efflux of the cytokinin trans-zeatin (tZ) as well as the auxin structural analogues tryptophan (Trp) and benzoic acid (BA). The application of AgNO 3 was accompanied by gradual water loss and plasmolysis. The observed effects were dependent on the availability of extracellular calcium ions (Ca 2+ ) as shown by comparison of transport assays in Ca 2+ -rich and Ca 2+ -free buffers and upon treatment with inhibitors of plasma membrane Ca 2+ -permeable channels Al 3+ and ruthenium red, both abolishing the effect of AgNO 3 . Confocal microscopy of Ca 2+ -sensitive fluorescence indicator Fluo-4FF, acetoxymethyl (AM) ester suggested that the extracellular Ca 2+ availability is necessary to trigger the response to silver ions and that the intracellular Ca 2+ pool alone is not sufficient for this effect. Altogether, our data suggest that in plant cells the effects of silver ions originate from the primal modification of the internal calcium levels, possibly by their interaction with Ca 2+ -permeable channels at the plasma membrane.

  20. Effect of exposed surface area, volume and environmental pH on the calcium ion release of three commercially available tricalcium silicate based dental cements

    OpenAIRE

    Rajasekharan, Sivaprakash; Vercruysse, Chris; Martens, Luc; Verbeeck, Ronald

    2018-01-01

    Tricalcium silicate cements (TSC) are used in dental traumatology and endodontics for their bioactivity which is mostly attributed to formation of calcium hydroxide during TSC hydration and its subsequent release of calcium and hydroxide ions. The aim of this study was to determine the effect of volume (Vol), exposed surface area (ESA) and pH of surrounding medium on calcium ion release. Three commercially available hydraulic alkaline dental cements were mixed and condensed into cylindrical t...

  1. An Empirical Model for Build-Up of Sodium and Calcium Ions in Small Scale Reverse Osmosis

    Directory of Open Access Journals (Sweden)

    Subriyer Nasir

    2011-05-01

    Full Text Available A simple models for predicting build-up of solute on membrane surface were formulated in this paper. The experiments were conducted with secondary effluent, groundwater and simulated feed water in small-scale of RO with capacity of 2000 L/d. Feed water used in the experiments contained varying concentrations of sodium, calcium, combined sodium and calcium. In order to study the effect of sodium and calcium ions on membrane performance, experiments with ground water and secondary effluent wastewater were also performed. Build-up of salts on the membrane surface was calculated by measuring concentrations of sodium and calcium ions in feed water permeate and reject streams using Atomic Absorption Spectrophotometer (AAS. Multiple linear regression of natural logarithmic transformation was used to develop the model based on four main parameters that affect the build-up of solute in a small scale of RO namely applied pressure, permeate flux, membrane resistance, and feed concentration. Experimental data obtained in a small scale RO unit were used to develop the empirical model. The predicted values of theoretical build-up of sodium and calcium on membrane surface were found in agreement with experimental data. The deviation in the prediction of build-up of sodium and calcium were found to be 1.4 to 10.47 % and 1.12 to 4.46%, respectively.

  2. The effect of exogenous calcium on mitochondria, respiratory metabolism enzymes and ion transport in cucumber roots under hypoxia.

    Science.gov (United States)

    He, Lizhong; Li, Bin; Lu, Xiaomin; Yuan, Lingyun; Yang, Yanjuan; Yuan, Yinghui; Du, Jing; Guo, Shirong

    2015-08-25

    Hypoxia induces plant stress, particularly in cucumber plants under hydroponic culture. In plants, calcium is involved in stress signal transmission and growth. The ultimate goal of this study was to shed light on the mechanisms underlying the effects of exogenous calcium on the mitochondrial antioxidant system, the activity of respiratory metabolism enzymes, and ion transport in cucumber (Cucumis sativus L. cv. Jinchun No. 2) roots under hypoxic conditions. Our experiments revealed that exogenous calcium reduces the level of reactive oxygen species (ROS) and increases the activity of antioxidant enzymes in mitochondria under hypoxia. Exogenous calcium also enhances the accumulation of enzymes involved in glycolysis and the tricarboxylic acid (TCA) cycle. We utilized fluorescence and ultrastructural cytochemistry methods to observe that exogenous calcium increases the concentrations of Ca(2+) and K(+) in root cells by increasing the activity of plasma membrane (PM) H(+)-ATPase and tonoplast H(+)-ATPase and H(+)-PPase. Overall, our results suggest that hypoxic stress has an immediate and substantial effect on roots. Exogenous calcium improves metabolism and ion transport in cucumber roots, thereby increasing hypoxia tolerance in cucumber.

  3. Binding of ligands to the catalytic zinc ion in horse liver alcohol dehydrogenase.

    Science.gov (United States)

    Syvertsen, C; McKinley-McKee, J S

    1984-01-01

    The affinity of nitrogen and sulfur ligands for the catalytic zinc ion in horse liver alcohol dehydrogenase has been investigated by their influence on the affinity labeling reaction with iodoacetate. All the nitrogen compounds including ammonia, a primary and a secondary amine, and heterocycles containing a pyridine-type nitrogen with the exception of 2,2-dipyridyl were found to activate the affinity labeling reaction. Activation results from inner-sphere ligand coordination to the catalytic zinc ion. Closely related pyridine compounds gave a regular increase in affinity for the enzyme with increasing basicity, as expected for coordination to a metal ion. The sulfur compounds penicillamine and mercaptoethanol also activated the affinity labeling reaction, but dimercaptopropanol bound very tightly as a bidentate inhibited the reaction. The anions hydrosulfide, diethyldithiocarbamate, and cyanide coordinated to the catalytic zinc ion, whereas azide, thiocyanate, tetrazole, and iodide complexed the anion-binding site. The anionic metal ligands increased the rate of inactivation of the enzyme with iodoacetamide by binding to the catalytic zinc ion, while the binding of iodoacetate to the anion-binding site was prevented.

  4. Numerical Simulations of Calcium Ions Spiral Wave in Single Cardiac Myocyte

    Science.gov (United States)

    Bai, Yong-Qiang; Zhu, Xing

    2010-04-01

    The calcium ions (Ca2+) spark is an elementary Ca2+ release event in cardiac myocytes. It is believed to buildup cell-wide Ca2+ signals, such as Ca2+ transient and Ca2+ wave, through a Ca2+-induced Ca2+ release (CICR) mechanism. Here the excitability of the Ca2+ wave in a single cardiac myocyte is simulated by employing the fire-diffuse-fire model. By modulating the dynamic parameters of Ca2+ release and re-uptake channels, we find three Ca2+ signaling states in a single cardiac myocyte: no wave, plane wave, and spiral wave. The period of a spiral wave is variable in the different regimes. This study indicates that the spiral wave or the excitability of the system can be controlled through micro-modulation in a living excitable medium.

  5. Specific reduction of calcium-binding protein (28-kilodalton calbindin-D) gene expression in aging and neurodegenerative diseases

    International Nuclear Information System (INIS)

    Iacopino, A.M.; Christakos, S.

    1990-01-01

    The present studies establish that there are specific, significant decreases in the neuronal calcium-binding protein (28-kDa calbindin-D) gene expression in aging and in neurodegenerative diseases. The specificity of the changes observed in calbindin mRNA levels was tested by reprobing blots with calmodulin, cyclophilin, and B-actin cDNAs. Gross brain regions of the aging rat exhibited specific, significant decreases in calbindin·mRNA and protein levels in the cerebellum, corpus striatum, and brain-stem region but not in the cerebral cortex or hippocampus. Discrete areas of the aging human brain exhibited significant decreases in calbindin protein and mRNA in the cerebellum, corpus striatum, and nucleus basalis but not in the neocortex, hippocampus, amygdala, locus ceruleus, or nucleus raphe dorsalis. Comparison of diseased human brain tissue with age- and sex-matched controls yielded significant decreases calbindin protein and mRNA in the substantia nigra (Parkinson disease), in the corpus striatum (Huntington disease), in the nucleus basalis (Alzheimer disease), and in the hippocampus and nucleus raphe dorsalis (Parkinson, Huntington, and Alzheimer diseases) but not in the cerebellum, neocortex, amygdala, or locus ceruleus. These findings suggest that decreased calbindin gene expression may lead to a failure of calcium buffering or intraneuronal calcium homeostasis, which contributes to calcium-mediated cytotoxic events during aging and in the pathogenesis of neurodegenerative diseases

  6. The comparison of calcium ion release and pH changes from modified MTA and bioceramics in regeneration

    Science.gov (United States)

    Irawan, R. M.; Margono, A.; Djauhari, N.

    2017-08-01

    The surface reactions of bioactive materials release and change dissolutions triggering intracellular and extracellular responses. Calcium ion release can promote alkalinizing activity, which is needed in tissue regeneration. To analyze calcium ion release and pH changes in modified MTA and bioceramics as bioactive materials. Thirty samples, measuring 3 mm in diameter and 3 mm in height, were prepared, with 15 consisting of modified MTA and 15 consisting of bioceramics. Both materials were immersed in deionized water for an hour, then measured and transferred into fresh solutions and soaked for 48 hours or 168 hours. The measurements were conducted using an atom absorption spectrophotometer and pHmeter. Mann Whitney’s post hoc statistic test showed a significant difference among all the 1-hour, 48-hour, and 168-hour measurement groups, with a value of p ≤ 0.05. Bioceramics released more calcium ions and raised pH levels higher than modified MTA for each of the three soak-time groups. Bioceramics released more calcium ion and had higher pH level compared to modified MTA which contributed to the tissue regeneration.

  7. Characterization of Calflagin, a Flagellar Calcium-Binding Protein from Trypanosoma congolense.

    Directory of Open Access Journals (Sweden)

    Brett A Eyford

    2016-04-01

    Full Text Available Identification of species-specific trypanosome molecules is important for laboratory- and field-based research into epidemiology and disease diagnosis. Although Trypanosoma congolense is the most important trypanosome pathogen of cattle in Africa, no species-specific molecules found in infective bloodstream forms (BSF of the parasites have been identified, thus limiting development of diagnostic tests.Immuno-mass spectrometric methods were used to identify a protein that is recognized by a T. congolense-specific monoclonal antibody (mAb Tc6/42.6.4. The identified molecule was expressed as a recombinant protein in E. coli and was tested in several immunoassays for its ability to interact with the mAb. The three dimensional structure of the protein was modeled and compared to crystal- and NMR-structures of the homologous proteins from T. cruzi and T. brucei respectively, in order to examine structural differences leading to the different immunoreactivity of the T. congolense molecule. Enzyme-linked immunosorbent assays (ELISA were used to measure antibodies produced by trypanosome-infected African cattle in order to assess the potential for use of T. congolense calflagin in a serodiagnostic assay.The antigen recognized by the T. congolense-specific mAb Tc6/42.6.4 was identified as a flagellar calcium-binding protein, calflagin. The recombinant molecule showed immunoreactivity with the T. congolense-specific mAb confirming that it is the cognate antigen. Immunofluorescence experiments revealed that Ca2+ modulated the localization of the calflagin molecule in trypanosomes. Structural modelling and comparison with calflagin homologues from other trypanosomatids revealed four non-conserved regions on the surface of the T. congolense molecule that due to differences in surface chemistry and structural topography may form species-specific epitopes. ELISAs using the recombinant calflagin as antigen to detect antibodies in trypanosome-infected cattle

  8. Effect of Exposed Surface Area, Volume and Environmental pH on the Calcium Ion Release of Three Commercially Available Tricalcium Silicate Based Dental Cements

    Directory of Open Access Journals (Sweden)

    Sivaprakash Rajasekharan

    2018-01-01

    Full Text Available Tricalcium silicate cements (TSC are used in dental traumatology and endodontics for their bioactivity which is mostly attributed to formation of calcium hydroxide during TSC hydration and its subsequent release of calcium and hydroxide ions. The aim of this study was to determine the effect of volume (Vol, exposed surface area (ESA and pH of surrounding medium on calcium ion release. Three commercially available hydraulic alkaline dental cements were mixed and condensed into cylindrical tubes of varying length and diameter (n = 6/group. For the effect of ESA and Vol, tubes were immersed in 10 mL of deionized water. To analyze the effect of environmental pH, the tubes were randomly immersed in 10 mL of buffer solutions with varying pH (10.4, 7.4 or 4.4. The solutions were collected and renewed at various time intervals. pH and/or calcium ion release was measured using a pH glass electrode and atomic absorption spectrophotometer respectively. The change of pH, short-term calcium ion release and rate at which calcium ion release reaches maximum were dependent on ESA (p < 0.05 while maximum calcium ion release was dependent on Vol of TSC (p < 0.05. Maximum calcium ion release was significantly higher in acidic solution followed by neutral and alkaline solution (p < 0.05.

  9. Effect of Exposed Surface Area, Volume and Environmental pH on the Calcium Ion Release of Three Commercially Available Tricalcium Silicate Based Dental Cements.

    Science.gov (United States)

    Rajasekharan, Sivaprakash; Vercruysse, Chris; Martens, Luc; Verbeeck, Ronald

    2018-01-13

    Tricalcium silicate cements (TSC) are used in dental traumatology and endodontics for their bioactivity which is mostly attributed to formation of calcium hydroxide during TSC hydration and its subsequent release of calcium and hydroxide ions. The aim of this study was to determine the effect of volume (Vol), exposed surface area (ESA) and pH of surrounding medium on calcium ion release. Three commercially available hydraulic alkaline dental cements were mixed and condensed into cylindrical tubes of varying length and diameter ( n = 6/group). For the effect of ESA and Vol, tubes were immersed in 10 mL of deionized water. To analyze the effect of environmental pH, the tubes were randomly immersed in 10 mL of buffer solutions with varying pH (10.4, 7.4 or 4.4). The solutions were collected and renewed at various time intervals. pH and/or calcium ion release was measured using a pH glass electrode and atomic absorption spectrophotometer respectively. The change of pH, short-term calcium ion release and rate at which calcium ion release reaches maximum were dependent on ESA ( p < 0.05) while maximum calcium ion release was dependent on Vol of TSC ( p < 0.05). Maximum calcium ion release was significantly higher in acidic solution followed by neutral and alkaline solution ( p < 0.05).

  10. Evaluation of ion binding to DNA duplexes using a size-modified Poisson-Boltzmann theory.

    Science.gov (United States)

    Chu, Vincent B; Bai, Yu; Lipfert, Jan; Herschlag, Daniel; Doniach, Sebastian

    2007-11-01

    Poisson-Boltzmann (PB) theory is among the most widely applied electrostatic theories in biological and chemical science. Despite its reasonable success in explaining a wide variety of phenomena, it fails to incorporate two basic physical effects, ion size and ion-ion correlations, into its theoretical treatment. Recent experimental work has shown significant deviations from PB theory in competitive monovalent and divalent ion binding to a DNA duplex. The experimental data for monovalent binding are consistent with a hypothesis that attributes these deviations to counterion size. To model the observed differences, we have generalized an existing size-modified Poisson-Boltzmann (SMPB) theory and developed a new numerical implementation that solves the generalized theory around complex, atomistic representations of biological molecules. The results of our analysis show that good agreement to data at monovalent ion concentrations up to approximately 150 mM can be attained by adjusting the ion-size parameters in the new size-modified theory. SMPB calculations employing calibrated ion-size parameters predict experimental observations for other nucleic acid structures and salt conditions, demonstrating that the theory is predictive. We are, however, unable to model the observed deviations in the divalent competition data with a theory that only accounts for size but neglects ion-ion correlations, highlighting the need for theoretical descriptions that further incorporate ion-ion correlations. The accompanying numerical solver has been released publicly, providing the general scientific community the ability to compute SMPB solutions around a variety of different biological structures with only modest computational resources.

  11. Protein synthesis in presynaptic endings from squid brain: modulation by calcium ions.

    Science.gov (United States)

    Benech, J C; Crispino, M; Kaplan, B B; Giuditta, A

    1999-03-15

    Previous biochemical, autoradiographic, and ultrastructural data have shown that, in the synaptosomal fraction of the squid optic lobe, protein synthesis is largely due to the presynaptic terminals of the retinal photoreceptor neurons (Crispino et al. [1993a] Mol. Cell. Neurosci. 4:366-374; Crispino et al. [1993b] J. Neurochem. 61:1144-1146; Crispino et al. [1997] J. Neurosci. 17:7694-7702). We now report that this process is close to its maximum at the basal concentration of cytosolic Ca++, and is markedly inhibited when the concentration of this ion is either decreased or increased. This conclusion is supported by the results of experiments with: 1) compounds known to increase the level of cytosolic Ca++, such as A23187, ionomycin, thapsigargin, and caffeine; 2) compounds sequestering cytosolic calcium ions such as BAPTA-AM; and 3) agents that block the role of Ca++ as second messenger, such as TFP and W7, which inhibit calmodulin, and calphostin, which inhibits protein kinase C. We conclude that variations in the level of cytosolic Ca++ induced in presynaptic terminals by neuronal activity may contribute to the modulation of the local synthesis of protein.

  12. Preparation of Co3O4 conical nanotube and its application in calcium ion biosensor

    Science.gov (United States)

    Yuan, Hongwen; Ma, Chi; Geng, Junlong; Zhang, Liqiang; Cui, Hai; Liu, Cunzhi

    2018-02-01

    Calcium ion (Ca2+) is an important ion involved in body life activities, and its content detection in biomedical field owns great significance. In this study, we fabricated Co3O4 conical nanotube on F-doped tin oxide (FTO) substrate for detecting Ca2+. Co3O4 is fabricated through a hydrothermal method and demonstrates a regular hexagon structure, with a length of 5-10 μm and wall thickness of 30 nm. The structure and morphology of Co3O4 were characterized by X-ray diffraction (XRD), scanning electron microscope, and transmission electron microscopy, respectively. In addition, then, we used electrochemical technique to characterize the Ca2+ concentration in the simulated body fluid. The detection of Ca2+ is originated from the electrochemical reaction of hydrogen peroxide using Co3O4 as a catalyst, in which Ca2+ plays a significant role for accelerating the decomposition of hydrogen peroxide catalytic performance. By monitoring the electron transfer signals changes during the electrochemical reaction, we can quickly quantify the Ca2+ concentrations. It is found that this Ca2+ sensor owns a wide detection range (0.1-1.1 mM), a low detection limit (3.767 μM), and good anti-interference ability.

  13. Hydroxyl Ion Diffusion through Radicular Dentine When Calcium Hydroxide Is Used under Different Conditions.

    Science.gov (United States)

    Cai, Michael; Abbott, Paul; Castro Salgado, Jacqueline

    2018-01-17

    Calcium hydroxide's anti-bacterial action relies on high pH. The aim here was to investigate hydroxyl ion diffusion through dentine under different conditions. Teeth were divided into control ( n = 4) and four experimental groups ( n = 10): Group 1-no medicament; Group 2-Calmix; Group 3-Calmix/Ledermix; Group 4-Calasept Plus/Ledermix; Group 5-Pulpdent/smear layer. Deep (inner dentine) and shallow (outer dentine) cavities were cut into each root. pH was measured in these cavities for 12 weeks. The inner and outer dentine pH in Group 2 was significantly higher than all groups. Inner dentine pH in Group 3 was slightly higher than that in Group 4 initially but subsequently comparable. After Day 2, Group 5 had significantly lower pH than Groups 3 and 4. The outer dentine pH in Group 3 started higher than that in Groups 4 and 5, but by Day 28 the difference was insignificant. The time for the inner dentine to reach maximum pH was one week for Group 2 and four weeks for Groups 3 and 4. The time for the outer dentine to reach maximum pH was eight weeks for all experimental groups. Mixing different Ca(OH)₂ formulations with Ledermix gave similar hydroxyl ion release but pH and total diffusion was lower than Ca(OH)₂ alone. The smear layer inhibited diffusion.

  14. The early asthmatic response is associated with glycolysis, calcium binding and mitochondria activity as revealed by proteomic analysis in rats

    Directory of Open Access Journals (Sweden)

    Xu Yu-Dong

    2010-08-01

    Full Text Available Abstract Background The inhalation of allergens by allergic asthmatics results in the early asthmatic response (EAR, which is characterized by acute airway obstruction beginning within a few minutes. The EAR is the earliest indicator of the pathological progression of allergic asthma. Because the molecular mechanism underlying the EAR is not fully defined, this study will contribute to a better understanding of asthma. Methods In order to gain insight into the molecular basis of the EAR, we examined changes in protein expression patterns in the lung tissue of asthmatic rats during the EAR using 2-DE/MS-based proteomic techniques. Bioinformatic analysis of the proteomic data was then performed using PPI Spider and KEGG Spider to investigate the underlying molecular mechanism. Results In total, 44 differentially expressed protein spots were detected in the 2-DE gels. Of these 44 protein spots, 42 corresponded to 36 unique proteins successfully identified using mass spectrometry. During subsequent bioinformatic analysis, the gene ontology classification, the protein-protein interaction networking and the biological pathway exploration demonstrated that the identified proteins were mainly involved in glycolysis, calcium binding and mitochondrial activity. Using western blot and semi-quantitative RT-PCR, we confirmed the changes in expression of five selected proteins, which further supports our proteomic and bioinformatic analyses. Conclusions Our results reveal that the allergen-induced EAR in asthmatic rats is associated with glycolysis, calcium binding and mitochondrial activity, which could establish a functional network in which calcium binding may play a central role in promoting the progression of asthma.

  15. Binding of ArgTX-636 in the NMDA receptor ion channel

    DEFF Research Database (Denmark)

    Poulsen, Mette H; Andersen, Jacob; Christensen, Rune

    2015-01-01

    The N-methyl-d-aspartate receptors (NMDARs) constitute an important class of ligand-gated cation channels that are involved in the majority of excitatory neurotransmission in the human brain. Compounds that bind in the NMDAR ion channel and act as blockers are use- and voltage-dependent inhibitor...

  16. Interactions of calcium ions with weakly acidic active ingredients slow cuticular penetration: a case study with glyphosate.

    Science.gov (United States)

    Schönherr, Jörg; Schreiber, Lukas

    2004-10-20

    Potassium and calcium salts of glyphosate were obtained by titrating glyphosate acid with the respective bases to pH 4.0, and rates of penetration of these salts across isolated astomatous cuticular membranes (CMs) were measured at 20 degrees C and 70, 80, 90, and 100% humidity. K-glyphosate exhibited first-order penetration kinetics, and rate constants (k) increased with increasing humidity. Ca-glyphosate penetrated only when the humidity above the salt residue was 100%. At 90% humidity and below, Ca-glyphosate formed a solid residue on the CMs and penetration was not measurable. With Ca-glyphosate, the k value at 100% humidity decreased with time and the initial rates were lower than for K-glyphosate by a factor of 3.68. After equimolar concentrations of ammonium oxalate were added to Ca-glyphosate, high penetration rates close to those measured with K-glyphosate were measured at all humidities. Adding ammonium sulfate or potassium carbonate also increased rates between 70 and 100% humidity, but they were not as high as with ammonium oxalate. The data indicate that at pH 4.0 one Ca2+ ion is bound to two glyphosate anions. This salt has its deliquescence point near 100% humidity. Therefore, it is a solid at lower humidity and does not penetrate. Its molecular weight is 1.82 times larger than that of K-glyphosate, and this greatly slows down rates of penetration, even at 100% humidity. The additives tested have low solubility products and form insoluble precipitates with Ca2+ ions, but only ammonium oxalate binds Ca2+ quantitatively. The resulting ammonium salt of glyphosate penetrates at 70-100% humidity and at rates comparable to K-glyphosate. The results contribute to a better understanding of the hard water antagonism observed with glyphosate. It is argued that other pesticides and hormones with carboxyl functions are likely to respond to Ca2+ ions in a similar fashion. In all of these cases, ammonium oxalate is expected to overcome hard water antagonism

  17. Spectrofluorometric and Molecular Modeling Studies on Binding of Nitrite Ion with Bovine Hemoglobin: Effect of Nitrite Ion on Amino Acid Residues

    Science.gov (United States)

    Madrakian, T.; Bagheri, H.; Afkhami, A.

    2015-05-01

    The interaction between nitrite ion and bovine hemoglobin was investigated by a spectrofluorometric technique. The experimental results indicated that the interaction causes a static quenching of the fluorescence of bovine hemoglobin, that the binding reaction is spontaneous, and that H-bonding interactions play a major role in binding of this ion to bovine hemoglobin. The formation constant for this interaction was calculated. Based on Förster's theory of nonradiative energy transfer, the binding distance between this ion and bovine hemoglobin was determined. Furthermore, the interaction of nitrite ion with tyrosine and tryptophan was investigated with synchronous fluorescence. There was no significant shift of the maximum emission wavelength with interactions of the mentioned ion with bovine hemoglobin, which implies that interaction of nitrite ion with bovine hemoglobin does not affect the microenvironment around the tryptophan and tyrosine residues. Furthermore, the effect of nitrite ion on amino acid residues of bovine hemoglobin was studied by a molecular docking technique.

  18. A mononuclear non-heme manganese(IV)-oxo complex binding redox-inactive metal ions.

    Science.gov (United States)

    Chen, Junying; Lee, Yong-Min; Davis, Katherine M; Wu, Xiujuan; Seo, Mi Sook; Cho, Kyung-Bin; Yoon, Heejung; Park, Young Jun; Fukuzumi, Shunichi; Pushkar, Yulia N; Nam, Wonwoo

    2013-05-01

    Redox-inactive metal ions play pivotal roles in regulating the reactivities of high-valent metal-oxo species in a variety of enzymatic and chemical reactions. A mononuclear non-heme Mn(IV)-oxo complex bearing a pentadentate N5 ligand has been synthesized and used in the synthesis of a Mn(IV)-oxo complex binding scandium ions. The Mn(IV)-oxo complexes were characterized with various spectroscopic methods. The reactivities of the Mn(IV)-oxo complex are markedly influenced by binding of Sc(3+) ions in oxidation reactions, such as a ~2200-fold increase in the rate of oxidation of thioanisole (i.e., oxygen atom transfer) but a ~180-fold decrease in the rate of C-H bond activation of 1,4-cyclohexadiene (i.e., hydrogen atom transfer). The present results provide the first example of a non-heme Mn(IV)-oxo complex binding redox-inactive metal ions that shows a contrasting effect of the redox-inactive metal ions on the reactivities of metal-oxo species in the oxygen atom transfer and hydrogen atom transfer reactions.

  19. A Mononuclear Non-Heme Manganese(IV)-Oxo Complex Binding Redox-Inactive Metal Ions

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Junying; Lee, Yong-Min; Davis, Katherine M.; Wu, Xiujuan; Seo, Mi Sook; Cho, Kyung-Bin; Yoon, Heejung; Park, Young Jun; Fukuzumi, Shunichi; Pushkar, Yulia N.; Nam, Wonwoo [Ewha; (Purdue); (Osaka)

    2013-05-29

    Redox-inactive metal ions play pivotal roles in regulating the reactivities of high-valent metal–oxo species in a variety of enzymatic and chemical reactions. A mononuclear non-heme Mn(IV)–oxo complex bearing a pentadentate N5 ligand has been synthesized and used in the synthesis of a Mn(IV)–oxo complex binding scandium ions. The Mn(IV)–oxo complexes were characterized with various spectroscopic methods. The reactivities of the Mn(IV)–oxo complex are markedly influenced by binding of Sc3+ ions in oxidation reactions, such as a ~2200-fold increase in the rate of oxidation of thioanisole (i.e., oxygen atom transfer) but a ~180-fold decrease in the rate of C–H bond activation of 1,4-cyclohexadiene (i.e., hydrogen atom transfer). The present results provide the first example of a non-heme Mn(IV)–oxo complex binding redox-inactive metal ions that shows a contrasting effect of the redox-inactive metal ions on the reactivities of metal–oxo species in the oxygen atom transfer and hydrogen atom transfer reactions.

  20. Structural and luminescence properties of Mn{sup 2+} ions doped calcium zinc borophosphate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Ming Hua, E-mail: wanminghua819@gmail.com [Phosphor Research Group, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Wong, Poh Sum, E-mail: pohsumwong@gmail.com [Phosphor Research Group, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Hussin, Rosli, E-mail: roslihussin@utm.my [Phosphor Research Group, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Lintang, Hendrik O., E-mail: hendrik@ibnusina.utm.my [Catalytic Science and Technology (CST) Research Group, Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Endud, Salasiah, E-mail: salasiah@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia)

    2014-05-15

    Highlights: • FT-IR revealed that the network structures are from borate and phosphate network. • The PL spectrum exhibits a green emission band at 582 nm ({sup 4}T{sub 1g} → {sup 6}A{sub 1g}). • As the concentration of Mn{sup 2+} ions is increased, the emission band had been red shifted. • These glasses are found to have potential applications as luminescent optical materials. - Abstract: Calcium zinc borophosphate glasses (CaZnBP) doped with various concentrations of Mn{sup 2+} ions and borate and phosphate as variable were prepared using conventional melt quenching technique. The structure of obtained glasses were examined by means of use: X-ray diffraction (XRD) and fourier transform infrared (FT-IR). XRD analysis confirmed amorphous nature of glass samples. The FT-IR spectra reveals the presence of both borate and phosphate vibrational modes in the prepared glasses. The doping of Mn{sup 2+} ions (2–10 mol%) shows no significant changes in the main IR vibrational bands. Optical properties were studied by measuring the near infrared photoluminescence (PL) spectra. CaZnBP glasses exhibited intense green emission peak (582 nm) (tetrahedral symmetry), which is assigned to a transition from the upper {sup 4}T{sub 1g} → {sup 6}A{sub 1g} ground state of Mn{sup 2+} ions. As the concentration of Mn{sup 2+} ions increases, the emission band increases from 582 nm to 650 nm and exhibited a red light emission (octahedral symmetry). The decay curves of {sup 4}T{sub 1g} level were examined for all concentrations and the measured lifetimes are found to depend strongly on Mn{sup 2+} concentrations. From the emission characteristic parameters of {sup 6}A{sub 1g} (S) level, it shows that the CaZnBP glasses could have potential applications as luminescent optical materials, visible lasers and fluorescent display devices.

  1. Simple molecular model for the binding of antibiotic molecules to bacterial ion channels

    Science.gov (United States)

    Mafé, Salvador; Ramírez, Patricio; Alcaraz, Antonio

    2003-10-01

    A molecular model aimed at explaining recent experimental data by Nestorovich et al. [Proc. Natl. Acad. Sci. USA 99, 9789 (2002)] on the interaction of ampicillin molecules with the constriction zone in a channel of the general bacterial porin, OmpF (outer membrane protein F), is presented. The model extends T. L. Hill's theory for intermolecular interactions in a pair of binding sites [J. Am. Chem. Soc. 78, 3330 (1956)] by incorporating two binding ions and two pairs of interacting sites. The results provide new physical insights on the role of the complementary pattern of the charge distributions in the ampicillin molecule and the narrowest part of the channel pore. Charge matching of interacting sites facilitates drug binding. The dependence of the number of ampicillin binding events per second with the solution pH and salt concentration is explained qualitatively using a reduced number of fundamental concepts.

  2. Identification of metal ion binding sites based on amino acid sequences

    Science.gov (United States)

    Cao, Xiaoyong; Zhang, Xiaojin; Gao, Sujuan; Ding, Changjiang; Feng, Yonge; Bao, Weihua

    2017-01-01

    The identification of metal ion binding sites is important for protein function annotation and the design of new drug molecules. This study presents an effective method of analyzing and identifying the binding residues of metal ions based solely on sequence information. Ten metal ions were extracted from the BioLip database: Zn2+, Cu2+, Fe2+, Fe3+, Ca2+, Mg2+, Mn2+, Na+, K+ and Co2+. The analysis showed that Zn2+, Cu2+, Fe2+, Fe3+, and Co2+ were sensitive to the conservation of amino acids at binding sites, and promising results can be achieved using the Position Weight Scoring Matrix algorithm, with an accuracy of over 79.9% and a Matthews correlation coefficient of over 0.6. The binding sites of other metals can also be accurately identified using the Support Vector Machine algorithm with multifeature parameters as input. In addition, we found that Ca2+ was insensitive to hydrophobicity and hydrophilicity information and Mn2+ was insensitive to polarization charge information. An online server was constructed based on the framework of the proposed method and is freely available at http://60.31.198.140:8081/metal/HomePage/HomePage.html. PMID:28854211

  3. Testin, a novel binding partner of the calcium-sensing receptor, enhances receptor-mediated Rho-kinase signalling

    International Nuclear Information System (INIS)

    Magno, Aaron L.; Ingley, Evan; Brown, Suzanne J.; Conigrave, Arthur D.; Ratajczak, Thomas; Ward, Bryan K.

    2011-01-01

    Highlights: → A yeast two-hybrid screen revealed testin bound to the calcium-sensing receptor. → The second zinc finger of LIM domain 1 of testin is critical for interaction. → Testin bound to a region of the receptor tail important for cell signalling. → Testin and receptor interaction was confirmed in mammalian (HEK293) cells. → Overexpression of testin enhanced receptor-mediated Rho signalling in HEK293 cells. -- Abstract: The calcium-sensing receptor (CaR) plays an integral role in calcium homeostasis and the regulation of other cellular functions including cell proliferation and cytoskeletal organisation. The multifunctional nature of the CaR is manifested through ligand-dependent stimulation of different signalling pathways that are also regulated by partner binding proteins. Following a yeast two-hybrid library screen using the intracellular tail of the CaR as bait, we identified several novel binding partners including the focal adhesion protein, testin. Testin has not previously been shown to interact with cell surface receptors. The sites of interaction between the CaR and testin were mapped to the membrane proximal region of the receptor tail and the second zinc-finger of LIM domain 1 of testin, the integrity of which was found to be critical for the CaR-testin interaction. The CaR-testin association was confirmed in HEK293 cells by coimmunoprecipitation and confocal microscopy studies. Ectopic expression of testin in HEK293 cells stably expressing the CaR enhanced CaR-stimulated Rho activity but had no effect on CaR-stimulated ERK signalling. These results suggest an interplay between the CaR and testin in the regulation of CaR-mediated Rho signalling with possible effects on the cytoskeleton.

  4. Binding of monovalent alkali metal ions with negatively charged phospholipid membranes.

    Science.gov (United States)

    Maity, Pabitra; Saha, Baishakhi; Kumar, Gopinatha Suresh; Karmakar, Sanat

    2016-04-01

    We have systematically investigated the effect of various alkali metal ions with negatively charged phospholipid membranes. Size distributions of large unilamellar vesicles have been confirmed using dynamic light scattering. Zeta potential and effective charges per vesicle in the presence of various alkali metal ions have been estimated from the measured electrophoretic mobility. We have determined the intrinsic binding constant from the zeta potential using electrostatic double layer theory. The reasonable and consistent value of the intrinsic binding constant of Na(+), found at moderate NaCl concentration (10-100 mM), indicates that the Gouy-Chapman theory cannot be applied for very high (> 100mM) and very low (concentrations. The isothermal titration calorimetry study has revealed that the net binding heat of interaction of the negatively charged vesicles with monovalent alkali metal ions is small and comparable to those obtained from neutral phosphatidylcholine vesicles. The overall endothermic response of binding heat suggests that interaction is primarily entropy driven. The entropy gain might arise due to the release of water molecules from the hydration layer vicinity of the membranes. Therefore, the partition model which does not include the electrostatic contribution suffices to describe the interaction. The binding constant of Na(+) (2.4 ± 0.1 M(-1)), obtained from the ITC, is in agreement with that estimated from the zeta potential (-2.0 M(-1)) at moderate salt concentrations. Our results suggest that hydration dynamics may play a vital role in the membrane solution interface which strongly affects the ion-membrane interaction. Copyright © 2016 Elsevier B.V. All rights reserved

  5. Sorption of tartrate ions to lanthanum (III)-modified calcium fluor- and hydroxyapatite.

    Science.gov (United States)

    Aissa, Abdallah; Debbabi, Mongi; Gruselle, Michel; Thouvenot, René; Flambard, Alexandrine; Gredin, Patrick; Beaunier, Patricia; Tõnsuaadu, Kaia

    2009-02-01

    The present article details the formation of lanthanum-modified apatites and the binding process of tartrate ions with these obtained apatites. Chemical analyses, FT-IR and (31)P NMR spectroscopies, XRD powder, TGA, and TEM analyses were employed for studying the reaction between Ca(10)(PO(4))(6)(OH)(2) (HAp) or Ca(10)(PO(4))(6)(F)(2) (FAp) and LaCl(3). The reaction was found to take place mainly through partial dissolution of the apatite followed by precipitation of a new phase containing lanthanum phosphate. When La(3+) was introduced in the presence of L(+)-tartaric acid (TAH(2)), no fundamental changes were observed in the HAp or FAp structures. However, there did occur a formation of a new phase of Ca or/and La tartrate salt.

  6. Stimulation of a Cd-binding protein, and inhibition of the vitamin D-dependent calcium-binding protein, by zinc or cadmium in organ-cultured embryonic chick duodenum

    International Nuclear Information System (INIS)

    Corradino, R.A.; Fullmer, C.S.

    1980-01-01

    Embryonic chick duodenum maintained in organ culture responds to 1 α,25-dihydroxy vitamin D 3 in the culture medium by de novo synthesis of a specific calcium-binding protein (CaBP). The addition of Cd 2+ (3-5 x 10 -5 M) or Zn 2+ (10 -5 -10 -4 M) to the medium inhibited CaBP, but stimulated biosynthesis of a Cd-binding protein (CdBP). CdBP in duodenal homogenate supernatants was assessed in two ways: first, by its 109 Cd-binding activity ( 109 CdBA) using a competitive ion exchange procedure; and, second, by the extent of [ 35 S]-cystine incorporation into a specific peak or band after gel filtration or analytical polyacrylamide disc gel electrophoresis, respectively. Regardless of whether cadmium- or zinc-stimulated, the 35 S-labeled CdBP - the only protein significantly labeled under the conditions employed - migrated identically upon gel filtration and electrophoresis, and comigrated with purified chick liver Cd-metallothionein. Neither actinomycin D nor α-amanitin, in concentrations sufficient to severely inhibit CaBP, significantly reduced CdBP production. However, cycloheximide did inhibit either Cd 2+ - or Zn 2+ -stimulated CdBP by about 50% at an inhibitor concentration which abolished CaBP. The inhibitor studies, coupled with the observations of extensive incorporation of [ 35 S]cystine into CdBP, suggest that the metals stimulated biosynthesis by a mechanism operating at the translational level. The organ-cultured duodenum seems well suited for studies of the regulation of CdBP biosynthesis especially since it responds predictably to the steroid hormone, 1α,25-dihydroxy vitamin D 3 , in the induction of another specific protein, CaBP, at the transcriptional level. The biosynthesis of CaBP thus may serve as a convenient control in studies of CdBP production under various experimental conditions

  7. Comparing the erosive effect of Iranian soft drinks with standard samples; A Calcium ion analysis

    Directory of Open Access Journals (Sweden)

    Fallahinejad Ghajari M.

    2007-05-01

    Full Text Available Background and Aim: Extensive and continuous consumption of acidic drinks is the main cause of enamel erosion in human teeth. The purpose of this study was to compare the erosive potential of two Iranian drinks with those of two imported ones. Materials and Methods: Two Iranian drinks (Cola Zamzam and Orange Zamzam and two imported ones (Pepsi and Miranda were studied in this experimental invitro study. 120 intact premolar teeth, extracted for orthodontic reasons were divided into 3 equal groups (A, B and C. Each group was exposed to one of the drinks for exposure times of: A: 15 minutes, B: 45 minutes and C: 12 hours. Each group was divided into 4 subgroups (each containing 10 teeth, which were exposed to 20 ml of one of the 4 drinks. The exposed surface was the same in all samples (a 5 mm in diameter semi circular window. The amount of Ca++ ion (mg/ml added to each drink at the end of exposure time was estimated by atomic absorption spectrophotometer. Results: 2 way ANOVA showed that the drinks were significantly different with regard to released Calcium ion. Time had significant effect on erosive potential. The two mentioned factors had significant interaction (P<0.001. The most erosive effect was seen in 12 hours in all of the drinks. The erosive effect of Orange Zamzam in 15 minutes and Pepsi in 45 minutes and 12 hours was significantly more than other groups (P<0.001. Conclusions: Pepsi had the most long term erosive effect among the four drinks, and Cola Zamzam had the least erosive potential.

  8. Hydroxyl Ion Diffusion through Radicular Dentine When Calcium Hydroxide Is Used under Different Conditions

    Directory of Open Access Journals (Sweden)

    Michael Cai

    2018-01-01

    Full Text Available Calcium hydroxide’s anti-bacterial action relies on high pH. The aim here was to investigate hydroxyl ion diffusion through dentine under different conditions. Teeth were divided into control (n = 4 and four experimental groups (n = 10: Group 1—no medicament; Group 2—Calmix; Group 3—Calmix/Ledermix; Group 4—Calasept Plus/Ledermix; Group 5—Pulpdent/smear layer. Deep (inner dentine and shallow (outer dentine cavities were cut into each root. pH was measured in these cavities for 12 weeks. The inner and outer dentine pH in Group 2 was significantly higher than all groups. Inner dentine pH in Group 3 was slightly higher than that in Group 4 initially but subsequently comparable. After Day 2, Group 5 had significantly lower pH than Groups 3 and 4. The outer dentine pH in Group 3 started higher than that in Groups 4 and 5, but by Day 28 the difference was insignificant. The time for the inner dentine to reach maximum pH was one week for Group 2 and four weeks for Groups 3 and 4. The time for the outer dentine to reach maximum pH was eight weeks for all experimental groups. Mixing different Ca(OH2 formulations with Ledermix gave similar hydroxyl ion release but pH and total diffusion was lower than Ca(OH2 alone. The smear layer inhibited diffusion.

  9. Use of multiple singular value decompositions to analyze complex intracellular calcium ion signals

    KAUST Repository

    Martinez, Josue G.

    2009-12-01

    We compare calcium ion signaling (Ca(2+)) between two exposures; the data are present as movies, or, more prosaically, time series of images. This paper describes novel uses of singular value decompositions (SVD) and weighted versions of them (WSVD) to extract the signals from such movies, in a way that is semi-automatic and tuned closely to the actual data and their many complexities. These complexities include the following. First, the images themselves are of no interest: all interest focuses on the behavior of individual cells across time, and thus, the cells need to be segmented in an automated manner. Second, the cells themselves have 100+ pixels, so that they form 100+ curves measured over time, so that data compression is required to extract the features of these curves. Third, some of the pixels in some of the cells are subject to image saturation due to bit depth limits, and this saturation needs to be accounted for if one is to normalize the images in a reasonably un-biased manner. Finally, the Ca(2+) signals have oscillations or waves that vary with time and these signals need to be extracted. Thus, our aim is to show how to use multiple weighted and standard singular value decompositions to detect, extract and clarify the Ca(2+) signals. Our signal extraction methods then lead to simple although finely focused statistical methods to compare Ca(2+) signals across experimental conditions.

  10. New generation of composite inorganic ion-exchangers with polyacrylonitrile binding matrix

    International Nuclear Information System (INIS)

    Sebesta, F.; John, J.; Motl, A.; Uvirova, K.; Smrckova, S.

    1998-01-01

    General procedure for treatment of powdered inorganic ion-exchangers using binding polymer - modified polyacrylonitrile (PAN) into beads suitable for the application in column packed beds was proposed earlier. These composite ion-exchangers were tested for many applications, some of them are used in the full-scale treatment of liquid radioactive wastes and/or for radioanalytical purposes. New generation of the composite ion-exchangers was developed to improve their volume exchange capacity and mechanical strength. Further, composite absorbers with new active components or their mixtures were prepared. The possibility of preparation of magnetic composite adsorbers and magnetic composite ion-exchangers was also studied. The new prepared materials were mainly tested for their application in caesium separation from highly active acidic waste streams. The efficiency of AMP-PAN (ammonium molybdophosphate active component) and ferrocyanides based composite ion-exchangers for caesium separation was studied in more details. Possibilities of regeneration of the above mentioned composite ion-exchangers were also studied. In preliminary experiments, mercury sorption from model mixed radioactive wastes onto ferro- and ferricyanide based absorbers was tested. The new generation of composite ion-exchangers with hydrated titanium oxide or sodium titanate as active component was tested for strontium separation from alkaline solutions. (author)

  11. Micro-Capillary Coatings Based on Spiropyran Polymeric Brushes for Metal Ion Binding, Detection, and Release in Continuous Flow

    Directory of Open Access Journals (Sweden)

    Aishling Dunne

    2018-04-01

    Full Text Available Micro-capillaries, capable of light-regulated binding and qualitative detection of divalent metal ions in continuous flow, have been realised through functionalisation with spiropyran photochromic brush-type coatings. Upon irradiation with UV light, the coating switches from the passive non-binding spiropyran form to the active merocyanine form, which binds different divalent metal ions (Zn2+, Co2+, Cu2+, Ni2+, Cd2+, as they pass through the micro-capillary. Furthermore, the merocyanine visible absorbance spectrum changes upon metal ion binding, enabling the ion uptake to be detected optically. Irradiation with white light causes reversion of the merocyanine to the passive spiropyran form, with simultaneous release of the bound metal ion from the micro-capillary coating.

  12. Calcium regulates ATP-sensitive microtubule binding by Chlamydomonas outer arm dynein.

    Science.gov (United States)

    Sakato, Miho; King, Stephen M

    2003-10-31

    The Chlamydomonas outer dynein arm contains three distinct heavy chains (alpha, beta, and gamma) that exhibit different motor properties. The LC4 protein, which binds 1-2 Ca2+ with KCa = 3 x 10-5 m, is associated with the gamma heavy chain and has been proposed to act as a sensor to regulate dynein motor function in response to alterations in intraflagellar Ca2+ levels. Here we genetically dissect the outer arm to yield subparticles containing different motor unit combinations and assess the microtubule-binding properties of these complexes both prior to and following preincubation with tubulin and ATP, which was used to inhibit ATP-insensitive (structural) microtubule binding. We observed that the alpha heavy chain exhibits a dominant Ca2+-independent ATP-sensitive MT binding activity in vitro that is inhibited by attachment of tubulin to the structural microtubule-binding domain. Furthermore, we show that ATP-sensitive microtubule binding by a dynein subparticle containing only the beta and gamma heavy chains does not occur at Ca2+ concentrations below pCa 6 but is maximally activated above pCa 5. This activity was not observed in mutant dyneins containing small deletions in the microtubule-binding region of the beta heavy chain or in dyneins that lack both the alpha heavy chain and the motor domain of the beta heavy chain. These findings strongly suggest that Ca2+ binding directly to a component of the dynein complex regulates ATP-sensitive interactions between the beta heavy chain and microtubules and lead to a model for how individual motor units are controlled within the outer dynein arm.

  13. Silver ions increase plasma membrane permeability through modulation of intracellular calcium levels in tobacco BY-2 cells

    Czech Academy of Sciences Publication Activity Database

    Klíma, Petr; Laňková, Martina; Vandenbussche, F.; Van Der Straeten, D.; Petrášek, Jan

    2018-01-01

    Roč. 37, č. 5 (2018), s. 809-818 ISSN 0721-7714 R&D Projects: GA ČR GA16-10948S Grant - others:OPPK(XE) CZ.2.16/3.1.00/21519 Institutional support: RVO:61389030 Keywords : Auxin * Calcium * Ethylene * Silver ions * Tobacco BY-2 cells * Transmembrane transport Subject RIV: ED - Physiology OBOR OECD: Cell biology Impact factor: 2.869, year: 2016

  14. VEGF-A isoform-specific regulation of calcium ion flux, transcriptional activation and endothelial cell migration.

    Science.gov (United States)

    Fearnley, Gareth W; Bruns, Alexander F; Wheatcroft, Stephen B; Ponnambalam, Sreenivasan

    2015-04-24

    Vascular endothelial growth factor A (VEGF-A) regulates many aspects of vascular physiology such as cell migration, proliferation, tubulogenesis and cell-cell interactions. Numerous isoforms of VEGF-A exist but their physiological significance is unclear. Here we evaluated two different VEGF-A isoforms and discovered differential regulation of cytosolic calcium ion flux, transcription factor localisation and endothelial cell response. Analysis of VEGF-A isoform-specific stimulation of VEGFR2-dependent signal transduction revealed differential capabilities for isoform activation of multiple signal transduction pathways. VEGF-A165 treatment promoted increased phospholipase Cγ1 phosphorylation, which was proportional to the subsequent rise in cytosolic calcium ions, in comparison to cells treated with VEGF-A121. A major consequence of this VEGF-A isoform-specific calcium ion flux in endothelial cells is differential dephosphorylation and subsequent nuclear translocation of the transcription factor NFATc2. Using reverse genetics, we discovered that NFATc2 is functionally required for VEGF-A-stimulated endothelial cell migration but not tubulogenesis. This work presents a new mechanism for understanding how VEGF-A isoforms program complex cellular outputs by converting signal transduction pathways into transcription factor redistribution to the nucleus, as well as defining a novel role for NFATc2 in regulating the endothelial cell response. © 2015. Published by The Company of Biologists Ltd.

  15. VEGF-A isoform-specific regulation of calcium ion flux, transcriptional activation and endothelial cell migration

    Directory of Open Access Journals (Sweden)

    Gareth W. Fearnley

    2015-07-01

    Full Text Available Vascular endothelial growth factor A (VEGF-A regulates many aspects of vascular physiology such as cell migration, proliferation, tubulogenesis and cell-cell interactions. Numerous isoforms of VEGF-A exist but their physiological significance is unclear. Here we evaluated two different VEGF-A isoforms and discovered differential regulation of cytosolic calcium ion flux, transcription factor localisation and endothelial cell response. Analysis of VEGF-A isoform-specific stimulation of VEGFR2-dependent signal transduction revealed differential capabilities for isoform activation of multiple signal transduction pathways. VEGF-A165 treatment promoted increased phospholipase Cγ1 phosphorylation, which was proportional to the subsequent rise in cytosolic calcium ions, in comparison to cells treated with VEGF-A121. A major consequence of this VEGF-A isoform-specific calcium ion flux in endothelial cells is differential dephosphorylation and subsequent nuclear translocation of the transcription factor NFATc2. Using reverse genetics, we discovered that NFATc2 is functionally required for VEGF-A-stimulated endothelial cell migration but not tubulogenesis. This work presents a new mechanism for understanding how VEGF-A isoforms program complex cellular outputs by converting signal transduction pathways into transcription factor redistribution to the nucleus, as well as defining a novel role for NFATc2 in regulating the endothelial cell response.

  16. Structural Insights into Membrane Targeting by the Flagellar Calcium-binding Protein (FCaBP) a Myristoylated and Palmitoylated Calcium Sensor in Trypanosoma cruzi

    Energy Technology Data Exchange (ETDEWEB)

    J Wingard; J Ladner; M Vanarotti; A Fisher; H Robinson; K Buchanan; D Engman; J Ames

    2011-12-31

    The flagellar calcium-binding protein (FCaBP) of the protozoan Trypanosoma cruzi is targeted to the flagellar membrane where it regulates flagellar function and assembly. As a first step toward understanding the Ca{sup 2+}-induced conformational changes important for membrane-targeting, we report here the x-ray crystal structure of FCaBP in the Ca{sup 2+}-free state determined at 2.2{angstrom} resolution. The first 17 residues from the N terminus appear unstructured and solvent-exposed. Residues implicated in membrane targeting (Lys-19, Lys-22, and Lys-25) are flanked by an exposed N-terminal helix (residues 26-37), forming a patch of positive charge on the protein surface that may interact electrostatically with flagellar membrane targets. The four EF-hands in FCaBP each adopt a 'closed conformation' similar to that seen in Ca{sup 2+}-free calmodulin. The overall fold of FCaBP is closest to that of grancalcin and other members of the penta EF-hand superfamily. Unlike the dimeric penta EF-hand proteins, FCaBP lacks a fifth EF-hand and is monomeric. The unstructured N-terminal region of FCaBP suggests that its covalently attached myristoyl group at the N terminus may be solvent-exposed, in contrast to the highly sequestered myristoyl group seen in recoverin and GCAP1. NMR analysis demonstrates that the myristoyl group attached to FCaBP is indeed solvent-exposed in both the Ca{sup 2+}-free and Ca{sup 2+}-bound states, and myristoylation has no effect on protein structure and folding stability. We propose that exposed acyl groups at the N terminus may anchor FCaBP to the flagellar membrane and that Ca{sup 2+}-induced conformational changes may control its binding to membrane-bound protein targets..

  17. Combined sodium ion sensitivity in agonist binding and internalization of vasopressin V1b receptors.

    Science.gov (United States)

    Koshimizu, Taka-Aki; Kashiwazaki, Aki; Taniguchi, Junichi

    2016-05-03

    Reducing Na(+) in the extracellular environment may lead to two beneficial effects for increasing agonist binding to cell surface G-protein coupled receptors (GPCRs): reduction of Na(+)-mediated binding block and reduce of receptor internalization. However, such combined effects have not been explored. We used Chinese Hamster Ovary cells expressing vasopressin V1b receptors as a model to explore Na(+) sensitivity in agonist binding and receptor internalization. Under basal conditions, a large fraction of V1b receptors is located intracellularly, and a small fraction is in the plasma membrane. Decreases in external Na(+) increased cell surface [(3)H]AVP binding and decreased receptor internalization. Substitution of Na(+) by Cs(+) or NH4(+) inhibited agonist binding. To suppress receptor internalization, the concentration of NaCl, but not of CsCl, had to be less than 50 mM, due to the high sensitivity of the internalization machinery to Na(+) over Cs(+). Iso-osmotic supplementation of glucose or NH4Cl maintained internalization of the V1b receptor, even in a low-NaCl environment. Moreover, iodide ions, which acted as a counter anion, inhibited V1b agonist binding. In summary, we found external ionic conditions that could increase the presence of high-affinity state receptors at the cell surface with minimum internalization during agonist stimulations.

  18. MtrA of the sodium ion pumping methyltransferase binds cobalamin in a unique mode.

    Science.gov (United States)

    Wagner, Tristan; Ermler, Ulrich; Shima, Seigo

    2016-06-21

    In the three domains of life, vitamin B12 (cobalamin) is primarily used in methyltransferase and isomerase reactions. The methyltransferase complex MtrA-H of methanogenic archaea has a key function in energy conservation by catalysing the methyl transfer from methyl-tetrahydromethanopterin to coenzyme M and its coupling with sodium-ion translocation. The cobalamin-binding subunit MtrA is not homologous to any known B12-binding proteins and is proposed as the motor of the sodium-ion pump. Here, we present crystal structures of the soluble domain of the membrane-associated MtrA from Methanocaldococcus jannaschii and the cytoplasmic MtrA homologue/cobalamin complex from Methanothermus fervidus. The MtrA fold corresponds to the Rossmann-type α/β fold, which is also found in many cobalamin-containing proteins. Surprisingly, the cobalamin-binding site of MtrA differed greatly from all the other cobalamin-binding sites. Nevertheless, the hydrogen-bond linkage at the lower axial-ligand site of cobalt was equivalently constructed to that found in other methyltransferases and mutases. A distinct polypeptide segment fixed through the hydrogen-bond linkage in the relaxed Co(III) state might be involved in propagating the energy released upon corrinoid demethylation to the sodium-translocation site by a conformational change.

  19. Molecular cloning of the apoptosis-related calcium-binding protein AsALG-2 in Avena sativa.

    Science.gov (United States)

    Hoat, Trinh Xuan; Nakayashiki, Hitoshi; Yang, Qian; Tosa, Yukio; Mayama, Shigeyuki

    2013-04-01

    Victorin, the host-selective toxin produced by the fungus Cochliobolus victoriae, induces programmed cell death (PCD) in victorin-sensitive oat lines with characteristic features of animal apoptosis, such as mitochondrial permeability transition, chromatin condensation, nuclear DNA laddering and rRNA/mRNA degradation. In this study, we characterized a calcium-binding protein, namely AsALG-2, which might have a role in the victorin-induced PCD. AsALG-2 is homologous to the Apoptosis-Linked Gene ALG-2 identified in mammalian cells. Northern blot analysis revealed that the accumulation of AsALG-2 transcripts increased during victorin-induced PCD, but not during necrotic cell death. Salicylic acid, chitosan and chitin strongly activated the expression of general defence response genes, such as PR-10; however, neither induced cell death nor the accumulation of AsALG-2 mRNA. Pharmacological studies indicated that victorin-induced DNA laddering and AsALG-2 expression were regulated through similar pathways. The calcium channel blocker, nifedipine, moderately inhibited the accumulation of AsALG-2 mRNA during cell death. Trifluoperazine (calmodulin antagonist) and K252a (serine-threonine kinase inhibitor) reduced the victorin-induced phytoalexin accumulation, but did not prevent the victorin-induced DNA laddering or accumulation of AsALG-2 mRNA. Taken together, our investigations suggest that there is a calcium-mediated signalling pathway in animal and plant PCD in common. © 2012 THE AUTHORS. MOLECULAR PLANT PATHOLOGY © 2012 BSPP AND BLACKWELL PUBLISHING LTD.

  20. Ionized calcium-binding adaptor molecule 1 positive macrophages and HO-1 up-regulation in intestinal muscularis resident macrophages

    DEFF Research Database (Denmark)

    Mikkelsen, Hanne B; Huizinga, Jan D; Larsen, Jytte O

    2017-01-01

    Small intestinal muscularis externa macrophages have been associated with interstitial cells of Cajal (ICC). They have been proposed to play various roles in motility disorders and to take part in a microbiota-driven regulation of gastrointestinal motility. Our objective was to understand...... the reaction of resident macrophages of the musculature to a pro-inflammatory stimulator, lipopolysaccharide (LPS). Mice were injected with LPS or saline and sacrificed after 6 hours. Whole mounts were stained with antibodies toward CD169, ionized calcium-binding adaptor molecule 1 (iba1) (microglial/macrophage...... marker) and heme oxygenase-1 (HO-1). Cell densities were measured using unbiased stereology. RESULTS: iba1(pos) cells showed an overall higher density than CD169(pos) and HO-1(pos) cells. Most HO-1(pos) and iba1(pos) cells were positive for CD 169 in serosa and at Auerbach's plexus (AP). At the deep...

  1. Immunomicroscopic localization of the 10,000 molecular weight calcium-binding protein in the human enterocyte

    DEFF Research Database (Denmark)

    Staun, M; Friis, S; Dabelsteen, E

    1989-01-01

    The cellular localization of the 10,000 molecular weight calcium-binding protein (CaBP or Calbindin-D) in the small intestinal epithelium of man was investigated by immunofluorescence and immunoelectron microscopy (immunogold staining). Indirect immunofluorescence on frozen sections showed...... intracellular staining in the enterocyte. The fluorescence was evenly distributed and no significant differences were observed between crypt and villus cells. No staining was found in goblet cells or in the submucosa. Correspondingly, immunogold labeled antibodies were scattered over the cytoplasm...... of the enterocyte. The terminal region appeared to be the most intensely decorated and the brush border region showed labeling above the background level. No labeling was associated with intracellular membranes or the basolateral membrane....

  2. Effect of calcium oxide on the efficiency of ferrous ion oxidation and total iron precipitation during ferrous ion oxidation in simulated acid mine drainage treatment with inoculation of Acidithiobacillus ferrooxidans.

    Science.gov (United States)

    Liu, Fenwu; Zhou, Jun; Jin, Tongjun; Zhang, Shasha; Liu, Lanlan

    2016-01-01

    Calcium oxide was added into ferrous ion oxidation system in the presence of Acidithiobacillus ferrooxidans at concentrations of 0-4.00 g/L. The pH, ferrous ion oxidation efficiency, total iron precipitation efficiency, and phase of the solid minerals harvested from different treatments were investigated during the ferrous ion oxidation process. In control check (CK) system, pH of the solution decreased from 2.81 to 2.25 when ferrous ions achieved complete oxidation after 72 h of Acidithiobacillus ferrooxidans incubation without the addition of calcium oxide, and total iron precipitation efficiency reached 20.2%. Efficiency of ferrous ion oxidation and total iron precipitation was significantly improved when the amount of calcium oxide added was ≤1.33 g/L, and the minerals harvested from systems were mainly a mixture of jarosite and schwertmannite. For example, the ferrous ion oxidation efficiency reached 100% at 60 h and total iron precipitation efficiency was increased to 32.1% at 72 h when 1.33 g/L of calcium oxide was added. However, ferrous ion oxidation and total iron precipitation for jarosite and schwertmannite formation were inhibited if the amount of calcium oxide added was above 2.67 g/L, and large amounts of calcium sulfate dihydrate were generated in systems.

  3. Ectopic expression of the calcium-binding protein parvalbumin in mouse liver endothelial cells

    DEFF Research Database (Denmark)

    Castillo, M B; Berchtold, M W; Rülicke, T

    1997-01-01

    To elucidate the physiological role of the Ca2+ binding protein parvalbumin, we have generated transgenic mice carrying the full-length complementary DNA (cDNA) of rat parvalbumin under the control of the heavy-metal inducible metallothionein IIA promoter. Immunohistochemical and biochemical...

  4. EFFECT OF ACTIVE ACCUMULATION OF CALCIUM AND PHOSPHATE IONS ON THE STRUCTURE OF RAT LIVER MITOCHONDRIA

    Science.gov (United States)

    Greenawalt, John W.; Rossi, Carlo S.; Lehninger, Albert L.

    1964-01-01

    Rat liver mitochondria allowed to accumulate maximal amounts of Ca++ and HPO4 = ions from the suspending medium in vitro during respiration have a considerably higher specific gravity than normal mitochondria and may be easily separated from the latter by isopycnic centrifugation in density gradients of sucrose or cesium chloride. When the mitochondria are allowed to accumulate less than maximal amounts of Ca++ and HPO4 = from the medium, they have intermediate specific gravities which are roughly proportional to their content of calcium phosphate. Maximally "loaded" mitochondria are relatively homogeneous with respect to specific gravity. Correlated biochemical and electron microscopic studies show that Ca++-loaded mitochondria contain numerous dense granules, of which some 85 per cent are over 500 A in diameter. These granules are electron-opaque not only following fixation and staining with heavy metal reagents, but also following fixation with formaldehyde, demonstrating that the characteristic granules in Ca++-loaded mitochondria have intrinsic electron-opacity. The dense granules are almost always located within the inner compartment of the mitochondria and not in the space between the inner and outer membranes. They are frequently located at or near the cristae and they often show electron-transparent "cores." Such granules appear to be made up of clusters of smaller dense particles, but preliminary x-ray diffraction analysis and electron diffraction studies have revealed no evidence of crystallinity in the deposits. The electron-opaque granules decrease in number when the Ca++-loaded mitochondria are incubated with 2,4-dinitrophenol; simultaneously there is discharge of Ca++ and phosphate from the mitochondria into the medium. PMID:14228516

  5. Synthesis and ion-binding properties of polymeric pseudocrown ethers II: Template ion induced cyclization of oligomeric ethylene glycol diacrylates

    Energy Technology Data Exchange (ETDEWEB)

    Mathur, A.M.; Scranton, A.B. [Michigan State Univ., East Lansing, MI (United States)

    1997-01-01

    Inexpensive polymeric pseudocrown ethers have been synthesized based upon a {open_quotes}template ion{close_quotes} effect in which oligomeric ethylene glycol diacrylates are induced to assume a circular conformation in which the unsaturated end-groups are in proximity. This synthetic scheme has considerable potential for the development of inexpensive materials for binding of target cations. In this contribution, the authors report a spectroscopic study of the induced cyclization caused by ion-dipole interactions between the templating cation and the electron lone pairs of the ethylene glycol ether linkages. Fluorescence spectroscopy was used to provide insight into the templatization process by examining excimer formation in pyrene end-labeled oligomeric ethylene glycol both in the absence and in the presence of the templating ion. Pyrene end-labeled tetraethylene glycol and pentaethylene glycol were synthesized and excimer fluorescence enhancement was studied with the introduction of cations such as nickel, chromium and tin in solvents such as tetrahydrofuran and chloroform. An increase in excimer fluorescence indicated enhanced excimer formation due to the templating effect of the cation which results in the end groups being close to each other. Molecular dynamics simulations of pyrene end-labeled ligands were performed to elucidate the effect of the large fluorescent chromophores on the chain conformations.

  6. Characteristics of the brown hagfish Paramyxine atami transthyretin: Metal ion-dependent thyroid hormone binding.

    Science.gov (United States)

    Suzuki, Shunsuke; Kasai, Kentaro; Nishiyama, Norihito; Ishihara, Akinori; Yamauchi, Kiyoshi

    2017-08-01

    Transthyretin (TTR) is a vertebrate-specific protein involved in thyroid hormone distribution in plasma, and its gene is thought to have emerged by gene duplication from the gene for the ancient TTR-related protein, 5-hydroxyisourate hydrolase, at some early stage of chordate evolution. We investigated the molecular and hormone-binding properties of the brown hagfish Paramyxine atami TTR. The amino acid sequence deduced from the cloned hagfish TTR cDNA shared 33-50% identities with those of other vertebrate TTRs but less than 24% identities with those of vertebrate and deuterostome invertebrate 5-hydroxyisourate hydrolases. Hagfish TTR, as well as lamprey and little skate TTRs, had an N-terminal histidine-rich segment, allowing purification by metal-affinity chromatography. The affinity of hagfish TTR for 3,3',5-triiodo-L-thyronine (T3) was 190 times higher than that for L-thyroxine, with a dissociation constant of 1.5-3.9nM at 4°C. The high-affinity binding sites were strongly sensitive to metal ions. Zn 2+ and Cu 2+ decreased the dissociation constant to one-order of magnitude, whereas a chelator, o-phenanthroline, increased it four times. The number of metal ions (mainly Zn 2+ and Cu 2+ ) was approximately 12/TTR (mol/mol). TTR was also a major T3-binding protein in adult hagfish sera and its serum concentration was approximately 8μM. These results suggest that metal ions and the acquisition of N-terminal histidine-rich segment may cooperatively contribute to the evolution toward an ancient TTR with high T3 binding activity from either 5-hydroxyisourate hydrolase after gene duplication. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Proton and metal ion binding to natural organic polyelectrolytes-I. Studies with synthetic model compounds

    Science.gov (United States)

    Marinsky, J.A.; Reddy, M.M.

    1984-01-01

    A unified physico-chemical model, based on a modified Henderson-Hasselbalch equation, for the analysis of ion complexation reactions involving charged polymeric systems is presented and verified. In this model pH = pKa+p(??Ka) + log(??/1 - ??) where Ka is the intrinsic acid dissociation constant of the ionizable functional groups on the polymer, ??Ka is the deviation of the intrinsic constant due to electrostatic interaction between the hydrogen ion and the polyanion, and alpha (??) is the polyacid degree of ionization. Using this approach pKa values for repeating acidic units of polyacrylic (PAA) and polymethacrylic (PMA) acids were found to be 4.25 ?? 0.03 and 4.8 ?? 0.1, respectively. The polyion electrostatic deviation term derived from the potentiometric titration data (i.e. p(??Ka)) is used to calculate metal ion concentration at the complexation site on the surface of the polyanion. Intrinsic cobalt-polycarboxylate binding constants (7.5 for PAA and 5.6 for PMA), obtained using this procedure, are consistent with the range of published binding constants for cobalt-monomer carboxylate complexes. In two phase systems incorporation of a Donnan membrane potential term allows determination of the intrinsic pKa of a cross-linked PMA gel, pKa = 4.83, in excellent agreement with the value obtained for the linear polyelectrolyte and the monomer. Similarly, the intrinsic stability constant for cobalt ion binding to a PMA-gel (??CoPMA+ = 11) was found to be in agreement with the linear polyelectrolyte analogue and the published data for cobalt-carboxylate monodentate complexes. ?? 1984.

  8. Transplacental effects of thyrocalcitonin on intestinal calcium-binding protein, alkaline phosphatase activity and ossification of long bones in rat fetuses.

    Science.gov (United States)

    Peshin, J; Ornoy, A; Menczel, J

    1976-03-01

    Pregnant rats were treated with 44, 88 and 176 Medical Research Council munits of thyrocalcitonin (TCT) twice daily during days 10 to 21 of gestation. Nonpregnant rats received the same treatment for 12 days. Administration of TCT to the pregnant rats increased the ash and calcium content of fetal bones and decreased the phosphorus content. The diaphyses were short and contained many persisting enchondral trabeculae and a reduced number of osteoclasts. TCT reduced the fetal intestinal alkaline phosphatase activity but elevated the intestinal calcium-binding protein content. In the pregnant and nonpregnant rats, treatment with TCT resulted in hypocalcemia and hypophosphatemia, and increased the calcium-binding protein content of the duodenal mucosa. In the fetuses, the calcium-binding protein content and alkaline phosphatase activity were higher in the jejunum and ileum than in the duodenum, and were much higher than the values found in adult animals. Our findings indicate that TCT passes through the rat placenta and affects the fetal skeleton and calcium metabolism directly, resulting primarily in decreased bone resorption.

  9. The Action of Red Cell Calcium Ions on Human Erythrophagocytosis in Vitro

    Directory of Open Access Journals (Sweden)

    Pedro J. Romero

    2017-12-01

    Full Text Available In the present work we have studied in vitro the effect of increasing red cell Ca2+ ions on human erythrophagocytosis by peripheral monocyte-derived autologous macrophages. In addition, the relative contribution to phagocytosis of phosphatidylserine exposure, autologous IgG binding, complement deposition and Gárdos channel activity was also investigated. Monocytes were obtained after ficoll-hypaque fractionation and induced to transform by adherence to glass coverslips, for 24 h at 37°C in a RPMI medium, containing 10% fetal calf serum. Red blood cells (RBC were loaded with Ca2+ using 10 μM A23187 and 1 mM Ca-EGTA buffers, in the absence of Mg2+. Ca2+-loaded cells were transferred to above coverslips and incubated for 2 h at 37°C under various experimental conditions, after which phagocytosis was assessed by light microscopy. Confirming earlier findings, phagocytosis depended on internal Ca2+. Accordingly; it was linearly raised from about 2–15% by increasing the free Ca2+ content of the loading solution from 0.5 to 20 μM, respectively. Such a linear increase was virtually doubled by the presence of 40% autologous serum. At 7 μM Ca2+, the phagocytosis degree attained with serum was practically equal to that obtained with either 2 mg/ml affinity-purified IgG or 40% IgG-depleted serum. However, phagocytosis was reduced to levels found with Ca2+ alone when IgG-depleted serum was inactivated by heat, implying an involvement of complement. On the other hand, phagocytosis in the absence of serum was markedly reduced by preincubating macrophages with phosphatidylserine-containing liposomes. In contrast, a similar incubation in the presence of serum affected it partially whereas employing liposomes made only of phosphatidylcholine essentially had no effect. Significantly, the Gárdos channel inhibitors clotrimazole (2 μM and TRAM-34 (100 nM fully blocked serum-dependent phagocytosis. These findings show that a raised internal Ca2+ promotes

  10. Influence of residual ion polarization on the coplanar symmetric (e, 2e) cross sections for calcium and argon

    Science.gov (United States)

    Hu, Xiao-Qing; Chen, Zhan-Bin; Wang, Yang; Wang, Kai

    2017-03-01

    Detailed calculations using a modified distorted wave Born approximation (DWBA) are carried out for the triple differential cross section (TDCS) in the coplanar symmetric single ionization of calcium and argon atoms. The effects of residual ion polarization on the TDCS are investigated systematically. Our results show that the residual ion polarization, arising from the interaction between the target ion and the two outgoing electrons in the final state, may lead to a considerable change in the TDCS with a more pronounced effect in the large scattering angle region at intermediate energies. The present attempt significantly improves the agreement between theoretical and experimental results. Contribution to the Topical Issue "Atomic and Molecular Data and their Applications", edited by Gordon W.F. Drake, Jung-Sik Yoon, Daiji Kato, Grzegorz Karwasz.

  11. Mineralization Process of Biocemented Sand and Impact of Bacteria and Calcium Ions Concentrations on Crystal Morphology

    OpenAIRE

    Xu, Guobin; Tang, Yang; Lian, Jijian; Yan, Yue; Fu, Dengfeng

    2017-01-01

    Microbial-induced calcite precipitation (MICP) is a sustainable technique used to improve sandy soil. Analysis of the mineralization process, as well as different bacterial suspensions and calcium concentrations on the crystal morphology, revealed that the mineralization process included four stages: self-organised hydrolysis of microorganisms, molecular recognition and interface interaction, growth modulation, and epitaxial growth. By increasing bacterial suspensions and calcium concentratio...

  12. Metal ion interaction of an oligopeptide fragment representing the regulatory metal binding site of a CueR protein

    DEFF Research Database (Denmark)

    Jancsó, Attila; Szokolai, Hajnalka; Roszahegyi, Livia

    2013-01-01

    Metalloregulatory proteins of the MerR family are transcriptional activators that sense/control the concentration of various metal ions inside bacteria.1 The Cu+ efflux regulator CueR, similarly to other MerR proteins, possesses a short multiple Cys-containing metal binding loop close to the C......-terminus. CueR has a high selectivity for Cu+, Ag+ and Au+, but exhibits no transcriptional activity for the divalent ions Hg2+ and Zn2+.2 The two Cys- residues of the metal binding loop were shown to settle M+ ions into a linear coordination environment but other factors may also play a role in the recognition...... of cognate metal ions.2 Nevertheless, it is an interesting question whether the same sequence, when removed from the protein, shows a flexibility to adopt different coordination environments and may efficiently bind metal ions having preferences for larger coordination numbers....

  13. Interplay of Plasma Membrane and Vacuolar Ion Channels, Together with BAK1, Elicits Rapid Cytosolic Calcium Elevations in Arabidopsis during Aphid Feeding[OPEN

    Science.gov (United States)

    Vincent, Thomas R.; Avramova, Marieta; Canham, James; Higgins, Peter; Bilkey, Natasha; Mugford, Sam T.; Pitino, Marco; Toyota, Masatsugu

    2017-01-01

    A transient rise in cytosolic calcium ion concentration is one of the main signals used by plants in perception of their environment. The role of calcium in the detection of abiotic stress is well documented; however, its role during biotic interactions remains unclear. Here, we use a fluorescent calcium biosensor (GCaMP3) in combination with the green peach aphid (Myzus persicae) as a tool to study Arabidopsis thaliana calcium dynamics in vivo and in real time during a live biotic interaction. We demonstrate rapid and highly localized plant calcium elevations around the feeding sites of M. persicae, and by monitoring aphid feeding behavior electrophysiologically, we demonstrate that these elevations correlate with aphid probing of epidermal and mesophyll cells. Furthermore, we dissect the molecular mechanisms involved, showing that interplay between the plant defense coreceptor BRASSINOSTEROID INSENSITIVE-ASSOCIATED KINASE1 (BAK1), the plasma membrane ion channels GLUTAMATE RECEPTOR-LIKE 3.3 and 3.6 (GLR3.3 and GLR3.6), and the vacuolar ion channel TWO-PORE CHANNEL1 (TPC1) mediate these calcium elevations. Consequently, we identify a link between plant perception of biotic threats by BAK1, cellular calcium entry mediated by GLRs, and intracellular calcium release by TPC1 during a biologically relevant interaction. PMID:28559475

  14. Red mud carbonation using carbon dioxide: Effects of carbonate and calcium ions on goethite surface properties and settling.

    Science.gov (United States)

    Liang, Gaojie; Chen, Wenmi; Nguyen, Anh V; Nguyen, Tuan A H

    2018-05-01

    Carbonation using CO 2 appears as an attractive solution for disposing of red mud suspensions, an aluminum industry hazardous waste since it also offers an option for CO 2 sequestration. Here we report the novel findings that CO 3 2- together with Ca 2+ can significantly affect the surface properties and settling of goethite, a major component of red mud. Specifically, their effects on the goethite surface chemistry, colloidal interaction forces and settling in alkaline solutions are investigated. The surface potential becomes more negative by the formation of carbonate inner-sphere complexes on goethite surface. It is consistent with the strong repulsion, decreased particle size and settling velocity with increased carbonate concentrations as measured by atomic force microscopy, particle size analysis, and particle settling. Adding Ca 2+ that forms outer-sphere complexes with pre-adsorbed carbonate changes goethite surface charge negligibly. Changing repulsion to the attraction between goethite surfaces by increasing calcium dosage indicates the surface bridging, in accordance with the increased settling velocity. The adverse effect of carbonate on goethite flocculation is probably due to its specific chemisorption and competition with flocculants. By forming outer-sphere complexes together with the flocculant-calcium bridging effect, calcium ions can eliminate the negative influence of carbonate and improve the flocculation of goethite particles. These findings contribute to a better understanding of goethite particle interaction with salt ions and flocculants in controlling the particle behavior in the handling processes, including the red mud carbonation. Copyright © 2018 Elsevier Inc. All rights reserved.

  15. The calcium-binding protein complex S100A8/A9 has a crucial role in controlling macrophage-mediated renal repair following ischemia/reperfusion

    NARCIS (Netherlands)

    Dessing, M.C.; Tammaro, A.; Pulskens, W.P.C.; Teske, G.J.; Butter, L.M.; Claessen, N.; Eijk, M. van; Poll, T. van der; Vogl, T.; Roth, J.; Florquin, S.; Leemans, J.C.

    2015-01-01

    Upon ischemia/reperfusion (I/R)-induced injury, several damage-associated molecular patterns are expressed including the calcium-binding protein S100A8/A9 complex. S100A8/A9 can be recognized by Toll-like receptor-4 and its activation is known to deleteriously contribute to renal I/R-induced injury.

  16. OsCCD1, a novel small calcium-binding protein with one EF-hand motif, positively regulates osmotic and salt tolerance in rice.

    Science.gov (United States)

    Jing, Pei; Zou, Juanzi; Kong, Lin; Hu, Shiqi; Wang, Biying; Yang, Jun; Xie, Guosheng

    2016-06-01

    Calcium-binding proteins play key roles in the signal transduction in the growth and stress response in eukaryotes. However, a subfamily of proteins with one EF-hand motif has not been fully studied in higher plants. Here, a novel small calcium-binding protein with a C-terminal centrin-like domain (CCD1) in rice, OsCCD1, was characterized to show high similarity with a TaCCD1 in wheat. As a result, OsCCD1 can bind Ca(2+) in the in vitro EMSA and the fluorescence staining calcium-binding assays. Transient expression of green fluorescent protein (GFP)-tagged OsCCD1 in rice protoplasts showed that OsCCD1 was localized in the nucleus and cytosol of rice cells. OsCCD1 transcript levels were transiently induced by osmotic stress and salt stress through the calcium-mediated ABA signal. The rice seedlings of T-DNA mutant lines showed significantly less tolerance to osmotic and salt stresses than wild type plants (psalt stresses than wild type plants (psalt stresses. In sum, OsCCD1 gene probably affects the DREB2B and its downstream genes to positively regulate osmotic and salt tolerance in rice seedlings. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Neuroprotective Effect of Ginseng against Alteration of Calcium Binding Proteins Immunoreactivity in the Mice Hippocampus after Radiofrequency Exposure

    Directory of Open Access Journals (Sweden)

    Dhiraj Maskey

    2013-01-01

    Full Text Available Calcium binding proteins (CaBPs such as calbindin D28-k, parvalbumin, and calretinin are able to bind Ca2+ with high affinity. Changes in Ca2+ concentrations via CaBPs can disturb Ca2+ homeostasis. Brain damage can be induced by the prolonged electromagnetic field (EMF exposure with loss of interacellular Ca2+ balance. The present study investigated the radioprotective effect of ginseng in regard to CaBPs immunoreactivity (IR in the hippocampus through immunohistochemistry after one-month exposure at 1.6 SAR value by comparing sham control with exposed and ginseng-treated exposed groups separately. Loss of dendritic arborization was noted with the CaBPs in the Cornu Ammonis areas as well as a decrease of staining intensity of the granule cells in the dentate gyrus after exposure while no loss was observed in the ginseng-treated group. A significant difference in the relative mean density was noted between control and exposed groups but was nonsignificant in the ginseng-treated group. Decrease in CaBP IR with changes in the neuronal staining as observed in the exposed group would affect the hippocampal trisynaptic circuit by alteration of the Ca2+ concentration which could be prevented by ginseng. Hence, ginseng could contribute as a radioprotective agent against EMF exposure, contributing to the maintenance of Ca2+ homeostasis by preventing impairment of intracellular Ca2+ levels in the hippocampus.

  18. Molecular imaging of in vivo calcium ion expression in area postrema of total sleep deprived rats: Implications for cardiovascular regulation by TOF-SIMS analysis

    Science.gov (United States)

    Mai, Fu-Der; Chen, Li-You; Ling, Yong-Chien; Chen, Bo-Jung; Wu, Un-In; Chang, Hung-Ming

    2010-05-01

    Excessive calcium influx in chemosensitive neurons of area postrema (AP) is detrimental for sympathetic activation and participates in the disruption of cardiovascular activities. Since total sleep deprivation (TSD) is a stressful condition known to harm the cardiovascular function, the present study is aimed to determine whether the in vivo calcium expression in AP would significantly alter following TSD by the use of time-of-flight secondary ion mass spectrometry (TOF-SIMS) and calretinin (a specific calcium sensor protein in AP neurons) immunohistochemistry. The results indicated that in normal rats, the calcium intensity was estimated to be 0.5 × 10 5 at m/ z 40.08. However, following TSD, the intensity for calcium ions was greatly increased to 1.2 × 10 5. Molecular imaging revealed that after TSD, various strongly expressed calcium signals were distributed throughout AP with clear identified profiles instead of randomly scattered within this region in normal rats. Immunohistochemical staining corresponded well with ionic image in which a majority of calcium-enriched gathering co-localized with calretinin positive neurons. The functional significance of TSD-induced calcium augmentation was demonstrated by increased heart rate and mean arterial pressure, clinical markers for cardiovascular dysfunction. Considering AP-mediated sympathetic activation is important for cardiovascular regulation, exaggerated calcium influx in AP would render this neurocircuitry more vulnerable to over-excitation, which might serve as the underlying mechanism for the development of TSD-relevant cardiovascular deficiency.

  19. Crystallization and preliminary crystallographic analysis of calcium-binding protein-2 from Entamoeba histolytica and its complexes with strontium and the IQ1 motif of myosin V

    Energy Technology Data Exchange (ETDEWEB)

    Gourinath, S., E-mail: sgourinath@mail.jnu.ac.in; Padhan, Narendra; Alam, Neelima; Bhattacharya, Alok [School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)

    2005-04-01

    Calcium-binding protein-2 (EhCaBP2) crystals were grown using MPD as a precipitant. EhCaBP2 also crystallized in complex with strontium (replacing calcium) at similar conditions. Preliminary data for EhCaBP2 crystals in complex with an IQ motif are also reported. Calcium plays a pivotal role in the pathogenesis of amoebiasis, a major disease caused by Entamoeba histolytica. Two domains with four canonical EF-hand-containing calcium-binding proteins (CaBPs) have been identified from E. histolytica. Even though they have very high sequence similarity, these bind to different target proteins in a Ca{sup 2+}-dependent manner, leading to different functional pathways. Calcium-binding protein-2 (EhCaBP2) crystals were grown using MPD as a precipitant. The crystals belong to space group P2{sub 1}, with unit-cell parameters a = 111.74, b = 68.83, c = 113.25 Å, β = 116.7°. EhCaBP2 also crystallized in complex with strontium (replacing calcium) at similar conditions. The crystals belong to space group P2{sub 1}, with unit-cell parameters a = 69.18, b = 112.03, c = 93.42 Å, β = 92.8°. Preliminary data for EhCaBP2 crystals in complex with an IQ motif are also reported. This complex was crystallized with MPD and ethanol as precipitating agents. These crystals belong to space group P2{sub 1}, with unit-cell parameters a = 60.5, b = 69.86, c = 86.5 Å, β = 97.9°.

  20. Specifically colorimetric recognition of calcium, strontium, and barium ions using 2-mercaptosuccinic acid-functionalized gold nanoparticles and its use in reliable detection of calcium ion in water.

    Science.gov (United States)

    Zhang, Jia; Wang, Yong; Xu, Xiaowen; Yang, Xiurong

    2011-10-07

    A colorimetric probe based on 2-mercaptosuccinic acid-functionalized gold nanoparticles has been developed to exhibit selectivity towards Ca(2+), Sr(2+), and Ba(2+) ions over other metallic cations under specified conditions and finds its practical application in detecting Ca(2+) levels in water.

  1. Cellulose Nanocrystals Obtained from Rice By-Products and Their Binding Potential to Metallic Ions

    Directory of Open Access Journals (Sweden)

    Vanessa L. Albernaz

    2015-01-01

    Full Text Available The present study aimed to develop and optimize a method to obtain cellulose nanocrystals from the agricultural by-products rice husk and straw and to evaluate their electrostructural modifications in the presence of metallic ions. First, different particle formation conditions and routes were tested and analyzed by spectrophotometry, dynamic light scattering (DLS, and Zeta potential measurements. Then, electrostructural effects of ions Na(I, Cd(II, and Al(III on the optimized nanoparticles were analyzed by atomic force microscopy (AFM, scanning electron microscopy (SEM, and electrical conductivity (EC assessments. The produced cellulose nanocrystals adopted a rod-like shape. AFM height distribution and EC data indicated that the nanocrystals have more affinity in binding with Na(I > Al(III > Cd(II. These data suggest that the use of these cellulose nanocrystals in the bioremediation field is promising, both in metal sorption from wastewater and as an alternative for water desalination.

  2. Calcium dependence of inactivation of calcium release from the sarcoplasmic reticulum in skeletal muscle fibers.

    Science.gov (United States)

    Simon, B J; Klein, M G; Schneider, M F

    1991-03-01

    The steady-state calcium dependence of inactivation of calcium release from the sarcoplasmic reticulum was studied in voltage-clamped, cut segments of frog skeletal muscle fibers containing two calcium indicators, fura-2 and anti-pyrylazo III (AP III). Fura-2 fluorescence was used to monitor resting calcium and relatively small calcium transients during small depolarizations. AP III absorbance signals were used to monitor larger calcium transients during larger depolarizations. The rate of release (Rrel) of calcium from the sarcoplasmic reticulum was calculated from the calcium transients. The equilibrium calcium dependence of inactivation of calcium release was determined using 200-ms prepulses of various amplitudes to elevate [Ca2+] to various steady levels. Each prepulse was followed by a constant test pulse. The suppression of peak Rrel during the test pulse provided a measure of the extent of inactivation of release at the end of the prepulse. The [Ca2+] dependence of inactivation indicated that binding of more than one calcium ion was required to inactivate each release channel. Half-maximal inactivation was produced at a [Ca2+] of approximately 0.3 microM. Variation of the prepulse duration and amplitude showed that the suppression of peak release was consistent with calcium-dependent inactivation of calcium release but not with calcium depletion. The same calcium dependence of inactivation was obtained using different amplitude test pulses to determine the degree of inactivation. Prepulses that produced near maximal inactivation of release during the following test pulse produced no suppression of intramembrane charge movement during the test pulse, indicating that inactivation occurred at a step beyond the voltage sensor for calcium release. Three alternative set of properties that were assumed for the rapidly equilibrating calcium-binding sites intrinsic to the fibers gave somewhat different Rrel records, but gave very similar calcium dependence of

  3. Composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix. Methods of modification of properties of inorganic ion-exchangers for application in column packed beds

    International Nuclear Information System (INIS)

    Sebesta, F.

    1997-01-01

    Methods of preparation of granules of inorganic ion exchangers as well as methods for improvement of granular strength of these materials are reviewed. The resulting ion exchangers are classified in three groups - 'intrinsic', supported and composite ion exchangers. Their properties are compared and possibilities of their technological application are evaluated. A new method of preparation of inorganic-organic composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix is described, advantages and disadvantages of such sorbents are discussed. Proposed fields of application include tratment of liquid radioactive and/or hazardous wastes, decontamination of natural water as well as analytical applications. (author)

  4. Effects of structural modification of calcium spirulan, a sulfated polysaccharide from Spirulina platensis, on antiviral activity.

    Science.gov (United States)

    Lee, J B; Srisomporn, P; Hayashi, K; Tanaka, T; Sankawa, U; Hayashi, T

    2001-01-01

    Calcium ion binding with the anionic part of a molecule was replaced with various metal cations and their inhibitory effects on the replication of herpes simplex virus type 1 were evaluated. Replacement of calcium ion with sodium and potassium ions maintained the antiviral activity while divalent and trivalent metal cations reduced the activity. Depolymerization of sodium spirulan with hydrogen peroxide decreased in antiviral activity as its molecular weight decreased.

  5. The role of calcium ions in the photocatalytic oxidation of humic acid at neutral pH.

    Science.gov (United States)

    Mariquit, Eden G; Salim, Chris; Hinode, Hirofumi

    2008-10-01

    Humic acids (HAs) are natural organic matter derived from the decomposition of plant, algal, and microbial materials. They belong to the group of the most predominant type of natural organic matter present in ground and surface waters. HAs affect the mobility and bioavailability of aquatic contaminants. However, if they are left unremoved from the water before water treatment processes, they can form carcinogenic disinfection by-products, such as trihalomethanes, haloacetic acids, and other halogenated disinfection by-products, that can pose a threat to human beings. An advanced oxidation process using UV light and a commercially available titanium dioxide was used to oxidize HA at a pH that is similar to that of natural water. The effect of adding calcium ions to the adsorption and the photocatalytic oxidation of HAs was studied. The effect of varying the TiO(2) load was also investigated. The experiment was done using a photochemical batch reactor equipped with a mercury lamp emitting light with wavelengths of 310-580 nm. The absorbances by the samples were determined at wavelengths of 254 nm and 436 nm, which represent the aromatic-compound content of and the color of the solution, respectively. Results indicated calcium ions have an effect on both the adsorption and the photocatalytic oxidation of HA at a pH within 8.0 +/- 0.5. Calcium ions facilitated adsorption of HA onto the surface of TiO(2) and resulted to faster photocatalytic oxidation. The data were plotted with respect to the normalized absorbances and irradiation time.

  6. Selective Binding, Self-Assembly and Nanopatterning of the Creutz-Taube Ion on Surfaces

    Directory of Open Access Journals (Sweden)

    Qingling Hang

    2009-02-01

    Full Text Available The surface attachment properties of the Creutz-Taube ion, i.e., [(NH35Ru(pyrazineRu(NH35]5+, on both hydrophilic and hydrophobic types of surfaces were investigated using X-ray photoelectron spectroscopy (XPS. The results indicated that the Creutz-Taube ions only bound to hydrophilic surfaces, such as SiO2 and –OH terminated organic SAMs on gold substrates. No attachment of the ions on hydrophobic surfaces such as –CH3 terminated organic SAMs and poly(methylmethacrylate (PMMA thin films covered gold or SiO2 substrates was observed. Further ellipsometric, atomic force microscopy (AFM and time-dependent XPS studies suggested that the attached cations could form an inorganic analog of the self-assembled monolayer on SiO2 substrate with a “lying-down” orientation. The strong electrostatic interaction between the highly charged cations and the anionic SiO2 surface was believed to account for these observations. Based on its selective binding property, patterning of wide (~200 nm and narrow (~35 nm lines of the Creutz-Taube ions on SiO2 surface were demonstrated through PMMA electron resist masks written by electron beam lithography (EBL.

  7. Binding of Cu(II) ions to peptides studied by fluorescence spectroscopy and isothermal titration calorimetry

    Science.gov (United States)

    Makowska, Joanna; Żamojć, Krzysztof; Wyrzykowski, Dariusz; Uber, Dorota; Wierzbicka, Małgorzata; Wiczk, Wiesław; Chmurzyński, Lech

    2016-01-01

    Steady-state and time-resolved fluorescence quenching measurements supported by Isothermal Titration Calorimetry (ITC) were used to study the interactions of Cu2 + with four peptides. Two of them were taken from the N-terminal part of the FBP28 protein (formin binding protein) WW domain: Tyr-Lys-Thr-Ala-Asp-Gly-Lys-Thr-Tyr-NH2 (D9) and its mutant Tyr-Lys-Thr-Ala-Asn-Gly-Lys-Thr-Tyr-NH2 (D9_M) as well as two mutated peptides from the B3 domain of the immunoglobulin binding protein G derived from Streptococcus: Asp-Val-Ala-Thr-Tyr-Thr-NH2 (J1) and Glu-Val-Ala-Thr-Tyr-Thr-NH2 (J2). The measurements were carried out at 298.15 K in 20 mM 2-(N-morpholino)ethanesulfonic acid (MES) buffer solution with a pH of 6. The fluorescence of all peptides was quenched by Cu2 + ions. The stoichiometry, conditional stability constants and thermodynamic parameters for the interactions of the Cu2 + ions with D9 and D9_M were determined from the calorimetric data. The values of the conditional stability constants were additionally determined from fluorescence quenching measurements and compared with those obtained from calorimetric studies. There was a good correlation between data obtained from the two techniques. On the other hand, the studies revealed that J1 and J2 do not exhibit an affinity towards metal ions. The obtained results prove that fluorescence quenching experiments may be successfully used in order to determine stability constants of complexes with fluorescent ligands. Finally, based on the obtained results, the coordinating properties of the peptides towards the Cu2 + ions are discussed.

  8. Cartilage Acidic Protein 2 a hyperthermostable, high affinity calcium-binding protein.

    Science.gov (United States)

    Anjos, Liliana; Gomes, Ana S; Melo, Eduardo P; Canário, Adelino V; Power, Deborah M

    2013-03-01

    Cartilage Acidic Protein 2 (CRTAC2) is a novel protein present from prokaryotes to vertebrates with abundant expression in the teleost fish pituitary gland and an isoform of CRTAC1, a chondrocyte marker in humans. The two proteins are non-integrins containing N-terminal integrin-like Ca(2+)-binding motifs and their structure and function remain to be assigned. Structural studies of recombinant sea bream (sb)CRTAC2 revealed it is composed of 8.8% α-helix, 33.4% β-sheet and 57.8% unordered protein. sbCRTAC2 bound Ca(2+) with high affinity (K(d)=1.46nM) and favourable Gibbs free energy (∆G=-12.4kcal/mol). The stoichiometry for Ca(2+) bound to sbCRTAC2 at saturation indicated six Ca(2+) ligand-binding sites exist per protein molecule. No conformational change in sbCRTAC2 occurred in the presence of Ca(2+). Fluorescence emission revealed that the tertiary structure of the protein is hyperthermostable between 25°C and 95°C and the fully unfolded state is only induced by chemical denaturing (4M GndCl). sbCRTAC has a widespread tissue distribution and is present as high molecular weight aggregates, although strong reducing conditions promote formation of the monomer. sbCRTAC2 promotes epithelial cell outgrowth in vitro suggesting it may share functional homology with mammalian CRTAC1, recently implicated in cell-cell and cell-matrix interactions. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. An explicitly solvated full atomistic model of the cardiac thin filament and application on the calcium binding affinity effects from familial hypertrophic cardiomyopathy linked mutations

    Science.gov (United States)

    Williams, Michael; Schwartz, Steven

    2015-03-01

    The previous version of our cardiac thin filament (CTF) model consisted of the troponin complex (cTn), two coiled-coil dimers of tropomyosin (Tm), and 29 actin units. We now present the newest revision of the model to include explicit solvation. The model was developed to continue our study of genetic mutations in the CTF proteins which are linked to familial hypertrophic cardiomyopathies. Binding of calcium to the cTnC subunit causes subtle conformational changes to propagate through the cTnC to the cTnI subunit which then detaches from actin. Conformational changes propagate through to the cTnT subunit, which allows Tm to move into the open position along actin, leading to muscle contraction. Calcium disassociation allows for the reverse to occur, which results in muscle relaxation. The inclusion of explicit TIP3 water solvation allows for the model to get better individual local solvent to protein interactions; which are important when observing the N-lobe calcium binding pocket of the cTnC. We are able to compare in silica and in vitro experimental results to better understand the physiological effects from mutants, such as the R92L/W and F110V/I of the cTnT, on the calcium binding affinity compared to the wild type.

  10. The effect of CPP-ACP-propolis chewing gum on calcium and phosphate ion release on caries-active subjects’ saliva and the formation of Streptococcus mutans biofilm

    Science.gov (United States)

    Hasnamudhia, F.; Bachtiar, E. W.; Sahlan, M.; Soekanto, S. A.

    2017-08-01

    The aim of this study was to analyze the effect of CPP-APP and propolis wax if they are combined in a chewing gum formulation, observed from the calcium and phosphate ion level released by CPP-ACP and the emphasis of Streptococcus mutans mass in the biofilm by propolis wax on caries-active subjects’ saliva. Chewing gum simulation was done in vitro on 25 caries-active subjects’ saliva using five concentrations of chewing gum (0% propolis + 0% CPP-ACP, 0% propolis + CPP-ACP, 2% propolis + CPP-ACP, 4% propolis + CPP-ACP, and 6% propolis + CPP-ACP) and was then tested using an atomic absorption spectrophotometer to analyze calcium ion levels, an ultraviolet-visible spectrophotometer to analyze phosphate ion levels, and a biofilm assay using crystal violet to analyze the decline in biofilm mass. After the chewing simulation, calcium ion levels on saliva+gum eluent increased significantly compared to the saliva control, with the highest calcium level released by CPP-ACP + 2% propolis chewing gum. There was an insignificant phosphate level change between the saliva control and saliva+gum eluent. There was also a significant decline of S. mutans biofilm mass in the saliva+gum eluent, mostly by the CPP-ACP chewing gum and CPP-ACP + 6% propolis. The CPP-ACP-propolis chewing gum simulation generated the largest increase in calcium and phosphate ion level and the largest decline in S. mutans biofilm mass.

  11. pH, calcium ion release, and setting time of an experimental mineral trioxide aggregate-based root canal sealer.

    Science.gov (United States)

    Massi, Santiago; Tanomaru-Filho, Mário; Silva, Guilherme Ferreira; Duarte, Marco Antonio Hungaro; Grizzo, Larissa Tercilia; Buzalaf, Marília Afonso Rabelo; Guerreiro-Tanomaru, Juliane Maria

    2011-06-01

    An experimental mineral trioxide aggregate sealer (MTAS) has been developed for use as a root canal sealer. The aim of this study was to evaluate the setting time, pH, and calcium ion release of MTAS compared with white Portland cement (CPB-40; Votorantin Cimentos, Camargo Correa SA, Pedro Leopoldo, MG, Brazil), white MTA Angelus (MTA; Angelus, Londrina, PR, Brazil), and AH Plus (Dentsply DeTrey, Konstanz, Germany). For the evaluation of setting time, each material was analyzed using Gilmore-type needles. Polyethylene tubes with the materials were immersed in distilled water for the measurement of pH (digital pH meter) and calcium release (atomic absorption spectrophotometry). The evaluations were performed at 3, 6, 12, 24, and 48 hours and 7, 14, and 28 days. Data were analyzed by analysis of variance and the Tukey test at 5% significance level. MTAS showed higher calcium release at all experimental periods, a greater increase in pH up to 48 hours and the longest setting time. MTAS presented favorable properties for its indication as a root canal sealer. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  12. Optical modulation of neurotransmission using calcium photocurrents through the ion channel LiGluR

    Directory of Open Access Journals (Sweden)

    Mercè eIzquierdo-Serra

    2013-03-01

    Full Text Available A wide range of light-activated molecules (photoswitches and phototriggers have been used to the study of computational properties of an isolated neuron by acting pre and postsynaptically. However, new tools are being pursued to elicit a presynaptic calcium influx that triggers the release of neurotransmitters, most of them based in calcium-permeable Channelrhodopsin-2 mutants. Here we describe a method to control exocytosis of synaptic vesicles through the use of a light-gated glutamate receptor (LiGluR, which has recently been demonstrated that supports secretion by means of calcium influx in chromaffin cells. Expression of LiGluR in hippocampal neurons enables reversible control of neurotransmission with light, and allows modulating the firing rate of the postsynaptic neuron with the wavelength of illumination. This method may be useful for the determination of the complex transfer function of individual synapses.

  13. EMF signals and ion/ligand binding kinetics: prediction of bioeffective waveform parameters.

    Science.gov (United States)

    Pilla, A A; Muehsam, D J; Markov, M S; Sisken, B F

    1999-02-01

    The kinetics of an electromagnetic field (EMF) target pathway are used to estimate frequency windows for EMF bioeffects. Ion/ligand binding is characterized via first order kinetics from which a specific electrical impedance can be derived. The resistance/capacitance properties of the binding pathway impedance, determined by the kinetics of the rate-determining step, define the frequency range over which the target pathway is most sensitive to external EMF. Applied signals may thus be configured such that their spectral content closely matches that of the target, using evaluation of the signal to thermal noise ratio to optimize waveform parameters. Using the approach proposed in this study, a pulsed radio frequency (PRF) waveform, currently employed clinically for soft tissue repair, was returned by modulation of burst duration, producing significant bioeffects at substantially reduced signal amplitude. Application is made to Ca2+/Calmodulin-dependent myosin phosphorylation, for which the binding time constants may be estimated from reported kinetics, neurite outgrowth from embryonic chick dorsal root explants and bone repair in a fracture model. The results showed that the retuned signal produced increased phosphorylation rates, neurite outgrowth and biomechanical strength that were indistinguishable from those produced by the clinical signal, but with a tenfold reduction in peak signal amplitude, approximately 800-fold reduction in average amplitude and approximately 10(6)-fold reduction in average power.

  14. Native Mass Spectrometry, Ion mobility, and Collision-Induced Unfolding Categorize Malaria Antigen/Antibody Binding

    Science.gov (United States)

    Huang, Yining; Salinas, Nichole D.; Chen, Edwin; Tolia, Niraj H.; Gross, Michael L.

    2017-09-01

    Plasmodium vivax Duffy Binding Protein (PvDBP) is a promising vaccine candidate for P. vivax malaria. Recently, we reported the epitopes on PvDBP region II (PvDBP-II) for three inhibitory monoclonal antibodies (2D10, 2H2, and 2C6). In this communication, we describe the combination of native mass spectrometry and ion mobility (IM) with collision induced unfolding (CIU) to study the conformation and stabilities of three malarial antigen-antibody complexes. These complexes, when collisionally activated, undergo conformational changes that depend on the location of the epitope. CIU patterns for PvDBP-II in complex with antibody 2D10 and 2H2 are highly similar, indicating comparable binding topology and stability. A different CIU fingerprint is observed for PvDBP-II/2C6, indicating that 2C6 binds to PvDBP-II on an epitope different from 2D10 and 2H2. This work supports the use of CIU as a means of classifying antigen-antibody complexes by their epitope maps in a high throughput screening workflow. [Figure not available: see fulltext.

  15. Networks of enzymatically oxidized membrane lipids support calcium-dependent coagulation factor binding to maintain hemostasis.

    Science.gov (United States)

    Lauder, Sarah N; Allen-Redpath, Keith; Slatter, David A; Aldrovandi, Maceler; O'Connor, Anne; Farewell, Daniel; Percy, Charles L; Molhoek, Jessica E; Rannikko, Sirpa; Tyrrell, Victoria J; Ferla, Salvatore; Milne, Ginger L; Poole, Alastair W; Thomas, Christopher P; Obaji, Samya; Taylor, Philip R; Jones, Simon A; de Groot, Phillip G; Urbanus, Rolf T; Hörkkö, Sohvi; Uderhardt, Stefan; Ackermann, Jochen; Vince Jenkins, P; Brancale, Andrea; Krönke, Gerhard; Collins, Peter W; O'Donnell, Valerie B

    2017-11-28

    Blood coagulation functions as part of the innate immune system by preventing bacterial invasion, and it is critical to stopping blood loss (hemostasis). Coagulation involves the external membrane surface of activated platelets and leukocytes. Using lipidomic, genetic, biochemical, and mathematical modeling approaches, we found that enzymatically oxidized phospholipids (eoxPLs) generated by the activity of leukocyte or platelet lipoxygenases (LOXs) were required for normal hemostasis and promoted coagulation factor activities in a Ca 2+ - and phosphatidylserine (PS)-dependent manner. In wild-type mice, hydroxyeicosatetraenoic acid-phospholipids (HETE-PLs) enhanced coagulation and restored normal hemostasis in clotting-deficient animals genetically lacking p12-LOX or 12/15-LOX activity. Murine platelets generated 22 eoxPL species, all of which were missing in the absence of p12-LOX. Humans with the thrombotic disorder antiphospholipid syndrome (APS) had statistically significantly increased HETE-PLs in platelets and leukocytes, as well as greater HETE-PL immunoreactivity, than healthy controls. HETE-PLs enhanced membrane binding of the serum protein β2GP1 (β2-glycoprotein 1), an event considered central to the autoimmune reactivity responsible for APS symptoms. Correlation network analysis of 47 platelet eoxPL species in platelets from APS and control subjects identified their enzymatic origin and revealed a complex network of regulation, with the abundance of 31 p12-LOX-derived eoxPL molecules substantially increased in APS. In summary, circulating blood cells generate networks of eoxPL molecules, including HETE-PLs, which change membrane properties to enhance blood coagulation and contribute to the excessive clotting and immunoreactivity of patients with APS. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  16. Structural model for dihydropyridine binding to L-type calcium channels.

    Science.gov (United States)

    Tikhonov, Denis B; Zhorov, Boris S

    2009-07-10

    1,4-Dihydropyridines (DHPs) constitute a major class of ligands for L-type Ca(2+) channels (LTCC). The DHPs have a boat-like, six-membered ring with an NH group at the stern, an aromatic moiety at the bow, and substituents at the port and starboard sides. Various DHPs exhibit antagonistic or agonistic activities, which were previously explained as stabilization or destabilization, respectively, of the closed activation gate by the portside substituents. Here we report a novel structural model in which agonist and antagonist activities are determined by different parts of the DHP molecule and have different mechanisms. In our model, which is based on Monte Carlo minimizations of DHP-LTCC complexes, the DHP moieties at the stern, bow, and starboard form H-bonds with side chains of the key DHP-sensing residues Tyr_IIIS6, Tyr_IVS6, and Gln_IIIS5, respectively. We propose that these H-bonds, which are common for agonists and antagonists, stabilize the LTCC conformation with the open activation gate. This explains why both agonists and antagonists increase probability of the long lasting channel openings and why even partial disruption of the contacts eliminates the agonistic action. In our model, the portside approaches the selectivity filter. Hydrophobic portside of antagonists may induce long lasting channel closings by destabilizing Ca(2+) binding to the selectivity filter glutamates. Agonists have either hydrophilic substituents or a hydrogen atom at their portside, and thus lack this destabilizing effect. The predicted orientation of the DHP core allows accommodation of long substituents in the domain interface or in the inner pore. Our model may be useful for developing novel clinically relevant LTCC blockers.

  17. Structural Model for Dihydropyridine Binding to L-type Calcium Channels*

    Science.gov (United States)

    Tikhonov, Denis B.; Zhorov, Boris S.

    2009-01-01

    1,4-Dihydropyridines (DHPs) constitute a major class of ligands for L-type Ca2+ channels (LTCC). The DHPs have a boat-like, six-membered ring with an NH group at the stern, an aromatic moiety at the bow, and substituents at the port and starboard sides. Various DHPs exhibit antagonistic or agonistic activities, which were previously explained as stabilization or destabilization, respectively, of the closed activation gate by the portside substituents. Here we report a novel structural model in which agonist and antagonist activities are determined by different parts of the DHP molecule and have different mechanisms. In our model, which is based on Monte Carlo minimizations of DHP-LTCC complexes, the DHP moieties at the stern, bow, and starboard form H-bonds with side chains of the key DHP-sensing residues Tyr_IIIS6, Tyr_IVS6, and Gln_IIIS5, respectively. We propose that these H-bonds, which are common for agonists and antagonists, stabilize the LTCC conformation with the open activation gate. This explains why both agonists and antagonists increase probability of the long lasting channel openings and why even partial disruption of the contacts eliminates the agonistic action. In our model, the portside approaches the selectivity filter. Hydrophobic portside of antagonists may induce long lasting channel closings by destabilizing Ca2+ binding to the selectivity filter glutamates. Agonists have either hydrophilic substituents or a hydrogen atom at their portside, and thus lack this destabilizing effect. The predicted orientation of the DHP core allows accommodation of long substituents in the domain interface or in the inner pore. Our model may be useful for developing novel clinically relevant LTCC blockers. PMID:19416978

  18. Subdivisions of the auditory midbrain (n. mesencephalicus lateralis, pars dorsalis in zebra finches using calcium-binding protein immunocytochemistry.

    Directory of Open Access Journals (Sweden)

    Priscilla Logerot

    Full Text Available The midbrain nucleus mesencephalicus lateralis pars dorsalis (MLd is thought to be the avian homologue of the central nucleus of the mammalian inferior colliculus. As such, it is a major relay in the ascending auditory pathway of all birds and in songbirds mediates the auditory feedback necessary for the learning and maintenance of song. To clarify the organization of MLd, we applied three calcium binding protein antibodies to tissue sections from the brains of adult male and female zebra finches. The staining patterns resulting from the application of parvalbumin, calbindin and calretinin antibodies differed from each other and in different parts of the nucleus. Parvalbumin-like immunoreactivity was distributed throughout the whole nucleus, as defined by the totality of the terminations of brainstem auditory afferents; in other words parvalbumin-like immunoreactivity defines the boundaries of MLd. Staining patterns of parvalbumin, calbindin and calretinin defined two regions of MLd: inner (MLd.I and outer (MLd.O. MLd.O largely surrounds MLd.I and is distinct from the surrounding intercollicular nucleus. Unlike the case in some non-songbirds, however, the two MLd regions do not correspond to the terminal zones of the projections of the brainstem auditory nuclei angularis and laminaris, which have been found to overlap substantially throughout the nucleus in zebra finches.

  19. Assessment of the relationship between the molecular properties of calcium channel blockers and plasma protein binding data

    Directory of Open Access Journals (Sweden)

    Odović Jadranka V.

    2017-01-01

    Full Text Available In this study we investigated the relationship between the calcium channel blockers (CCBs, amlodipine, felodipine, isradipine, nicardipine, nifedipine, nimodipine, nisoldipine, verapamil and diltiazem, and their calculated molecular descriptors: polar surface area (PSA, molecular weight (Mw, volume value (Vol, aqueous solubility data (logS, lipophilicity (logP, acidity (pKa values and plasma protein binding (PPB data, obtained from relevant literature. The relationships between the computed molecular properties of selected CCBs and their PPB data were investigated by simple linear regression analysis that revealed very low correlations (R2<0.35. When multiple linear regression (MLR analysis was applied to investigate reliable correlations between the CCBs’ calculated molecular descriptors and PPB data, the best correlations were found for the relationships between CCBs, and PPB data and lipophilicity, and with application of the molecular descriptor (Mw, Vol, or pKa data as additional independent variables (R2=0.623; R2=0.741; R2=0.657, respectively, with an acceptable probability value (P<0.05, confirming that lipophilicity, together with other molecular properties, are essential for the drugs’ PPB. We conclude that this could be considered as an additional in vitro approach for modeling CCBs. [Projekat Ministarstva nauke Republike Srbije, br. TR34031

  20. Towards the role of metal ions in the structural variability of proteins: CdII speciation of a metal ion binding loop motif

    DEFF Research Database (Denmark)

    Jancsó, Attila; Szunyogh, Dániel; Gyurcsik, Béla

    2011-01-01

    A de novo designed dodecapeptide (HS), inspired by the metal binding loops of metal-responsive transcriptional activators, was synthesized. The aim was to create a model system for structurally promiscuous and intrinsically unstructured proteins, and explore the effect of metal ions on their stru...... the peptide is exchanging between a number of structures also in its metal ion bound state(s), as indicated by NMR and PAC data. © 2011 The Royal Society of Chemistry....

  1. Selective Binding and Precipitation of Cesium Ions from Aqueous Solutions: A Size-Driven Supramolecular Reaction.

    Science.gov (United States)

    Bengiat, Ravell; Bogoslavsky, Benny; Mandler, Daniel; Almog, Joseph

    2018-03-02

    The nuclear disasters of Chernobyl and Fukushima presented an urgent need for finding solutions to treatment of radioactive wastes. Among the by-products of nuclear fission is radioactive 137 Cs, which evokes an environmental hazard due to its long half-life (>30 years) and high solubility in water. In this work, a water-soluble organic ligand, readily obtained from alloxan and 1,3,5-benzenetriol, has been found to selectively bind and precipitate Cs + ions from aqueous solutions. The special rigid structure of the ligand, which consists of a "tripodal" carbonyl base above and below an aromatic plane, contributes to the size-driven selectivity towards the large Cs + ions and the formation of a giant, insoluble supramolecular complex. In addition to the low costs of the ligand, high yields and effectiveness in precipitating Cs + ions, the Cs-complex revealed a high endurance to continuous doses of γ-radiation, increasing its potential to act as a precipitating agent for 137 Cs. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Effects of urea, metal ions and surfactants on the binding of baicalein with bovine serum albumin

    Directory of Open Access Journals (Sweden)

    Atanu Singha Roy

    2016-08-01

    Full Text Available The interaction of baicalein with bovine serum albumin (BSA was investigated with the help of spectroscopic and molecular docking studies. The binding affinity of baicalein towards BSA was estimated to be in order of 105 M−1 from fluorescence quenching studies. Negative ΔH° (−5.66±0.14 kJ/mol and positive (ΔS° (+79.96±0.65 J/mol K indicate the presence of electrostatic interactions along with the hydrophobic forces that result in a positive ΔS°. The hydrophobic association of baicalein with BSA diminishes in the presence of sodium dodecyl sulfate (SDS due to probable hydrophobic association of baicalein with SDS, resulting in a negative ΔS° (−40.65±0.87 J/mol K. Matrix-assisted laser desorption ionization/time of flight (MALDI--TOF experiments indicate a 1:1 complexation between baicalein and BSA. The unfolding and refolding phenomena of BSA were investigated in the absence and presence of baicalein using steady-state and fluorescence lifetime measurements. It was observed that the presence of urea ruptured the non-covalent interaction between baicalein and BSA. The presence of metal ions (Ag+, Mg2+, Ni2+, Mn2+, Co2+and Zn2+ increased the binding affinity of ligand towards BSA. The changes in conformational aspects of BSA after ligand binding were also investigated using circular dichroism (CD and Fourier transform infrared (FT-IR spectroscopic techniques. Site selectivity studies following molecular docking analyses indicated the binding of baicalein to site 1 (subdomain IIA of BSA.

  3. In vitro effects of salicylic acid, calcium and copper ions on growth ...

    African Journals Online (AJOL)

    Yomi

    2012-08-30

    Aug 30, 2012 ... 1Department of Crop Sciences, Faculty of Agriculture and Food Sciences, Universiti Putra Malaysia, Bintulu Campus,. Sarawak, Malaysia. .... magnesium, copper, carbon, salicylic acid and nitrogen are critical variables for ... Five concentrations of calcium chloride anhydrous powder (Merck,. Darmstadt ...

  4. Actin filaments as the fast pathways for calcium ions involved in ...

    Indian Academy of Sciences (India)

    2015-08-14

    Aug 14, 2015 ... All these facts motivated us to elaborate a new approach in order to try to explain still uncompleted answer of how calcium mediates so efficiently this active nonlinear ... quote some earlier models. In section 3, we applied the stan- dard Manning's model (Manning 1996, 2011) for the conden- sation of ...

  5. Sorption behavior of Zn(II) ions on synthetic apatitic calcium phosphates

    Science.gov (United States)

    Sebei, Haroun; Pham Minh, Doan; Nzihou, Ange; Sharrock, Patrick

    2015-12-01

    The synthesis, characterization and the reactivity of apatitic calcium phosphates (Ca-HA, chemical formula Ca10(PO4)6(OH)2) is reported. Calcium carbonate (CaCO3) and potassium dihydrogen orthophosphate (KH2PO4) were selected as economical starting materials for the synthesis of Ca-HA under atmospheric conditions. Monocalcium phosphate monohydrate (MCPM), dicalcium phosphate dihydrate (DCPD), and octacalcium phosphate pentahydrate (OCP) were identified as the main intermediates of the synthesis reaction. The product obtained after 48 h of reaction contains mainly low-crystalline Ca-HA and small amounts of other calcium phosphates such as octacalcium phosphate (OCP), B-type carbonate apatite (CAP), as well as unreacted calcium carbonate. This Ca-HA was found to be active for the removal of Zn2+ from an aqueous solution. Its sorption capacity reached up to 120 mg of Zn2+ per g of Ca-HA powder after 24 h of reaction. The monitoring of soluble Zn, Ca and P during the sorption experiment allowed characterizing the mechanism of Zn uptake. Dissolution-precipitation, ionic exchange and surface complexation are the three main mechanisms involved in the sorption processes. The contribution of these mechanisms is discussed in detail.

  6. Evaluation of pH and calcium ion release in capseal I and II and in two other root canal sealers.

    Science.gov (United States)

    Bae, Keun Hyung; Chang, Seok Woo; Bae, Kwang-Shik; Park, Dong Sung

    2011-11-01

    The aim of this study was to compare the pHs and calcium ion releases of newly developed, calcium phosphate-based root canal sealers (Capseal I and II) with those of Sealapex (SA) and Sankin Apatite Root Sealer III (SARS III). Each material (n = 10) was mixed, inserted into polyvinyl chloride (PVC) tubes, and immersed in a vial containing deionized water. The control group consisted of empty PVC tubes (n = 10). The pHs and calcium ion releases were measured by pH meter and ICP-AES (inductively coupled plasma atomic emission spectrometer) at 24 hours and 96 hours, and at 7, 15, and 28 days. The results were analyzed with the Kruskal-Wallis test. Capseal I and II produced pHs and calcium ion releases higher than or equal to those of SA and SARS III (P < .05). Capseal I and II resulted in higher alkalinity and higher calcium ion releases than SA and SARS III. Copyright © 2011 Mosby, Inc. All rights reserved.

  7. Mechanical properties and ion release from bioactive restorative composites containing glass fillers and calcium phosphate nano-structured particles.

    Science.gov (United States)

    Chiari, Marina D S; Rodrigues, Marcela C; Xavier, Tathy A; de Souza, Eugen M N; Arana-Chavez, Victor E; Braga, Roberto R

    2015-06-01

    To evaluate the effect of the replacement of barium glass by dicalcium phosphate dihydrate (DCPD) particles on the mechanical properties and degree of conversion (DC) of composites. Additionally, calcium and hydrogen phosphate (HPO4(2-)) release were followed for 28 days. Nine composites containing equal parts (in mols) of BisGMA and TEGDMA and 40, 50 or 60 vol% of total filler were manipulated. Filler phase was constituted by silanated barium glass and 0%, 10% or 20% of DCPD particles. DC was determined by near-FTIR. Biaxial flexural strength (BFS) and modulus (E) were tested using the "piston on three balls" method, while fracture toughness (KIc) used the "single edge notched beam" method. Specimens were tested after 24h and 28 days in water. Ion release was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Data were analyzed by ANOVA/Tukey (DC and ion release) or Kruskal-Wallis/Mann-Whitney (mechanical properties; alpha: 5%). DC was not affected by DCPD. The presence of DCPD reduced BFS for both storage times, while differences in E became evident after 28 days. After 24h, KIc increased with the addition of DCPD; after 28 days, however, KIc decreased only for DCPD-containing composites. Calcium release was similar for both DCPD contents and remained fairly constant during the 28-day period. Overall, HPO4(2-) release was higher at 7 days and did not decrease after 14 days. The composite with the highest filler level and 10% DCPD represented the best compromise between mechanical properties after aging in water and ion release. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. The Calmodulin-like calcium binding protein EhCaBP3 of Entamoeba histolytica regulates phagocytosis and is involved in actin dynamics.

    Directory of Open Access Journals (Sweden)

    Saima Aslam

    2012-12-01

    Full Text Available Phagocytosis is required for proliferation and pathogenesis of Entamoeba histolytica and erythrophagocytosis is considered to be a marker of invasive amoebiasis. Ca²⁺ has been found to play a central role in the process of phagocytosis. However, the molecular mechanisms and the signalling mediated by Ca²⁺ still remain largely unknown. Here we show that Calmodulin-like calcium binding protein EhCaBP3 of E. histolytica is directly involved in disease pathomechanism by its capacity to participate in cytoskeleton dynamics and scission machinery during erythrophagocytosis. Using imaging techniques EhCaBP3 was found in phagocytic cups and newly formed phagosomes along with actin and myosin IB. In vitro studies confirmed that EhCaBP3 directly binds actin, and affected both its polymerization and bundling activity. Moreover, it also binds myosin 1B in the presence of Ca²⁺. In cells where EhCaBP3 expression was down regulated by antisense RNA, the level of RBC uptake was reduced, myosin IB was found to be absent at the site of pseudopod cup closure and the time taken for phagocytosis increased, suggesting that EhCaBP3 along with myosin 1B mediate the closure of phagocytic cups. Experiments with EhCaBP3 mutant defective in Ca²⁺-binding showed that Ca²⁺ binding is required for phagosome formation. Liposome binding assay revealed that EhCaBP3 recruitment and enrichment to membrane is independent of any cellular protein as it binds directly to phosphatidylserine. Taken together, our results suggest a novel pathway mediating phagocytosis in E. histolytica, and an unusual mechanism of modulation of cytoskeleton dynamics by two calcium binding proteins, EhCaBP1 and EhCaBP3 with mostly non-overlapping functions.

  9. The calcium-binding protein ALG-2 regulates protein secretion and trafficking via interactions with MISSL and MAP1B proteins.

    Science.gov (United States)

    Takahara, Terunao; Inoue, Kuniko; Arai, Yumika; Kuwata, Keiko; Shibata, Hideki; Maki, Masatoshi

    2017-10-13

    Mobilization of intracellular calcium is essential for a wide range of cellular processes, including signal transduction, apoptosis, and vesicular trafficking. Several lines of evidence have suggested that apoptosis-linked gene 2 (ALG-2, also known as PDCD6 ), a calcium-binding protein, acts as a calcium sensor linking calcium levels with efficient vesicular trafficking, especially at the endoplasmic reticulum (ER)-to-Golgi transport step. However, how ALG-2 regulates these processes remains largely unclear. Here, we report that M APK1- i nteracting and s pindle- s tabilizing (MISS)- l ike (MISSL), a previously uncharacterized protein, interacts with ALG-2 in a calcium-dependent manner. Live-cell imaging revealed that upon a rise in intracellular calcium levels, GFP-tagged MISSL (GFP-MISSL) dynamically relocalizes in a punctate pattern and colocalizes with ALG-2. MISSL knockdown caused disorganization of the components of the ER exit site, the ER-Golgi intermediate compartment, and Golgi. Importantly, knockdown of either MISSL or ALG-2 attenuated the secretion of se creted a lkaline p hosphatase (SEAP), a model secreted cargo protein, with similar reductions in secretion by single- and double-protein knockdowns, suggesting that MISSL and ALG-2 act in the same pathway to regulate the secretion process. Furthermore, ALG-2 or MISSL knockdown delayed ER-to-Golgi transport of procollagen type I. We also found that ALG-2 and MISSL interact with microtubule-associated protein 1B (MAP1B) and that MAP1B knockdown reverts the reduced secretion of SEAP caused by MISSL or ALG-2 depletion. These results suggest that a change in the intracellular calcium level plays a role in regulation of the secretory pathway via interaction of ALG-2 with MISSL and MAP1B. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  10. Binding of iron, zinc, and lead ions from aqueous solution by shea butter (Butyrospermun Parkii) seed husks

    Energy Technology Data Exchange (ETDEWEB)

    Eromosele, I.C.; Otitolaye, O.O. (Federal Univ. of Technology, Yola, Adamawa State (Nigeria))

    1994-08-01

    Several workers have reported on the potential use of agricultural products as substrates for the removal of metal ions from aqueous solutions. These studies demonstrated that considerable amounts of metal ions can be removed from aqueous solutions by cellulosic materials. The merit in the use of the latter is their relative abundance and cheapness compared to conventional materials for the removal of toxic metal ions from waste-waters. In some of the studies, chemical modification of cellulosic materials significantly enhanced their ion-binding properties, providing greater flexibility in their applications to a wide range of heavy metal ions. Shea butter plant (Butyrospermun Parkii) normally grows in the wild within the guinea-savana zone of Nigeria. The seeds are a rich source of edible oils and the husks are usually discarded. The husk is thus available in abundance and, hence, there is reason to examine its ion-binding properties for its possible application in the removal of toxic metal ions from industrial waste-waters. This paper reports on preliminary studies of the sorption of iron, zinc and lead ions from aqueous solution by modified and unmodified shea butter seed husks. 8 refs., 5 figs., 1 tab.

  11. Measuring calcium, potassium, and nitrate in plant nutrient solutions using ion-selective electrodes in hydroponic greenhouse of some vegetables.

    Science.gov (United States)

    Vardar, Gökay; Altıkatoğlu, Melda; Ortaç, Deniz; Cemek, Mustafa; Işıldak, İbrahim

    2015-01-01

    Generally, the life cycle of plants depends on the uptake of essential nutrients in a balanced manner and on toxic elements being under a certain concentration. Lack of control of nutrient levels in nutrient solution can result in reduced plant growth and undesired conditions such as blossom-end rot. In this study, sensitivity and selectivity tests for various polyvinylchloride (PVC)-based ion-selective membranes were conducted to identify those suitable for measuring typical concentration ranges of macronutrients, that is, NO(3-), K(+), and Ca(2+), in hydroponic solutions. The sensitivity and selectivity of PVC-membrane-based ion-selective sensors prepared with tetradodecylammoniumnitrate for NO(3-), valinomycin for K(+), and Ca ionophore IV for Ca(2+) were found to be satisfactory for measuring NO(3-), K(+), and Ca(2+) ions in nutrient solutions over typical ranges of hydroponic concentrations. Potassium, calcium, and nitrate levels that were utilized by cucumber and tomato seedlings in the greenhouse were different. The findings show that tomato plants consumed less amounts of nitrate than cucumber plants over the first 2 months of their growth. We also found that the potassium intake was higher than other nutritional elements tested for all plants. © 2014 International Union of Biochemistry and Molecular Biology, Inc.

  12. Structural insight into the calcium ion modulated interdomain electron transfer in cellobiose dehydrogenase

    Czech Academy of Sciences Publication Activity Database

    Kádek, Alan; Kavan, Daniel; Felice, A.K.G.; Ludwig, R.; Halada, Petr; Man, Petr

    2015-01-01

    Roč. 589, č. 11 (2015), s. 1194-1199 ISSN 0014-5793 R&D Projects: GA ČR GAP206/12/0503; GA MŠk(CZ) EE2.3.20.0055; GA MŠk(CZ) ED1.1.00/02.0109 Institutional support: RVO:61388971 Keywords : Hydrogen / deuterium exchange * Cellobiose dehydrogenase * Calcium effect Subject RIV: CE - Biochemistry Impact factor: 3.519, year: 2015

  13. The toposome, essential for sea urchin cell adhesion and development, is a modified iron-less calcium-binding transferrin.

    Science.gov (United States)

    Noll, Hans; Alcedo, Joy; Daube, Michael; Frei, Erich; Schiltz, Emile; Hunt, John; Humphries, Tom; Matranga, Valeria; Hochstrasser, Martin; Aebersold, Ruedi; Lee, Hookeun; Noll, Markus

    2007-10-01

    We describe the structure and function of the toposome, a modified calcium-binding, iron-less transferrin, the first member of a new class of cell adhesion proteins. In addition to the amino acid sequence of the precursor, we determined by Edman degradation the N-terminal amino acid sequences of the mature hexameric glycoprotein present in the egg as well as that of its derived proteolytically modified fragments necessary for development beyond the blastula stage. The approximate C-termini of the fragments were determined by a combination of mass spectrometry and migration in reducing gels before and after deglycosylation. This new member of the transferrin family shows special features which explain its evolutionary adaptation to development and adhesive function in sea urchin embryos: (i) a protease-inhibiting WAP domain, (ii) a 280 amino acid cysteine-less insertion in the C-terminal lobe, and (iii) a 240 residue C-terminal extension with a modified cystine knot motif found in multisubunit external cell surface glycoproteins. Proteolytic removal of the N-terminal WAP domain generates the mature toposome present in the oocyte. The modified cystine knot motif stabilizes cell-bound trimers upon Ca-dependent dissociation of hexamer-linked cells. We determined the positions of the developmentally regulated cuts in the cysteine-less insertion, which produce the fragments observed previously. These fragments remain bound to the hexameric 22S particle in vivo and are released only after treatment of the purified toposome with reducing agents. In addition, some soluble smaller fragments with possible signal function are produced. Sequence comparison of five sea urchin species reveals the location of the cell-cell contact site targeted by the species-specific embryo dissociating antibodies. The evolutionary tree of 2-, 1-, and 0-ferric transferrins implies their evolution from a basic cation-activated allosteric design modified to serve multiple functions.

  14. Binding of antioxidant flavonol morin to the native state of bovine serum albumin: Effects of urea and metal ions on the binding

    Energy Technology Data Exchange (ETDEWEB)

    Singha Roy, Atanu; Dinda, Amit Kumar; Chaudhury, Susmitnarayan; Dasgupta, Swagata, E-mail: swagata@chem.iitkgp.ernet.in

    2014-01-15

    In consideration of the various medicinal aspects of the flavonoid polyphenols, the interaction of morin with bovine serum albumin (BSA) has been investigated using multi-spectroscopic approaches. The pKa{sub 1} of morin being 5.09, which is below physiological pH, binding studies provide important insights into its potential use as a biotherapeutic. The binding was performed under different pH (5, 7 and 9) conditions and in absence and presence of Cu(II) and Fe(III) ions. It is observed that the presence of metal ions affect the binding of morin towards BSA. The binding with BSA results in a motional restriction of morin in solution that causes an increase in anisotropy (r), rotational correlation time (t{sub r}) and steady-state lifetime (t{sub av}) of the ligand. Urea causes denaturation of BSA resulting in the release of morin from the protein core as determined from both the steady-state fluorescence and anisotropy (r) measurements. The possibility of non-radiative energy transfer from the donor tryptophan to the acceptor morin is detected following the Förster's theory. The site marker displacement studies along with the molecular docking results indicated that morin binds to the hydrophobic pocket of site 1 (subdomain IIA) near Trp 213 of BSA. -- Highlights: • Binding mainly occurs through the electrostatic forces with partial hydrophobic association. • Negative ΔG° indicates the spontaneity of the complexation between morin and BSA. • Morin binds near Trp 213 (site 1, subdomain IIA) of BSA only in its native state. • Lifetime of morin increases as a function of BSA. • Motional restriction of morin occurs in the presence of BSA.

  15. Potential New Ligand Systems for Binding Uranyl Ions in Seawater Environments

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, John [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2014-12-13

    Work began this quarter on a new project involving a combined computational and biosynthetic approach to selective recognition of uranyl ion in aqueous solution. This project exploits the results of computational studies to discover new ligand classes. Synthetic studies will follow to generate target systems for uranyl binding and determination of binding constants. The process will be iterative, with results from computation informing synthesis, and vice versa. The theme of the ligand classes to be examined initially will be biologically based. New phosphonate-containing α-amino acid N-carboxyanhydride (NCA) monomers were used recently to prepare well-defined phosphonate-containing poly-peptides and block copolypeptides. Our first approach is to utilize these phosphate- and phosphonate-containing NCAs for the coordination of uranyl. The work includes the laboratory-scale preparation of a series of NCAs and the full thermodynamic and spectroscopic characterization of the resulting uranyl complexes. We are also evaluating the sequestering activity in different physiological and environmental conditions of these copolymers as well as their biodegradability.

  16. The binding of in vitro synthesized adenovirus DNA binding protein to single-stranded DNA is stimulated by zinc ions

    NARCIS (Netherlands)

    Vos, H.L.; Lee, F.M. van der; Sussenbach, J.S.

    1988-01-01

    We have synthesized wild type DNA binding protein (DBP) of adenovirus type 5 (Ad5) and several truncated forms of this protein by a combination of in vitro transcription and translation. The proteins obtained were tested for binding to a single-stranded DNA-cellulose column. It could be shown that

  17. Selectivity of externally facing ion-binding sites in the Na/K pump to alkali metals and organic cations.

    Science.gov (United States)

    Ratheal, Ian M; Virgin, Gail K; Yu, Haibo; Roux, Benoît; Gatto, Craig; Artigas, Pablo

    2010-10-26

    The Na/K pump is a P-type ATPase that exchanges three intracellular Na(+) ions for two extracellular K(+) ions through the plasmalemma of nearly all animal cells. The mechanisms involved in cation selection by the pump's ion-binding sites (site I and site II bind either Na(+) or K(+); site III binds only Na(+)) are poorly understood. We studied cation selectivity by outward-facing sites (high K(+) affinity) of Na/K pumps expressed in Xenopus oocytes, under voltage clamp. Guanidinium(+), methylguanidinium(+), and aminoguanidinium(+) produced two phenomena possibly reflecting actions at site III: (i) voltage-dependent inhibition (VDI) of outwardly directed pump current at saturating K(+), and (ii) induction of pump-mediated, guanidinium-derivative-carried inward current at negative potentials without Na(+) and K(+). In contrast, formamidinium(+) and acetamidinium(+) induced K(+)-like outward currents. Measurement of ouabain-sensitive ATPase activity and radiolabeled cation uptake confirmed that these cations are external K(+) congeners. Molecular dynamics simulations indicate that bound organic cations induce minor distortion of the binding sites. Among tested metals, only Li(+) induced Na(+)-like VDI, whereas all metals tested except Na(+) induced K(+)-like outward currents. Pump-mediated K(+)-like organic cation transport challenges the concept of rigid structural models in which ion specificity at site I and site II arises from a precise and unique arrangement of coordinating ligands. Furthermore, actions by guanidinium(+) derivatives suggest that Na(+) binds to site III in a hydrated form and that the inward current observed without external Na(+) and K(+) represents cation transport when normal occlusion at sites I and II is impaired. These results provide insights on external ion selectivity at the three binding sites.

  18. Metal Ion Binding at the Catalytic Site Induces Widely Distributed Changes in a Sequence Specific Protein-DNA Complex.

    Science.gov (United States)

    Sinha, Kaustubh; Sangani, Sahil S; Kehr, Andrew D; Rule, Gordon S; Jen-Jacobson, Linda

    2016-11-08

    Metal ion cofactors can alter the energetics and specificity of sequence specific protein-DNA interactions, but it is unknown if the underlying effects on structure and dynamics are local or dispersed throughout the protein-DNA complex. This work uses EcoRV endonuclease as a model, and catalytically inactive lanthanide ions, which replace the Mg 2+ cofactor. Nuclear magnetic resonance (NMR) titrations indicate that four Lu 3+ or two La 3+ cations bind, and two new crystal structures confirm that Lu 3+ binding is confined to the active sites. NMR spectra show that the metal-free EcoRV complex with cognate (GATATC) DNA is structurally distinct from the nonspecific complex, and that metal ion binding sites are not assembled in the nonspecific complex. NMR chemical shift perturbations were determined for 1 H- 15 N amide resonances, for 1 H- 13 C Ile-δ-CH 3 resonances, and for stereospecifically assigned Leu-δ-CH 3 and Val-γ-CH 3 resonances. Many chemical shifts throughout the cognate complex are unperturbed, so metal binding does not induce major conformational changes. However, some large perturbations of amide and side chain methyl resonances occur as far as 34 Å from the metal ions. Concerted changes in specific residues imply that local effects of metal binding are propagated via a β-sheet and an α-helix. Both amide and methyl resonance perturbations indicate changes in the interface between subunits of the EcoRV homodimer. Bound metal ions also affect amide hydrogen exchange rates for distant residues, including a distant subdomain that contacts DNA phosphates and promotes DNA bending, showing that metal ions in the active sites, which relieve electrostatic repulsion between protein and DNA, cause changes in slow dynamics throughout the complex.

  19. Metal Ion Binding at the Catalytic Site Induces Widely Distributed Changes in a Sequence Specific Protein–DNA Complex

    Science.gov (United States)

    2016-01-01

    Metal ion cofactors can alter the energetics and specificity of sequence specific protein–DNA interactions, but it is unknown if the underlying effects on structure and dynamics are local or dispersed throughout the protein–DNA complex. This work uses EcoRV endonuclease as a model, and catalytically inactive lanthanide ions, which replace the Mg2+ cofactor. Nuclear magnetic resonance (NMR) titrations indicate that four Lu3+ or two La3+ cations bind, and two new crystal structures confirm that Lu3+ binding is confined to the active sites. NMR spectra show that the metal-free EcoRV complex with cognate (GATATC) DNA is structurally distinct from the nonspecific complex, and that metal ion binding sites are not assembled in the nonspecific complex. NMR chemical shift perturbations were determined for 1H–15N amide resonances, for 1H–13C Ile-δ-CH3 resonances, and for stereospecifically assigned Leu-δ-CH3 and Val-γ-CH3 resonances. Many chemical shifts throughout the cognate complex are unperturbed, so metal binding does not induce major conformational changes. However, some large perturbations of amide and side chain methyl resonances occur as far as 34 Å from the metal ions. Concerted changes in specific residues imply that local effects of metal binding are propagated via a β-sheet and an α-helix. Both amide and methyl resonance perturbations indicate changes in the interface between subunits of the EcoRV homodimer. Bound metal ions also affect amide hydrogen exchange rates for distant residues, including a distant subdomain that contacts DNA phosphates and promotes DNA bending, showing that metal ions in the active sites, which relieve electrostatic repulsion between protein and DNA, cause changes in slow dynamics throughout the complex. PMID:27786446

  20. Elucidating the structures and cooperative binding mechanism of cesium salts to the multitopic ion-pair receptor through density functional theory calculations.

    Science.gov (United States)

    Sadhu, Biswajit; Sundararajan, Mahesh; Velmurugan, Gunasekaran; Venuvanalingam, Ponnambalam

    2015-09-21

    Designing new and innovative receptors for the selective binding of radionuclides is central to nuclear waste management processes. Recently, a new multi-topic ion-pair receptor was reported which binds a variety of cesium salts. Due to the large size of the receptor, quantum chemical calculations on the full ion-pair receptors are restricted, thus the binding mechanisms are not well understood at the molecular level. We have assessed the binding strengths of various cesium salts to the recently synthesized multi-topic ion-pair receptor molecule using density functional theory based calculations. Our calculations predict that the binding of cesium salts to the receptor predominantly occurs via the cooperative binding mechanism. Cesium and the anion synergistically assist each other to bind favorably inside the receptor. Energy decomposition analysis on the ion-pair complexes shows that the Cs salts are bound to the receptor mainly through electrostatic interactions with small contribution from covalent interactions for large ionic radius anions. Further, QTAIM analysis characterizes the importance of different inter-molecular interactions between the ions and the receptor inside the ion-pair complexes. The role of the crystallographic solvent molecule contributes significantly by ~10 kcal mol(-1) to the overall binding affinities which is quite significant. Further, unlike the recent molecular mechanics (MM) calculations, our calculated binding affinity trends for various Cs ion-pair complexes (CsF, CsCl and CsNO3) are now in excellent agreement with the experimental binding affinity trends.

  1. In situ Gelation of Monodisperse Alginate Hydrogel in Microfluidic Channel Based on Mass Transfer of Calcium Ions

    International Nuclear Information System (INIS)

    Song, YoungShin; Lee, Chang-Soo

    2014-01-01

    A microfluidic method for the in situ production of monodispersed alginate hydrogels using biocompatible polymer gelation by crosslinker mass transfer is described. Gelation of the hydrogel was achieved in situ by the dispersed calcium ion in the microfluidic device. The capillary number (Ca) and the flow rate of the disperse phase which are important operating parameters mainly influenced the formation of three distinctive flow regions, such as dripping, jetting, and unstable dripping. Under the formation of dripping region, monodispersed alginate hydrogels having a narrow size distribution (C.V=2.71%) were produced in the microfluidic device and the size of the hydrogels, ranging from 30 to 60 µm, could be easily controlled by varying the flow rate, viscosity, and interfacial tension. This simple microfluidic method for the production of monodisperse alginate hydrogels shows strong potential for use in delivery systems of foods, cosmetics, inks, and drugs, and spherical alginate hydrogels which have biocompatibility will be applied to cell transplantation

  2. In situ Gelation of Monodisperse Alginate Hydrogel in Microfluidic Channel Based on Mass Transfer of Calcium Ions

    Energy Technology Data Exchange (ETDEWEB)

    Song, YoungShin; Lee, Chang-Soo [Chungnam National University, Daejeon (Korea, Republic of)

    2014-10-15

    A microfluidic method for the in situ production of monodispersed alginate hydrogels using biocompatible polymer gelation by crosslinker mass transfer is described. Gelation of the hydrogel was achieved in situ by the dispersed calcium ion in the microfluidic device. The capillary number (Ca) and the flow rate of the disperse phase which are important operating parameters mainly influenced the formation of three distinctive flow regions, such as dripping, jetting, and unstable dripping. Under the formation of dripping region, monodispersed alginate hydrogels having a narrow size distribution (C.V=2.71%) were produced in the microfluidic device and the size of the hydrogels, ranging from 30 to 60 µm, could be easily controlled by varying the flow rate, viscosity, and interfacial tension. This simple microfluidic method for the production of monodisperse alginate hydrogels shows strong potential for use in delivery systems of foods, cosmetics, inks, and drugs, and spherical alginate hydrogels which have biocompatibility will be applied to cell transplantation.

  3. Stretch induced endothelin-1 secretion by adult rat astrocytes involves calcium influx via stretch-activated ion channels (SACs)

    International Nuclear Information System (INIS)

    Ostrow, Lyle W.; Suchyna, Thomas M.; Sachs, Frederick

    2011-01-01

    Highlights: → Endothelin-1 expression by adult rat astrocytes correlates with cell proliferation. → Stretch-induced ET-1 is inhibited by GsMtx-4, a specific inhibitor of Ca 2+ permeant SACs. → The less specific SAC inhibitor streptomycin also inhibits ET-1 secretion. → Stretch-induced ET-1 production depends on a calcium influx. → SAC pharmacology may provide a new class of therapeutic agents for CNS pathology. -- Abstract: The expression of endothelins (ETs) and ET-receptors is often upregulated in brain pathology. ET-1, a potent vasoconstrictor, also inhibits the expression of astrocyte glutamate transporters and is mitogenic for astrocytes, glioma cells, neurons, and brain capillary endothelia. We have previously shown that mechanical stress stimulates ET-1 production by adult rat astrocytes. We now show in adult astrocytes that ET-1 production is driven by calcium influx through stretch-activated ion channels (SACs) and the ET-1 production correlates with cell proliferation. Mechanical stimulation using biaxial stretch ( 2+ threshold. This coupling of mechanical stress to the astrocyte endothelin system through SACs has treatment implications, since all pathology deforms the surrounding parenchyma.

  4. Calcium binding proteins

    National Research Council Canada - National Science Library

    Perm︠i︡akov, E. A; Kretsinger, Robert H

    2011-01-01

    .... It summarizes ongoing research and presents general hypotheses that help to focus future research, and also provides a conceptual framework and a description of the underlying techniques that permits someone entering the field to become conversant."--Provided by publisher.

  5. Calcium in plant cells

    Directory of Open Access Journals (Sweden)

    V. V. Schwartau

    2014-04-01

    Full Text Available The paper gives the review on the role of calcium in many physiological processes of plant organisms, including growth and development, protection from pathogenic influences, response to changing environmental factors, and many other aspects of plant physiology. Initial intake of calcium ions is carried out by Ca2+-channels of plasma membrane and they are further transported by the xylem owing to auxins’ attractive ability. The level of intake and selectivity of calcium transport to ove-ground parts of the plant is controlled by a symplast. Ca2+enters to the cytoplasm of endoderm cells through calcium channels on the cortical side of Kaspary bands, and is redistributed inside the stele by the symplast, with the use of Ca2+-АТPases and Ca2+/Н+-antiports. Owing to regulated expression and activity of these calcium transporters, calclum can be selectively delivered to the xylem. Important role in supporting calcium homeostasis is given to the vacuole which is the largest depo of calcium. Regulated quantity of calcium movement through the tonoplast is provided by a number of potential-, ligand-gated active transporters and channels, like Ca2+-ATPase and Ca2+/H+ exchanger. They are actively involved in the inactivation of the calcium signal by pumping Ca2+ to the depo of cells. Calcium ATPases are high affinity pumps that efficiently transfer calcium ions against the concentration gradient in their presence in the solution in nanomolar concentrations. Calcium exchangers are low affinity, high capacity Ca2+ transporters that are effectively transporting calcium after raising its concentration in the cell cytosol through the use of protons gradients. Maintaining constant concentration and participation in the response to stimuli of different types also involves EPR, plastids, mitochondria, and cell wall. Calcium binding proteins contain several conserved sequences that provide sensitivity to changes in the concentration of Ca2+ and when you

  6. Microstructure and spectroscopic investigations of calcium zinc bismuth phosphate glass ceramics doped with manganese ions

    Science.gov (United States)

    Suneel Kumar, A.; Sambasiva Rao, M. V.; Chinna Ram, G.; Krishna Rao, D.

    2018-01-01

    Multi-component 10CaF2-20ZnO-(15 - x)Bi2O3-55P2O5:xMnO (0 ≤ x ≤ 2.5) glass ceramics were synthesised by melt quenching technique and heat treatment. The prepared glass ceramics were characterised by XRD, DTA, EDS and SEM. Spectroscopic studies such as optical absorption, EPR, FTIR and Raman were also carried out on these glass ceramics. The XRD and SEM studies have indicated that ceramic samples contain well defined and randomly distributed grains of different crystalline phases. The observed increase of enthalpy from DTA patterns up to 1 mol% of MnO indicates that the crystallisation starts initially from the surface of the material then gradually it is extended to the volume of the material and this influence is meagre at higher concentrations of MnO. The absorption spectra of manganese doped glass ceramics have exhibited two types of conventional bands; one due to Mn2+ ions and other due to Mn3+ ions. The EPR spectra of MnO doped glass ceramics showed a resonance signal around g2 = 2.023 with a six line hyperfine structure and another signal at about g1 = 4.314. The relative intensity and half-width of these two signals are observed to increase with the increase in the concentration of manganese ions up to 1 mol% beyond this concentration it is found to decrease. Such observation indicates the conversion of part of Mn2+ ions into Mn3+ ions in the glass ceramic matrix. The observed increase in the intensity of symmetrical structural units at the expense of asymmetrical structural units from the FTIR and Raman spectra at higher concentration of MnO indicating that Mn2+ ions occupy the network forming positions in the glass ceramic structure.

  7. Influence des ions étrangers et de la matière organique sur la cristallisation des carbonates de calcium Influence of Foreign Ions and of Organic Matter on the Crystallization of Calcium Carbonates

    Directory of Open Access Journals (Sweden)

    Cailleau P.

    2006-11-01

    Full Text Available On présente les résultats d'un travail de recherche entrepris pour des aspects de la diagenèse des roches carbonatées : la cimentation cal le rôle est capital pour la conservation ou le colmatage de la porosit de ce type de sédiments. Après une synthèse bibliographique des connaissances actuelles sur et la cimentation du CaC03 en milieu naturel et en laboratoire, on a mentalement l'influence des ions étrangers et de la matière organique sur germination et la croissance des carbonates de calcium. Les principaux résultats obtenus peuvent se résumer comme suit a En ce qui concerne les ions étrangers. Leur action se traduit en général par une augmentation du temps de germination et une réduction de la vitesse de croissance des cristaux de CaCO3; l'apparition de faciès particuliers pour certains des minéraux formés ; l'inhibition des transformations d'une variété en une autre. On obtient un classement par ordre d'efficacité croissante action à peu près nulle: K+, CI-; action modérée : Bat+, Na+, AI3+, Cul+, Sr2+, SO2 , P0;-; action dominante de Mg'+. b Pour les matières organiques. Seules l'acide citrique et, dans une moindre mesure, l'acide tartrique, ont une influence notable, d'ailleurs analogue à celle des ions étrangers en ce qui concerne les cinétiques de germination et de croissance du CaCO. L'adsorption de certains de ces produits se traduit en outre par des faciès particuliers des minéraux formés et éventuellement par l'inhibition des transformations d'une variété en une autre. This article gives the results of a research project undertaken to study one of the aspects of the diagénesis of carbonate rocks, 1. e. calcite cementing, which plays a capital role in preserving or plugging up the original porosity of such sediments.After making a bibliographic synthesis of what is now known about the origin and cementation of CaC03 in a natural environment and in the laboratory, the article experimentally

  8. Relation between heat of vaporization, ion transport, molar volume, and cation-anion binding energy for ionic liquids.

    Science.gov (United States)

    Borodin, Oleg

    2009-09-10

    A number of correlations between heat of vaporization (H(vap)), cation-anion binding energy (E(+/-)), molar volume (V(m)), self-diffusion coefficient (D), and ionic conductivity for 29 ionic liquids have been investigated using molecular dynamics (MD) simulations that employed accurate and validated many-body polarizable force fields. A significant correlation between D and H(vap) has been found, while the best correlation was found for -log(DV(m)) vs H(vap) + 0.28E(+/-). A combination of enthalpy of vaporization and a fraction of the cation-anion binding energy was suggested as a measure of the effective cohesive energy for ionic liquids. A deviation of some ILs from the reported master curve is explained based upon ion packing and proposed diffusion pathways. No general correlations were found between the ion diffusion coefficient and molecular volume or the diffusion coefficient and cation/anion binding energy.

  9. Nacre calcification in the freshwater mussel Unio pictorum: carbonic anhydrase activity and purification of a 95 kDa calcium-binding glycoprotein.

    Science.gov (United States)

    Marie, Benjamin; Luquet, Gilles; Bédouet, Laurent; Milet, Christian; Guichard, Nathalie; Medakovic, Davorin; Marin, Frédéric

    2008-10-13

    The formation of the molluscan shell is finely tuned by macromolecules of the shell organic matrix. Previous results have shown that the acid-soluble fraction of the nacre matrix of the freshwater paleoheterodont bivalve Unio pictorum shell displays a number of remarkable properties, such as calcium-binding activity, the presence of extensive glycosylations and the capacity to interfere at low concentration with in vitro calcium carbonate precipitation. Here we have found that the nacre-soluble matrix exhibits a carbonic anhydrase activity, an important function in calcification processes. This matrix is composed of three main proteinaceous discrete fractions. The one with the highest apparent molecular weight is a 95 kDa glycoprotein that is specific to the nacreous layer. P95, as it is provisionally named, is enriched in Gly, Glx and Asx and exhibits an apparent pI value of approximately 4, or approximately 7 when chemically deglycosylated. Furthermore, its glycosyl moiety, consisting of sulfated polysaccharides, is involved in calcium binding. Purified fractions of the three main proteins were digested with trypsin, and the resulting peptides were analysed by mass spectrometry. Our results suggest that identical peptides are constitutive domains of the different proteins. Partial primary structures were obtained by de novo sequencing and compared with known sequences from other mollusc shell proteins. Our results are discussed from an evolutionary viewpoint.

  10. Actin filaments as the fast pathways for calcium ions involved in ...

    Indian Academy of Sciences (India)

    2015-08-14

    Aug 14, 2015 ... stimulus; spring of tip-link exerts a force on the trap door and opens the ionic channel. 550. Miljko V Sataric et al. ... copy to detect Ca2+ ions entry and distribution within stereo- cilia of hair cells. They also .... resistance R0 ~ 108 Ω. The corresponding characteristic time of discharging such elementary unit is ...

  11. Comparative Analysis of Calcium-Binding Myeloid-Related Protein-8/14 in Saliva and Serum of Patients With Periodontitis and Healthy Individuals.

    Science.gov (United States)

    Haririan, Hady; Andrukhov, Oleh; Pablik, Eleonore; Neuhofer, Michaela; Moritz, Andreas; Rausch-Fan, Xiaohui

    2016-02-01

    This study aims to investigate calcium-binding myeloid-related protein (MRP)-8/14 in the saliva and serum of individuals with periodontitis and periodontally healthy individuals for the assessment of its role in the pathogenesis and clinical diagnosis of periodontitis. This cross-sectional study includes 56 patients with periodontitis and 44 periodontally healthy individuals. Saliva and serum were collected for the detection of MRP-8/14 and calcium levels. Periodontopathic bacteria were determined by polymerase chain reaction in saliva. Correlations between salivary and serum MRP-8/14 levels and clinical parameters, bacteria, and calcium were analyzed with Pearson correlation in a multiple regression model. MRP-8/14 levels were documented with receiver operating characteristic (ROC) curves. Compared with healthy individuals, MRP-8/14 levels were significantly higher in both the saliva and serum of patients with periodontitis, but calcium was increased only in saliva. A high diagnostic potential of salivary MRP-8/14 was detected for periodontitis (ROC = 0.86). Salivary MRP-8/14 levels correlated significantly with the presence of the periodontopathogen Treponema denticola, as well as with the clinical parameters of periodontitis. MRP-8/14 in saliva might be a potential diagnostic parameter for periodontal disease.

  12. Effect of calcium chelators on heat coagulation and heat-induced changes of concentrated micellar casein solutions: The role of calcium-ion activity and micellar integrity

    NARCIS (Netherlands)

    Kort, de E.J.P.; Minor, M.; Snoeren, T.A.L.; Hooijdonk, van A.C.M.; Linden, van der E.

    2012-01-01

    There is general consensus that calcium chelators enhance heat stability in milk. However, they increase the heat stability to considerably different extents. For this reason, the effect of various calcium chelators on heat coagulation and heat-induced changes of concentrated micellar casein

  13. Positive cooperativity of the specific binding between Hg2+ ion and T:T mismatched base pairs in duplex DNA

    International Nuclear Information System (INIS)

    Torigoe, Hidetaka; Miyakawa, Yukako; Ono, Akira; Kozasa, Tetsuo

    2012-01-01

    Highlights: ► Hg 2+ specifically bound with the T:T mismatched base pair at 1:1 molar ratio. ► The binding constant between Hg 2+ and the T:T mismatched base pair was 10 6 M −1 . ► The binding constant was larger than those for nonspecific metal–DNA interactions. ► The binding constant for the second Hg 2+ was larger than that for the first Hg 2+ . ► The positive cooperative binding was observed between Hg 2+ and multiple T:T. - Abstract: Metal-mediated base pairs by the interaction between metal ions and artificial bases in oligonucleotides have been developed for their potential applications in nanotechnology. We recently found that a natural T:T mismatched base pair bound with Hg 2+ ion to form a novel T–Hg–T base pair. Here, we examined the thermodynamic properties of the binding between Hg 2+ and each of the single and double T:T mismatched base pair duplex DNAs by isothermal titration calorimetry. Hg 2+ specifically bound with the T:T mismatched base pair at 1:1 molar ratio with 10 6 M −1 binding constant, which was significantly larger than those for nonspecific metal ion–DNA interactions. In the Hg 2+ –double T:T mismatched base pair interaction, the affinity for the second Hg 2+ binding was significantly larger than that for the first Hg 2+ binding. The positively cooperative binding may be favorable to align multiple Hg 2+ in duplex DNA for the application of the metal-mediated base pairs in nanotechnology.

  14. Calcium in pollen-pistil interaction in `Petunia hybrida Hor`. Pt. 1. Localization of Ca{sup 2+} ions in mature pollen grain using pyroantimonate and autoradiographic methods

    Energy Technology Data Exchange (ETDEWEB)

    Bednarska, E.; Butowt, R. [Uniwersytet Mikolaja Kopernika, Torun (Poland)

    1994-12-31

    The localization of Ca{sup 2+} in the mature pollen grain and the flow of these ions the somatic tissues of the anther to the pollen grains has been studied using pyroantimonate and autoradiographic methods. In the pollen grain, Ca{sup 2+} ions have been localized in the sporoderm in the cytoplasmic vesicles of probably dictyosomal origin. Calcium ions were transported into the sporoderm together with the compounds of degenerating tapetum. The material of degenerating tapetum forms pollen coat surrounding the mature pollen grains. (author). 18 refs, 9 figs.

  15. Comparative distribution of relaxin-3 inputs and calcium-binding protein-positive neurons in rat amygdala

    Directory of Open Access Journals (Sweden)

    Fabio N Santos

    2016-04-01

    Full Text Available The neural circuits involved in mediating complex behaviors are being rapidly elucidated using various newly developed and powerful anatomical and molecular techniques, providing insights into the neural basis for anxiety disorders, depression, addiction, and dysfunctional social behaviors. Many of these behaviors and associated physiological processes involve the activation of the amygdala in conjunction with cortical and hippocampal circuits. Ascending subcortical projections provide modulatory inputs to the extended amygdala and its related nodes (or ‘hubs’ within these key circuits. One such input arises from the nucleus incertus (NI in the tegmentum, which sends amino acid- and peptide-containing projections throughout the forebrain. Notably, a distinct population of GABAergic NI neurons expresses the highly-conserved neuropeptide, relaxin-3, and relaxin-3 signaling has been implicated in the modulation of reward/motivation and anxiety- and depressive-like behaviors in rodents via actions within the extended amygdala. Thus, a detailed description of the relaxin-3 innervation of the extended amygdala would provide an anatomical framework for an improved understanding of NI and relaxin-3 modulation of these and other specific amygdala-related functions. Therefore, in this study, we examined the distribution of NI projections and relaxin-3-positive elements (axons/fibers/terminals within the amygdala, relative to the distribution of neurons expressing the calcium-binding proteins, parvalbumin, calretinin and/or calbindin. Anterograde tracer injections into the NI revealed a topographic distribution of NI efferents within the amygdala that was near identical to the distribution of relaxin-3-immunoreactive fibers. Highest densities of anterogradely-labeled elements and relaxin-3-immunoreactive fibers were observed in the medial nucleus of the amygdala, medial divisions of the bed nucleus of the stria terminalis (BST and in the endopiriform

  16. Incorporation of phosphorus guest ions in the calcium silicate phases of Portland cement from 31P MAS NMR spectroscopy.

    Science.gov (United States)

    Poulsen, Søren L; Jakobsen, Hans J; Skibsted, Jørgen

    2010-06-21

    Portland cements may contain small quantities of phosphorus (typically below 0.5 wt % P(2)O(5)), originating from either the raw materials or alternative sources of fuel used to heat the cement kilns. This work reports the first (31)P MAS NMR study of anhydrous and hydrated Portland cements that focuses on the phase and site preferences of the (PO(4))(3-) guest ions in the main clinker phases and hydration products. The observed (31)P chemical shifts (10 to -2 ppm), the (31)P chemical shift anisotropy, and the resemblance of the lineshapes in the (31)P and (29)Si MAS NMR spectra strongly suggest that (PO(4))(3-) units are incorporated in the calcium silicate phases, alite (Ca(3)SiO(5)) and belite (Ca(2)SiO(4)), by substitution for (SiO(4))(4-) tetrahedra. This assignment is further supported by a determination of the spin-lattice relaxation times for (31)P in alite and belite, which exhibit the same ratio as observed for the corresponding (29)Si relaxation times. From simulations of the intensities, observed in inversion-recovery spectra for a white Portland cement, it is deduced that 1.3% and 2.1% of the Si sites in alite and belite, respectively, are replaced by phosphorus. Charge balance may potentially be achieved to some extent by a coupled substitution mechanism where Ca(2+) is replaced by Fe(3+) ions, which may account for the interaction of the (31)P spins with paramagnetic Fe(3+) ions as observed for the ordinary Portland cements. A minor fraction of phosphorus may also be present in the separate phase Ca(3)(PO(4))(2), as indicated by the observation of a narrow resonance at delta((31)P) = 3.0 ppm for two of the studied cements. (31)P{(1)H} CP/MAS NMR spectra following the hydration of a white Portland cement show that the resonances from the hydrous phosphate species fall in the same spectral range as observed for (PO(4))(3-) incorporated in alite. This similarity and the absence of a large (31)P chemical shift ansitropy indicate that the hydrous (PO(4

  17. The influence of potassium and calcium ions on nitrogen metabolism of cucumber seedlings

    Directory of Open Access Journals (Sweden)

    Genowefa Kubik-Dobosz

    2014-01-01

    Full Text Available It was found that K+ or Ca2+ deficiency in a nitrate or ammonium medium increased the amount of accumulated total and non-protein nitrogen in some organs of cucumber seedlings, as also caused changes in accumulated potassium and calcium. Lack of K+ or Ca2+ in a medium which did not contain nitrogen led to an increased level of glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase activity in the cotyledons and roots of cucumbers. Similar changes in the activity of these enzymes were noted in certain organs of seedlings growing in nitrate or ammonium medium with decreased K+ or Ca2+ contents, although the magnitude of these changes depended upon the applied dosage of these cations, the form of mineral nitrogen, developmental phase of plants and the plant organ dealt with.

  18. The conserved potassium channel filter can have distinct ion binding profiles: structural analysis of rubidium, cesium, and barium binding in NaK2K.

    Science.gov (United States)

    Lam, Yee Ling; Zeng, Weizhong; Sauer, David Bryant; Jiang, Youxing

    2014-08-01

    Potassium channels are highly selective for K(+) over the smaller Na(+). Intriguingly, they are permeable to larger monovalent cations such as Rb(+) and Cs(+) but are specifically blocked by the similarly sized Ba(2+). In this study, we used structural analysis to determine the binding profiles for these permeant and blocking ions in the selectivity filter of the potassium-selective NaK channel mutant NaK2K and also performed permeation experiments using single-channel recordings. Our data revealed that some ion binding properties of NaK2K are distinct from those of the canonical K(+) channels KcsA and MthK. Rb(+) bound at sites 1, 3, and 4 in NaK2K, as it does in KcsA. Cs(+), however, bound predominantly at sites 1 and 3 in NaK2K, whereas it binds at sites 1, 3, and 4 in KcsA. Moreover, Ba(2+) binding in NaK2K was distinct from that which has been observed in KcsA and MthK, even though all of these channels show similar Ba(2+) block. In the presence of K(+), Ba(2+) bound to the NaK2K channel at site 3 in conjunction with a K(+) at site 1; this led to a prolonged block of the channel (the external K(+)-dependent Ba(2+) lock-in state). In the absence of K(+), however, Ba(2+) acts as a permeating blocker. We found that, under these conditions, Ba(2+) bound at sites 1 or 0 as well as site 3, allowing it to enter the filter from the intracellular side and exit from the extracellular side. The difference in the Ba(2+) binding profile in the presence and absence of K(+) thus provides a structural explanation for the short and prolonged Ba(2+) block observed in NaK2K. © 2014 Lam et al.

  19. NIR fluorescence spectroscopic investigations of Er{sup 3+}-ions doped borate based tellurium calcium zinc niobium oxide glasses

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, O. [Department of Instrumentation, Sri Venkateswara University, Tirupati 517502 (India); Dhoble, S.J. [Department of Physics, RTM Nagpur University, Nagpur 440033 (India); Ramesh, B.; Devarajulu, G. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Reddy, C. Madhukar [Department of Physics, AP Model School, Yerravaripalem 517194 (India); Linganna, K. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Reddy, G. Rajasekhar [Department of Instrumentation, Sri Venkateswara University, Tirupati 517502 (India); Raju, B. Deva Prasad, E-mail: drdevaprasadraju@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Department of Future Studies, Sri Venkateswara University, Tirupati 517502 (India)

    2015-08-15

    A series of Er{sup 3+} ions doped tellurium calcium zinc niobium borate glasses were prepared by the melt quenching technique. The prepared samples were investigated by optical absorption and near infrared fluorescence spectroscopic studies. The obtained Judd–Ofelt intensity parameters Ω{sub λ} (λ=2, 4 and 6) were determined through experimental and calculated oscillator strengths obtained from absorption spectra and their results are studied and compared with reported literature. The stark-level energies of {sup 4}I{sub 13/2} excited and {sup 4}I{sub 15/2} ground states were evaluated by using both the absorption and emission measurements. The effect of Er{sup 3+} ion concentration on the emission intensity of {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} transition was discussed. Intense and broad 1.53 µm infrared fluorescence is observed at 980 nm diode laser excitation. Photoluminescence (PL) and its decay behavior studies were carried out for the transition {sup 4}I{sub 13/2}→{sup 4}I{sub 15/2} at 1.53 µm emission. The broad emission together with higher values of the bandwidth (81 nm), stimulated emission cross-section (32.25×10{sup −22} cm{sup 2}) and lifetime (530 µs for 1.0 mol% of Er{sup 3+}) of level {sup 4}I{sub 13/2} make these glasses attractive for broadband amplifiers. From the analysis of spectroscopic data, the present glass is a prospective photonic material for practical applications in the visible and NIR region. - Highlights: • In this study we prepared TCZNB glasses doped with Er{sup 3+} ions. • Glasses are characterized with absorption, emission and lifetime analysis. • Judd–Ofelt theory is used to calculate radiative properties. • TCZNB glasses could be used as NIR lasers.

  20. Quantifying metal ions binding onto dissolved organic matter using log-transformed absorbance spectra.

    Science.gov (United States)

    Yan, Mingquan; Wang, Dongsheng; Korshin, Gregory V; Benedetti, Marc F

    2013-05-01

    This study introduces the concept of consistent examination of changes of log-transformed absorbance spectra of dissolved organic matter (DOM) at incrementally increasing concentrations of heavy metal cations such as copper, cadmium, and aluminum at environmentally relevant concentrations. The approach is designed to highlight contributions of low-intensity absorbance features that appear to be especially sensitive to DOM reactions. In accord with this approach, log-transformed absorbance spectra of fractions of DOM from the Suwannee River were acquired at varying pHs and concentrations of copper, cadmium, and aluminum. These log-transformed spectra were processed using the differential approach and used to examine the nature of the observed changes of DOM absorbance and correlate them with the extent of Me-DOM complexation. Two alternative parameters, namely the change of the spectral slope in the range of wavelengths 325-375 nm (DSlope325-375) and differential logarithm of DOM absorbance at 350 nm (DLnA350) were introduced to quantify Cu(II), Cd(II), and Al(III) binding onto DOMs. DLnA350 and DSlope325-375 datasets were compared with the amount of DOM-bound Cu(II), Cd(II), and Al(III) estimated based on NICA-Donnan model calculations. This examination showed that the DLnA350 and DSlope325-375 acquired at various pH values, metal ions concentrations, and DOM types were strongly and unambiguously correlated with the concentration of DOM-bound metal ions. The obtained experimental results and their interpretation indicate that the introduced DSlope325-375 and DLnA35 parameters are predictive of and can be used to quantify in situ metal ions interactions with DOMs. The presented approach can be used to gain more information about DOM-metal interactions and for further optimization of existing formal models of metal-DOM complexation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  1. The plasminogen binding site of the C-type lectin tetranectin is located in the carbohydrate recognition domain, and binding is sensitive to both calcium and lysine

    DEFF Research Database (Denmark)

    Graversen, Jonas Heilskov; Lorentsen, R H; Jacobsen, C

    1998-01-01

    Tetranectin, a homotrimeric protein belonging to the family of C-type lectins and structurally highly related to corresponding regions of the mannose-binding proteins, is known specifically to bind the plasminogen kringle 4 protein domain, an interaction sensitive to lysine. Surface plasmon...

  2. Calcium D-saccharate

    DEFF Research Database (Denmark)

    Garcia, André Castilho; Hedegaard, Martina Vavrusova; Skibsted, Leif Horsfelt

    2016-01-01

    -saccharate becomes spontaneously supersaturated with both d-gluconate and d-saccharate calcium salts, from which only calcium d-saccharate slowly precipitates. Calcium d-saccharate is suggested to act as a stabilizer of supersaturated solutions of other calcium hydroxycarboxylates with endothermic complex formation......Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc...

  3. Iron ions and haeme modulate the binding properties of complement subcomponent C1q and of immunoglobulins.

    Science.gov (United States)

    Dimitrov, J D; Roumenina, L T; Doltchinkova, V R; Vassilev, T L

    2007-03-01

    The complement system and circulating antibodies play a major role in the defence against infection. They act at the sites of inflammation, where the harsh microenvironment and the oxidative stress lead to the release of free iron ions and haeme. The aim of this study was to analyse the consequences of the exposure of C1q and immunoglobulins to iron ions or haeme. The changes in target recognition by C1q and in the rheumatoid factor activity of the immunoglobulins were investigated. The exposure of C1q to ferrous ions increased its binding to IgG and to IgM. In contrast, haeme inhibited C1q binding to all studied targets, especially to IgG1 and C-reactive protein. Thus, the haeme released as a result of tissue damage and oxidative stress may act as a negative feedback regulator of an inappropriate complement triggering as seen in ischaemia-reperfusion tissue injury. The results also show that iron ions and haeme were able to reveal rheumatoid factor activity of IgG. The modulation of the C1q-target binding as well as the revealing of rheumatoid factor activity of IgG by exposure to redox-active agents released at the sites of inflammation may have important consequences for the understanding of the immunopathological mechanisms of inflammatory and autoimmune diseases.

  4. A survey of the interaction of calcium ions with mitochondria from different tissues and species

    Science.gov (United States)

    Carafoli, Ernesto; Lehninger, Albert L.

    1971-01-01

    A survey was made of the capacity of mitochondria isolated from a number of different tissues and species to accumulate Ca2+ from the suspending medium during electron transport. The species examined included the rat, mouse, rabbit, hamster, guinea pig, cow, chicken, turtle, blowfly, yeast and Neurospora crassa. The tissues examined included vertebrate liver, kidney, brain, heart, spleen, thyroid and adrenal cortex, and the flight muscle of the blowfly. The mitochondria from all vertebrate tissues examined showed: (a) stimulation of State 4 respiration by added Ca2+ (Ca2+/~ activation ratio about 2.0), accompanied by accumulation of Ca2+ and ejection of H+, with a H+/Ca2+ ratio about 1.0; (b) a requirement of phosphate for accumulation of large amounts of Ca2+; (c) respiration-independent high-affinity binding sites for Ca2+; (d) endogenous Ca2+, which is largely released by uncoupling agents. However, mitochondria from yeast and blowfly flight muscle are unable to accumulate Ca2+ in a respiration-dependent process and possess no high-affinity Ca2+-binding sites. These findings support the view that the high-affinity sites represent the ligand-binding sites of a specific Ca2+ `permease' or transport system in the membrane. The relatively high affinity for Ca2+, which equals or exceeds the affinity for ADP, and the generally uniform characteristics of Ca2+ transport in all the vertebrate mitochondria tested strongly suggest that respiration-linked Ca2+ accumulation plays a general and fundamental role in vertebrate cell physiology. PMID:5129264

  5. Effect of pyrophosphate ions on the conversion of calcium-lithium-borate glass to hydroxyapatite in aqueous phosphate solution.

    Science.gov (United States)

    Fu, Hailuo; Rahaman, Mohamed N; Day, Delbert E; Huang, Wenhai

    2010-10-01

    The conversion of glass to a hydroxyapatite (HA) material in an aqueous phosphate solution is used as an indication of the bioactive potential of the glass, as well as a low temperature route for preparing biologically useful materials. In this work, the effect of varying concentrations of pyrophosphate ions in the phosphate solution on the conversion of a calcium-lithium-borate glass to HA was investigated. Particles of the glass (150-355 μm) were immersed for up to 28 days in 0.25 M K(2)HPO(4) solution containing 0-0.1 M K(4)P(2)O(7). The kinetics of degradation of the glass particles and their conversion to HA were monitored by measuring the weight loss of the particles and the ionic concentration of the solution. The structure and composition of the conversion products were analyzed using X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. For K(4)P(2)O(7) concentrations of up to 0.01 M, the glass particles converted to HA, but the time for complete conversion increased from 2 days (no K(4)P(2)O(7)) to 10 days (0.01 M K(4)P(2)O(7)). When the K(4)P(2)O(7) concentration was increased to 0.1 M, the product consisted of an amorphous calcium phosphate material, which eventually crystallized to a pyrophosphate product (predominantly K(2)CaP(2)O(7) and Ca(2)P(2)O(7)). The consequences of the results for the formation of HA materials and devices by the glass conversion route are discussed.

  6. The interaction of human serum albumin with selected lanthanide and actinide ions: Binding affinities, protein unfolding and conformational changes.

    Science.gov (United States)

    Ali, Manjoor; Kumar, Amit; Kumar, Mukesh; Pandey, Badri N

    2016-04-01

    Human serum albumin (HSA), the most abundant soluble protein in blood plays critical roles in transportation of biomolecules and maintenance of osmotic pressure. In view of increasing applications of lanthanides- and actinides-based materials in nuclear energy, space, industries and medical applications, the risk of exposure with these metal ions is a growing concern for human health. In present study, binding interaction of actinides/lanthanides [thorium: Th(IV), uranium: U(VI), lanthanum: La(III), cerium: Ce(III) and (IV)] with HSA and its structural consequences have been investigated. Ultraviolet-visible, Fourier transform-infrared, Raman, Fluorescence and Circular dichroism spectroscopic techniques were applied to study the site of metal ions interaction, binding affinity determination and the effect of metal ions on protein unfolding and HSA conformation. Results showed that these metal ions interacted with carbonyl (CO..:)/amide(N..-H) groups and induced exposure of aromatic residues of HSA. The fluorescence analysis indicated that the actinide binding altered the microenvironment around Trp214 in the subdomain IIA. Binding affinity of U(VI) to HSA was slightly higher than that of Th(IV). Actinides and Ce(IV) altered the secondary conformation of HSA with a significant decrease of α-helix and an increase of β-sheet, turn and random coil structures, indicating a partial unfolding of HSA. A correlation was observed between metal ion's ability to alter HSA conformation and protein unfolding. Both cationic effects and coordination ability of metal ions seemed to determine the consequences of their interaction with HSA. Present study improves our understanding about the protein interaction of these heavy ions and their impact on its secondary structure. In addition, binding characteristics may have important implications for the development of rational antidote for the medical management of health effects of actinides and lanthanides. Copyright © 2016 Elsevier

  7. Aggregation of sponge cells. XIV. Possible substitution of calcium ions by polycations.

    Science.gov (United States)

    Müller, W E; Zahn, R K; Kurelec, B; Müller, I

    1978-05-01

    Single cells from the siliceous sponge Geodia cydonium, obtained after chemical dissociation, reaggregate in the presence of the aggregation factor in Ca2+-containing medium to large aggregates. It was found that polyvalent organic cations (polylysine, spermine, spermidine, putrescine) enhance the Ca2+-mediated cell aggregation. In Ca2+-free medium these compounds also cause reaggregation; aggregates of a diameter up to 800 micron are formed within 120 min. Proteins, containing basic groups of amino acid residues have no influence on cell aggregation. Monovalent cations inhibit the reaggregation process. The enhancing effect of polyvalent organic cations on cell aggregation is dependent on the presence of the soluble aggregation factor. From the findings that polycations do not alter the duration of the lag phase (a characteristic of the aggregation factor-mediated Geodia cell reaggregation) and act in cooperation with the aggregation receptor, we assume that the polycations bind between the aggregation factor and the aggregation receptor.

  8. Targeted regulation of hygroscopicity of soybean antioxidant pentapeptide powder by zinc ions binding to the moisture absorption sites.

    Science.gov (United States)

    Xue, Peiyu; Sun, Na; Li, Yong; Cheng, Sheng; Lin, Songyi

    2018-03-01

    In the present study, a targeted regulation of hygroscopicity of soybean antioxidant pentapeptide (SAP) powder was explored by zinc ions binding to its moisture absorption sites. Scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy and an energy-dispersive X-ray spectroscope were used to confirm the formation of the SAP-zinc complex. The results showed that morphology of SAP-zinc complex belonged to crystalline nanoparticles. The moisture sorption/desorption kinetics of the SAP-zinc complex changed compared to that of the SAP. In particular, the moisture sorption capacity of the SAP decreased and the distribution of adsorbed water changed after zinc chelation. Based on the binding of zinc ions to the moisture absorption sites, the hygroscopicity of SAP powder could be target regulated. Thus, this study could provide a new method to regulate the hygroscopicity of peptide powder. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. First-Principles Investigation on Ionization Strength, Volume Expansion, and Water Rotational Rigidity of Small Water Cluster Systems Formed around Sodium(I), Calcium(II), and Iron(II) Ions

    Science.gov (United States)

    Kuncoro, Handoko Setyo; Sakaue, Mamoru; Nakanishi, Hiroshi; Kasai, Hideaki; Dipojono, Hermawan Kresno

    2011-02-01

    Some ionic effects on small water cluster systems formed around sodium(I), calcium(II), and iron(II) cations have been investigated using the density functional theory. By assuming that the numbers of water molecules in the first and the second water layers are 6 and 12, respectively, it is shown that (i) the Ca(II) aqueous cluster shrinks and its volume becomes similar to that of a pure (H2O)18 cluster whereas the Fe(II) and Na(I) aqueous clusters expand; (ii) owing to the water dipole--dipole interactions induced by the ion in the second water layer binding, the ionization strength of the Ca(II) aqueous cluster is close to that of Fe(II) but sufficiently higher than that of Na(I); (iii) the isotropicity of s-type Ca(II) and Na(I) cation orbitals as the cause of the reduction in water rotational rigidity in the ion--water bonding has been clarified by analyzing the charge transfer and non interacting kinetic energy. By considering the three ionic effects, we predict that the Ca(II) ion is one of the more competitive water cationic impurities in the PEMFC membrane.

  10. A silver ion-doped calcium phosphate-based ceramic nanopowder-coated prosthesis increased infection resistance.

    Science.gov (United States)

    Kose, Nusret; Otuzbir, Ali; Pekşen, Ceren; Kiremitçi, Abdurrahman; Doğan, Aydin

    2013-08-01

    Despite progress in surgical techniques, 1% to 2% of joint arthroplasties become complicated by infection. Coating implant surfaces with antimicrobial agents have been attempted to prevent initial bacterial adhesion to implants with varying success rates. We developed a silver ion-containing calcium phosphate-based ceramic nanopowder coating to provide antibacterial activity for orthopaedic implants. We asked whether titanium prostheses coated with this nanopowder would show resistance to bacterial colonization as compared with uncoated prostheses. We inserted titanium implants (uncoated [n = 9], hydroxyapatite-coated [n = 9], silver-coated [n = 9]) simulating knee prostheses into 27 rabbits' knees. Before implantation, 5 × 10(2) colony-forming units of Staphylococcus aureus were inoculated into the femoral canal. Radiology, microbiology, and histology findings were quantified at Week 6 to define the infection, microbiologically by increased rate of implant colonization/positive cultures, histologically by leukocyte infiltration, necrosis, foreign-body granuloma, and devitalized bone, and radiographically by periosteal reaction, osteolysis, or sequestrum formation. Swab samples taken from medullary canals and implants revealed a lower proportion of positive culture in silver-coated implants (one of nine) than in uncoated (eight of nine) or hydroxyapatite-coated (five of nine) implants. Silver-coated implants also had a lower rate of colonization. No cellular inflammation or foreign-body granuloma was observed around the silver-coated prostheses. Silver ion-doped ceramic nanopowder coating of titanium implants led to an increase in resistance to bacterial colonization compared to uncoated implants. Silver-coated orthopaedic implants may be useful for resistance to local infection but will require in vivo confirmation.

  11. Study of the calcium carbonate scaling in the desalination units by electrodialysis: natural inhibition by magnesium ion

    International Nuclear Information System (INIS)

    Ben Salah, Ilhem; Tlili, Mohamed; Ben Amor, Mohamed

    2009-01-01

    The processes based on the separation by membranes seem to become very powerful tools for the purification and the retraining of the fluids. Competed by the inverse osmosis in the domain of the desalination of waters, the electrodialysis (ED) occupies a large place in the agro-alimentary industries to treat the co-products on the one hand and to contribute to the retraining of containing sewages of the heavy metals and toxic, on the other hand. Although it is appreciable for cost and reliability in several domains, the ED suffers to scaling problem caused by the concentration of some ions. Since the technique is used currently for the desalination of water in some industries, we have opted to study mechanisms of membrane scaling by calcium carbonate, one of salts the more frequently met in the stations of desalination in Tunisia. The survey uses a method of accelerated scaling of a pilot unit of electrodialysis. By means of this method, we studied the effect of the initial pH and the composition of water on the kinetics of the scaling formation. The treated waters are synthetic solutions. The results showed that the CO 2 quantity initially dissolved in the solutions is an important factor in the scaling process. According to the composition of water, domains of CO 2 pressure were defined in whom a small variation can generate the rupture of the metastability state in the compartment of concentration and provoke CaCO 3 nucleation in the compartment of concentration and/or on the membranes and conducts. The presence in solution of magnesium in only a Ca/Mg ratio of 0,5 delayed considerably the CaCO 3 nucleation. This ratio is considered like a low bottom limit of magnesium action, ion to natural inhibitory effect present in the natural waters.

  12. Fibrillin binds calcium and is coded by cDNAs that reveal a multidomain structure and alternatively spliced exons at the 5[prime] end

    Energy Technology Data Exchange (ETDEWEB)

    Corson, G.M.; Chalberg, S.C.; Charbonneau, N.L.; Sakai, L.Y. (Oregon Health Sciences Univ., Portland (United States)); Dietz, H.C. (Johns Hopkins Univ. School of Medicine, Baltimore, MD (United States))

    1993-08-01

    Fibrillin is an important structural protein of the extracellular matrix. It is a large cysteine-rich glycoprotein with extensive intrachain disulfide bonds, likely contributed by multiple EGF-like repeats. The authors have previously published 6.9 kb of FBN1 cDNA sequence. FBN1 cDNA clones that extend the sequence 3089 bp in the 5[prime] direction are described in this report. The deduced primary structure suggests that fibrillin in composed of multiple domains. The most predominant features the presence of 43 calcium binding EGF-like repeats. They demonstrate here that fibrillin molecules bind calcium. In addition, three alternatively spliced exons at the 5[prime] end are described. Analysis of 5.8 kb of surrounding genomic sequence revealed a 1.8-kb CpG island spanning the alternatively spliced exons and the next downstream exon. Since FBN1 is the gene responsible for Marfan syndrome, the information presented here will be useful in identifying new mutations and in understanding the function of fibrillin in the pathogenesis of the disease. 42 refs., 7 figs.

  13. Four novel FBN1 mutations: Significance for mutant transcript level and EGF-like domain calcium binding in the pathogenesis of Marfan syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Dietz, H.C.; McIntosh, I.; Pyeritz, R.E.; Francomano, C.A. (Johns Hopkins Univ. School of Medicine, Baltimore, MD (United States)); Sakai, L.Y.; Corson, G.M.; Chalberg, S.C. (Oregon Health Sciences Univ., Portland (United States))

    1993-08-01

    Defects of fibrillin (FBN1), a glycoprotein component of the extracellular microfibril, cause Marfan syndrome. This disorder is characterized by marked inter- and intrafamilial variation in phenotypic severity. To understand the molecular basis for this clinical observation, the authors have screened the fibrillin gene (FBN1) on chromosome 15, including the newly cloned 5[prime] coding sequence, for disease-producing alterations in a panel of patients with a wide range of manifestations and clinical severity. All the missense mutations identified to date, including two novel mutations discussed here, are associated with classic and moderate to severe disease and occur at residues with putative significance for calcium binding to epidermal growth factor (EGF)-like domains. In contrast, two new mutations that create premature signals for termination of translation of mRNA and are associated with reduction in the amount of mutant allele transcript produce a range of phenotypic severity. The patient with the lowest amount of mutant transcript has the mildest disease. These data support a role for altered calcium binding to EGF-like domains in the pathogenesis of Marfan syndrome and suggest a dominant negative mechanism for the pathogenesis of this disorder. 26 refs., 6 figs., 1 tab.

  14. Tyrosine hydroxylase-producing neurons in the human cerebral cortex do not colocalize with calcium-binding proteins or the serotonin 3A receptor.

    Science.gov (United States)

    Asmus, Stephen E; Raghanti, Mary Ann; Beyerle, Eric R; Fleming-Beattie, Julia C; Hawkins, Sarah M; McKernan, Courtney M; Rauh, Nicholas A

    2016-12-01

    Interneurons of the cerebral cortex play a significant role in cortical information processing and are of clinical interest due to their involvement in neurological disorders. In the human neocortex, three subsets of interneurons can be identified based on the production of the calcium-binding proteins parvalbumin, calretinin or calbindin. A subset of interneurons in the mouse cortex expresses the serotonin 3A receptor (5-HT 3A R). Previous work in humans has also demonstrated the presence of a subgroup of cortical neurons that produces the catecholaminergic enzyme tyrosine hydroxylase (TH). Many TH-producing cells in the rat cortex coexpress calretinin and are adjacent to blood vessels. However, little is known about the phenotype of these TH interneurons in humans. Here we immunohistochemically examined the coexpression of TH with parvalbumin, calretinin, calbindin or 5-HT 3A R in human Brodmann's areas 10 and 24, cortical regions with high densities of TH-containing neurons. Colocalization of TH with these calcium-binding proteins and with 5-HT 3A R was not detected in either area. Cortical TH cells were rarely apposed to blood vessels, denoted by immunolabeling for the gliovascular marker aquaporin-4. Our results suggest that the TH-immunoreactive cells in the human cortex do not overlap with any known neurochemically-defined subsets of interneurons and provide further evidence of differences in the phenotype of these cells across species. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Neuronal calcium-binding proteins 1/2 localize to dorsal root ganglia and excitatory spinal neurons and are regulated by nerve injury

    DEFF Research Database (Denmark)

    Zhang, Ming Dong; Tortoriello, Giuseppe; Hsueh, Brian

    2014-01-01

    /2 neurons are much more abundant in DRGs than the Ca2+-binding proteins (parvalbumin, calbindin, calretinin, and secretagogin) studied to date. In the spinal cord, the NECAB1/2 distribution is mainly complementary. NECAB1 labels interneurons and a plexus of processes in superficial layers of the dorsal horn......Neuronal calcium (Ca2+)-binding proteins 1 and 2 (NECAB1/2) are members of the phylogenetically conserved EF-hand Ca2+-binding protein superfamily. To date, NECABs have been explored only to a limited extent and, so far, not at all at the spinal level. Here, we describe the distribution, phenotype....... In the dorsal horn, most NECAB1/2 neurons are glutamatergic. Both NECAB1/2 are transported into dorsal roots and peripheral nerves. Peripheral nerve injury reduces NECAB2, but not NECAB1, expression in DRG neurons. Our study identifies NECAB1/2 as abundant Ca2+-binding proteins in pain-related DRG neurons...

  16. Evaluation of radiopacity, pH, release of calcium ions, and flow of a bioceramic root canal sealer.

    Science.gov (United States)

    Candeiro, George Táccio de Miranda; Correia, Fabrícia Campelo; Duarte, Marco Antônio Húngaro; Ribeiro-Siqueira, Danieli Colaço; Gavini, Giulio

    2012-06-01

    The aim of the present study was to evaluate the physicochemical properties of a bioceramic root canal sealer, Endosequence BC Sealer. Radiopacity, pH, release of calcium ions (Ca(2+)), and flow were analyzed, and the results were compared with AH Plus cement. Radiopacity and flow were evaluated according to ISO 6876/2001 standards. For the radiopacity analysis, metallic rings with 10-mm diameter and 1-mm thickness were filled with cements. The radiopacity value was determined according to radiographic density (mm Al). The flow test was performed with 0.05 mL of cement placed on a glass plate. A 120-g weight was carefully placed over the cement. The largest and smallest diameters of the disks formed were measured by using a digital caliper. The release of Ca(2+) and pH were measured at periods of 3, 24, 72, 168, and 240 hours with spectrophotometer and pH meter, respectively. Data were analyzed by analysis of variance and Tukey test (P pH analysis showed that Endosequence BC Sealer showed pH and release of Ca(2+) greater than those of AH Plus (P root canal sealer. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  17. Serum albumin forms a lactoferrin-like soluble iron-binding complex in presence of hydrogen carbonate ions.

    Science.gov (United States)

    Ueno, Hiroshi M; Urazono, Hiroshi; Kobayashi, Toshiya

    2014-02-15

    The iron-lactoferrin complex is a common food ingredient because of its iron-solubilizing capability in the presence of hydrogen carbonate ions. However, it is unclear whether the formation of a stable iron-binding complex is limited to lactoferrin. In this study, we investigated the effects of bovine serum albumin (BSA) on iron solubility and iron-catalyzed lipid oxidation in the presence of hydrogen carbonate ions. BSA could solubilize >100-fold molar equivalents of iron at neutral pH, exceeding the specific metal-binding property of BSA. This iron-solubilizing capability of BSA was impaired by thermally denaturing BSA at ≥ 70 °C for 10 min at pH 8.5. The resulting iron-BSA complex inhibited iron-catalyzed oxidation of soybean oil in a water-in-oil emulsion measured using the Rancimat test. Our study is the first to show that BSA, like lactoferrin, forms a soluble iron-binding complex in the presence of hydrogen carbonate ions. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Binding selectivity of vitamin K3 based chemosensors towards nickel(II) and copper(II) metal ions

    Science.gov (United States)

    Patil, Amit; Lande, Dipali N.; Nalkar, Archana; Gejji, Shridhar P.; Chakrovorty, Debamitra; Gonnade, Rajesh; Moniz, Tânia; Rangel, Maria; Pereira, Eulália; Salunke-Gawali, Sunita

    2017-09-01

    The vitamin K3 derivatives 2-methyl-3-[(pyridin-2-ylmethyl)-amino]-1,4-naphthoquinone (M-1), 2-methyl-3-[(pyridin-2-ylethyl)-amino]-1,4-naphthoquinone (M-2), 2-methyl-3-((2-(thiophen-2-yl)methyl)amino)naphthalene-1,4-dione (M-3) and 2-methyl-3-((2-(thiophen-2-yl)ethyl)amino)naphthalene-1,4-dione (M-4) have been synthesized, characterized and studied for their chemosensor abilities towards transition metal ions. Crystal structures of M-1 to M-4 revealed a variety of Nsbnd H⋯O, Csbnd H⋯O, Csbnd H⋯π and π⋯π interactions. Minor variations in such interactions by chemical stimuli such as metal ions, results in change in color that can be visualized by naked eyes. It has been shown that electronic structure and 1H NMR, vibrational as well as electronic spectra from the density functional theory agree well with the experiments. The metal ion binding in ethanol, ethanol-water and in mild base triethylamine brings forth recognizing ability of M-1 toward Ni2+ whereas M-2 exhibits large sensing ability for Cu2+ ion. Interestingly M-1 display varying metal ion binding specificity in different solvents with the association constant in ethanol being 11,786 M-1 for Ni2+ compared to 9462 M-1 for the Cu2+. A reversal in preferential binding of M-2 with the respective association constants being 4190 M-1 and 6370 M-1 is discernible.

  19. Energy recovery from effluents of sugar processing industries in the UASB reactors seeded with granular sludge developed under low and high concentrations of calcium ion

    Energy Technology Data Exchange (ETDEWEB)

    Raphael, D.M.; Rubindamayugi, M.S.T. [Univ. of Dar es Salaam, Dept. of Botany, Applied Microbiology Unit (Tanzania, United Republic of)

    1997-12-31

    The digestion of wastewater from sugar processing industries in a single phase UASB reactor was evaluated by a step wise increase in organic loading rate. This study was conducted to compare the treatability of effluents from sugar processing industries in a single phase UASB reactors inoculated with granular sludge developed under low and high concentrations of calcium ions. At OLR of 11.34 g COD/l/day and HRT of 16 hours, UASB reactor R2 attained a COD removal efficiency of 90% with a maximum methane production rate of 3 l/l/day. From the results, the digestion of the wastewater from sugar industries in the UASB reactor inoculated with granular sludge developed under high calcium ion concentration seem feasible with regard to COD removal efficiency and methane production rate. (au) 24 refs.

  20. Calcium-dependent and -independent binding of the pentraxin serum amyloid P component to glycosaminoglycans and amyloid proteins

    DEFF Research Database (Denmark)

    Danielsen, B; Sørensen, I J; Nybo, Mads

    1997-01-01

    and beta2M) by ELISA. An increase in the dose-dependent binding of SAP to heparan sulfate, AA-protein and beta2M was observed as the pH decreased from 8.0 to 5.0. Furthermore, a lower, but significant Ca2(+)-independent binding of SAP to heparan sulfate, dermatan sulfate, AA protein and the amyloid...... precursor protein beta2M was observed. This binding was also enhanced at slightly acid pH, most pronounced at pH 5.0. The results of this study indicate that SAP can exhibit both Ca2(+)-dependent and -independent binding to ligands involved in amyloid fibril formation and that the binding is enhanced under...

  1. Signaling Network of Environmental Sensing and Adaptation in Plants:. Key Roles of Calcium Ion

    Science.gov (United States)

    Kurusu, Takamitsu; Kuchitsu, Kazuyuki

    2011-01-01

    Considering the important issues concerning food, environment, and energy that humans are facing in the 21st century, humans mostly depend on plants. Unlike animals which move from an inappropriate environment, plants do not move, but rapidly sense diverse environmental changes or invasion by other organisms such as pathogens and insects in the place they root, and adapt themselves by changing their own bodies, through which they developed adaptability. Whole genetic information corresponding to the blueprints of many biological systems has recently been analyzed, and comparative genomic studies facilitated tracing strategies of each organism in their evolutional processes. Comparison of factors involved in intracellular signal transduction between animals and plants indicated diversification of different gene sets. Reversible binding of Ca2+ to sensor proteins play key roles as a molecular switch both in animals and plants. Molecular mechanisms for signaling network of environmental sensing and adaptation in plants will be discussed with special reference to Ca2+ as a key element in information processing.

  2. Effects of protein-protein interactions and ligand binding on the ion permeation in KCNQ1 potassium channel.

    Science.gov (United States)

    Jalily Hasani, Horia; Ganesan, Aravindhan; Ahmed, Marawan; Barakat, Khaled H

    2018-01-01

    The voltage-gated KCNQ1 potassium ion channel interacts with the type I transmembrane protein minK (KCNE1) to generate the slow delayed rectifier (IKs) current in the heart. Mutations in these transmembrane proteins have been linked with several heart-related issues, including long QT syndromes (LQTS), congenital atrial fibrillation, and short QT syndrome. Off-target interactions of several drugs with that of KCNQ1/KCNE1 ion channel complex have been known to cause fatal cardiac irregularities. Thus, KCNQ1/KCNE1 remains an important avenue for drug-design and discovery research. In this work, we present the structural and mechanistic details of potassium ion permeation through an open KCNQ1 structural model using the combined molecular dynamics and steered molecular dynamics simulations. We discuss the processes and key residues involved in the permeation of a potassium ion through the KCNQ1 ion channel, and how the ion permeation is affected by (i) the KCNQ1-KCNE1 interactions and (ii) the binding of chromanol 293B ligand and its derivatives into the complex. The results reveal that interactions between KCNQ1 with KCNE1 causes a pore constriction in the former, which in-turn forms small energetic barriers in the ion-permeation pathway. These findings correlate with the previous experimental reports that interactions of KCNE1 dramatically slows the activation of KCNQ1. Upon ligand-binding onto the complex, the energy-barriers along ion permeation path are more pronounced, as expected, therefore, requiring higher force in our steered-MD simulations. Nevertheless, pulling the ion when a weak blocker is bound to the channel does not necessitate high force in SMD. This indicates that our SMD simulations have been able to discern between strong and week blockers and reveal their influence on potassium ion permeation. The findings presented here will have some implications in understanding the potential off-target interactions of the drugs with the KCNQ1/KCNE1 channel

  3. On the interaction of peptides with calcium ions as studied by matrix-assisted laser desorption/ionization Fourier transform mass spectrometry: towards peptide fishing using metal ion baits.

    Science.gov (United States)

    Jobst, Karl J; Terlouw, Johan K; Luider, Theo M; Burgers, Peter C

    2008-10-03

    In a previous report [J.W. de Beukelaar, J.W. Gratama, P.A. Sillevis Smitt, G.M. Verjans, J. Kraan, Th.M. Luider, P.C. Burgers, Rapid Commun. Mass Spectrom. 21 (2007) 1282] on the quality assessment of synthetic peptides used in protein-spanning peptide pools by matrix-assisted laser desorption/ionization Fourier transform mass spectrometry (MALDI-FTMS) we noted that certain peptides showed remarkably intense signals for their calcium-containing analogues. Here we report on a detailed mass spectrometric study of the unimolecular chemistry of these calcium-containing peptides. By integration of the experimental findings with computational results derived from DFT and the CBS-QB3 model chemistry, we have traced the processes induced by Ca(2+) attachment in the peptide ions. Key to our analysis is the observation that all of the studied calcium-bound peptides containing a threonine or serine residue show prominent losses of CH(3)CHO (from threonine) and/or CH(2)O (from serine) in both the positive and the negative ion mode. In the first step, Ca(2+) attaches itself to a negatively charged in-chain carboxylate group. Next, electrophilic attack of the calcium ion on the CH(R)OH group of threonine (RCH(3)) or serine (RH) releases the hydroxyl proton which can then move to a suitable acceptor site, viz. a peptide bond. This leads to the formation of a very stable ionic bidentate structure. Upon collisional activation (MS/MS), this bidentate opens up leading to the loss of the exposed acetaldehyde or formaldehyde molecule, to yield another bidentate structure. MS/MS spectra of selected peptides interacting with other metal ions have also been investigated and it is found that only divalent ions follow the Ca(2+)-induced transformations.

  4. Modulation of membrane conductance in rods of Bufo marinus by intracellular calcium ion.

    Science.gov (United States)

    Oakley, B; Pinto, L H

    1983-06-01

    Double-barrel micropipettes were used to pressure-inject EGTA into the outer segments of rods in the isolated retina of Bufo marinus. We used these pipettes to point voltage clamp the cell to its resting membrane voltage during the injection of EGTA in order to prevent changes in membrane voltage from occurring. The input conductance of the rod was assessed by measuring the incremental membrane current required to hyperpolarize the membrane by less than or equal to 10 mV. When the retina was bathed in normal Ringer solution, the injection of EGTA during point voltage clamp evoked an inward membrane current and in increase in input conductance. This observation is consistent with an EGTA-evoked increase in conductance for an ion with an equilibrium potential more depolarized than the resting membrane potential. Injections of control solutions that did not contain EGTA had no effect. The effects of injected EGTA were not altered by variations in the pH or buffering capacity of the injection solution, or by the addition of equimolar Mg2+. Furthermore, injections of a solution containing equimolar Ca2+ and EGTA were without effect. Thus, the observed effects of injected EGTA were due to the lowering of the [Ca2+]i. Replacement of extracellular Na+ with choline+ abolished both the response to light and the EGTA-evoked increase in input conductance. A low [Na+]o solution containing 10(-8) M-Ca2+ reduced the response to injected EGTA by approximately the same amount as it reduced the response to light. Replacement of extracellular Cl- by methanesulphonate was without significant effect on either the response to light or to injected EGTA. These results are consistent with the interpretation that a lowered [Ca2+]i increases primarily the sodium conductance, gNa, of the plasma membrane of the rod outer segment. The conductance that is affected by a lowered [Ca2+]i appears to have the same specificity as the light-dependent conductance. This conclusion is consistent with a

  5. A kinetic study of Ca-containing ions reacting with O, O2, CO2 and H2O: implications for calcium ion chemistry in the upper atmosphere.

    Science.gov (United States)

    Broadley, Sarah; Vondrak, Tomas; Wright, Timothy G; Plane, John M C

    2008-09-14

    A series of gas-phase reactions involving molecular Ca-containing ions was studied by the pulsed laser ablation of a calcite target to produce Ca+ in a fast flow of He, followed by the addition of reagents downstream and detection of ions by quadrupole mass spectrometry. Most of the reactions that were studied are important for describing the chemistry of meteor-ablated calcium in the earth's upper atmosphere. The following rate coefficients were measured: k(CaO+ + O --> Ca+ + O2) = (4.2 +/- 2.8) x 10(-11) at 197 K and (6.3 +/- 3.0) x 10(-11) at 294 K; k(CaO+ + CO --> Ca+ + CO2, 294 K) = (2.8 +/- 1.5) x 10(-10); k(Ca+.CO2 + O2 --> CaO2+ + CO2, 294 K) = (1.2 +/- 0.5) x10(-10); k(Ca+.CO2 + H2O --> Ca+.H2O + CO2) = (13.0 +/- 4.0) x 10(-10); and k(Ca+.H2O + O2 --> CaO2+ + H2O, 294 K) = (4.0 +/- 2.5) x 10(-10) cm3 molecule(-1) s(-1). The quoted uncertainties are a combination of the 1 sigma standard errors in the kinetic data and the systematic errors in the models used to extract the rate coefficients. Rate coefficients were also obtained for the following recombination (also termed association) reactions in He bath gas: k(Ca+.CO2 + CO2 --> Ca+.(CO2)2, 294 K) = (2.6 +/- 1.0) x 10(-29); k(Ca+.H2O + H2O --> Ca+.(H2O)2) = (1.6 +/- 1.1) x 10(-27); and k(CaO2+ + O2 --> CaO2+.O2) high level quantum chemistry calculations and RRKM theory using an inverse Laplace transform solution of the master equation. The surprisingly slow reaction between CaO+ and O was explained using quantum chemistry calculations on the lowest 2A', 2A'' and 4A'' potential energy surfaces. These calculations indicate that reaction mostly occurs on the 2A' surface, leading to production of Ca+ (2S) + O2(1 Delta g). The importance of this reaction for controlling the lifetime of Ca+ in the upper mesosphere and lower thermosphere is then discussed.

  6. Ion binding by humic and fulvic acids: A computational procedure based on functional site heterogeneity and the physical chemistry of polyelectrolyte solutions

    International Nuclear Information System (INIS)

    Marinsky, J.A.; Reddy, M.M.; Ephraim, J.; Mathuthu, A.

    1988-04-01

    Ion binding equilibria for humic and fulvic acids are examined from the point of view of functional site heterogeneity and the physical chemistry of polyelectrolyte solutions. A detailed explanation of the potentiometric properties of synthetic polyelectrolytes and ion-exchange gels is presented first to provide the basis for a parallel consideration of the potentiometric properties exhibited by humic and fulvic acids. The treatment is then extended to account for functional site heterogeneity. Sample results are presented for analysis of the ion-binding reactions of a standard soil fulvic acid (Armadale Horizons Bh) with this approach to test its capability for anticipation of metal ion removal from solution. The ultimate refined model is shown to be adaptable, after appropriate consideration of the heterogeneity and polyelectrolyte factors, to programming already available for the consideration of ion binding by inorganics in natural waters. (orig.)

  7. Membrane binding of the neuronal calcium sensor recoverin – modulatory role of the charged carboxy-terminus

    Directory of Open Access Journals (Sweden)

    Philippov Pavel P

    2007-11-01

    Full Text Available Abstract Background The Ca2+-binding protein recoverin operates as a Ca2+-sensor in vertebrate photoreceptor cells. It undergoes a so-called Ca2+-myristoyl switch when cytoplasmic Ca2+-concentrations fluctuate in the cell. Its covalently attached myristoyl-group is exposed at high Ca2+-concentrations and enables recoverin to associate with lipid bilayers and to inhibit its target rhodopsin kinase. At low Ca2+-concentrations the myristoyl group is inserted into a hydrophobic pocket of recoverin thereby relieving inhibitory constraint on rhodopsin kinase. Hydrophobic and electrostatic interactions of recoverin with membranes have not been clearly determined, in particular the function of the positively charged carboxy-terminus in recoverin 191QKVKEKLKEKKL202 in this context is poorly understood. Results Binding of myristoylated recoverin to lipid bilayer depends on the charge distribution in phospholipids. Binding was tested by equilibrium centrifugation and surface plasmon resonance (SPR assays. It is enhanced to a certain degree by the inclusion of phosphatidylserine (up to 60% in the lipid mixture. However, a recoverin mutant that lacked the charged carboxy-terminus displayed the same relative binding amplitudes as wildtype (WT recoverin when bound to neutral or acidic lipids. Instead, the charged carboxy-terminus of recoverin has a significant impact on the biphasic dissociation of recoverin from membranes. On the other hand, the nonmyristoylated WT and truncated mutant form of recoverin did not bind to lipid bilayers to a substantial amount as binding amplitudes observed in SPR measurements are similar to bulk refractive index changes. Conclusion Our data indicate a small, but evident electrostatic contribution to the overall binding energy of recoverin association with lipid bilayer. Properties of the charged carboxy-terminus are consistent with a role of this region as an internal effector region that prolongs the time recoverin stays on

  8. Glycosaminoglycans are interactants of Langerin: comparison with gp120 highlights an unexpected calcium-independent binding mode.

    Directory of Open Access Journals (Sweden)

    Eric Chabrol

    Full Text Available Langerin is a C-type lectin specifically expressed in Langerhans cells. As recently shown for HIV, Langerin is thought to capture pathogens and mediate their internalisation into Birbeck Granules for elimination. However, the precise functions of Langerin remain elusive, mostly because of the lack of information on its binding properties and physiological ligands. Based on recent reports that Langerin binds to sulfated sugars, we conducted here a comparative analysis of Langerin interaction with mannose-rich HIV glycoprotein gp120 and glycosaminoglycan (GAGs, a family of sulfated polysaccharides expressed at the surface of most mammalian cells. Our results first revealed that Langerin bound to these different glycans through very distinct mechanisms and led to the identification of a novel, GAG-specific binding mode within Langerin. In contrast to the canonical lectin domain, this new binding site showed no Ca(2+-dependency, and could only be detected in entire, trimeric extracellular domains of Langerin. Interestingly binding to GAGs, did not simply rely on a net charge effect, but rather on more discrete saccharide features, such as 6-O-sulfation, or iduronic acid content. Using molecular modelling simulations, we proposed a model of Langerin/heparin complex, which located the GAG binding site at the interface of two of the three Carbohydrate-recognition domains of the protein, at the edge of the a-helix coiled-coil. To our knowledge, the binding properties that we have highlighted here for Langerin, have never been reported for C-type lectins before. These findings provide new insights towards the understanding of Langerin biological functions.

  9. Effects of mutagenesis of aspartic acid residues in the putative phosphoribosyl diphosphate binding site of Escherichia coli phosphoribosyl diphosphate synthetase on metal ion specificity and ribose-5-phosphate binding

    DEFF Research Database (Denmark)

    Willemoës, Martin; Nilsson, Dan; Hove-Jensen, Bjarne

    1996-01-01

    The three conserved aspartic acid residues of the 5-phospho-d-ribosyl a-1-diphosphate binding site (213-GRDCVLVDDMIDTGGT-228) of Escherichia coli phosphoribosyl diphosphate synthetase were studied by analysis of the mutant enzymes D220E, D220F, D221A, D224A, and D224S. The mutant enzymes showed...... enzymes were dependent on the metal ion present, suggesting a function of the investigated aspartic acid residues both in the binding of ribose 5-phosphate, possibly via a divalent metal ion, and in the interaction with a divalent metal ion during catalysis....

  10. Benchmarking a computational design method for the incorporation of metal ion-binding sites at symmetric protein interfaces.

    Science.gov (United States)

    Hansen, William A; Khare, Sagar D

    2017-08-01

    The design of novel metal-ion binding sites along symmetric axes in protein oligomers could provide new avenues for metalloenzyme design, construction of protein-based nanomaterials and novel ion transport systems. Here, we describe a computational design method, symmetric protein recursive ion-cofactor sampling (SyPRIS), for locating constellations of backbone positions within oligomeric protein structures that are capable of supporting desired symmetrically coordinated metal ion(s) chelated by sidechains (chelant model). Using SyPRIS on a curated benchmark set of protein structures with symmetric metal binding sites, we found high recovery of native metal coordinating rotamers: in 65 of the 67 (97.0%) cases, native rotamers featured in the best scoring model while in the remaining cases native rotamers were found within the top three scoring models. In a second test, chelant models were crossmatched against protein structures with identical cyclic symmetry. In addition to recovering all native placements, 10.4% (8939/86013) of the non-native placements, had acceptable geometric compatibility scores. Discrimination between native and non-native metal site placements was further enhanced upon constrained energy minimization using the Rosetta energy function. Upon sequence design of the surrounding first-shell residues, we found further stabilization of native placements and a small but significant (1.7%) number of non-native placement-based sites with favorable Rosetta energies, indicating their designability in existing protein interfaces. The generality of the SyPRIS approach allows design of novel symmetric metal sites including with non-natural amino acid sidechains, and should enable the predictive incorporation of a variety of metal-containing cofactors at symmetric protein interfaces. © 2017 The Protein Society.

  11. Ion binding to natural organic matter : General considerations and the NICA-Donnan model

    NARCIS (Netherlands)

    Koopal, L.K.; Saito, T.; Pinheiro, J.P.; Riemsdijk, van W.H.

    2005-01-01

    The general principles of cation binding to humic matter and the various aspects of modeling used in general-purpose speciation programs are discussed. The discussion will focus on (1) the discrimination between chemical and electrostatic interactions, (2) the binding site heterogeneity, (3) the

  12. Sigma-1 receptor agonist increases axon outgrowth of hippocampal neurons via voltage-gated calcium ions channels.

    Science.gov (United States)

    Li, Dong; Zhang, Shu-Zhuo; Yao, Yu-Hong; Xiang, Yun; Ma, Xiao-Yun; Wei, Xiao-Li; Yan, Hai-Tao; Liu, Xiao-Yan

    2017-12-01

    Sigma-1 receptors (Sig-1Rs) are unique endoplasmic reticulum proteins that have been implicated in both neurodegenerative and ischemic diseases, such as Alzheimer's disease and stroke. Accumulating evidence has suggested that Sig-1R plays a role in neuroprotection and axon outgrowth. The underlying mechanisms of Sig-1R-mediated neuroprotection have been well elucidated. However, the mechanisms underlying the effects of Sig-1R on axon outgrowth are not fully understood. To clarify this issue, we utilized immunofluorescence to compare the axon lengths of cultured naïve hippocampal neurons before and after the application of the Sig-1R agonist, SA4503. Then, electrophysiology and immunofluorescence were used to examine voltage-gated calcium ion channel (VGCCs) currents in the cell membranes and growth cones. We found that Sig-1R activation dramatically enhanced the axonal length of the naïve hippocampal neurons. Application of the Sig-1R antagonist NE100 and gene knockdown techniques both demonstrated the effects of Sig-1R. The growth-promoting effect of SA4503 was accompanied by the inhibition of voltage-gated Ca 2+ influx and was recapitulated by incubating the neurons with the L-type, N-type, and P/Q-type VGCC blockers, nimodipine, MVIIA and ω-agatoxin IVA, respectively. This effect was unrelated to glial cells. The application of SA4503 transformed the growth cone morphologies from complicated to simple, which favored axon outgrowth. Sig-1R activation can enhance axon outgrowth and may have a substantial influence on neurogenesis and neurodegenerative diseases. © 2017 John Wiley & Sons Ltd.

  13. Angiotensin II modulates mouse skeletal muscle resting conductance to chloride and potassium ions and calcium homeostasis via the AT1 receptor and NADPH oxidase.

    Science.gov (United States)

    Cozzoli, Anna; Liantonio, Antonella; Conte, Elena; Cannone, Maria; Massari, Ada Maria; Giustino, Arcangela; Scaramuzzi, Antonia; Pierno, Sabata; Mantuano, Paola; Capogrosso, Roberta Francesca; Camerino, Giulia Maria; De Luca, Annamaria

    2014-10-01

    Angiotensin II (ANG II) plays a role in muscle wasting and remodeling; however, little evidence shows its direct effects on specific muscle functions. We presently investigated the acute in vitro effects of ANG II on resting ionic conductance and calcium homeostasis of mouse extensor digitorum longus (EDL) muscle fibers, based on previous findings that in vivo inhibition of ANG II counteracts the impairment of macroscopic ClC-1 chloride channel conductance (gCl) in the mdx mouse model of muscular dystrophy. By means of intracellular microelectrode recordings we found that ANG II reduced gCl in the nanomolar range and in a concentration-dependent manner (EC50 = 0.06 μM) meanwhile increasing potassium conductance (gK). Both effects were inhibited by the ANG II receptors type 1 (AT1)-receptor antagonist losartan and the protein kinase C inhibitor chelerythrine; no antagonism was observed with the AT2 antagonist PD123,319. The scavenger of reactive oxygen species (ROS) N-acetyl cysteine and the NADPH-oxidase (NOX) inhibitor apocynin also antagonized ANG II effects on resting ionic conductances; the ANG II-dependent gK increase was blocked by iberiotoxin, an inhibitor of calcium-activated potassium channels. ANG II also lowered the threshold for myofiber and muscle contraction. Both ANG II and the AT1 agonist L162,313 increased the intracellular calcium transients, measured by fura-2, with a two-step pattern. These latter effects were not observed in the presence of losartan and of the phospholipase C inhibitor U73122 and the in absence of extracellular calcium, disclosing a Gq-mediated calcium entry mechanism. The data show for the first time that the AT1-mediated ANG II pathway, also involving NOX and ROS, directly modulates ion channels and calcium homeostasis in adult myofibers. Copyright © 2014 the American Physiological Society.

  14. Metal Cation Binding to Gas-Phase Pentaalanine: Divalent Ions Restructure the Complex

    NARCIS (Netherlands)

    Dunbar, R.C.; Steill, J.D.; Polfer, N.C.; Oomens, J.

    2013-01-01

    Ion-neutral complexes of pentaalalanine with several singly- and doubly charged metal ions are examined using conformation analysis by infrared multiple photon dissociation (IRMPD) spectroscopy and density functional theory (DFT) computations. The infrared spectroscopy in the 1500-1800 cm(-1) region

  15. Dansyl-naphthalimide dyads as molecular probes: effect of spacer group on metal ion binding properties.

    Science.gov (United States)

    Shankar, Balaraman H; Ramaiah, Danaboyina

    2011-11-17

    Interaction of a few dansyl-naphthalimide conjugates 1a-e linked through polymethylene spacer groups with various metal ions was investigated through absorption, fluorescence, NMR, isothermal calorimetric (ITC), and laser flash photolysis techniques. The characteristic feature of these dyads is that they exhibit competing singlet-singlet energy transfer (SSET) and photoinduced electron transfer (PET) processes, both of which decrease with the increase in spacer length. Depending on the spacer group, these dyads interact selectively with divalent Cu(2+) and Zn(2+) ions, as compared to other mono- and divalent metal ions. Jobs plot analysis showed that these dyads form 2:3 complexes with Cu(2+) ions, while 1:1 complexes were observed with Zn(2+) ions. The association constants for the Zn(2+) and Cu(2+) complexes were determined and are found to be in the order 10(3)-10(5) M(-1). Irrespective of the length of the spacer group, these dyads interestingly act as fluorescence ratiometric molecular probes for Cu(2+) ions by altering the emission intensity of both dansyl and naphthalimide chromophores. In contrast, only the fluorescence intensity of the naphthalimide chromophore of the lower homologues (n = 1-3) was altered by Zn(2+) ions. (1)H NMR and ITC measurements confirmed the involvement of both sulfonamide and dimethylamine groups in the complexation with Cu(2+) ions, while only the latter group was involved with Zn(2+) ions. Laser excitation of the dyads 1a-e showed formation of a transient absorption which can be attributed to the radical cation of the naphthalimide chromophore, whereas only the triplet excited state of the dyads 1a-e was observed in the presence of Cu(2+) ions. Uniquely, the complexation of 1a-e with Cu(2+) ions affects both PET and SSET processes, while only the PET process was partially inhibited by Zn(2+) ions in the lower homologues (n = 1-3) and the higher homologues exhibited negligible changes in their emission properties. Our results

  16. Bioinformatic analysis and molecular modelling of human ameloblastin suggest a two-domain intrinsically unstructured calcium-binding protein

    Czech Academy of Sciences Publication Activity Database

    Vymětal, Jiří; Slabý, I.; Spahr, A.; Vondrášek, Jiří; Lyngstadaas, S. P.

    2008-01-01

    Roč. 116, č. 2 (2008), s. 124-134 ISSN 0909-8836 R&D Projects: GA ČR GA203/05/0009; GA ČR GA203/06/1727; GA MŠk LC512 Grant - others:EU(XE) QLK3-CT-2001-00090 Institutional research plan: CEZ:AV0Z40550506 Keywords : ameloblastin * bioinformatic modelling * calcium * intrinsically unstructured protein Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.957, year: 2008

  17. Integrin binding and MAPK signal pathways in primary cell responses to surface chemistry of calcium silicate cements.

    Science.gov (United States)

    Shie, Ming-You; Ding, Shinn-Jyh

    2013-09-01

    Cell attachment, proliferation and differentiation on different materials depend largely on the surface properties of the materials. This study sheds light on the mechanism by which the modulation of the chemical composition of calcium silicate cements with different Si/Ca molar ratios could produce different cell responses. Two primary cell types (human mesenchymal stem cells (hMSCs) and human dental pulp cells (hDPCs)) were used to elicit the changes in total DNA content, integrin subunit levels, phosphor-focal adhesion kinase (pFAK) levels, and mitogen-activated protein kinase (MAPK) signaling pathway activity at the cell attachment stage. The effect of small interfering RNA (siRNA) transfection targeting collagen type I (COL I) and fibronectin (FN) was also evaluated. The results indicated that increased total DNA content, pFAK and total integrin levels were observed upon an increase in cement Si content. Cements with different Si/Ca ratios did not cause the variations of interleukin 1β (IL-1β), epidermal growth factor (EGF) and tumor necrosis factor-α (TNF-α) ligands. The Si-rich cement facilitated COL I and α2β1 subintegrin expression, while Ca-rich cement promoted FN and αvβ3 subintegrin expression. Si component of the calcium silicates stimulated cell adhesion via activation of MAPK/extracellular signal-regulated kinase (ERK) and p38 signaling pathways more effectively than did by Ca component, but it did not affect c-Jun NH2-terminal kinase (JNK) activity. Inhibition of MAPK/ERK and MAPK/p38 signaling pathways in hMSCs and hDPCs significantly attenuated adhesion, proliferation and differentiation as assessed according to total DNA content and alkaline phosphatase activity. hMSCs and hDPCs from the three different donors exhibited a similar preference for cell behaviors. The results of the current study suggest that calcium silicate cements with a higher Si content have the potential to serve as excellent supports for primary cells. Unraveling the

  18. Acute sleep deprivation increases serum levels of neuron-specific enolase (NSE) and S100 calcium binding protein B (S-100B) in healthy young men.

    Science.gov (United States)

    Benedict, Christian; Cedernaes, Jonathan; Giedraitis, Vilmantas; Nilsson, Emil K; Hogenkamp, Pleunie S; Vågesjö, Evelina; Massena, Sara; Pettersson, Ulrika; Christoffersson, Gustaf; Phillipson, Mia; Broman, Jan-Erik; Lannfelt, Lars; Zetterberg, Henrik; Schiöth, Helgi B

    2014-01-01

    To investigate whether total sleep deprivation (TSD) affects circulating concentrations of neuron-specific enolase (NSE) and S100 calcium binding protein B (S-100B) in humans. These factors are usually found in the cytoplasm of neurons and glia cells. Increasing concentrations of these factors in blood may be therefore indicative for either neuronal damage, impaired blood brain barrier function, or both. In addition, amyloid β (Aβ) peptides 1-42 and 1-40 were measured in plasma to calculate their ratio. A reduced plasma ratio of Aβ peptides 1-42 to 1-40 is considered an indirect measure of increased deposition of Aβ 1-42 peptide in the brain. Subjects participated in two conditions (including either 8-h of nocturnal sleep [22:30-06:30] or TSD). Fasting blood samples were drawn before and after sleep interventions (19:30 and 07:30, respectively). Sleep laboratory. 15 healthy young men. TSD increased morning serum levels of NSE (P = 0.002) and S-100B (P = 0.02) by approximately 20%, compared with values obtained after a night of sleep. In contrast, the ratio of Aβ peptides 1-42 to 1-40 did not differ between the sleep interventions. Future studies in which both serum and cerebrospinal fluid are sampled after sleep loss should elucidate whether the increase in serum neuron-specific enolase and S100 calcium binding protein B is primarily caused by neuronal damage, impaired blood brain barrier function, or is just a consequence of increased gene expression in non-neuronal cells, such as leukocytes.

  19. Metal ions-binding T4 lysozyme as an intramolecular protein purification tag compatible with X-ray crystallography.

    Science.gov (United States)

    Boura, Evzen; Baumlova, Adriana; Chalupska, Dominika; Dubankova, Anna; Klima, Martin

    2017-06-01

    Phage T4 lysozyme is a well folded and highly soluble protein that is widely used as an insertion tag to improve solubility and crystallization properties of poorly behaved recombinant proteins. It has been used in the fusion protein strategy to facilitate crystallization of various proteins including multiple G protein-coupled receptors, lipid kinases, or sterol binding proteins. Here, we present a structural and biochemical characterization of its novel, metal ions-binding mutant (mbT4L). We demonstrate that mbT4L can be used as a purification tag in the immobilized-metal affinity chromatography and that, in many respects, it is superior to the conventional hexahistidine tag. In addition, structural characterization of mbT4L suggests that mbT4L can be used as a purification tag compatible with X-ray crystallography. © 2017 The Protein Society.

  20. The role of the counter-ions present in syntheses on the thermal stabilization of strontium and/or calcium apatites

    Energy Technology Data Exchange (ETDEWEB)

    Melo da Silva, Leila; Santos Menezes, Daniela dos; Almeida, Luis Eduardo [Laboratório de Biomateriais – P" 2CEM, Universidade Federal de Sergipe, Av. Marechal Rondon, s/n, São Cristóvão, 49100-000 Sergipe (Brazil); Anselme, Karine; Dentzer, Joseph [Institut de Science des Matériaux de Mulhouse (IS2M), CNRS UMR7361, Université de Haute-Alsace, 15, rue Jean Starcky, BP 2488, 68057 Mulhouse (France); Araujo dos Santos, Euler, E-mail: euler@ufs.br [Laboratório de Biomateriais – P" 2CEM, Universidade Federal de Sergipe, Av. Marechal Rondon, s/n, São Cristóvão, 49100-000 Sergipe (Brazil)

    2015-09-15

    Highlights: • Counter-ions present in syntheses can affect thermal stabilization of apatites. • Ions with different charges and sizes can stabilize the apatite structure. • Co-substitution is an important way to design biomimetic hydroxyapatites. - Abstract: The goal of this work was to study the thermal stabilization of calcium apatites in which the Ca{sup 2+} ions were substituted for Sr{sup 2+} in increasing concentrations via ionic co-substitutions. Two distinct standard syntheses were proposed for comparative purposes: one using counter-ions that were not easily incorporated into the apatite structure (NH{sub 4}{sup +}/NO{sub 3}{sup −}) and one using counter-ions that can be easily incorporated into the structure (Na{sup +}/Cl{sup −}). After calcination, only the apatites synthesized in the presence of NH{sub 4}{sup +}/NO{sub 3}{sup −} presented phase transformation. In contrast, the apatites synthesized in the presence of Na{sup +}/Cl{sup −} formed a solid solution after calcination, with Na{sup +}, Ca{sup 2+}, Sr{sup 2+} and Cl{sup −} sharing the same apatite lattice. Wavelength dispersive X-ray fluorescence spectroscopy (WDXRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and temperature-programmed desorption (TPD) techniques showed that the counter-ions present during the syntheses that are associated with CO{sub 3}{sup 2−} play an important role in the thermal stabilization of the apatites.

  1. Novel control of cardiac myofilament response to calcium by S-glutahionylation at specific sites of myosin binding protein C

    Directory of Open Access Journals (Sweden)

    Bindiya G Patel

    2013-11-01

    Full Text Available Our previous studies demonstrated a relation between glutathionylation of cardiac myosin binding protein C and diastolic dysfunction in a hypertensive mouse model stressed by treatment with salt, deoxycorticosterone acetate, and unilateral nephrectomy. Although these results strongly indicated an important role for S-glutathionylation of myosin binding protein C as a modifier of myofilament function, indirect effects of other post-translational modifications may have occurred. Moreover, we did not determine the sites of thiol modification by glutathionylation. To address these issues, we developed an in vitro method to mimic the in situ S-glutathionylation of myofilament proteins and determined direct functional effects and sites of oxidative modification employing Western blotting and mass spectrometry. We induced glutathionylation in vitro by treatment of isolated myofibrils and detergent extracted fiber bundles (skinned fibers with oxidized glutathione (GSSG. Immuno-blotting results revealed increased glutathionylation with GSSG treatment of a protein band around 140 kDa. Using tandem mass spectrometry, we identified the 140 kDa band as cardiac myosin binding protein C and determined the sites of glutathionylation to be at cysteines 655, 479, and 627. Determination of the relation between Ca2+-activation of myofibrillar acto-myosin ATPase rate demonstrated an increased Ca2+-sensitivity induced by the S-glutathionylation. Force generating skinned fiber bundles also showed an increase in Ca-sensitivity when treated with oxidized glutathione, which was reversed with the reducing agent, dithiothreitol. Our data demonstrate that a specific and direct effect of S-glutathionylation of myosin binding protein C is a significant increase in myofilament Ca2+-sensitivity. Our data also provide new insights into the functional significance of oxidative modification of myosin binding protein C and the potential role of domains not previously considered to

  2. Selective Binding, Self-Assembly and Nanopatterning of the Creutz-Taube Ion on Surfaces

    OpenAIRE

    Wang, Yuliang; Lieberman, Marya; Hang, Qingling; Bernstein, Gary

    2009-01-01

    The surface attachment properties of the Creutz-Taube ion, i.e., [(NH3)5Ru(pyrazine)Ru(NH3)5]5+, on both hydrophilic and hydrophobic types of surfaces were investigated using X-ray photoelectron spectroscopy (XPS). The results indicated that the Creutz-Taube ions only bound to hydrophilic surfaces, such as SiO2 and –OH terminated organic SAMs on gold substrates. No attachment of the ions on hydrophobic surfaces such as –CH3 terminated organic SAMs and poly(methylmethacrylate) (PMMA) thin film...

  3. Composite absorbers consisting of inorganic ion-exchangers and polyacrylonitrile binding matrix

    International Nuclear Information System (INIS)

    Sebesta, F.; John, J.; Motl, A.; Peka, V.; Vackova, E.

    1997-01-01

    Both cementation and vitrification was shown by preliminary experiments to be applicable for treatment of the spent composite absorbers with polyacrylonitrile binding matrix for final disposal. Loading of cement mix with composite absorbers up to 5-9% (w/w) were achieved Admixtures of natural clinoptilolite were found to improve compressive strength of the samples. The presence of PAN binding polymer was found not to disqualify the composite absorber tested from final treatment by vitrification. (author)

  4. Calcium bioaccessibility and uptake by human intestinal like cells following in vitro digestion of casein phosphopeptide-calcium aggregates.

    Science.gov (United States)

    Perego, Silvia; Del Favero, Elena; De Luca, Paola; Dal Piaz, Fabrizio; Fiorilli, Amelia; Cantu', Laura; Ferraretto, Anita

    2015-06-01

    Casein phosphopeptides (CPPs), derived by casein proteolysis, can bind calcium ions and keep them in solution. In vitro studies have demonstrated CPP-induced cell calcium uptake, depending on the formation of (CPP + calcium) complexes and on the degree of differentiation of the intestinal cells. With the present study, we address the persistence of the complexes and of the CPP-induced calcium uptake in intestinal like cells after the digestion process, thus examining their eligibility to serve as nutraceuticals. A calcium-preloaded CPP preparation of commercial origin (Ca-CPPs) was subjected to in vitro digestion. The evolution of the supramolecular structure of the Ca-CPP complexes was studied using laser-light and X-ray scattering. The bioactivity of the pre- and post-digestion Ca-CPPs was determined in differentiated Caco2 and HT-29 cells by video imaging experiments using Fura-2. We found that Ca-CPP aggregates keep a complex supramolecular organization upon digestion, despite getting smaller in size and increasing internal calcium dispersion. Concomitantly and most interestingly, digested Ca-CPPs clearly enhance the uptake of calcium ions, especially in Caco2 cells. In contrast, digestion depletes the ability of post-loaded decalcified-CPPs (Ca-dekCPPs), with a weaker internal structure, to induce calcium uptake. The enhanced bioactivity reached upon digestion strongly suggests a recognized role of Ca-CPPs, in the form used here, as nutraceuticals.

  5. Quantitative imaging of chemical composition in single cells by secondary ion mass spectrometry: cisplatin affects calcium stores in renal epithelial cells.

    Science.gov (United States)

    Chandra, Subhash

    2010-01-01

    A detailed protocol for quantitative single cell mass spectrometry imaging (MSI) analysis is described in this chapter with examples of the treatment of cells with anticancer drug, cisplatin. Cisplatin, cis-diamminedichloridoplatinum ii (CDDP), is widely used for the treatment of many malignancies, including testicular, ovarian, bladder, cervical, head and neck, and small cell and non-small cell lung cancers. The possibility of renal injury by cisplatin treatment is a major dose-limiting factor in this cancer therapy. At present, the mechanisms of cisplatin-induced renal cytotoxicity are poorly understood. In this work, secondary ion mass spectrometry (SIMS) was used for investigating cisplatin-induced alterations in intracellular chemical composition in a well-established model (LLC-PK(1) cell line) for studying renal injury. The cells were cryogenically prepared by the sandwich freeze-fracture method for subcellular imaging analysis of chemical composition (total concentrations of K(+), Na(+), and Ca(2+)) in individual cells. The single cell analysis of these diffusible ions necessitates the use of reliable cryogenic sample preparations for SIMS. The sandwich freeze-fracture method offers a simple approach for cryogenically preserving diffusible ions and molecules inside the cells for SIMS analysis. A CAMECA IMS-3f SIMS ion microscope instrument capable of producing chemical images of single cells with 500-nm spatial resolution was used in the study. In cisplatin-treated cells, SIMS imaging showed the presence of detectable amount of platinum at mass 195, as (195)Pt(+) secondary ions in individual cells. SIMS observations also revealed that individual cells differed in their response to cisplatin. While the chemical composition of some cells was unaffected by cisplatin, others showed a reduction in cytoplasmic calcium stores that was not associated with changes in their intracellular K or Na concentrations. Another population of cells displayed an increase in

  6. The interaction of uranyl ions with inorganic pyrophosphatase from baker's yeast

    International Nuclear Information System (INIS)

    Bienwald, B.; Heitmann, P.

    1978-01-01

    The interaction of uranyl ions with inorganic pyrophosphatase from baker's yeast was investigated by measurement of their effect on the protein fluorescence. Fluorescence titrations of the native enzyme with uranyl nitrate show that there is a specific binding of uranyl ions to the enzyme. It was deduced that each subunit of the enzyme binds one uranyl ion. The binding constant was estimated to be in the order of 10 7 M -1 . The enzyme which contains a small number of chemically modified carboxyl groups was not able to bind uranyl ions specifically. The modification of carboxyl groups was carried out by use of a water soluble carbodiimide and the nucleophilic reagent N-(2,4-dinitro-phenyl)-hexamethylenediamine. The substrate analogue calcium pyrophosphate displaced the uranyl ions from their binding sites at the enzyme From the results it is concluded that carboxyl groups of the active site are the ligands for the binding of uranyl ions. (author)

  7. Fabrication and characterization of magnesium and calcium trimesate complexes via ion-exchange and one-pot self-assembly reaction

    Science.gov (United States)

    Ozer, Demet; Oztas, Nursen Altuntas; Köse, Dursun A.; Şahin, Onur

    2018-03-01

    Using two different synthesis methods, two diversified magnesium and calcium complexes were successfully prepared. When the ion exchange method was used, C9H14MgO11.H2O and C18H30Ca3O24 complexes were obtained. When the one-pot self-assembly reaction was used, C18H34Mg3O26.4H2O and C9H12CaO10 complexes were produced. The structural characterizations were performed by using X-ray diffraction, FT-IR and elemental analyses. Thermal behavior of complexes were also determined via TGA method. The both complexes of magnesium and calcium trimesate have micro and mesoporosity with low porosity because of hydrogen bonds. Then hydrogen storage capacities of complexes were also determined. The differences in synthesis method result in the differences on complexes structure, morphology (shape, particle size and specific surface area) and hydrogen storage capacities.

  8. Osteoclastic differentiation and resorption is modulated by bioactive metal ions Co2+, Cu2+ and Cr3+ incorporated into calcium phosphate bone cements

    Science.gov (United States)

    Bernhardt, Anne; Schamel, Martha; Gbureck, Uwe; Gelinsky, Michael

    2017-01-01

    Biologically active metal ions in low doses have the potential to accelerate bone defect healing. For successful remodelling the interaction of bone graft materials with both bone-forming osteoblasts and bone resorbing osteoclasts is crucial. In the present study brushite forming calcium phosphate cements (CPC) were doped with Co2+, Cu2+ and Cr3+ and the influence of these materials on osteoclast differentiation and activity was examined. Human osteoclasts were differentiated from human peripheral blood mononuclear cells (PBMC) both on the surface and in indirect contact to the materials on dentin discs. Release of calcium, phosphate and bioactive metal ions was determined using ICP-MS both in the presence and absence of the cells. While Co2+ and Cu2+ showed a burst release, Cr3+ was released steadily at very low concentrations (below 1 μM) and both calcium and phosphate release of the cements was considerably changed in the Cr3+ modified samples. Direct cultivation of PBMC/osteoclasts on Co2+ cements showed lower attached cell number compared to the reference but high activity of osteoclast specific enzymes tartrate resistant acid phosphatase (TRAP), carbonic anhydrase II (CAII) and cathepsin K (CTSK) and significantly increased gene expression of vitronectin receptor. Indirect cultivation with diluted Co2+ cement extracts revealed highest resorbed area compared to all other modifications and the reference. Cu2+ cements had cytotoxic effect on PBMC/osteoclasts during direct cultivation, while indirect cultivation with diluted extracts from Cu2+ cements did not provoke cytotoxic effects but a strictly inhibited resorption. Cr3+ doped cements did not show cytotoxic effects at all. Gene expression and enzyme activity of CTSK was significantly increased in direct culture. Indirect cultivation with Cr3+ doped cements revealed significantly higher resorbed area compared to the reference. In conclusion Cr3+ doped calcium phosphate cements are an innovative cement

  9. Binding energies and isomerization in metallocene ions from threshold photoelectron photoion coincidence spectroscopy.

    Science.gov (United States)

    Révész, Agnes; Szepes, László; Baer, Tomas; Sztáray, Bálint

    2010-12-22

    Metallocene ions (Cp(2)M(+), M = Cr, Co, Ni) were studied by threshold photoelectron photoion coincidence spectroscopy (TPEPICO) to investigate the mechanism, energetics, and kinetics of the ionic dissociation processes. The examined energy-selected Cp(2)M(+) ions fragment by losing the neutral cyclopentadienyl ligand. In addition, CH and C(2)H(2) losses appear as minor channels, while the cobaltocene ion also loses an H atom. A possible isomerization pathway has also been observed for Cp(2)Ni(+), yielding a complex with pentafulvalene (C(10)H(8)) with a loss of H(2). In order to determine the 0 K appearance energies for the CpM(+) fragment ions, the asymmetric time-of-flight peak shapes and the breakdown diagrams of the energy-selected metallocene ions were modeled by both the rigid activated complex (RAC) Rice-Ramsperger-Kassel-Marcus (RRKM) theory and the simplified statistical adiabatic channel model (SSACM). The following appearance energies were obtained with SSACM, which is more reliable for loose transition states: 10.57 ± 0.14, 11.01 ± 0.13, and 10.18 ± 0.13 eV for M = Cr, Co, and Ni, respectively. These values combined with the corresponding adiabatic ionization energies yield M-Cp bond dissociation energies in Cp(2)M(+) ions of 5.04 ± 0.16, 5.77 ± 0.15, and 3.96 ± 0.15 eV. Density functional calculations at the B3LYP/6-311G(d,p) level of theory were used to determine the structures of these complexes and to provide parameters necessary for the analysis of the experimental data. The trends in the M-Cp bond energies can be related to the electronic structures of the metallocene ions based on a simple molecular orbital picture.

  10. Binding of alphaherpesvirus glycoprotein H to surface α4β1-integrins activates calcium-signaling pathways and induces phosphatidylserine exposure on the plasma membrane.

    Science.gov (United States)

    Azab, Walid; Gramatica, Andrea; Herrmann, Andreas; Osterrieder, Nikolaus

    2015-10-20

    Intracellular signaling connected to integrin activation is known to induce cytoplasmic Ca(2+) release, which in turn mediates a number of downstream signals. The cellular entry pathways of two closely related alphaherpesviruses, equine herpesviruses 1 and 4 (EHV-1 and EHV-4), are differentially regulated with respect to the requirement of interaction of glycoprotein H (gH) with α4β1-integrins. We show here that binding of EHV-1, but not EHV-4, to target cells resulted in a rapid and significant increase in cytosolic Ca(2+) levels. EHV-1 expressing EHV-4 gH (gH4) in lieu of authentic gH1 failed to induce Ca(2+) release, while EHV-4 with gH1 triggered significant Ca(2+) release. Blocking the interaction between gH1 and α4β1-integrins, inhibiting phospholipase C (PLC) activation, or blocking binding of inositol 1,4,5-triphosphate (IP3) to its receptor on the endoplasmic reticulum (ER) abrogated Ca(2+) release. Interestingly, phosphatidylserine (PS) was exposed on the plasma membrane in response to cytosolic calcium increase after EHV-1 binding through a scramblase-dependent mechanism. Inhibition of both Ca(2+) release from the ER and scramblase activation blocked PS scrambling and redirected virus entry to the endocytic pathway, indicating that PS may play a role in facilitating virus entry directly at the plasma membrane. Herpesviruses are a large family of enveloped viruses that infect a wide range of hosts, causing a variety of diseases. These viruses have developed a number of strategies for successful entry into different cell types. We and others have shown that alphaherpesviruses, including EHV-1 and herpes simplex virus 1 (HSV-1), can route their entry pathway and do so by manipulation of cell signaling cascades to ensure viral genome delivery to nuclei. We show here that the interaction between EHV-1 gH and cellular α4β1-integrins is necessary to induce emptying of ER calcium stores, which induces phosphatidylserine exposure on the plasma membrane

  11. Trifluoperazine, a Well-Known Antipsychotic, Inhibits Glioblastoma Invasion by Binding to Calmodulin and Disinhibiting Calcium Release Channel IP3R.

    Science.gov (United States)

    Kang, Seokmin; Hong, Jinpyo; Lee, Jung Moo; Moon, Hyo Eun; Jeon, Borami; Choi, Jungil; Yoon, Nal Ae; Paek, Sun Ha; Roh, Eun Joo; Lee, C Justin; Kang, Sang Soo

    2017-01-01

    Calcium (Ca 2+ ) signaling is an important signaling process, implicated in cancer cell proliferation and motility of the deadly glioblastomas that aggressively invade neighboring brain tissue. We have previously demonstrated that caffeine blocks glioblastoma invasion and extends survival by inhibiting Ca 2+ release channel inositol 1,4,5-trisphosphate receptor (IP 3 R) subtype 3. Trifluoperazine (TFP) is an FDA-approved antipsychotic drug for schizophrenia. Interestingly, TFP has been recently reported to show a strong anticancer effect on lung cancer, hepatocellular carcinoma, and T-cell lymphoma. However, the possible anticancer effect of TFP on glioblastoma has not been tested. Here, we report that TFP potently suppresses proliferation, motility, and invasion of glioblastoma cells in vitro, and tumor growth in in vivo xenograft mouse model. Unlike caffeine, TFP triggers massive and irreversible release of Ca 2+ from intracellular stores by IP 3 R subtype 1 and 2 by directly interacting at the TFP-binding site of a Ca 2+ -binding protein, calmodulin subtype 2 (CaM2). TFP binding to CaM2 causes a dissociation of CaM2 from IP 3 R and subsequent opening of IP 3 R. Compared with the control neural stem cells, various glioblastoma cell lines showed enhanced expression of CaM2 and thus enhanced sensitivity to TFP. On the basis of these findings, we propose TFP as a potential therapeutic drug for glioblastoma by aberrantly and irreversibly increasing Ca 2+ in glioblastoma cells. Mol Cancer Ther; 16(1); 217-27. ©2016 AACR. ©2016 American Association for Cancer Research.

  12. Competition of dipositive metal ions for Fe (III) binding sites in chelation therapy of Iron Load

    International Nuclear Information System (INIS)

    Rehmani, Fouzia S.

    2005-01-01

    Iron overload is a condition in which excessive iron deposited in the liver, kidney and spleen of human beings in the patients of beta thalassemia and sickle cell anemia. Instead of its importance iron could be toxic when in excess, it damages the tissues. For the treatment of iron overload, a drug desferrioxamine mesylate has been used. It is linear trihydroxamic acid, a natural siderophore produced by streptomyces which removes the extra iron from body. Salicylhydroxamate type siderphore. In present research salicylhydroxamate was used for the complexation with dipositive metal ions which are available in biological environments such as Mn (II), Co (II), Ni (II) and Cu (II). The aim of our work was to study the competition reactions between Fe (III) and other dipositive ions; to calculate the thermodynamic data of chelation of these metal ions complexes with hydroxamate by computer program and comparison with hydroxamate complexes. (author)

  13. Synaptotagmin I regulates patterned spontaneous activity in the developing rat retina via calcium binding to the C2AB domains.

    Directory of Open Access Journals (Sweden)

    Chung-Wei Chiang

    Full Text Available BACKGROUND: In neonatal binocular animals, the developing retina displays patterned spontaneous activity termed retinal waves, which are initiated by a single class of interneurons (starburst amacrine cells, SACs that release neurotransmitters. Although SACs are shown to regulate wave dynamics, little is known regarding how altering the proteins involved in neurotransmitter release may affect wave dynamics. Synaptotagmin (Syt family harbors two Ca(2+-binding domains (C2A and C2B which serve as Ca(2+ sensors in neurotransmitter release. However, it remains unclear whether SACs express any specific Syt isoform mediating retinal waves. Moreover, it is unknown how Ca(2+ binding to C2A and C2B of Syt affects wave dynamics. Here, we investigated the expression of Syt I in the neonatal rat retina and examined the roles of C2A and C2B in regulating wave dynamics. METHODOLOGY/PRINCIPAL FINDINGS: Immunostaining and confocal microscopy showed that Syt I was expressed in neonatal rat SACs and cholinergic synapses, consistent with its potential role as a Ca(2+ sensor mediating retinal waves. By combining a horizontal electroporation strategy with the SAC-specific promoter, we specifically expressed Syt I mutants with weakened Ca(2+-binding ability in C2A or C2B in SACs. Subsequent live Ca(2+ imaging was used to monitor the effects of these molecular perturbations on wave-associated spontaneous Ca(2+ transients. We found that targeted expression of Syt I C2A or C2B mutants in SACs significantly reduced the frequency, duration, and amplitude of wave-associated Ca(2+ transients, suggesting that both C2 domains regulate wave temporal properties. In contrast, these C2 mutants had relatively minor effects on pairwise correlations over distance for wave-associated Ca(2+ transients. CONCLUSIONS/SIGNIFICANCE: Through Ca(2+ binding to C2A or C2B, the Ca(2+ sensor Syt I in SACs may regulate patterned spontaneous activity to shape network activity during development

  14. Effects of copper ions on DNA binding and cytotoxic activity of a chiral salicylidene Schiff base.

    Science.gov (United States)

    Fei, Bao-Li; Xu, Wu-Shuang; Tao, Hui-Wen; Li, Wen; Zhang, Yu; Long, Jian-Ying; Liu, Qing-Bo; Xia, Bing; Sun, Wei-Yin

    2014-03-05

    A chiral Schiff base HL N-(5-bromo-salicylaldehyde)dehydroabietylamine (1) and its chiral dinuclear copper complex [Cu2L4]·4DMF (2) have been synthesized and fully characterized. The interactions of 1 and 2 with salmon sperm DNA have been investigated by viscosity measurements, UV, fluorescence and circular dichroism (CD) spectroscopic techniques. Absorption spectral (Kb=3.30 × 10(5)M(-)(1) (1), 6.63 × 10(5)M(-)(1)(2)), emission spectral (Ksv=7.58 × 10(3)M(-)(1) (1), 1.52 × 10(4)M(-)(1) (2)), and viscosity measurements reveal that 1 and 2 interact with DNA through intercalation and 2 exhibits a higher DNA binding ability. In addition, CD study indicates 2 cause a more evident perturbation on the base stacking and helicity of B-DNA upon binding to it. In fluorimetric studies, the enthalpy (ΔH>0) and entropy (ΔS>0) changes of the reactions between the compounds with DNA demonstrate hydrophobic interactions. 1 and 2 were also screened for their cytotoxic ability and 2 demonstrates higher growth inhibition of the selected cancer cells at concentration of 50 μM, this result is identical with their DNA binding ability order. All the experimental results show that the involvement of Cu (II) centers has some interesting effect on DNA binding ability and cytotoxicity of the chiral Schiff base. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. K+ congeners that do not compromise Na+ activation of the Na+,K+-ATPase: hydration of the ion binding cavity likely controls ion selectivity.

    Science.gov (United States)

    Mahmmoud, Yasser A; Kopec, Wojciech; Khandelia, Himanshu

    2015-02-06

    The Na(+),K(+)-ATPase is essential for ionic homeostasis in animal cells. The dephosphoenzyme contains Na(+) selective inward facing sites, whereas the phosphoenzyme contains K(+) selective outward facing sites. Under normal physiological conditions, K(+) inhibits cytoplasmic Na(+) activation of the enzyme. Acetamidinium (Acet(+)) and formamidinium (Form(+)) have been shown to permeate the pump through the outward facing sites. Here, we show that these cations, unlike K(+), are unable to enter the inward facing sites in the dephosphorylated enzyme. Consistently, the organic cations exhibited little to no antagonism to cytoplasmic Na(+) activation. Na(+),K(+)-ATPase structures revealed a previously undescribed rotamer transition of the hydroxymethyl side chain of the absolutely conserved Thr(772) of the α-subunit. The side chain contributes its hydroxyl to Na(+) in site I in the E1 form and rotates to contribute its methyl group toward K(+) in the E2 form. Molecular dynamics simulations to the E1·AlF4 (-)·ADP·3Na(+) structure indicated that 1) bound organic cations differentially distorted the ion binding sites, 2) the hydroxymethyl of Thr(772) rotates to stabilize bound Form(+) through water molecules, and 3) the rotamer transition is mediated by water traffic into the ion binding cavity. Accordingly, dehydration induced by osmotic stress enhanced the interaction of the congeners with the outward facing sites and profoundly modified the organization of membrane domains of the α-subunit. These results assign a catalytic role for water in pump function, and shed light on a backbone-independent but a conformation-dependent switch between H-bond and dispersion contact as part of the catalytic mechanism of the Na(+),K(+)-ATPase. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. Ion adsorption on oxides : surface charge formation and cadmium binding on rutile and hematite

    NARCIS (Netherlands)

    Fokkink, L.G.J.

    1987-01-01

    The adsorption of charge-determining (H +and OH -) and cadmium ions on rutile (TiO 2 ) and hematite (α-Fe

  17. Binding of nickel and zinc ions with activated carbon prepared from ...

    African Journals Online (AJOL)

    Activated carbon was prepared from sugar cane fibre by carbonizing at 500 oC for 30 minutes. This was followed by activation with ammonium chloride. The activated carbon was characterised in terms of pH, bulk density, ash content, surface area and surface charge. Equilibrium sorption of nickel and zinc ions by the ...

  18. Preferential affinity of calcium ions to charged phosphatidic acid surface from a mixed calcium/barium solution: X-ray reflectivity and fluorescence studies.

    Science.gov (United States)

    Bu, Wei; Flores, Kevin; Pleasants, Jacob; Vaknin, David

    2009-01-20

    X-ray reflectivity and fluorescence near total reflection experiments were performed to examine the affinities of divalent ions (Ca(2+) and Ba(2+)) from aqueous solution to a charged phosphatidic acid (PA) surface. A phospholipid (1,2-dimyristoyl-sn-glycero-3-phosphate, DMPA), spread as a monolayer at the air/water interface, was used to form and control the charge density at the interface. We find that, for solutions of the pure salts (i.e., CaCl(2) and BaCl(2)), the number of bound ions per DMPA at the interface is saturated at concentrations that exceed 10(-3) M. For 1:1 Ca(2+)/Ba(2+) mixed solutions, we find that the bound Ca(2+)/Ba(2+) ratio at the interface is 4:1. If the only property determining charge accumulation near PA were the ionic charges, the concentration of mixed Ca(2+)/Ba(2+) at the interface would equal that of the bulk. Our results show a clear specific affinity of PA for Ca compared to Ba. We provide some discussion on this issue as well as some implications for biological systems. Although our results indicate an excess of counterion charge with respect to the surface charge, that is, charge inversion, the analysis of both reflectivity and fluorescence do not reveal an excess of co-ions (namely, Cl(-) or I(-)).

  19. Calcium Carbonate Phosphate Binding Ion Exchange Filtration and Accelerated Denitrification Improve Public Health Standards and Combat Eutrophication in Aquatic Ecosystems

    OpenAIRE

    Yanamadala, Vijay

    2005-01-01

    Cultural eutrophication, the process by which a lake becomes rich in dissolved nutrients as a result of point and nonpoint pollutant sources, is a major cause of the loss of natural lake ecosystems throughout the world. The process occurs naturally in all lakes, but phosphate-rich nutrient runoff from sources such as storm drains and agricultural runoff is a major cause of excess phosphate-induced eutrophication. Especially in Madrona Marsh, one of the last remaining vernal marshes in the gre...

  20. Biopharmaceutical characterisation of ciprofloxacin-metallic ion interactions: comparative study into the effect of aluminium, calcium, zinc and iron on drug solubility and dissolution.

    Science.gov (United States)

    Stojković, Aleksandra; Tajber, Lidia; Paluch, Krzysztof J; Djurić, Zorica; Parojčić, Jelena; Corrigan, Owen I

    2014-03-01

    Ciprofloxacin bioavailability may be reduced when ciprofloxacin is co-administered with metallic ion containing preparations. In our previous study, physicochemical interaction between ciprofloxacin and ferrous sulphate was successfully simulated in vitro. In the present work, comparative in vitro ciprofloxacin solubility and dissolution studies were performed in the reactive media containing aluminium hydroxide, calcium carbonate or zinc sulphate. Solid phases collected from the dissolution vessel with aluminium hydroxide, calcium carbonate and zinc sulphate were investigated for their properties. The results obtained indicate that different types of adducts may form and retard ciprofloxacin solubility and dissolution. In the case of aluminium, no phase changes were observed. The solid phase generated in the presence of calcium carbonate was identified as hydrated ciprofloxacin base. Similarly to iron, a new complex consistent with Zn(SO4)2(Cl)2(ciprofloxacin)2 × nH2O stoichiometry was generated in the presence of relatively high concentrations of ciprofloxacin hydrochloride and zinc sulphate, indicating that small volume dissolution experiments can be useful for biorelevant dissolution tests.

  1. Spatially resolved product formation in the reaction of formic acid with calcium carbonate (1014): the role of step density and adsorbed water-assisted ion mobility.

    Science.gov (United States)

    Usher, Courtney R; Baltrusaitis, Jonas; Grassian, Vicki H

    2007-06-19

    The reaction of calcium carbonate (1014) single-crystal surfaces with formic acid (HCOOH) vapor was investigated using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). AFM images indicate the reaction produces rather well-defined crystallites, preferentially at step edges and at distinct angles to one another and mirroring the rhombohedral structure of the calcite surface, while exposing unreacted carbonate surface. The size and surface density of the crystallites depend upon substrate step density, exposure time, and relative humidity. XPS data confirmed the crystallite composition as the expected calcium formate product. The AFM images show erosion and pit formation of the calcite surface in the vicinity of the product crystallites, clearly providing the spatially resolved characterization of the source of Ca ions. AFM experiments exploring the effects of water vapor on the reacted surface show that the calcium formate crystallites are mobile under conditions of high relative humidity, combining to form larger crystallites and nanometer-sized crystals with an orthorhombohedral habit consistent with the alpha form, as confirmed by X-ray diffraction. The implications for the reactions described here are discussed.

  2. Biopharmaceutical characterisation of ciprofloxacin-metallic ion interactions: Comparative study into the effect of aluminium, calcium, zinc and iron on drug solubility and dissolution

    Directory of Open Access Journals (Sweden)

    Stojković Aleksandra

    2014-03-01

    Full Text Available Ciprofloxacin bioavailability may be reduced when ciprofloxacin is co-administered with metallic ion containing preparations. In our previous study, physicochemical interaction between ciprofloxacin and ferrous sulphate was successfully simulated in vitro. In the present work, comparative in vitro ciprofloxacin solubility and dissolution studies were performed in the reactive media containing aluminium hydroxide, calcium carbonate or zinc sulphate. Solid phases collected from the dissolution vessel with aluminium hydroxide, calcium carbonate and zinc sulphate were investigated for their properties. The results obtained indicate that different types of adducts may form and retard ciprofloxacin solubility and dissolution. In the case of aluminium, no phase changes were observed. The solid phase generated in the presence of calcium carbonate was identified as hydrated ciprofloxacin base. Similarly to iron, a new complex consistent with Zn(SO42(Cl2(ciprofloxacin2 × nH2O stoichiometry was generated in the presence of relatively high concentrations of ciprofloxacin hydrochloride and zinc sulphate, indicating that small volume dissolution experiments can be useful for biorelevant dissolution tests.

  3. The IQD Family of Calmodulin-Binding Proteins Links Calcium Signaling to Microtubules, Membrane Subdomains, and the Nucleus1[OPEN

    Science.gov (United States)

    Plötner, Romina; Stamm, Gina; Hause, Gerd; Mitra, Dipannita; Abel, Steffen

    2017-01-01

    Calcium (Ca2+) signaling and dynamic reorganization of the cytoskeleton are essential processes for the coordination and control of plant cell shape and cell growth. Calmodulin (CaM) and closely related calmodulin-like (CML) polypeptides are principal sensors of Ca2+ signals. CaM/CMLs decode and relay information encrypted by the second messenger via differential interactions with a wide spectrum of targets to modulate their diverse biochemical activities. The plant-specific IQ67 DOMAIN (IQD) family emerged as possibly the largest class of CaM-interacting proteins with undefined molecular functions and biological roles. Here, we show that the 33 members of the IQD family in Arabidopsis (Arabidopsis thaliana) differentially localize, using green fluorescent protein (GFP)-tagged proteins, to multiple and distinct subcellular sites, including microtubule (MT) arrays, plasma membrane subdomains, and nuclear compartments. Intriguingly, the various IQD-specific localization patterns coincide with the subcellular patterns of IQD-dependent recruitment of CaM, suggesting that the diverse IQD members sequester Ca2+-CaM signaling modules to specific subcellular sites for precise regulation of Ca2+-dependent processes. Because MT localization is a hallmark of most IQD family members, we quantitatively analyzed GFP-labeled MT arrays in Nicotiana benthamiana cells transiently expressing GFP-IQD fusions and observed IQD-specific MT patterns, which point to a role of IQDs in MT organization and dynamics. Indeed, stable overexpression of select IQD proteins in Arabidopsis altered cellular MT orientation, cell shape, and organ morphology. Because IQDs share biochemical properties with scaffold proteins, we propose that IQD families provide an assortment of platform proteins for integrating CaM-dependent Ca2+ signaling at multiple cellular sites to regulate cell function, shape, and growth. PMID:28115582

  4. The IQD Family of Calmodulin-Binding Proteins Links Calcium Signaling to Microtubules, Membrane Subdomains, and the Nucleus.

    Science.gov (United States)

    Bürstenbinder, Katharina; Möller, Birgit; Plötner, Romina; Stamm, Gina; Hause, Gerd; Mitra, Dipannita; Abel, Steffen

    2017-03-01

    Calcium (Ca 2+ ) signaling and dynamic reorganization of the cytoskeleton are essential processes for the coordination and control of plant cell shape and cell growth. Calmodulin (CaM) and closely related calmodulin-like (CML) polypeptides are principal sensors of Ca 2+ signals. CaM/CMLs decode and relay information encrypted by the second messenger via differential interactions with a wide spectrum of targets to modulate their diverse biochemical activities. The plant-specific IQ67 DOMAIN (IQD) family emerged as possibly the largest class of CaM-interacting proteins with undefined molecular functions and biological roles. Here, we show that the 33 members of the IQD family in Arabidopsis ( Arabidopsis thaliana ) differentially localize, using green fluorescent protein (GFP)-tagged proteins, to multiple and distinct subcellular sites, including microtubule (MT) arrays, plasma membrane subdomains, and nuclear compartments. Intriguingly, the various IQD-specific localization patterns coincide with the subcellular patterns of IQD-dependent recruitment of CaM, suggesting that the diverse IQD members sequester Ca 2+ -CaM signaling modules to specific subcellular sites for precise regulation of Ca 2+ -dependent processes. Because MT localization is a hallmark of most IQD family members, we quantitatively analyzed GFP-labeled MT arrays in Nicotiana benthamiana cells transiently expressing GFP-IQD fusions and observed IQD-specific MT patterns, which point to a role of IQDs in MT organization and dynamics. Indeed, stable overexpression of select IQD proteins in Arabidopsis altered cellular MT orientation, cell shape, and organ morphology. Because IQDs share biochemical properties with scaffold proteins, we propose that IQD families provide an assortment of platform proteins for integrating CaM-dependent Ca 2+ signaling at multiple cellular sites to regulate cell function, shape, and growth. © 2017 American Society of Plant Biologists. All Rights Reserved.

  5. Removal of 89Sr and 137Cs from effluents with considerable content of calcium by ion exchange on synthetic resins

    International Nuclear Information System (INIS)

    Svabic, A.; Vukovic, Z.; Bojovic, P.

    1964-10-01

    Decontamination factors for 89 Sr and 137 Cs from synthetic solutions with considerable contents of calcium, and calcium and magnesium were determined. The decontamination for different ratios of calcium concentrations to concentrations of the above two radioelements, then as a function of the velocity of flow of the solution through the column, i.e. the time of solution-resin contact, the geometry of the column and the pH of the solution. The saturated columns on which the above radioactive isotopes were accumulated were regenerated with a NaCl solution of different concentrations. Conditions were investigated under which the best regeneration is obtained with the least possible quantity of NaCl, thus allowing the obtaining of a considerable degree of radioactive effluent concentration and the possibility of using the resins several times (author)

  6. New tumoricidal semisynthetic ether phospholipid, plasmanyl-(N-acyl)ethanolamine (PNAE(s)) and enhancement of its tumoricidal activity by calcium ions.

    Science.gov (United States)

    Kára, J; Konovalova, A L; Krasnova, M A; Liebl, V; Bejsovcová, L

    1993-01-01

    Recently we described a novel, nontoxic, natural ether phospholipid with selective antitumor activity, 1-0-alkyl-2-acyl-sn-glycero-3-phospho-(N-acyl)ethanolamine, i.e., plasmanyl-(N-acyl)ethanolamine (PNAE), isolated from ischemic tissue of chick embryo. The chemical structure of PNAE has been confirmed by partial synthesis. The semisynthetic preparation PNAE(s), 1-0-octadecyl-2-oleoyl-sn-glycero-3-phospho-(N-palmitoyl)ethanolamine, exhibited tumoricidal activity against human tumor cells T24 and mouse sarcoma cells Mcll as well as in vivo against murine sarcomas S-180 and Mcll. PNAE(s) selectively destroyed tumor cell membranes as has been demonstrated by scanning electron microscopy. The antitumor activity of PNAE(s) in vitro and in vivo was significantly enhanced by Ca2+ ions. These results may be explained by selective damage of tumor cell membranes by PNAE(s), increasing also the tumor cell membrane permeability for exogenous Ca2+ ions and altering the intracellular calcium homeostasis in tumor cells. By increased concentration of Ca2+ in tumor cell cytosol selective damage and lysis of tumor cells was induced. The combined use of parenteral administration of PNAE(s) and peroral doses of calcium gluconate may provide a new approach to enhancement of antitumor activity of PNAE(s) by Ca2+ in a very selective and nontoxic antitumor therapy.

  7. Measurement of Cadmium Ion in the Presence of Metal-Binding Biopolymers in Aqueous Sample

    Directory of Open Access Journals (Sweden)

    Jian Pu

    2013-01-01

    Full Text Available In aqueous environment, water-soluble polymers are effectively used to separate free metal ions from metal-polymer complexes. The feasibilities of four different analytical techniques, cadmium ion-selective electrode, dialysis sack, chelate disk cartridge, and ultrafiltration, in distinguishing biopolymer-bound and nonbound cadmium in aqueous samples were investigated. And two different biopolymers were used, including bovine serum albumin (BSA and biopolymer solution extracted from cultivated activated sludge (ASBP. The ISE method requires relatively large amount of sample and contaminates sample during the pretreatment. After the long reaction time of dialysis, the equilibrium of cadmium in the dialysis sack would be shifted. Due to the sample nature, chelate disk cartridge could not filter within recommended time, which makes it unavailable for biopolymer use. Ultrafiltration method would not experience the difficulties mentioned above. Ultrafiltration method measuring both weakly and strongly bound cadmium was included in nominally biopolymer-cadmium complex. It had significant correlation with the Ion-selective electrode (ISE method (R2=0.989 for BSA, 0.985 for ASBP.

  8. Impact of citric acid and calcium ions on acid solubilization of mechanically separated turkey meat: effect on lipid and pigment content.

    Science.gov (United States)

    Hrynets, Y; Omana, D A; Xu, Y; Betti, M

    2011-02-01

    Increased demand for poultry products has resulted in an increased availability of by-products, such as the neck, back, and frame, that can be processed into mechanically separated poultry meat. The major problems with mechanically separated poultry meat are its high lipid content, color instability, and high susceptibility to lipid oxidation. The present work was undertaken to determine the effect of different concentrations of citric acid and calcium ions on protein yield, color characteristics, and lipid removal from protein isolates prepared using an acid-aided extraction process. Six levels of citric acid (0, 2, 4, 6, 8, and 10 mmol/L) and 2 levels of calcium chloride (0 and 8 mmol/L) were examined. The entire experiment was replicated 3 times, resulting in 36 extractions (3 × 6 × 2). The highest (P turkey meat, ranging from 86.2 to 94.7%. The lowest amount (1.14%) of total lipids obtained was for samples treated with 4 mmol/L of citric acid. Maximum removal of neutral lipids (96.5%) and polar lipids (96.4%) was attained with the addition of 6 and 2 mmol/L of citric acid, respectively. Polar lipid content was found to be significantly (P = 0.0045) affected by the presence of calcium chloride. The isolated proteins were less (P turkey meat. The most efficient removal of total heme pigment was obtained with the addition of 6 or 8 mmol/L of citric acid. Addition of calcium chloride had a negative effect on total pigment content. The study revealed that acid extractions with the addition of citric acid resulted in substantial removal of lipids and pigments from mechanically separated turkey meat, improved stability of the recovered proteins against lipid oxidation, and appreciable protein recovery yields.

  9. Metal ion coupled protein folding and allosteric motions

    Science.gov (United States)

    Wang, Wei

    2014-03-01

    Many proteins need the help of cofactors for their successful folding and functioning. Metal ions, i.e., Zn2+, Ca2+, and Mg2+ etc., are typical biological cofactors. Binding of metal ions can reshape the energy landscapes of proteins, thereby modifying the folding and allosteric motions. For example, such binding may make the intrinsically disordered proteins have funneled energy landscapes, consequently, ensures their spontaneous folding. In addition, the binding may activate certain biological processes by inducing related conformational changes of regulation proteins. However, how the local interactions involving the metal ion binding can induce the global conformational motions of proteins remains elusive. Investigating such question requires multiple models with different details, including quantum mechanics, atomistic models, and coarse grained models. In our recent work, we have been developing such multiscale methods which can reasonably model the metal ion binding induced charge transfer, protonation/deprotonation, and large conformational motions of proteins. With such multiscale model, we elucidated the zinc-binding induced folding mechanism of classical zinc finger and the calcium-binding induced dynamic symmetry breaking in the allosteric motions of calmodulin. In addition, we studied the coupling of folding, calcium binding and allosteric motions of calmodulin domains. In this talk, I will introduce the above progresses on the metal ion coupled protein folding and allosteric motions. We thank the finacial support from NSFC and the 973 project.

  10. Differential sensitivity of [3H]nitrendipine binding to cations of toxicological interest in various rat brain areas

    International Nuclear Information System (INIS)

    Rius, R.A.; Govoni, S.; Battaini, F.

    1985-01-01

    [ 3 H]Nitrendipine ([ 3 H]NTP) is a radiolabelled calcium antagonist which can be used to study neuronal calcium (Ca 2+ ) channels. The interaction of Mn 2+ , Zn 2+ , Pb 2+ and La 3+ on [ 3 H]NTP binding was studied in 3 brain areas particularly rich in [ 3 H]NTP binding sites. Differences were observed in the brain regional distribution of [ 3 H]NTP binding as well as in their sensitivity to the metal ions Pb, Mn and Zn. The binding data suggest that neuronal Ca 2+ channels in different brain areas display distinct sensitivity to selected divalent cations. (Auth.)

  11. Selective binding of oligonucleotide on TiO{sub 2} surfaces modified by swift heavy ion beam lithography

    Energy Technology Data Exchange (ETDEWEB)

    Vicente Pérez-Girón, J. [Nanoate, S.L. C/Poeta Rafael Morales 2, San Sebastian de los Reyes, 28702 Madrid (Spain); Emerging Viruses Department Heinrich Pette Institute, Hamburg 20251 (Germany); Hirtz, M. [Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology - KIT, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); McAtamney, C.; Bell, A.P. [Advanced Microscopy Laboratory, CRANN, Trinity College Dublin, Dublin 2 (Ireland); Antonio Mas, J. [Laboratorio de Genómica del Centro de Apoyo Tecnológico, Universidad Rey Juan Carlos, Campus de Alcorcón 28922, Madrid (Spain); Jaafar, M. [Nanoate, S.L. C/Poeta Rafael Morales 2, San Sebastian de los Reyes, 28702 Madrid (Spain); Departamento de Física de la Materia Condensada, Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Cantoblanco, 28049 Madrid (Spain); Luis, O. de [Nanoate, S.L. C/Poeta Rafael Morales 2, San Sebastian de los Reyes, 28702 Madrid (Spain); Departamento de Bioquímica, Fisiología y Genética Molecular, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Campus de Alcorcón, 28922 Madrid (Spain); Fuchs, H. [Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility (KNMF), Karlsruhe Institute of Technology - KIT, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Physical Institute and Center for Nanotechnology (CeNTech), Wilhelm-Klemm-Straße 10, University of Münster (Germany); and others

    2014-11-15

    We have used swift heavy-ion beam based lithography to create patterned bio-functional surfaces on rutile TiO{sub 2} single crystals. The applied lithography method generates a permanent and well defined periodic structure of micrometre sized square holes having nanostructured TiO{sub 2} surfaces, presenting different physical and chemical properties compared to the surrounding rutile single crystal surface. On the patterned substrates selective binding of oligonucleotides molecules is possible at the surfaces of the holes. This immobilisation process is only being controlled by UV light exposure. The patterned transparent substrates are compatible with fluorescence detection techniques, are mechanically robust, have a high tolerance to extreme chemical and temperature environments, and apparently do not degrade after ten cycles of use. These qualities make the patterned TiO{sub 2} substrates useful for potential biosensor applications.

  12. Consequences of activating the calcium-permeable ion channel TRPV1 in breast cancer cells with regulated TRPV1 expression.

    Science.gov (United States)

    Wu, Tina T L; Peters, Amelia A; Tan, Ping T; Roberts-Thomson, Sarah J; Monteith, Gregory R

    2014-08-01

    Increased expression of specific calcium channels in some cancers and the role of calcium signaling in proliferation and invasion have led to studies assessing calcium channel inhibitors as potential therapies for some cancers. The use of channel activators to promote death of cancer cells has been suggested, but the risk of activators promoting cancer cell proliferation and the importance of the degree of channel over-expression is unclear. We developed an MCF-7 breast cancer cell line with inducible TRPV1 overexpression and assessed the role of TRPV1 levels on cell death mediated by the TRPV1 activator capsaicin and the potential for submaximal activation to promote proliferation. The TRPV1 level was a determinant of cell death induced by capsaicin. A concentration response curve with varying TRPV1 expression levels identified the minimum level of TRPV1 required for capsaicin induced cell death. At no level of TRPV1 over-expression or capsaicin concentration did TRPV1 activation enhance proliferation. Cell death induced by capsaicin was necrotic and associated with up-regulation of c-Fos and RIP3. These studies suggest that activators of specific calcium channels may be an effective way to induce necrosis and that this approach may not always be associated with enhancement of cancer cell proliferation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Calcium Intake and Ion Transporter Genetic Polymorphisms Interact in Human Colorectal Neoplasia Risk in a 2-Phase Study123

    Science.gov (United States)

    Zhu, Xiangzhu; Liang, Ji; Shrubsole, Martha J.; Ness, Reid M.; Cai, Qiuyin; Long, Jirong; Chen, Zhi; Li, Guoliang; Wiese, Dawn; Zhang, Bing; Smalley, Walter E.; Edwards, Todd L.; Giovannucci, Edward; Zheng, Wei; Dai, Qi

    2014-01-01

    Background: The kidney-specific sodium-potassium-chloride cotransporter (NKCC2) protein encoded by solute carrier family 12 member 1 (SLC12A1) is the direct downstream effector of the inward-rectifier potassium channel (ROMK) encoded by potassium inwardly-rectifying channel, subfamily J, member 1 (KCNJ1), both of which are critical for calcium reabsorption in the kidney. Objective: We hypothesized that polymorphisms in KCNJ1, SLC12A1, and 7 other genes may modify the association between calcium intake and colorectal neoplasia risk. Methods: We conducted a 2-phase study in 1336 cases and 2891 controls from the Tennessee Colorectal Polyp Study. Results: In phase I, we identified 5 single-nucleotide polymorphisms (SNPs) that significantly interacted with calcium intake in adenoma risk. In phase II, rs2855798 in KCNJ1 was replicated. In combined analysis of phases I and II, the P values for interactions between calcium intake and rs2855798 were 1 × 10−4 for all adenoma and 5 × 10−3 for multiple/advanced adenoma. The highest calcium intake was not associated with risk among those with no variant allele but was significantly associated with a 41% reduced adenoma risk among those who carried at least 1 variant allele in KCNJ1. The corresponding reduction in risk of multiple or advanced adenomas was 52% among those with at least 1 variant allele. The P values for interactions between calcium intake and combined SNPs from the KCNJ1 and SLC12A1 genes were 7.5 × 10−5 for adenoma and 9.9 × 10−5 for multiple/advanced adenoma. The highest calcium intake was not associated with risk among those with nonvariant alleles in 2 genes but was significantly associated with a 34% reduced adenoma risk among those who carried a variant allele in 1 of the genes. The corresponding reduction in risk of multiple or advanced adenomas was 64% among those with variant alleles in both genes. Conclusion: These findings, if confirmed, will be critical for the development of personalized

  14. El ion calcio: su regulación y función en la célula ß pancreática Ion calcium: its regulation and function in the pancreatic cell

    Directory of Open Access Journals (Sweden)

    Oscar Díaz Horta

    2003-12-01

    Full Text Available En el presente trabajo se realiza una revisión del conocimiento actual sobre la regulación de las concentraciones intracelulares del ion calcio, los principales mecanismos de entrada y salida de este a través de la membrana plasmática, con especial atención en el intercambiador Na+/Ca2+, y la función de este importante segundo mensajero en la secreción de insulina, así como la muerte celular programada de las células ß pancreáticas.The present paper made a review of the present knowledge on regulation of intracellular concentrations of calcium ion, the main mechanisms of inlet/outlet through the plasma membrane, with special attention to Na+/Ca2+, and the function of this important second messenger in insulin secretion and in programmed cell death of pancreatic cells.

  15. Lanthanide ion containing polymers; investigation of the ion binding properties of tactic poly (methacrylic acid) and degradation of polymers by γ-irradiation using Tb3+ ion as a fluorescent probe

    International Nuclear Information System (INIS)

    Okamoto, Yoshiyuki; Lujan, H.; Cho, Myung D.

    1994-01-01

    Fluorescence properties of lanthanide ions, such as Tb 3+ and Eu 3+ , are extremely sensitive to their environment. Thus, the authors have studied ionomer structure and the ion binding properties of synthetic polyelectrolytes using a Tb 3+ fluorescence probe. They observed that the fluorescence intensity of the isotactic poly (methacrylic acid)-Tb 3+ complex was much larger than that of the syndiotactic poly (methacrylic acid)-Tb 3+ complex. The results indicated that isotactic PMA is bound more strongly with Tb 3+ ion than syndiotactic PMA. They have also investigated the degradation of various polymers in aqueous solution and in the solid state using Tb 3+ fluorescence probe. When poly(ethylene oxide) blended with TbCl 3 films were irradiated with γ-irradiation in air, the fluorescence intensity of Tb 3+ was found to be greatly increased. This result suggests that radiolysis caused chain degradation of PEO and produced carbonyl groups (aldehyde moiety) at the end of the cleaved polymer chain. The chromophore moiety produced transfers energy to the Tb 3+ ion sited within the non-radiative energy transfer distance. It is suggested that blended films of PEO with Tb 3+ may used as convenient and fast detectors of γ-irradiation doses

  16. The Recent Evolution of a Symbiotic Ion Channel in the Legume Family Altered Ion Conductance and Improved Functionality in Calcium Signaling[C][W

    Science.gov (United States)

    Venkateshwaran, Muthusubramanian; Cosme, Ana; Han, Lu; Banba, Mari; Satyshur, Kenneth A.; Schleiff, Enrico; Parniske, Martin; Imaizumi-Anraku, Haruko; Ané, Jean-Michel

    2012-01-01

    Arbuscular mycorrhiza and the rhizobia-legume symbiosis are two major root endosymbioses that facilitate plant nutrition. In Lotus japonicus, two symbiotic cation channels, CASTOR and POLLUX, are indispensable for the induction of nuclear calcium spiking, one of the earliest plant responses to symbiotic partner recognition. During recent evolution, a single amino acid substitution in DOES NOT MAKE INFECTIONS1 (DMI1), the POLLUX putative ortholog in the closely related Medicago truncatula, rendered the channel solo sufficient for symbiosis; castor, pollux, and castor pollux double mutants of L. japonicus were rescued by DMI1 alone, while both Lj-CASTOR and Lj-POLLUX were required for rescuing a dmi1 mutant of M. truncatula. Experimental replacement of the critical serine by an alanine in the selectivity filter of Lj-POLLUX conferred a symbiotic performance indistinguishable from DMI1. Electrophysiological characterization of DMI1 and Lj-CASTOR (wild-type and mutants) by planar lipid bilayer experiments combined with calcium imaging in Human Embryonic Kidney-293 cells expressing DMI1 (the wild type and mutants) suggest that the serine-to-alanine substitution conferred reduced conductance with a long open state to DMI1 and improved its efficiency in mediating calcium oscillations. We propose that this single amino acid replacement in the selectivity filter made DMI1 solo sufficient for symbiosis, thus explaining the selective advantage of this allele at the mechanistic level. PMID:22706284

  17. The recent evolution of a symbiotic ion channel in the legume family altered ion conductance and improved functionality in calcium signaling.

    Science.gov (United States)

    Venkateshwaran, Muthusubramanian; Cosme, Ana; Han, Lu; Banba, Mari; Satyshur, Kenneth A; Schleiff, Enrico; Parniske, Martin; Imaizumi-Anraku, Haruko; Ané, Jean-Michel

    2012-06-01

    Arbuscular mycorrhiza and the rhizobia-legume symbiosis are two major root endosymbioses that facilitate plant nutrition. In Lotus japonicus, two symbiotic cation channels, CASTOR and POLLUX, are indispensable for the induction of nuclear calcium spiking, one of the earliest plant responses to symbiotic partner recognition. During recent evolution, a single amino acid substitution in DOES NOT MAKE INFECTIONS1 (DMI1), the POLLUX putative ortholog in the closely related Medicago truncatula, rendered the channel solo sufficient for symbiosis; castor, pollux, and castor pollux double mutants of L. japonicus were rescued by DMI1 alone, while both Lj-CASTOR and Lj-POLLUX were required for rescuing a dmi1 mutant of M. truncatula. Experimental replacement of the critical serine by an alanine in the selectivity filter of Lj-POLLUX conferred a symbiotic performance indistinguishable from DMI1. Electrophysiological characterization of DMI1 and Lj-CASTOR (wild-type and mutants) by planar lipid bilayer experiments combined with calcium imaging in Human Embryonic Kidney-293 cells expressing DMI1 (the wild type and mutants) suggest that the serine-to-alanine substitution conferred reduced conductance with a long open state to DMI1 and improved its efficiency in mediating calcium oscillations. We propose that this single amino acid replacement in the selectivity filter made DMI1 solo sufficient for symbiosis, thus explaining the selective advantage of this allele at the mechanistic level.

  18. Density functional theory investigations on the binding modes of amidoximes with uranyl ions.

    Science.gov (United States)

    Yang, Chuting; Pei, Shuqi; Chen, Baihua; Ye, Lina; Yu, Haizhu; Hu, Sheng

    2016-02-21

    Density functional theory (DFT) calculations have been carried out to examine the relative facilities of different coordination modes of aromatic amidoximes (AOs) with UO2(NO3)2. Various η(1)-, η(2)- and chelated κ(2)-coordination modes of the possible neutral AO, tautomerized neutral (TAO, with the hydroxylic hydrogen transferring to the oximic nitrogen atom) and anionic amidoxime (AAO, formed by the deprotonation of AO) were examined. The results indicate that η(1)-O of the TAO and η(1)-O/η(2)-NO of AAO are the most plausible coordination modes. Three types of uranyl complexes, i.e. UO2(NO3)2(TAO)(AAO), UO2(NO3)2(AAO)2 and UO2(EtOH)2(AAO)2 are the predominant binding structures. The good consistency between the calculation results and the experimental observations verifies the proposed conclusions.

  19. Application of equilibrium binding model for analysis of conformational transitions in poly(rA)poly(rU) complexes with metal ions

    OpenAIRE

    Sorokin V. A.; Gladchenko G. O.; Usenko E. L.; Egupov S. A.; Blagoi Yu. P.

    2010-01-01

    Aim. The study is aimed at generalization of the previous experimental results on the metal ion (Mg2+, Ni2+, Cd2+) effects on conformation transitions in poly(rA)·poly(rU). The objective was to find out how the type of a metal ion-polynucleotide complex influences the phase transitions and to estimate the constants (K) of ions binding to polymers of different structures. Methods. The K values were obtained upon theoretical and experimental transition temperature fitting by the least-square me...

  20. Making sense with TRP channels: store-operated calcium entry and the ion channel Trpm5 in taste receptor cells.

    Science.gov (United States)

    Pérez, Cristian A; Margolskee, Robert F; Kinnamon, Sue C; Ogura, Tatsuya

    2003-01-01

    The sense of taste plays a critical role in the life and nutritional status of organisms. During the last decade, several molecules involved in taste detection and transduction have been identified, providing a better understanding of the molecular physiology of taste receptor cells. However, a comprehensive catalogue of the taste receptor cell signaling machinery is still unavailable. We have recently described the occurrence of calcium signaling mechanisms in taste receptor cells via apparent store-operated channels and identified Trpm5, a novel candidate taste transduction element belonging to the mammalian family of transient receptor potential channels. Trpm5 is expressed in a tissue-restricted manner, with high levels in gustatory tissue. In taste cells, Trpm5 is co-expressed with taste-signaling molecules such as alpha-gustducin, Ggamma(13), phospholipase C beta(2) and inositol 1,4,5-trisphosphate receptor type III. Biophysical studies of Trpm5 heterologously expressed in Xenopus oocytes and mammalian CHO-K1 cells indicate that it functions as a store-operated channel that mediates capacitative calcium entry. The role of store-operated channels and Trpm5 in capacitative calcium entry in taste receptor cells in response to bitter compounds is discussed.

  1. Electron binding energies of aqueous alkali and halide ions: EUV photoelectron spectroscopy of liquid solutions and combined ab initio and molecular dynamics calculations.

    Science.gov (United States)

    Winter, Bernd; Weber, Ramona; Hertel, Ingolf V; Faubel, Manfred; Jungwirth, Pavel; Brown, Eric C; Bradforth, Stephen E

    2005-05-18

    Photoelectron spectroscopy combined with the liquid microjet technique enables the direct probing of the electronic structure of aqueous solutions. We report measured and calculated lowest vertical electron binding energies of aqueous alkali cations and halide anions. In some cases, ejection from deeper electronic levels of the solute could be observed. Electron binding energies of a given aqueous ion are found to be independent of the counterion and the salt concentration. The experimental results are complemented by ab initio calculations, at the MP2 and CCSD(T) level, of the ionization energies of these prototype ions in the aqueous phase. The solvent effect was accounted for in the electronic structure calculations in two ways. An explicit inclusion of discrete water molecules using a set of snapshots from an equilibrium classical molecular dynamics simulations and a fractional charge representation of solvent molecules give good results for halide ions. The electron binding energies of alkali cations computed with this approach tend to be overestimated. On the other hand, the polarizable continuum model, which strictly provides adiabatic binding energies, performs well for the alkali cations but fails for the halides. Photon energies in the experiment were in the EUV region (typically 100 eV) for which the technique is probing the top layers of the liquid sample. Hence, the reported energies of aqueous ions are closely connected with both structures and chemical reactivity at the liquid interface, for example, in atmospheric aerosol particles, as well as fundamental bulk solvation properties.

  2. Growth of etiolated barley plants in weak static and 50 Hz electromagnetic fields tuned to calcium ion cyclotron resonance

    OpenAIRE

    Pazur, Alexander; Rassadina, Valentina; Dandler, Jörg; Zoller, Jutta

    2006-01-01

    Background The effects of weak magnetic and electromagnetic fields in biology have been intensively studied on animals, microorganisms and humans, but comparably less on plants. Perception mechanisms were attributed originally to ferrimagnetism, but later discoveries required additional explanations like the "radical pair mechanism" and the "Ion cyclotron resonance" (ICR), primarily considered by Liboff. The latter predicts effects by small ions involved in biological processes, that occur in...

  3. Application of equilibrium binding model for analysis of conformational transitions in poly(rApoly(rU complexes with metal ions

    Directory of Open Access Journals (Sweden)

    Sorokin V. A.

    2010-09-01

    Full Text Available Aim. The study is aimed at generalization of the previous experimental results on the metal ion (Mg2+, Ni2+, Cd2+ effects on conformation transitions in poly(rA·poly(rU. The objective was to find out how the type of a metal ion-polynucleotide complex influences the phase transitions and to estimate the constants (K of ions binding to polymers of different structures. Methods. The K values were obtained upon theoretical and experimental transition temperature fitting by the least-square method with the root mean square deviation minimized through the procedure of the gradient descent in the multidimensional space. Results. Calcula- tions of diagrams with Mg2+ are shown to permit obtaining satisfactory results if concentration-independent, mean values of constants are used. For Ni2+ and Cd2+ the concentration dependence of K must be taken into account, especially for high ion contents at which compaction of single-stranded poly(rA emerges. It was revealed that the main factor responsible for the differences in diagrams with Ni2+ and Cd2+ is a significant distinction of their constants of binding to poly(rA and poly(rU. Conclusions. The model theory of equilibrium binding is capable to describe adequately conformation transitions in polynucleotides in the presence of metal ions.

  4. The Role of Magnesium and Calcium in Governing Yeast Agglomeration

    Directory of Open Access Journals (Sweden)

    Rosslyn M. Birch

    2002-01-01

    Full Text Available »Grit« formation by agglomerating cells of baker’s yeast is an idiosyncratic phenomenon of irreversible cellular aggregation that is detrimental to yeast quality. Agglomeration results in failure of rehydrated dried yeast to evenly resuspend and has economic consequences for both yeast manufacturers and bakers. Several environmental factors are implicated in governing yeast agglomeration, but no significant differences between 'gritty' and 'non-gritty' yeast in terms of cell hydrophobicity or flocculence have been reported. In this study, analysis of cellular metal ions has revealed high levels of calcium in 'gritty' strains of Saccharomyces cerevisiae, which suggests that calcium ions may positively influence agglomeration. In contrast, it was found that cellular magnesium levels were higher in 'non-gritty' yeast. Furthermore, by increasing magnesium concentrations in molasses yeast growth media, a reduction in cellular calcium was observed and this concomitantly reduced the tendency of cells to agglomerate and form grit. Magnesium thus acted antagonistically against calcium-induced agglomeration, possibly by blocking calcium binding to yeast cell surface receptors. Results suggested that yeast agglomeration and metal ion bioavailability were inextricably linked and the findings are discussed in relation to possible measures of alleviating cellular agglomeration in the production of baker’s yeast.

  5. Electron Ion Collider: The Next QCD Frontier - Understanding the glue that binds us all

    CERN Document Server

    Accardi, A.; Anselmino, M.; Armesto, N.; Aschenauer, E.C.; Bacchetta, A.; Boer, D.; Brooks, W.K.; Burton, T.; Chang, N.B.; Deng, W.T.; Deshpande, A.; Diehl, M.; Dumitru, A.; Dupré, R.; Ent, R.; Fazio, S.; Gao, H.; Guzey, V.; Hakobyan, H.; Hao, Y.; Hasch, D.; Holt, R.; Horn, T.; Huang, M.; Hutton, A.; Hyde, C.; Jalilian-Marian, J.; Klein, S.; Kopeliovich, B.; Kovchegov, Y.; Kumar, K.; Kumerički, K.; Lamont, M.A.C.; Lappi, T.; Lee, J.H.; Lee, Y.; Levin, E.M.; Lin, F.L.; Litvinenko, V.; Ludlam, T.W.; Marquet, C.; Meziani, Z.E.; McKeown, R.; Metz, A.; Milner, R.; Morozov, V.S.; Mueller, A.H.; Müller, B.; Müller, Dieter; Nadel-Turonski, P.; Paukkunen, H.; Prokudin, A.; Ptitsyn, V.; Qian, X.; Qiu, J.W.; Ramsey-Musolf, M.; Roser, T.; Sabatié, F.; Sassot, R.; Schnell, G.; Schweitzer, P.; Sichtermann, E.; Stratmann, M.; Strikman, M.; Sullivan, M.; Taneja, S.; Toll, T.; Trbojevic, D.; Ullrich, T.; Venugopalan, R.; Vigdor, S.; Vogelsang, W.; Weiss, C.; Xiao, B.W.; Yuan, F.; Zhang, Y.H.; Zheng, L.

    2016-01-01

    This White Paper presents the science case of an Electron-Ion Collider (EIC), focused on the structure and interactions of gluon-dominated matter, with the intent to articulate it to the broader nuclear science community. It was commissioned by the managements of Brookhaven National Laboratory (BNL) and Thomas Jefferson National Accelerator Facility (JLab) with the objective of presenting a summary of scientific opportunities and goals of the EIC as a follow-up to the 2007 NSAC Long Range plan. This document is a culmination of a community-wide effort in nuclear science following a series of workshops on EIC physics and, in particular, the focused ten-week program on "Gluons and quark sea at high energies" at the Institute for Nuclear Theory in Fall 2010. It contains a brief description of a few golden physics measurements along with accelerator and detector concepts required to achieve them, and it benefited from inputs from the users' communities of BNL and JLab. This White Paper offers the promise to prope...

  6. Antiviral activity and metal ion-binding properties of some 2-hydroxy-3-methoxyphenyl acylhydrazones.

    Science.gov (United States)

    Carcelli, M; Fisicaro, E; Compari, C; Contardi, L; Rogolino, D; Solinas, C; Stevaert, A; Naesens, L

    2018-02-01

    Here we report on the results obtained from an antiviral screening, including herpes simplex virus, vaccinia virus, vesicular stomatitis virus, Coxsackie B4 virus or respiratory syncytial virus, parainfluenza-3 virus, reovirus-1 and Punta Toro virus, of three 2-hydroxy-3-methoxyphenyl acylhydrazone compounds in three cell lines (i.e. human embryonic lung fibroblast cells, human cervix carcinoma cells, and African Green monkey kidney cells). Interesting antiviral EC 50 values are obtained against herpes simplex virus-1 and vaccinia virus. The biological activity of acylhydrazones is often attributed to their metal coordinating abilities, so potentiometric and microcalorimetric studies are here discussed to unravel the behavior of the three 2-hydroxy-3-methoxyphenyl compounds in solution. It is worth of note that the acylhydrazone with the higher affinity for Cu(II) ions shows the best antiviral activity against herpes simplex and vaccinia virus (EC 50  ~ 1.5 µM, minimal cytotoxic concentration = 60 µM, selectivity index = 40).

  7. Evaluation of pH and calcium ion release of a dual-cure bisphenol A ethoxylate dimethacrylate/mineral trioxide aggregate-based root-end filling material.

    Science.gov (United States)

    Linhares, Giane da Silva; Cenci, Maximiliano Sérgio; Knabach, César Blaas; Oliz, Camila Mizette; Vieira, Mariana Antunes; Ribeiro, Anderson Schwingel; Zanchi, César Henrique; Jacinto, Rogério Castilho

    2013-12-01

    The incorporation of light-curable resins has been proposed for mineral trioxide aggregate (MTA) to improve its properties and reduce its setting time. The aim of the present study was to assess the pH and calcium ion release of an experimental bisphenol A ethoxylate dimethacrylate/MTA-based root-end filling material (E-MTA) in comparison with white MTA Angelus (Angelus, Londrina, PR, Brazil) (W-MTA) and to evaluate the influence of the addition of calcium chloride (CaCl2) on these properties. Polyethylene tubes filled with the materials were immersed in deionized water for the measurement of pH (digital pH meter) and calcium release (atomic absorption spectrophotometry). The evaluations were performed at 3 and 24 hours and 7, 15, and 30 days. Data were measured using 2-way repeated measures of variance followed by the Holm-Sidak method (P MTA showed a significantly lower calcium ion release capacity when compared with W-MTA (P MTA + 5% CaCl2 was similar to W-MTA (P > .05). The monomer bisphenol A ethoxylate dimethacrylate added to MTA formed a material with a lower capacity of calcium release than W-MTA despite maintaining a similar pH. However, the addition of CaCl2 improved the calcium release of this material. Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  8. Effects of calcium phosphate coating to SLA surface implants by the ion-beam-assisted deposition method on self-contained coronal defect healing in dogs

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Heun-Joo; Song, Ji-Eun; Um, Yoo-Jung; Chae, Gyung Joon; Jung, Ui-Won; Kim, Chang-Sung; Choi, Seong-Ho [Department of Periodontology, Research Institute for Periodontal Regeneration, College of Dentistry, Yonsei University, 134 Shinchon-Dong, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Chung, Sung-Min [Dentium Co., Seoul (Korea, Republic of); Lee, In-Seop, E-mail: shchoi726@yuhs.a [Institute of Physics and Applied Physics, Atomic-scale Surface Science Research Center, Yonsei University, Seoul (Korea, Republic of)

    2009-08-15

    The aim of this study was to evaluate the healing of self-contained coronal defects on a sand-blasted, large-grit, acid-etched (SLA) surface implant, which had a calcium phosphate (CaP) coating applied by ion-beam-assisted deposition (IBAD). We also evaluated the effect of heating the coating to different temperatures. The CaP-coated SLA implants exhibited a slightly larger bone healing capacity in the self-contained coronal defect than SLA implants, indicating that combining SLA surface implants and a CaP coating by the IBAD method had synergistic effects on bone healing. There was no difference in the healing capacity between 350 deg. C and 450 deg. C heat treatment of the coating layer.

  9. Calcium channel activity of purified human synexin and structure of the human synexin gene

    International Nuclear Information System (INIS)

    Burns, A.L.; Magendzo, K.; Shirvan, A.; Srivastava, M.; Rojas, E.; Alijani, M.R.; Pollard, H.B.

    1989-01-01

    Synexin is a calcium-dependent membrane binding protein that not only fuses membranes but also acts as a voltage-dependent calcium channel. The authors have isolated and sequenced a set of overlapping cDNA clones for human synexin. The derived amino acid sequence of synexin reveals strong homology in the C-terminal domain with a previously identified class of calcium-dependent membrane binding proteins. These include endonexin II, lipocortin I, calpactin I heavy chain (p36), protein II, and calelectrin 67K. The M r 51,000 synexin molecule can be divided into a unique, highly hydrophobic N-terminal domain of 167 amino acids and a conserved C-terminal region of 299 amino acids. The latter domain is composed of alternating hydrophobic and hydrophilic segments. Analysis of the entire structure reveals possible insights into such diverse properties as voltage-sensitive calcium channel activity, ion selectivity, affinity for phospholipids, and membrane fusion

  10. Variation in one residue associated with the metal ion-dependent adhesion site regulates αIIbβ3 integrin ligand binding affinity.

    Directory of Open Access Journals (Sweden)

    Joel Raborn

    Full Text Available The Asp of the RGD motif of the ligand coordinates with the β I domain metal ion dependent adhesion site (MIDAS divalent cation, emphasizing the importance of the MIDAS in ligand binding. There appears to be two distinct groups of integrins that differ in their ligand binding affinity and adhesion ability. These differences may be due to a specific residue associated with the MIDAS, particularly the β3 residue Ala(252 and corresponding Ala in the β1 integrin compared to the analogous Asp residue in the β2 and β7 integrins. Interestingly, mutations in the adjacent to MIDAS (ADMIDAS of integrins α4β7 and αLβ2 increased the binding and adhesion abilities compared to the wild-type, while the same mutations in the α2β1, α5β1, αVβ3, and αIIbβ3 integrins demonstrated decreased ligand binding and adhesion. We introduced a mutation in the αIIbβ3 to convert this MIDAS associated Ala(252 to Asp. By combination of this mutant with mutations of one or two ADMIDAS residues, we studied the effects of this residue on ligand binding and adhesion. Then, we performed molecular dynamics simulations on the wild-type and mutant αIIbβ3 integrin β I domains, and investigated the dynamics of metal ion binding sites in different integrin-RGD complexes. We found that the tendency of calculated binding free energies was in excellent agreement with the experimental results, suggesting that the variation in this MIDAS associated residue accounts for the differences in ligand binding and adhesion among different integrins, and it accounts for the conflicting results of ADMIDAS mutations within different integrins. This study sheds more light on the role of the MIDAS associated residue pertaining to ligand binding and adhesion and suggests that this residue may play a pivotal role in integrin-mediated cell rolling and firm adhesion.

  11. Prenatal acoustic stimulation influences neuronal size and the expression of calcium-binding proteins (calbindin D-28K and parvalbumin) in chick hippocampus.

    Science.gov (United States)

    Chaudhury, Sraboni; Nag, Tapas Chandra; Wadhwa, Shashi

    2006-12-01

    Prenatal auditory enrichment by species-specific sounds and sitar music enhances the expression of immediate early genes, synaptic proteins and calcium binding proteins (CaBPs) as well as modifies the structural components of the brainstem auditory nuclei and auditory imprinting area in chicks. There is also facilitation of postnatal auditory preference of the chicks to maternal calls following both types of sound stimulation indicating prenatal perceptual learning. To examine whether the sound enrichment protocol also affects the areas related to learning and memory, we assessed morphological changes in the hippocampus at post-hatch day 1 of control and prenatally sound-stimulated chicks. Additionally, the proportions of neurons containing calbindin D-28K and parvalbumin immunoreactivity as well as their protein levels were determined. Fertilized eggs of domestic chick were incubated under normal conditions of temperature, humidity, forced draft of air as well as light and dark (12:12h) photoperiods. They were exposed to patterned sounds of species-specific and sitar music at 65 dB for 15 min per hour over a day/night cycle from day 10 of incubation till hatching. The hippocampal volume, neuronal nuclear size and total number of neurons showed a significant increase in the music-stimulated group as compared to the species-specific sound-stimulated and control groups. However, in both the auditory-stimulated groups the protein levels of calbindin and parvalbumin as well as the percentage of the immunopositive neurons were increased. The enhanced proportion of CaBPs in the sound-enriched groups suggests greater Ca(2+) influx, which may influence long-term potentiation and short-term memory.

  12. Removal of Heavy Metal Ions by using Calcium Carbonate Extracted from Starfish Treated by Protease and Amylase

    Directory of Open Access Journals (Sweden)

    Kyong-Soo Hong

    2011-10-01

    Full Text Available CaCO3 extracted from starfish by using the commercial protein lyase having α-amylase, β-amylase, and protease is applied to remove heavy metal ions. The extracted CaCO3 shows excellent characteristics in removing heavy metal ions such as Cu2+, Cd2+, Pb2+, and Cr6+ compared with conventional materials such as crab shells, sawdust, and activated carbon except for removing Zn2+. SEM images reveal that the extracted CaCO33 has a good morphology and porosity. We characterize the removal efficiencies of the extracted CaCO3 for the heavy metal ions according to the concentrations, pH, temperatures, and conditions of empty bed contact times.

  13. The hemodynamic effect of calcium ion concentration in the infusate during predilution hemofiltration in chronic renal failure

    DEFF Research Database (Denmark)

    Karamperis, N.; Sloth, E.; Jensen, Jens Dam

    2005-01-01

    [SBP], and diastolic blood pressure [DBP]), pulse rate, arterial and venous temperature, energy transfer, and relative blood volume were measured at 15-minute intervals. Cardiac output, total peripheral resistance, stroke volume, and iCa were measured hourly. The 2 treatments were matched......Eq/L (1.25 mmol/L; low-calcium session [L-HF]) or 3.5 mEq/L (1.75 mmol/L; high-calcium session [H-HF]) during 4.5 hours of predilution HF with a volume of 1.24 +/- 0.09 L/kg dry body weight and a temperature of 37 degrees C. Ultrafiltration was kept constant in each patient. Blood pressure (mean, systolic...... with the exception of iCa concentration. RESULTS: A significant intratreatment reduction in cardiac output and stroke volume was shown to the same extent for both groups. Intertreatment comparisons showed a significantly lower mean arterial pressure, SBP, DBP, and total peripheral resistance in the L-HF compared...

  14. Labeling by ( sup 3 H)1,3-di(2-tolyl)guanidine of two high affinity binding sites in guinea pig brain: Evidence for allosteric regulation by calcium channel antagonists and pseudoallosteric modulation by sigma ligands

    Energy Technology Data Exchange (ETDEWEB)

    Rothman, R.B.; Reid, A.; Mahboubi, A.; Kim, C.H.; De Costa, B.R.; Jacobson, A.E.; Rice, K.C. (National Institute of Mental Health, Bethesda, MD (USA))

    1991-02-01

    Equilibrium binding studies with the sigma receptor ligand ({sup 3}H)1,3-di(2-tolyl)guanidine (({sup 3}H)DTG) demonstrated two high affinity binding sites in membranes prepared from guinea pig brain. The apparent Kd values of DTG for sites 1 and 2 were 11.9 and 37.6 nM, respectively. The corresponding Bmax values were 1045 and 1423 fmol/mg of protein. Site 1 had high affinity for (+)-pentazocine, haloperidol, (R)-(+)-PPP, carbepentane, and other sigma ligands, suggesting a similarity with the dextromethorphan/sigma 1 binding site described by Musacchio et al. (Life Sci. 45:1721-1732 (1989)). Site 2 had high affinity for DTG and haloperidol (Ki = 36.1 nM) and low affinity for most other sigma ligands. Kinetic experiments demonstrated that ({sup 3}H)DTG dissociated in a biphasic manner from both site 1 and site 2. DTG and haloperidol increased the dissociation rate of ({sup 3}H)DTG from site 1 and site 2, demonstrating the presence of pseudoallosteric interactions. Inorganic calcium channel blockers such as Cd2+ selectively increased the dissociation rate of ({sup 3}H)DTG from site 2, suggesting an association of this binding site with calcium channels.

  15. Energy loss and charge state distribution of calcium ions in dense moderately coupled carbon plasma; Energieverlust und Ladungsverteilung von Calciumionen in dichtem, schwach gekoppeltem Kohlenstoffplasma

    Energy Technology Data Exchange (ETDEWEB)

    Ortner, Alex

    2015-07-15

    In this thesis the interaction of swift calcium ions (Energy: 3.5 MeV/u) with a dense and moderately coupled carbon plasma (Coupling parameter: Γ=0.1-0.5) is investigated. The plasma state is generated by heating a thin carbon foil volumetrically by thermal X-ray radiation. The thermal X-ray radiation itself is generated by the conversion of a high energy laser beam in a hohlraum cavity. Compared to earlier ion stopping experiments the electron density and the plasma coupling parameter could be increased by an order of magnitude. This work provides the first time experimental energy loss and charge state distribution data in this moderately coupled interaction regime. The thesis consists of a theoretical part where the ion beam plasma interaction is studied for a broad range of plasma parameters and an experimental part where the ion beam interaction with the hohlraum plasma target is measured. All the described experiments were carried out at the GSI Helmholtzzentrum fuer Schwerionenforschung in Darmstadt. This facility offers the unique possibility to combine a heavy ion beam from an accelerator with a high energy laser beam in one interaction chamber. An intense laser pulse (150 J of laser energy in 1 ns at λ{sub L}=527 nm) is focused inside a 600 μm diameter spherical cavity and generates a hot gold plasma that emits X-rays. The absorbed and reemitted radiation establishes a spatially uniform temperature distribution in the cavity and serves as an intense, isotropic X-ray source with a quasi-thermal spectral distribution. These thermal X-rays with a radiation temperature of T{sub r}=98±6 eV then propagate into a secondary cylindrical hohlraum (diameter: 1000 μm, length: 950 μm) where they volumetrically heat two thin carbon foils to the plasma state. The radiation temperature in the secondary hohlraum is T{sub r}=33±5 eV. This indirect laser heating scheme has the advantage that the whole sample volume is instantaneously heated and that the plasma is

  16. Mutational analysis of the role of calcium ions in the Lactobacillus reuteri strain 121 fructosyltransferase (levansucrase and inulosucrase) enzymes

    NARCIS (Netherlands)

    Ozimek, L.K.; Euverink, G.J.W.; Maarel, M.J.E.C. van der; Dijkhuizen, L.

    2005-01-01

    Bacterial fructosyltransferase enzymes belonging to glycoside hydrolase family 68 (GH68) are not known to require a metal cofactor. Here, we show that Ca2+ ions play an important structural role in the Lactobacillus reuteri 121 levansucrase (Lev) and inulosucrase (Inu) enzymes. Analysis of the

  17. Zinc, magnesium, and calcium ion supplementation confers tolerance to acetic acid stress in industrial Saccharomyces cerevisiae utilizing xylose.

    Science.gov (United States)

    Ismail, Ku Syahidah Ku; Sakamoto, Takatoshi; Hasunuma, Tomohisa; Zhao, Xin-Qing; Kondo, Akihiko

    2014-12-01

    Lignocellulosic biomass is a potential substrate for ethanol production. However, pretreatment of lignocellulosic materials produces inhibitory compounds such as acetic acid, which negatively affect ethanol production by Saccharomyces cerevisiae. Supplementation of the medium with three metal ions (Zn(2+) , Mg(2+) , and Ca(2+) ) increased the tolerance of S. cerevisiae toward acetic acid compared to the absence of the ions. Ethanol production from xylose was most improved (by 34%) when the medium was supplemented with 2 mM Ca(2+) , followed by supplementation with 3.5 mM Mg(2+) (29% improvement), and 180 μM Zn(2+) (26% improvement). Higher ethanol production was linked to high cell viability in the presence of metal ions. Comparative transcriptomics between the supplemented cultures and the control suggested that improved cell viability resulted from the induction of genes controlling the cell wall and membrane. Only one gene, FIT2, was found to be up-regulated in common between the three metal ions. Also up-regulation of HXT1 and TKL1 might enhance xylose consumption in the presence of acetic acid. Thus, the addition of ionic nutrients is a simple and cost-effective method to improve the acetic acid tolerance of S. cerevisiae. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Calcium signaling in neurodegeneration

    Directory of Open Access Journals (Sweden)

    Dreses-Werringloer Ute

    2009-05-01

    Full Text Available Abstract Calcium is a key signaling ion involved in many different intracellular and extracellular processes ranging from synaptic activity to cell-cell communication and adhesion. The exact definition at the molecular level of the versatility of this ion has made overwhelming progress in the past several years and has been extensively reviewed. In the brain, calcium is fundamental in the control of synaptic activity and memory formation, a process that leads to the activation of specific calcium-dependent signal transduction pathways and implicates key protein effectors, such as CaMKs, MAPK/ERKs, and CREB. Properly controlled homeostasis of calcium signaling not only supports normal brain physiology but also maintains neuronal integrity and long-term cell survival. Emerging knowledge indicates that calcium homeostasis is not only critical for cell physiology and health, but also, when deregulated, can lead to neurodegeneration via complex and diverse mechanisms involved in selective neuronal impairments and death. The identification of several modulators of calcium homeostasis, such as presenilins and CALHM1, as potential factors involved in the pathogenesis of Alzheimer's disease, provides strong support for a role of calcium in neurodegeneration. These observations represent an important step towards understanding the molecular mechanisms of calcium signaling disturbances observed in different brain diseases such as Alzheimer's, Parkinson's, and Huntington's diseases.

  19. Desalted duck egg white peptides promote calcium uptake by counteracting the adverse effects of phytic acid.

    Science.gov (United States)

    Hou, Tao; Liu, Weiwei; Shi, Wen; Ma, Zhili; He, Hui

    2017-03-15

    The structure of the desalted duck egg white peptides-calcium chelate was characterized by fluorescence spectroscopy, fourier transform infrared spectroscopy, and dynamic light scattering. Characterization results showed structural folding and aggregation of amino acids or oligopeptides during the chelation process. Desalted duck egg white peptides enhanced the calcium uptake in the presence of oxalate, phosphate and zinc ions in Caco-2 monolayers. Animal model indicated that desalted duck egg white peptides effectively enhanced the mineral absorption and counteracted the deleterious effects of phytic acid. These findings suggested that desalted duck egg white peptides might promote calcium uptake in three pathways: 1) desalted duck egg white peptides bind with calcium to form soluble chelate and avoid precipitate; 2) the chelate is absorbed as small peptides by enterocyte; and 3) desalted duck egg white peptides regulate the proliferation and differentiation of enterocytes through the interaction with transient receptor potential vanilloid 6 calcium channel. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Sequential water molecule binding enthalpies for aqueous nanodrops containing a mono-, di- or trivalent ion and between 20 and 500 water molecules.

    Science.gov (United States)

    Heiles, Sven; Cooper, Richard J; DiTucci, Matthew J; Williams, Evan R

    2017-04-01

    Sequential water molecule binding enthalpies, Δ H n , n -1 , are important for a detailed understanding of competitive interactions between ions, water and solute molecules, and how these interactions affect physical properties of ion-containing nanodrops that are important in aerosol chemistry. Water molecule binding enthalpies have been measured for small clusters of many different ions, but these values for ion-containing nanodrops containing more than 20 water molecules are scarce. Here, Δ H n , n -1 values are deduced from high-precision ultraviolet photodissociation (UVPD) measurements as a function of ion identity, charge state and cluster size between 20-500 water molecules and for ions with +1, +2 and +3 charges. The Δ H n , n -1 values are obtained from the number of water molecules lost upon photoexcitation at a known wavelength, and modeling of the release of energy into the translational, rotational and vibrational motions of the products. The Δ H n , n -1 values range from 36.82 to 50.21 kJ mol -1 . For clusters containing more than ∼250 water molecules, the binding enthalpies are between the bulk heat of vaporization (44.8 kJ mol -1 ) and the sublimation enthalpy of bulk ice (51.0 kJ mol -1 ). These values depend on ion charge state for clusters with fewer than 150 water molecules, but there is a negligible dependence at larger size. There is a minimum in the Δ H n , n -1 values that depends on the cluster size and ion charge state, which can be attributed to the competing effects of ion solvation and surface energy. The experimental Δ H n , n -1 values can be fit to the Thomson liquid drop model (TLDM) using bulk ice parameters. By optimizing the surface tension and temperature change of the logarithmic partial pressure for the TLDM, the experimental sequential water molecule binding enthalpies can be fit with an accuracy of ±3.3 kJ mol -1 over the entire range of cluster sizes.

  1. Effects of water pH and calcium concentration on ion balance in fish of the Rio Negro, Amazon.

    Science.gov (United States)

    Gonzalez, R J; Wood, C M; Wilson, R W; Patrick, M L; Bergman, H L; Narahara, A; Val, A L

    1998-01-01

    We examined the effects of acute low-pH exposure on ion balance (Na+, Cl-, K+) in several species of fish captured from the Rio Negro, a dilute, acidic tributary of the Amazon. At pH 5.5 (untreated Rio Negro water), the four Rio Negro species tested (piranha preta, Serrasalmus rhombeus; piranha branca, Serrasalmus cf. holandi; aracu, Leporinus fasciatus; and pacu, Myleus sp.) were at or near ion balance; upon exposure to pH 3.5, while Na+ and Cl- loss rates became significant, they were relatively mild. In comparison, tambaqui (Colossoma macropomum), which were obtained from aquaculture and held and tested under the same conditions as the other fish, had loss rates seven times higher than all the Rio Negro species. At pH 3.0, rates of Na+ and Cl- loss for the Rio Negro fish increased three- to fivefold but were again much less than those observed in tambaqui. Raising water Ca2+ concentration from 10 micromol L-1 to 100 micromol L-1 during exposure to the same low pH's had no effect on rates of ion loss in the three species tested (piranha preta, piranha branca, aracu), which suggests that either they have such a high branchial affinity for Ca2+ that all sites are saturated at 10 micromol L-1 and additional Ca2+ had no effect, or that Ca2+ may not be involved in regulation of branchial ion permeability. For a final Rio Negro species, the cardinal tetra (Paracheirodon axelrodi), we monitored body Na+ concentration during 5 d of exposure to pH 6.0, 4.0, or 3.5. These pH's had no effect on body Na+ concentration. These data together suggest that exceptional acid tolerance is a general characteristic of fish that inhabit the dilute acidic Rio Negro and raise questions about the role of Ca2+ in regulation of branchial ion permeability in these fish.

  2. Effect of Metal Chelators on γ-Secretase Indicates That Calcium and Magnesium Ions Facilitate Cleavage of Alzheimer Amyloid Precursor Substrate

    Directory of Open Access Journals (Sweden)

    Michael Ho

    2011-01-01

    Full Text Available Gamma-secretase is involved in the production of Aβ amyloid peptides. It cleaves the transmembrane domain of the amyloid precursor protein (APP at alternative sites to produce Aβ and the APP intracellular domain (AICD. Metal ions play an important role in Aβ aggregation and metabolism, thus metal chelators and ligands represent potential therapeutic agents for AD treatment. A direct effect of metal chelators on γ-secretase has not yet been investigated. The authors used an in vitro  γ-secretase assay consisting of cleavage of APP C100-3XFLAG by endogenous γ-secretase from rodent brains and human neuroblastoma SH-SY5Y, and detected AICD production by western blotting. Adding metalloprotease inhibitors to the reaction showed that clioquinol, phosphoramidon, and zinc metalloprotease inhibitors had no significant effect on γ-secretase activity. In contrast, phenanthroline, EDTA, and EGTA markedly decreased γ-secretase activity that could be restored by adding back calcium and magnesium ions. Mg2+ stabilized a 1,000 kDa presenilin 1 complex through blue native gel electrophoresis and size-exclusion chromatography. Data suggest that Ca2+ and Mg2+ stabilize γ-secretase and enhance its activity.

  3. The role of albumin conformation in the binding of diazepam to human serum albumin

    NARCIS (Netherlands)

    Wilting, J.; Hart, B.J. 't; Gier, J.J. de

    2006-01-01

    The effect of hydrogen, chloride and calcium ions on the binding of diazepare to human serum albumin has been studied by circular dichroism and equilibrium dialysis. In all cases the molar ellipticity of the diazepam-albumin complex increases with pH over the pH range 5 to 9. Under these

  4. [(3)H]chlorpromazine photolabeling of the torpedo nicotinic acetylcholine receptor identifies two state-dependent binding sites in the ion channel.

    Science.gov (United States)

    Chiara, David C; Hamouda, Ayman K; Ziebell, Michael R; Mejia, Luis A; Garcia, Galo; Cohen, Jonathan B

    2009-10-27

    Chlorpromazine (CPZ), a potent nicotinic acetylcholine receptor (nAChR) noncompetitive antagonist, binds with higher affinity in the ion channel in the desensitized state than in the closed channel state and with low affinity to additional sites in nAChR-rich membranes. For nAChR equilibrated with agonist, we confirm previous reports that [(3)H]CPZ occupies a site near the cytoplasmic end of the M2 ion channel domain, photolabeling positions M2-2, M2-6, and/or M2-9 in each subunit. We find that [(3)H]CPZ also binds at the extracellular end of the channel, photolabeling amino acids at positions M2-16 (alpha,gamma), M2-17 (alpha,beta,delta), and M2-20 (alpha,beta,delta). The photolabeling at the cytoplasmic end of the channel is fully inhibitable by phencyclidine or proadifen, whereas neither drug inhibits [(3)H]CPZ photolabeling at the extracellular end, establishing that positively charged drugs can bind simultaneously at the cytoplasmic and extracellular ends of the ion channel. [(3)H]CPZ photolabeling is not detected in the transmembrane domain outside the ion channel, but it photolabels alphaMet-386 and alphaSer-393 in the cytoplasmic alphaMA helix. In the nAChR equilibrated with alpha-bungarotoxin to stabilize the nAChR in a closed state, [(3)H]CPZ photolabels amino acids at M2-5 (alpha), M2-6 (alpha,beta,delta), and M2-9 (beta,delta), with no labeling at M2-2. These results provide novel information about the modes of drug binding within the nAChR ion channel and indicate that within the nAChR transmembrane domain, the binding of cationic aromatic amine antagonists can be restricted to the ion channel domain, in contrast to the uncharged, allosteric potentiators and inhibitors that also bind within the delta subunit helix bundle and at subunit interfaces.

  5. Thermodynamic Studies of Cu(I) and Other d10 Metal Ions Binding to Proteins in the Copper Homeostasis Pathway and the Organomercurial Detoxification Pathway

    Science.gov (United States)

    Stevenson, Michael James

    Copper(I) is the predominant oxidation state of this essential metal in living cells due to reducing intracellular conditions. Because of deleterious copper-mediated Fenton chemistry, intracellular copper trafficking pathways involve strict regulation by metallochaperone proteins. Previous studies of the 68-residue metallochaperone, HAH1, have shown that it coordinates Cu(I) with two cysteines for transport from Ctr1 in the cell membrane to ATPases in the Golgi network. Using isothermal titration calorimetry (ITC), and methods to suppress oxidation and disproportionation of Cu(I), the thermodynamics of Cu(I), as well as other metal ions, binding to HAH1 have been accurately quantified. During the course of this study, the Cu(I) binding thermodynamics with the stabilizing ligand hexamethyltrien were determined in order to accurately quantify the Cu(I) binding thermodynamics with proteins, and revealed an unexpected Cu(I) coordination chemistry with this ligand. In addition, HAH1 binding the Cu(I) analogue Ag(I), the abundant cellular metal ion Zn(II), and the thiophilic toxic metal ion Hg(II), have been quantified. The binding thermodynamics of these metal ions were also determined in the presence of glutathione to more accurately model physiological conditions. HAH1 has a high affinity for Cu(I), which is both enthalpically and entropically favorable. It has a substantially lower affinity for Zn(II), which is entropically favored, suggesting that Zn(II) is not able to compete with Cu(I) for HAH1 in vivo. However, HAH1 has an exceptionally high affinity for Hg(II), with its larger thiophilicity, and it will displace Cu(I). Mercury(II) and particularly organomercurial compounds are very toxic, yet proteins from the bacterial mer operon provide resistance to this toxicity. In particular, the organomercurial lyase MerB, whose only known structural homologue is a putative copper metallochaperone, is responsible for cleavage of the carbon-mercury bond of MeHg(II) and

  6. GsCML27, a Gene Encoding a Calcium-Binding Ef-Hand Protein from Glycine soja, Plays Differential Roles in Plant Responses to Bicarbonate, Salt and Osmotic Stresses.

    Directory of Open Access Journals (Sweden)

    Chao Chen

    Full Text Available Calcium, as the most widely accepted messenger, plays an important role in plant stress responses through calcium-dependent signaling pathways. The calmodulin-like family genes (CMLs encode Ca2+ sensors and function in signaling transduction in response to environmental stimuli. However, until now, the function of plant CML proteins, especially soybean CMLs, is largely unknown. Here, we isolated a Glycine soja CML protein GsCML27, with four conserved EF-hands domains, and identified it as a calcium-binding protein through far-UV CD spectroscopy. We further found that expression of GsCML27 was induced by bicarbonate, salt and osmotic stresses. Interestingly, ectopic expression of GsCML27 in Arabidopsis enhanced plant tolerance to bicarbonate stress, but decreased the salt and osmotic tolerance during the seed germination and early growth stages. Furthermore, we found that ectopic expression of GsCML27 decreases salt tolerance through modifying both the cellular ionic (Na+, K+ content and the osmotic stress regulation. GsCML27 ectopic expression also decreased the expression levels of osmotic stress-responsive genes. Moreover, we also showed that GsCML27 localized in the whole cell, including cytoplasm, plasma membrane and nucleus in Arabidopsis protoplasts and onion epidermal cells, and displayed high expression in roots and embryos. Together, these data present evidence that GsCML27 as a Ca2+-binding EF-hand protein plays a role in plant responses to bicarbonate, salt and osmotic stresses.

  7. GsCML27, a Gene Encoding a Calcium-Binding Ef-Hand Protein from Glycine soja, Plays Differential Roles in Plant Responses to Bicarbonate, Salt and Osmotic Stresses.

    Science.gov (United States)

    Chen, Chao; Sun, Xiaoli; Duanmu, Huizi; Zhu, Dan; Yu, Yang; Cao, Lei; Liu, Ailin; Jia, Bowei; Xiao, Jialei; Zhu, Yanming

    2015-01-01

    Calcium, as the most widely accepted messenger, plays an important role in plant stress responses through calcium-dependent signaling pathways. The calmodulin-like family genes (CMLs) encode Ca2+ sensors and function in signaling transduction in response to environmental stimuli. However, until now, the function of plant CML proteins, especially soybean CMLs, is largely unknown. Here, we isolated a Glycine soja CML protein GsCML27, with four conserved EF-hands domains, and identified it as a calcium-binding protein through far-UV CD spectroscopy. We further found that expression of GsCML27 was induced by bicarbonate, salt and osmotic stresses. Interestingly, ectopic expression of GsCML27 in Arabidopsis enhanced plant tolerance to bicarbonate stress, but decreased the salt and osmotic tolerance during the seed germination and early growth stages. Furthermore, we found that ectopic expression of GsCML27 decreases salt tolerance through modifying both the cellular ionic (Na+, K+) content and the osmotic stress regulation. GsCML27 ectopic expression also decreased the expression levels of osmotic stress-responsive genes. Moreover, we also showed that GsCML27 localized in the whole cell, including cytoplasm, plasma membrane and nucleus in Arabidopsis protoplasts and onion epidermal cells, and displayed high expression in roots and embryos. Together, these data present evidence that GsCML27 as a Ca2+-binding EF-hand protein plays a role in plant responses to bicarbonate, salt and osmotic stresses.

  8. 125 MeV Si 9+ ion irradiation of calcium phosphate thin film coated by rf-magnetron sputtering technique

    Science.gov (United States)

    Elayaraja, K.; Joshy, M. I. Ahymah; Suganthi, R. V.; Kalkura, S. Narayana; Palanichamy, M.; Ashok, M.; Sivakumar, V. V.; Kulriya, P. K.; Sulania, I.; Kanjilal, D.; Asokan, K.

    2011-01-01

    Titanium substrate was coated with hydroxyapatite by radiofrequency magnetron sputtering (rf-magnetron sputtering) technique and subjected to swift heavy ion (SHI) irradiation of 125 MeV with Si 9+ at fluences of 1 × 10 10, 1 × 10 11 and 1 × 10 12 ions/cm 2. The glancing incidence X-ray diffraction (GIXRD) analysis confirmed the HAp phase of the irradiated film. There was a considerable decrease in crystallinity and particle size after irradiation. In addition, DRS-UV reflectance spectra revealed a decrease in optical band gap ( Eg) from 5.2 to 4.6 eV. Wettability of biocompatible materials plays an important role in biological cells proliferation for tissue engineering, drug delivery, gene transfer and bone growth. HAp thin films irradiated with 1 × 10 11 ions/cm 2 fluence showed significant increase in wettability. While the SHI irradiated samples exhibited enhanced bioactivity, there was no significant variation in cell viability. Surface roughness, pores and average particle size were analyzed by atomic force microscopy (AFM).

  9. Expression of calcium-binding proteins S100A8, S100A9 and S100A12 in otitis media.

    Science.gov (United States)

    Hong, Wenzhou; Khampang, Pawjai; Samuels, Tina L; Kerschner, Joseph E; Yan, Ke; Simpson, Pippa

    2017-10-01

    Calgranulins (calcium-binding proteins S100A8, S100A9 and S100A12) are predominant cytoplasmic proteins of neutrophils and produced by various cells, playing multiple functions in innate immunity and the inflammatory process. Although up-regulated expression of S100A8 and S100A9 genes were observed in an animal model of otitis media (OM), their expressions have not been studied in human middle ear epithelial cells in response to the OM pathogen or in patients with recurrent or chronic OM (recurrent OM/RecOM or chronic OM with effusion/COME). Gene expressions were compared between Streptococcus pneumoniae (SP)-infected and non-infected human middle ear epithelial cells (HMEECs) as well as between chronic OM patients and control patients (CI). Gene expressions were profiled by quantitative real time PCR (qPCR). S100 proteins in OM patient and CI middle ear biopsies were detected by immunostaining. S100A8, S100A9 and S100A12 gene expressions were elevated in SP-infected HMEECs in time-dependent manner. S100A8 and S100A9 but not S100A12 gene expression was significantly elevated in the middle ear mucosa of OM patients. S100A8 and S100A9 protein were observed in middle ear mucosa of OM, but not CI patients. Minimal co-localization was observed between S100A8 and S100A9 with neutrophil elastase and cytokeratin in ME sections of OM patients. Elevated S100A8 and S100A9 gene expression in SP-infected HMEECs and in the middle ear mucosa of OM, minor co-localized with neutrophil markers suggests that middle ear epithelial cell secretion of S100A8 and S100A9 may play a role in the pathogenesis of recurrent and chronic OM. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. S100 calcium binding protein B as a biomarker of delirium duration in the intensive care unit – an exploratory analysis

    Directory of Open Access Journals (Sweden)

    Khan BA

    2013-12-01

    Full Text Available Babar A Khan,1–3 Mark O Farber,1 Noll Campbell,2–5 Anthony Perkins,2,3 Nagendra K Prasad,6 Siu L Hui,1–3 Douglas K Miller,1–3 Enrique Calvo-Ayala,1 John D Buckley,1 Ruxandra Ionescu,1 Anantha Shekhar,1 E Wesley Ely,7,8 Malaz A Boustani1–3 1Indiana University School of Medicine, 2Indiana University Center for Aging Research, 3Regenstrief Institute, Inc., 4Wishard Health Services, Indianapolis, 5Department of Pharmacy Practice, Purdue University College of Pharmacy, West Lafayette, 6Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN, 7Vanderbilt University School of Medicine, 8VA Tennessee Valley Geriatric Research Education Clinical Center (GRECC, Nashville, TN, USA Background: Currently, there are no valid and reliable biomarkers to identify delirious patients predisposed to longer delirium duration. We investigated the hypothesis that elevated S100 calcium binding protein B (S100β levels will be associated with longer delirium duration in critically ill patients. Methods: A prospective observational cohort study was performed in the medical, surgical, and progressive intensive care units (ICUs of a tertiary care, university affiliated, and urban hospital. Sixty-three delirious patients were selected for the analysis, with two samples of S100β collected on days 1 and 8 of enrollment. The main outcome measure was delirium duration. Using the cutoff of <0.1 ng/mL and $0.1 ng/mL as normal and abnormal levels of S100β, respectively, on day 1 and day 8, four exposure groups were created: Group A, normal S100β levels on day 1 and day 8; Group B, normal S100β level on day 1 and abnormal S100β level on day 8; Group C, abnormal S100β level on day 1 and normal on day 8; and Group D, abnormal S100β levels on both day 1 and day 8. Results: Patients with abnormal levels of S100β showed a trend towards higher delirium duration (P=0.076; Group B (standard deviation (7.0 [3.2] days, Group C (5.5 [6.3] days, and Group D

  11. Participation of the oviductal s100 calcium binding protein G in the genomic effect of estradiol that accelerates oviductal embryo transport in mated rats

    Directory of Open Access Journals (Sweden)

    Croxatto Horacio B

    2011-05-01

    Full Text Available Abstract Background Mating changes the mechanism by which E2 regulates oviductal egg transport, from a non-genomic to a genomic mode. Previously, we found that E2 increased the expression of several genes in the oviduct of mated rats, but not in unmated rats. Among the transcripts that increased its level by E2 only in mated rats was the one coding for an s100 calcium binding protein G (s100 g whose functional role in the oviduct is unknown. Methods Herein, we investigated the participation of s100 g on the E2 genomic effect that accelerates oviductal transport in mated rats. Thus, we determined the effect of E2 on the mRNA and protein level of s100 g in the oviduct of mated and unmated rats. Then, we explored the effect of E2 on egg transport in unmated and mated rats under conditions in which s100 g protein was knockdown in the oviduct by a morpholino oligonucleotide against s100 g (s100 g-MO. In addition, the localization of s100 g in the oviduct of mated and unmated rats following treatment with E2 was also examined. Results Expression of s100 g mRNA progressively increased at 3-24 h after E2 treatment in the oviduct of mated rats while in unmated rats s100 g increased only at 12 and 24 hours. Oviductal s100 g protein increased 6 h following E2 and continued elevated at 12 and 24 h in mated rats, whereas in unmated rats s100 g protein increased at the same time points as its transcript. Administration of a morpholino oligonucleotide against s100 g transcript blocked the effect of E2 on egg transport in mated, but not in unmated rats. Finally, immunoreactivity of s100 g was observed only in epithelial cells of the oviducts of mated and unmated rats and it was unchanged after E2 treatment. Conclusions Mating affects the kinetic of E2-induced expression of s100 g although it not changed the cellular localization of s100 g in the oviduct after E2 . On the other hand, s100 g is a functional component of E2 genomic effect that accelerates egg

  12. Dentinal pH changes following electrophoretically activated calcium hydroxide ions in the root canal space of bovine teeth.

    Science.gov (United States)

    Tsesis, Igor; Lin, Shaul; Weiss, Ervin I; Fuss, Zvi

    2005-06-01

    The aim of the study was to evaluate pH changes of external root dentin surface at different depths following electrophoretic activation of calcium hydroxide (CH) in the root canals. For the study, 60 cavities were drilled on three external root surfaces of 20 bovine teeth specimens to obtain remaining dentin thickness (RDT) of 0.3, 0.7 and 1.0 mm. CH paste was inserted in the lumens. In the experimental group (10 specimens) CH paste was electrophoretically activated. Microelectrode was used to measure pH changes in the cavities immediately after placement of CH, following electrophoretical activation, and after 30 days storage. A significant (P pH following electrophoresis was found in all specimens in the experimental group. Cavities with 0.4 mm RDT showed a maximal pH increase to the value of 11.3 +/- 0.4. In the control group no change in pH was observed after 3 min. A similar increase in pH was observed in both groups after 30 days. The pH changes were significantly depended on the RDT (P pH of external root surface within minutes up to 30 days.

  13. Natural silica sand modified by calcium oxide as a new adsorbent for uranyl ions removal from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Elhefnawy, O.A.; Elabd, A.A. [Nuclear and Radiological Regulatory Authority (NRRA), Cairo (Egypt). Nuclear Safeguards and Physical Protection Dept.

    2017-07-01

    Calcium oxide modified El-Zafarana silica sand (CMZS) was prepared as a new adsorbent for U(VI) removal from aqueous solutions in a series of batch experiments. The new adsorbent CMZS was characterized by different analysis techniques SEM, EDX, XRD, and FTIR. The influence of many parameters on the removal process like; effect of pH, contact time, U(VI) initial concentration and temperature on U(VI) removal were investigated. Kinetic experiments showed that U(VI) removal on CMZS followed pseudo-second-order kinetics model appropriately and the equilibrium data agreed well with the Langmuir isotherm model. Kinetics and isothermal data reveal the chemisorption process of U(VI) on CMZS. The thermodynamic parameters (ΔH {sup circle}, ΔS {sup circle}, ΔG {sup circle}) were evaluated from temperature dependent adsorption data and the U(VI) removal on CMZS was found to be endothermic and spontaneous in nature. U(VI) desorption from CMZS was studied by a simple acid treatment. The results indicate that CMZS is an effective adsorbent for U(VI) from aqueous solutions.

  14. Effects of metal ions on stability and activity of hyperthermophilic pyrolysin and further stabilization of this enzyme by modification of a Ca2+-binding site.

    Science.gov (United States)

    Zeng, Jing; Gao, Xiaowei; Dai, Zheng; Tang, Bing; Tang, Xiao-Feng

    2014-05-01

    Pyrolysin is an extracellular subtilase produced by the marine hyperthermophilic archaeon Pyrococcus furiosus. This enzyme functions at high temperatures in seawater, but little is known about the effects of metal ions on the properties of pyrolysin. Here, we report that the supplementation of Na(+), Ca(2+), or Mg(2+) salts at concentrations similar to those in seawater destabilizes recombinant pyrolysin but leads to an increase in enzyme activity. The destabilizing effect of metal ions on pyrolysin appears to be related to the disturbance of surface electrostatic interactions of the enzyme. In addition, mutational analysis of two predicted high-affinity Ca(2+)-binding sites (Ca1 and Ca2) revealed that the binding of Ca(2+) is important for the stabilization of this enzyme. Interestingly, Asn substitutions at residues Asp818 and Asp820 of the Ca2 site, which is located in the C-terminal extension of pyrolysin, resulted in improvements in both enzyme thermostability and activity without affecting Ca(2+)-binding affinity. These effects were most likely due to the elimination of unfavorable electrostatic repulsion at the Ca2 site. Together, these results suggest that metal ions play important roles in modulating the stability and activity of pyrolysin.

  15. Effects of Metal Ions on Stability and Activity of Hyperthermophilic Pyrolysin and Further Stabilization of This Enzyme by Modification of a Ca2+-Binding Site

    Science.gov (United States)

    Zeng, Jing; Gao, Xiaowei; Dai, Zheng; Tang, Bing

    2014-01-01

    Pyrolysin is an extracellular subtilase produced by the marine hyperthermophilic archaeon Pyrococcus furiosus. This enzyme functions at high temperatures in seawater, but little is known about the effects of metal ions on the properties of pyrolysin. Here, we report that the supplementation of Na+, Ca2+, or Mg2+ salts at concentrations similar to those in seawater destabilizes recombinant pyrolysin but leads to an increase in enzyme activity. The destabilizing effect of metal ions on pyrolysin appears to be related to the disturbance of surface electrostatic interactions of the enzyme. In addition, mutational analysis of two predicted high-affinity Ca2+-binding sites (Ca1 and Ca2) revealed that the binding of Ca2+ is important for the stabilization of this enzyme. Interestingly, Asn substitutions at residues Asp818 and Asp820 of the Ca2 site, which is located in the C-terminal extension of pyrolysin, resulted in improvements in both enzyme thermostability and activity without affecting Ca2+-binding affinity. These effects were most likely due to the elimination of unfavorable electrostatic repulsion at the Ca2 site. Together, these results suggest that metal ions play important roles in modulating the stability and activity of pyrolysin. PMID:24561589

  16. Binding Affinity of a Highly Sensitive Au/Ag/Au/Chitosan-Graphene Oxide Sensor Based on Direct Detection of Pb2+ and Hg2+ Ions

    Directory of Open Access Journals (Sweden)

    Nur Hasiba Kamaruddin

    2017-10-01

    Full Text Available The study of binding affinity is essential in surface plasmon resonance (SPR sensing because it allows researchers to quantify the affinity between the analyte and immobilised ligands of an SPR sensor. In this study, we demonstrate the derivation of the binding affinity constant, K, for Pb2+ and Hg2+ ions according to their SPR response using a gold/silver/gold/chitosan–graphene oxide (Au/Ag/Au/CS–GO sensor for the concentration range of 0.1–5 ppm. The higher affinity of Pb2+ to binding with the CS–GO sensor explains the outstanding sensitivity of 2.05 °ppm−1 against 1.66 °ppm−1 of Hg2+. The maximum signal-to-noise ratio (SNR upon detection of Pb2+ is 1.53, and exceeds the suggested logical criterion of an SNR. The Au/Ag/Au/CS–GO SPR sensor also exhibits excellent repeatability in Pb2+ due to the strong bond between its functional groups and this cation. The adsorption data of Pb2+ and Hg2+ on the CS–GO sensor fits well with the Langmuir isotherm model where the affinity constant, K, of Pb2+ and Hg2+ ions is computed. The affinity of Pb2+ ions to the Au/Ag/Au/CS–GO sensor is significantly higher than that of Hg2+ based on the value of K, 7 × 105 M−1 and 4 × 105 M−1, respectively. The higher shift in SPR angles due to Pb2+ and Hg2+ compared to Cr3+, Cu2+ and Zn2+ ions also reveals the greater affinity of the CS–GO SPR sensor to them, thus supporting the rationale for obtaining K for these two heavy metals. This study provides a better understanding on the sensing performance of such sensors in detecting heavy metal ions.

  17. Anomalous DNA binding by E2 regulatory protein driven by spacer sequence TATA.

    Science.gov (United States)

    Xi, Zhiqun; Zhang, Yongli; Hegde, Rashmi S; Shakked, Zippora; Crothers, Donald M

    2010-06-01

    We have investigated the anomalously weak binding of human papillomavirus (HPV) regulatory protein E2 to a DNA target containing the spacer sequence TATA. Experiments in magnesium (Mg(2+)) and calcium (Ca(2+)) ion buffers revealed a marked reduction in cutting by DNase I at the CpG sequence in the protein-binding site 3' to the TATA spacer sequence, Studies of the cation dependence of DNA-E2 affinities showed that upon E2 binding the TATA sequence releases approximately twice as many Mg(2+) ions as the average of the other spacer sequences. Binding experiments for TATA spacer relative to ATAT showed that in potassium ion (K(+)) the E2 affinity of the two sequences is nearly equal, but the relative dissociation constant (K(d)) for TATA increases in the order K(+ )TATA relative to ATAT is independent of ion concentration, whereas for Mg(2+) the affinity for TATA drops sharply as ion concentration increases. Thus, ions of increasing positive charge density increasingly distort the E2 binding site, weakening the affinity for protein. In the case of Mg(2+), additional ions are bound to TATA that require displacement for protein binding. We suggest that the TATA sequence may bias the DNA structure towards a conformation that binds the protein relatively weakly.

  18. Interpretation with a Donnan-based concept of the influence of simple salt concentration on the apparent binding of divalent ions to the polyelectrolytes polystyrenesulfonate and dextran sulfate

    Science.gov (United States)

    Marinsky, J.A.; Baldwin, Robert F.; Reddy, M.M.

    1985-01-01

    It has been shown that the apparent enhancement of divalent metal ion binding to polyions such as polystyrenesulfonate (PSS) and dextran sulfate (DS) by decreasing the ionic strength of these mixed counterion systems (M2+, M+, X-, polyion) can be anticipated with the Donnan-based model developed by one of us (J.A.M.). Ion-exchange distribution methods have been employed to measure the removal by the polyion of trace divalent metal ion from simple salt (NaClO4)-polyion (NaPSS) mixtures. These data and polyion interaction data published earlier by Mattai and Kwak for the mixed counterion systems MgCl2-LiCl-DS and MgCl2-CsCl-DS have been shown to be amenable to rather precise analysis by this model. ?? 1985 American Chemical Society.

  19. Water-soluble metal-binding polymers with ultrafiltration: A technology for the removal, concentration, and recovery of metal ions from aqueous streams

    International Nuclear Information System (INIS)

    Smith, B.F.; Robison, T.W.; Jarvinen, G.D.

    1997-01-01

    The use of water-soluble metal-binding polymers coupled with ultrafiltration (UF) is a technology under development to selectively concentrate and recover valuable or regulated metal-ions from dilute process or waste waters. The polymers have a sufficiently large molecular size that they can be separated and concentrated using commercially available UF technology. The polymers can then be reused by changing the solution conditions to release the metal-ions, which are recovered in a concentrated form for recycle or disposal. Pilot-scale demonstrations have been completed for a variety of waste streams containing low concentrations of metal ions including electroplating wastes (zinc and nickel) and nuclear waste streams (plutonium and americium). Many other potential commercial applications exist including remediation of contaminated solids. An overview of both the pilot-scale demonstrated applications and small scale testing of this technology are presented

  20. Water-soluble metal-binding polymers with ultrafiltration: A technology for the removal, concentration, and recovery of metal ions from aqueous streams

    Energy Technology Data Exchange (ETDEWEB)

    Smith, B.F.; Robison, T.W.; Jarvinen, G.D.

    1997-12-31

    The use of water-soluble metal-binding polymers coupled with ultrafiltration (UF) is a technology under development to selectively concentrate and recover valuable or regulated metal-ions from dilute process or waste waters. The polymers have a sufficiently large molecular size that they can be separated and concentrated using commercially available UF technology. The polymers can then be reused by changing the solution conditions to release the metal-ions, which are recovered in a concentrated form for recycle or disposal. Pilot-scale demonstrations have been completed for a variety of waste streams containing low concentrations of metal ions including electroplating wastes (zinc and nickel) and nuclear waste streams (plutonium and americium). Many other potential commercial applications exist including remediation of contaminated solids. An overview of both the pilot-scale demonstrated applications and small scale testing of this technology are presented.

  1. Calcium cation enhanced cathode/electrolyte interface property of Li2FeSiO4/C cathode for lithium-ion batteries with long-cycling life

    Science.gov (United States)

    Qu, Long; Li, Mingtao; Tian, Xiaolu; Liu, Pei; Yi, Yikun; Yang, Bolun

    2018-03-01

    Currently, the cycle performance at low rate is one of the most critical factor for realizing practical applications of Li2FeSiO4/C as a cathode of the lithium-ion batteries. To meet this challenge, calcium (Ca)-doped Li2FeSiO4/C is prepared by using the sol-gel method with soluble Li, Fe, Si and Ca sources. X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy measurements are carried out to determine the crystal structures, morphologies, particle sizes and chemical valence states of the resulting products. Rietveld refinement confirms that Ca-doped Li2FeSiO4 has a monoclinic P21/n structure and that a Ca cation occupies the Fe site in the Li2FeSiO4 lattice. The grain size of Ca-doped Li2FeSiO4 is approximately 20 nm and the nanoparticles are interconnected tightly with amorphous carbon layer. As a cathode material for the lithium-ion batteries, Li2Fe0.97Ca0.03SiO4/C delivers a high discharge capacity of 186 mAh g-1 at a 0.5 C rate. Its capacity retention after the 100th cycle reaches 87%, which increases by 25 percentage points compared with Li2FeSiO4/C. The Li2Fe0.97Ca0.03SiO4/C cathode exhibits good rate performance, with corresponding discharge capacities of 170, 157, 144 and 117 mAh g-1 at 1 C, 2 C, 5 C and 10 C rates, respectively. In summary, the improvement of the electrochemical performance can be attributed to a coefficient of the strengthened crystal structure stability during Li+ deintercalation-intercalation and restrained side reactions between electrode and electrolyte.

  2. ions

    African Journals Online (AJOL)

    (MP2 B2). In order to draw the final conclusion about the content of the isomers of pentaatomic ions in saturated vapor over cesium chloride, we have taken into account the entropy factor. We considered the isomerization reactions which are given below: Cs3Cl2. + (V-shaped) = Cs3Cl2. + (cyclic or bipyramidal). (1). Cs2Cl3.

  3. Effects of calcium ion incorporation on osteoblast gene expression in MC3T3-E1 cells cultured on microstructured titanium surfaces.

    Science.gov (United States)

    Park, Jin-Woo; Suh, Jo-Young; Chung, Hyun-Ju

    2008-07-01

    The surface characteristics of a calcium ion (Ca)-incorporated titanium (Ti) surface, produced by hydrothermal treatment using an alkaline Ca-containing solution, and its effects on osteoblastic differentiation were investigated. MC3T3-E1 pre-osteoblastic cells were cultured on machined or grit-blasted Ti surfaces with and without Ca incorporation. The MTT assay was used to determine cell proliferation, and real-time PCR was used for quantitative analysis of osteoblastic gene expression. Hydrothermal treatment with a Ca-containing solution produced a crystalline CaTiO(3) nanostructure of approximately 100 nm in dimension, preserving original micron-scaled surface topographies and microroughness caused by machining, blasting, or blasting and etching treatments. After immersion in Hank's balanced salt solution, considerable apatite formation was observed on all surfaces of the Ca-incorporated samples. Significantly more cell proliferation was found on Ca-incorporated Ti surfaces than on untreated Ti surfaces (p < 0.001). Quantitative real-time PCR analysis showed notably higher alkaline phosphatase, osteopontin, and osteocalcin mRNA levels in cells grown on Ca-incorporated blasted surfaces than on other surfaces at an early time point. Thus, Ca incorporation may have a beneficial effect on osseointegration of microstructured Ti implants by accelerating osteoblast proliferation and differentiation during the early healing phase following implantation. (c) 2007 Wiley Periodicals, Inc.

  4. Effects of Calcium and Magnesium Ions on Acute Copper Toxicity to Glochidia and Early Juveniles of the Chinese Pond Mussel Anodonta woodiana.

    Science.gov (United States)

    Liu, Hongbo; Chen, Xiubao; Su, Yanping; Kang, Ik Joon; Qiu, Xuchun; Shimasaki, Yohei; Oshima, Yuji; Yang, Jian

    2016-10-01

    We evaluated the effects of calcium (Ca(2+)) and magnesium (Mg(2+)) ions on copper (Cu) toxicity to glochidia and newly-transformed juvenile mussels (age 1-2 days) of the Chinese pond mussel (Anodonta woodiana). Acute Cu toxicity tests were performed with glochidia for 24 h and juveniles for 96 h with measured Ca(2+) concentrations of 1.1, 14, 26, 51, and 99 mg L(-1), or measured Mg(2+) concentrations of 2.6, 11, 21, and 39 mg L(-1). The Ca(2+) and Mg(2+) cations provided no statistically significant protection against Cu toxicity to glochidia or juveniles. The 24-h EC50 value for glochidia was 82 μg L(-1) Cu, and contrastly, 96-h EC50 value for newly-transformed juvenile mussels was as low as 12 μg L(-1) Cu, implying that the juveniles of A. woodiana are more vulnerable to Cu contamination at concentrations close to currently-accepted levels.

  5. Growth of etiolated barley plants in weak static and 50 Hz electromagnetic fields tuned to calcium ion cyclotron resonance

    Science.gov (United States)

    Pazur, Alexander; Rassadina, Valentina; Dandler, Jörg; Zoller, Jutta

    2006-01-01

    Background The effects of weak magnetic and electromagnetic fields in biology have been intensively studied on animals, microorganisms and humans, but comparably less on plants. Perception mechanisms were attributed originally to ferrimagnetism, but later discoveries required additional explanations like the "radical pair mechanism" and the "Ion cyclotron resonance" (ICR), primarily considered by Liboff. The latter predicts effects by small ions involved in biological processes, that occur in definite frequency- and intensity ranges ("windows") of simultaneously impacting magnetic and electromagnetic fields related by a linear equation, which meanwhile is proven by a number of in vivo and in vitro experiments. Methods Barley seedlings (Hordeum vulgare, L. var. Steffi) were grown in the dark for 5 and 6 days under static magnetic and 50 Hz electromagnetic fields matching the ICR conditions of Ca2+. Control cultures were grown under normal geomagnetic conditions, not matching this ICR. Morphology, pigmentation and long-term development of the adult plants were subsequently investigated. Results The shoots of plants exposed to Ca2+-ICR exposed grew 15–20% shorter compared to the controls, the plant weight was 10–12% lower, and they had longer coleoptiles that were adhering stronger to the primary leaf tissue. The total pigment contents of protochlorophyllide (PChlide) and carotenoids were significantly decreased. The rate of PChlide regeneration after light irradiation was reduced for the Ca2+-ICR exposed plants, also the Shibata shift was slightly delayed. Even a longer subsequent natural growing phase without any additional fields could only partially eliminate these effects: the plants initially exposed to Ca2+-ICR were still significantly shorter and had a lower chlorophyll (a+b) content compared to the controls. A continued cultivation and observation of the adult plants under natural conditions without any artificial electromagnetic fields showed a

  6. Uranium Isotopes in Calcium Carbonate: A Possible Proxy for Paleo-pH and Carbonate Ion Concentration?

    Science.gov (United States)

    Chen, X.; Romaniello, S. J.; Herrmann, A. D.; Wasylenki, L. E.; Anbar, A. D.

    2015-12-01

    abiotic CaCO3 reflect changes in aqueous U(VI) speciation, which are in turn a function of carbonate ion chemistry and pH. Hence, the door is opened to the development of a possible 238U/235U proxy for the carbonate ion system. [1] DeCarlo et al., (2015), GCA, 162,151-165. [2] Reeder et a., (2001), GCA, 65, 3491-3503. [3] Weyer et al., (2008) GCA 72, 345-359.

  7. Calcium – how and why?

    Indian Academy of Sciences (India)

    Unknown

    calcium has achieved this status with a brief mention of the history of calcium research in biology. It appears that during the origin and early evolution of life the Ca2+ ion was given a ... tion and development of tissues (bone and calcareous skeleton) (Ringer and Sainsbury 1894), conduction of nerve impulse to muscle, cell ...

  8. Novel molecular-level evidence of iodine binding to natural organic matter from Fourier transform ion cyclotron resonance mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Chen, E-mail: xuchen66@tamu.edu [Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A and M University, Building 3029, Galveston, TX 77551 (United States); Chen, Hongmei [Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529 (United States); Sugiyama, Yuko [Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529 (United States); University of Hyogo, 1-1-12, Shinzaike-honcho, Himeji, Hyogo 670-0092 (Japan); Zhang, Saijin; Li, Hsiu-Ping; Ho, Yi-Fang; Chuang, Chia-ying; Schwehr, Kathleen A. [Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A and M University, Building 3029, Galveston, TX 77551 (United States); Kaplan, Daniel I. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Yeager, Chris [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Roberts, Kimberly A. [Savannah River National Laboratory, Aiken, SC 29808 (United States); Hatcher, Patrick G. [Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529 (United States); Santschi, Peter H. [Laboratory for Environmental and Oceanographic Research, Department of Marine Sciences, Texas A and M University, Building 3029, Galveston, TX 77551 (United States)

    2013-04-01

    Major fractions of radioiodine ({sup 129}I) are associated with natural organic matter (NOM) in the groundwater and surface soils of the Savannah River Site (SRS). Electrospray ionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS) was applied to elucidate the interactions between inorganic iodine species (iodide and iodate) and a fulvic acid (FA) extracted from a SRS surface soil. Iodate is likely reduced to reactive iodine species by the lignin- and tannin-like compounds or the carboxylic-rich alicyclic molecules (CRAM), during which condensed aromatics and lignin-like compounds were generated. Iodide is catalytically oxidized into reactive iodine species by peroxides, while FA is oxidized by peroxides into more aliphatic and less aromatic compounds. Only 9% of the total identified organo-iodine compounds derived from molecules originally present in the FA, whereas most were iodine binding to newly-produced compounds. The resulting iodinated molecules were distributed in three regions in the van Krevelen diagrams, denoting unsaturated hydrocarbons, lignin and protein. Moreover, characteristics of these organo-iodine compounds, such as their relatively low O/C ratios (< 0.2 or < 0.4) and yet some degree of un-saturation close to that of lignin, have multiple important environmental implications concerning possibly less sterically-hindered aromatic ring system for iodine to get access to and a lower hydrophilicity of the molecules thus to retard their migration in the natural aquatic systems. Lastly, ∼ 69% of the identified organo-iodine species contains nitrogen, which is presumably present as -NH{sub 2} or -HNCOR groups and a ring-activating functionality to favor the electrophilic substitution. The ESI-FTICR-MS technique provides novel evidence to better understand the reactivity and scavenging properties of NOM towards radioiodine and possible influence of NOM on {sup 129}I migration. Highlights: ► IO{sub 3}{sup

  9. Binding of nickel and zinc ions with activated carbon prepared from sugar cane fibre (Saccharum officinarum L.

    Directory of Open Access Journals (Sweden)

    E.U. Ikhuoria

    2007-04-01

    Full Text Available Activated carbon was prepared from sugar cane fibre by carbonizing at 500 oC for 30 minutes. This was followed by activation with ammonium chloride. The activated carbon was characterised in terms of pH, bulk density, ash content, surface area and surface charge. Equilibrium sorption of nickel and zinc ions by the activated carbon was studied using a range of metal ion concentrations. The sorption data was observed to have an adequate fit for the Langmuir isotherm equation. The level of metal ion uptake was found to be of the order: Ni2+ > Zn2+. The difference in the removal efficiency could be explained in terms of the hydration energy of the metal ions. The distribution coefficient for a range of concentration of the metal ions at the sorbent water interface is found to be higher than the concentration in the continuous phase.

  10. Evaluation of Hydroxyl Ion Diffusion in Dentin and Injectable Forms and a Simple Powder-Water Calcium Hydroxide Paste: An in Vitro Study

    OpenAIRE

    Eftekhar, Behrooz; Moghimipour, Eskandar; Eini, Ebrahim; Jafarzadeh, Mansour; Behrooz, Narges

    2014-01-01

    Background: Intra canal medicaments are used to reduce the number of bacteria and reinfection in endodontic procedures. Calcium Hydroxide was introduced to endodontics by Herman as an intracanal antimicrobial agent. Objectives: The aim of this study was to present an injectable formulation of calcium hydroxide then compare the final pH of this new formulation with Metapaste and evaluate the effect of a mixture of Calcium Hydroxide powder with water on human extracted teeth. Patients and Metho...

  11. Brain calbindin-D28k and an Mr 29,000 calcium binding protein in cerebellum are different but related proteins: Evidence obtained from sequence analysis by tandem mass spectroscopy

    International Nuclear Information System (INIS)

    Gabrielides, C.; Christakos, S.; McCormack, A.L.; Hunt, D.F.

    1991-01-01

    A calcium binding protein of M r 29,000 which cross-reacts with antibodies raised against chick calbindin-D 28k was previously reported to be present in rat cerebellum. It was suggested that the M r 29,000 protein represents another form of calbindin-D 28k . In the authors laboratory they were able to identify M r 28,000 and 29,000 proteins in rat, human, and chick cerebellum by their ability to bind 45 Ca in a 45 Ca blot assay. Two calcium binding proteins of M r 27,680 and 29,450 were isolated from rat cerebelli by the use of gel permeation chromatography and preparative gel electrophoresis. After reverse-phase high-performance liquid chromatography (HPLC) the proteins were sequenced. Sequence analysis by tandem mass spectrometry indicated only 52% identity between the rat cerebellar M r 28,000 and 29,000 proteins. Thus they are not different forms of the same protein, as previously suggested. Eighty-nine percent identity was observed between the rate cerebellar M r 29,000 protein and chick calretinin. The difference in identity between the rat cerebellar M r 29,000 protein and chick calretinin may be due to species differences, and thus this protein is most likely rat calretinin. These results suggest either posttranscriptional regulation of calretinin in cerebellum or species differences. The study also suggests that previous immunocytochemical mapping for calbindin using antisera which cross-reacted with both proteins detected brain regions that expressed not only calbindin but also calretinin or a calretinin-like protein

  12. Calcium in pollen-pistil interaction in `Petunia hybrida Hat`. Pt. 3. Localization of Ca{sup 2+} ions and Ca{sup 2+}-ATPase in pollinated pistil

    Energy Technology Data Exchange (ETDEWEB)

    Bednarska, E.; Butowt, R. [Uniwersytet Mikolaja Kopernika, Torun (Poland)

    1995-12-31

    Studies were carried out of Ca{sup 2+} and Ca{sup 2+}-ATPase localization in pollinated (6 and 48 h after pollination) pistils of `Petunia hybrida`. The results were confronted with Ca{sup 2+} localization in mature pollen grain and in unpollinated pistil. It has been found that after pollination the number of Ca{sup 2+} sequestered in the stigmal exudate and in the sporoderm of the pollen grain gets lower. That phenomenon was associated with the appearance of a large number of Sb/Ca precipitates in the submembrane cytoplasm of the germinating pollen. In the vacuolized pollen grain, i.e. grown into a pollen tube, there were only a few precipitates. In the pollen tube, Ca{sup 2+} were found in the organelles of the tip cytoplasm and in the external pectin cell wall. Studies with the use of {sup 45}Ca{sup 2+} have revealed that the source of calcium ions incorporated into the pollen tube tip and its pectin wall is the transmitting tract of the style. In the transmitting tract overgrown with pollen tubes, Ca{sup 2+} were localized in the intercellular matrix and in the transmitting cell. Sb/Ca precipitates occurred in the nuclei, around the secretary vesicles and on the plasmalemma in the transverse walls region. Elevated Ca{sup 2+} level was found in degenerating cells (inhibited pollen tubes, transmitting cells, nucellar cells). The progressing degeneration process of the cells of the transmitting tract of the pollinated pistil was associated with a decrease in the activity of plasmalemma Ca{sup 2+}-ATPase. (author). 30 refs, 19 figs.

  13. ACE applied to the quantitative characterization of benzo-18-crown-6-ether binding with alkali metal ions in a methanol-water solvent system

    Czech Academy of Sciences Publication Activity Database

    Ehala, Sille; Makrlík, E.; Toman, Petr; Kašička, Václav

    2010-01-01

    Roč. 31, č. 4 (2010), s. 702-708 ISSN 0173-0835 R&D Projects: GA ČR(CZ) GA203/08/1428; GA ČR(CZ) GA203/09/0675; GA AV ČR 1ET400500402 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z40500505 Keywords : affinity capillary electrophoresis * alkali metal ions * binding constant Subject RIV: CB - Analytical Chemistry , Separation Impact factor: 3.569, year: 2010

  14. Physicochemical characterization of zinc-substituted calcium ...

    Indian Academy of Sciences (India)

    Zinc embedded into calcium phosphate may enhance the bone formation and in addition exhibits antifungal and antibacterial properties. Therefore, it is rational to form structures incorporated with this ion. In this paper the incorporation of the Zn ions into natural and synthetic calcium phosphates has been reported.Natural ...

  15. Effect of Patiromer on Urinary Ion Excretion in Healthy Adults

    Science.gov (United States)

    Spiegel, David M.; Gross, Coleman; Benton, Wade W.; Fogli, Jeanene; Hill Gallant, Kathleen M.; Du Mond, Charles; Block, Geoffrey A.; Weir, Matthew R.; Pitt, Bertram

    2016-01-01

    Background and objectives Patiromer is a nonabsorbed potassium-binding polymer that uses calcium as the counterexchange ion. The calcium released with potassium binding has the potential to be absorbed or bind phosphate. Because binding is not specific for potassium, patiromer can bind other cations. Here, we evaluate the effect of patiromer on urine ion excretion in healthy adults, which reflects gastrointestinal ion absorption. Design, setting, participants, & measurements We analyzed the effect of patiromer on urine potassium, sodium, magnesium, calcium, and phosphate in two studies. Healthy adults on controlled diets in a clinical research unit were given patiromer up to 50.4 g/d divided three times a day for 8 days (dose-finding study) or 25.2 g/d in a crossover design as daily or divided (two or three times a day) doses for 18 days (dosing regimen study). On the basis of 24-hour collections, urinary ion excretion during the baseline period (days 5–11) was compared with that during the treatment period (days 13–19; dose-finding study), and the last 4 days of each period were compared across regimens (dosing regimen study). Results In the dose-finding study, patiromer induced a dose-dependent decrease in urine potassium, urine magnesium, and urine sodium (Purine potassium (mean±SD) by 1140±316 mg/d, urine magnesium by 45±1 mg/d, and urine sodium by 225±145 mg/d. Urine calcium increased in a dose-dependent manner, and urine phosphate decreased in parallel (both Purine calcium by 73±23 mg/d and decreased urine phosphate by 64±40 mg/d. Urine potassium, urine sodium, and urine magnesium were unaffected by dosing regimen, whereas the increase in urine calcium was significantly lower with daily compared with three times a day dosing (P=0.01). Urine phosphate also decreased less with daily compared with two or three times a day dosing (Purine potassium, urine sodium, urine magnesium, and urine phosphate, while modestly increasing urine calcium. Compared with

  16. Biophysical characterization of Ca2+-binding of S100A5 and Ca2+-induced interaction with RAGE.

    Science.gov (United States)

    Kim, Iktae; Lee, Ko On; Yun, Young-Joo; Jeong, Jea Yeon; Kim, Eun-Hee; Cheong, Haekap; Ryu, Kyoung-Seok; Kim, Nak-Kyoon; Suh, Jeong-Yong

    2017-01-29

    S100A5 is a calcium-binding protein of S100 family, which represents a major ligand to the receptor for advanced glycation end product (RAGE), a pattern recognition receptor engaged in diverse pathological processes. Here we have characterized calcium binding of S100A5 and the complex formation between S100A5 and RAGE using calorimetry and NMR spectroscopy. S100A5 binds to calcium ions in a sequential manner with the equilibrium dissociation constants (K D ) of 1.3 μM and 3.5 μM, which corresponds to the calcium-binding at the C-terminal and N-terminal EF-hands. Upon calcium binding, S100A5 interacts with the V domain of RAGE (RAGE-v) to form a heterotrimer (K D ∼5.9 μM) that is distinct among the S100 family proteins. Chemical shift perturbation data from NMR titration experiments indicates that S100A5 employs the periphery of the dimer interface to interact with RAGE-v. Distinct binding mode and stoichiometry of RAGE against different S100 family proteins could be important to modulate diverse RAGE signaling. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Functional modulation of cerebral gamma-aminobutyric acidA receptor/benzodiazepine receptor/chloride ion channel complex with ethyl beta-carboline-3-carboxylate: Presence of independent binding site for ethyl beta-carboline-3-carboxylate

    Energy Technology Data Exchange (ETDEWEB)

    Taguchi, J.; Kuriyama, K. (Kyoto Prefectural Univ. of Medicine (Japan))

    1990-05-01

    Effect of ethyl beta-carboline-3-carboxylate (beta-CCE) on the function of gamma-aminobutyric acid (GABA)A receptor/benzodiazepine receptor/chloride ion channel complex was studied. Beta-CCE noncompetitively and competitively inhibited (3H)flunitrazepam binding to benzodiazepine receptor, but not (3H)muscimol binding to GABAA receptor as well as t-(3H)butylbicycloorthobenzoate (( 3H) TBOB) binding to chloride ion channel, in particulate fraction of the mouse brain. Ro15-1788 also inhibited competitively (3H) flunitrazepam binding. On the other hand, the binding of beta-(3H)CCE was inhibited noncompetitively and competitively by clonazepam and competitively by Ro15-1788. In agreement with these results, benzodiazepines-stimulated (3H)muscimol binding was antagonized by beta-CCE and Ro15-1788. Gel column chromatography for the solubilized fraction from cerebral particulate fraction by 0.2% sodium deoxycholate (DOC-Na) in the presence of 1 M KCl indicated that beta-(3H)CCE binding site was eluted in the same fraction (molecular weight, 250,000) as the binding sites for (3H)flunitrazepam, (3H)muscimol and (3H)TBOB. GABA-stimulated 36Cl- influx into membrane vesicles prepared from the bovine cerebral cortex was stimulated and attenuated by flunitrazepam and beta-CCE, respectively. These effects of flunitrazepam and beta-CCE on the GABA-stimulated 36Cl- influx were antagonized by Ro15-1788. The present results suggest that the binding site for beta-CCE, which resides on GABAA receptor/benzodiazepine receptor/chloride ion channel complex, may be different from that for benzodiazepine. Possible roles of beta-CCE binding site in the allosteric inhibitions on benzodiazepine binding site as well as on the functional coupling between chloride ion channel and GABAA receptor are also suggested.

  18. Fluorochloridone induces primary cultured Sertoli cells apoptosis: Involvement of ROS and intracellular calcium ions-mediated ERK1/2 activation.

    Science.gov (United States)

    Liu, Luqing; Chang, Xiuli; Zhang, Yubin; Wu, Chunhua; Li, Rui; Tang, Liming; Zhou, Zhijun

    2018-03-01

    Fluorochloridone (FLC) is a widely used pyrrolidone selective herbicide and reported to induce testis injuries in male rats, but the underlying mechanism is largely unknown. In the present study, primary-cultured Sertoli cells were exposed to FLC at the concentration of 0-10.00μM to study the mechanism of FLC-induced apoptosis. The roles of ROS, intracellular calcium, endoplasmic reticulum (ER), and ERK1/2 were looked at with ROS scavenger N-acetyl-cysteine (NAC), intracellular calcium chelator BAPTA-AM, ER calcium depleting agent thapsigargin (TG), and ERK1/2 inhibitor U0126, respectively. FLC induced dose-dependent apoptosis increase as well as the elevation in levels of ROS, intracellular calcium, and ERK1/2 activation. FLC treatment led to constantly increasing apoptotic rates and ERK1/2 activation over time, while inversed-V shaped change tendencies of ROS and intracellular calcium levels were observed. FLC-induced ROS generation disrupted the intracellular calcium homeostasis by attacking the ER, and the elevated intracellular calcium levels resulted in ERK1/2 over-phosphorylation and consequently promoted Sertoli cell apoptosis. Taken together, ROS and intracellular calcium-mediated ERK1/2 activation led to FLC-induced Sertoli cell apoptosis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Functional SNP in the microRNA-367 binding site in the 3'UTR of the calcium channel ryanodine receptor gene 3 (RYR3) affects breast cancer risk and calcification.

    Science.gov (United States)

    Zhang, Lina; Liu, Yuexin; Song, Fengju; Zheng, Hong; Hu, Limei; Lu, Hong; Liu, Peifang; Hao, Xishan; Zhang, Wei; Chen, Kexin

    2011-08-16

    We have evaluated and provided evidence that the ryanodine receptor 3 gene (RYR3), which encodes a large protein that forms a calcium channel, is important for the growth, morphology, and migration of breast cancer cells. A putative binding site for microRNA-367 (miR-367) exists in the 3'UTR of RYR3, and a genetic variant, rs1044129 A→G, is present in this binding region. We confirmed that miR-367 regulates the expression of a reporter gene driven by the RYR3 3'UTR and that the regulation was affected by the RYR3 genotype. A thermodynamic model based on base pairing and the secondary structure of the RYR3 mRNA and miR-367 miRNA showed that miR-367 had a higher binding affinity for the A genotype than for the G genotype. The rs1044129 SNP was genotyped in 1,532 breast cancer cases and 1,600 healthy Chinese women. The results showed that compared with the AA genotype, G was a risk genotype for breast cancer development and was also associated with breast cancer calcification and poor survival. Thus, rs1044129 is a unique SNP that resides in a miRNA-gene regulatory loop that affects breast cancer risk, calcification, and survival.

  20. The Effects in the Rat of Varying Intakes of Dietary Calcium, Phosphorus, and Hydrogen Ion on Hyperparathyroidism Due to Chronic Renal Failure

    Science.gov (United States)

    Kaye, Michael

    1974-01-01

    Renal failure of 4 wk duration in rats led to parathyroid enlargement, increased bone resorption, and decreased tubular reabsorption of phosphate by the remnant kidney. The degree of hyperparathyroidism was influenced by each of the three dietary factors investigated. In the first study increasing calcium intake reduced the size of the parathyroids by increasing calcium and reducing phosphate absorption. In the second study phosphate intake was linearly related to parathyroid gland size in the uremic animals and associated with rising plasma phosphate levels. In the last study acidosis led directly to increased bone resorption but small parathyroid glands associated with elevated ionized calcium levels. Alkalosis lowered the serum ionized calcium and led to parathyroid enlargement and the expected associated findings. It was shown that parathyroid weight reflected both metabolic activity as judged by amino acid uptake, and the content of immunoassayable parathyroid hormone. In all studies gland weight was inversely related to serum ionized calcium. PMID:4808640

  1. 43. Calmodulin regulating calcium sensitivity of Na channels

    Directory of Open Access Journals (Sweden)

    R. Vegiraju

    2016-07-01

    Full Text Available By extrapolating information from existing research and observing previous assumptions regarding the structure of the Na Channel, this experiment was conducted under the hypothesis that the Na Channel is in part regulated by the calmodulin protein, as a result proving calcium sensitivity of the Na Channel. Furthermore, we assume that there is a one to one stoichiometry between the Na Channel and the Calmodulin. There has been extensive research into the functionality and structure of sodium ion channels (Na channels, as several diseases are associated with the lack of regulation of sodium ions, that is caused by the disfunction of these Na channels. However, one highly controversial matter in the field is the importance of the protein calmodulin (CaM and calcium in Na channel function. Calmodulin is a protein that is well known for its role as a calcium binding messenger protein, and that association is believed to play an indirect role in regulating the Na channel through the Na channel’s supposed calcium sensitivity. While there are proponents for both sides, there has been relatively little research that provides strong evidence for either case. In this experiment, the effect of calmodulin on NaV 1.5 is tested by preparing a set of cardiac cells (of the human specie with the NaV 1.5 C-Termini and CaM protein, which were then to be placed in solutions with varying concentrations of calcium. We took special care to test multiple concentrations of calcium, as previous studies have tested very low concentrations, with Manu Ben-Johny’s team from the John Hopkins laboratory in particular testing up to a meager 50 micromolar, despite producing a well-respected paper (By comparison, the average Na channel can naturally sustain a concentration of almost 1-2 millimolar and on some occasions, reaching even higher concentrations. After using light scattering and observing the signals given off by the calcium interacting with these Nav1.5/Ca

  2. Effect of Mg2+, Al3+, and Fe3+ ions on crystallization of type α hemi-hydrated calcium sulfate under simulated conditions of hemi-hydrate process of phosphoric acid

    Science.gov (United States)

    Yang, Lin; Cao, Jianxin; Luo, Tong

    2018-03-01

    The present study investigated the effects of Mg2+, Al3+, and Fe3+ ions, as additives, on crystallization of type α hemi-hydrated calcium sulfate (α-HH) under simulated conditions of hemi-hydrate wet-process phosphoric acid production. Results showed that induction time of α-HH without additives reduces with increasing supersaturated ratios, but increases in the presence of Mg2+, Al3+, and Fe3+ ions. Under the same concentration of impurity ions, the order of extending induction time of α-HH is as follows: Fe3+>Mg2+>Al3+, and surface energy and critical nucleus radius of α-HH increase in the presence of Mg2+, Al3+, and Fe3+ ions. Accordingly, nucleation rate and growth efficiency of α-HH crystals reduce. Length of α-HH crystals decreases and its diameter thicken in the presence of Mg2+, Al3+, and Fe3+ ions. The crystals of α-HH easily grow in the direction of [0 1 0], and feature long-needles. On the other hand, Mg2+, Al3+, and Fe3+ ions are mainly adsorbed on the exposed surface {1 -1 0} of α-HH crystals. Thus, crystal shapes of α-HH eventually show wedge or short columns.

  3. Conserved epitope on several human vitamin K-dependent proteins: location of the antigenic site and influence of metal ions on antibody binding

    International Nuclear Information System (INIS)

    Church, W.R.; Messier, T.; Howard, P.R.; Amiral, J.; Meyer, D.; Mann, K.G.

    1988-01-01

    A murine monoclonal antibody (designated H-11) produced by injecting mice with purified human protein C was found to bind several human vitamin K-dependent proteins. Using a solid-phase competitive radioimmunoassay with antibody immobilized onto microtiter plates, binding of 125 I-labeled protein C to the antibody was inhibited by increasing amounts of protein C, prothrombin, and Factors X and VII over a concentration range of 1 x 10 -8 to 1 x 10 -6 M. Chemical treatment of prothrombin with a variety of agents did not destroy the antigenic site recognized by the antibody as measured by immunoblotting of prothrombin or prothrombin derivative immobilized onto nitrocellulose. Immunoblotting of purified vitamin K-dependent polypeptides with the monoclonal antibody following sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrophoretic transfer to nitrocellulose indicated that the antigenic site was found on the light chains of protein C and Factor X. The exact location of the antigenic determinant for antibody H-11 was established using synthetic peptides. Comparison of protein sequences of bovine and human vitamin K-dependent proteins suggests that the sequence Phe-Leu-Glu-Glu-Xaa-Arg/Lys is required for antibody binding. Increasing concentrations of Ca 2+ , Mg 2+ , or Mn 2+ partially inhibited binding of 125 I-protein C to the antibody in a solid-phase assay system with half-maximal binding observed at divalent metal ion concentrations of 2, 4, and 0.6 mM, respectively. The antigenic site thus recognized by monoclonal antibody H-11 is located at the amino-terminal region in the highly conserved γ-carboxyglutamic acid-containing domains of several, but not all, vitamin K-dependent proteins

  4. Novel short-chain analogues of somatostatin as ligands for Cu(II) ions. Role of the metal ion binding on the spatial structure of the ligand.

    Science.gov (United States)

    Marciniak, Aleksandra; Cebrat, Marek; Czyżnikowska, Żaneta; Brasuń, Justyna

    2012-12-01

    In this paper we present the studies on coordination abilities of two short-chain analogues of somatostatin with free N-terminal and protected amino group towards copper (II) ions. The octreotide is the most popular analogue of the somatostatin (peptide hormone) used in medicine. Somatostatin analogues are used in diagnosis and treatment of the neuroendocrine tumors. Both analyzed analogues are characterized by the presence of two His instead of Cys residues in characteristic fragment of native peptide. We characterize coordination abilities of the ligands using potentiometric and spectroscopic methods. His-analogues of somatostatin are effective ligands for copper (II) ions. Both peptides are able to form the complexes with the cyclic structure. Copyright © 2012 Elsevier Inc. All rights reserved.

  5. Dissociation kinetics of excited ions: PEPICO measurements of Os3(CO)12 — The 7-35 eV single ionization binding energy region

    Science.gov (United States)

    Schalk, Oliver; Josefsson, Ida; Geng, Ting; Richter, Robert; Sa'adeh, Hanan; Thomas, Richard D.; Mucke, Melanie

    2018-02-01

    In this article, we study the photoinduced dissociation pathways of a metallocarbonyl, Os3(CO)12, in particular the consecutive loss of CO groups. To do so, we performed photoelectron-photoion coincidence (PEPICO) measurements in the single ionization binding energy region from 7 to 35 eV using 45-eV photons. Zero-energy ion appearance energies for the dissociation steps were extracted by modeling the PEPICO data using the statistical adiabatic channel model. Upon ionization to the excited ionic states above 13 eV binding energy, non-statistical behavior was observed and assigned to prompt CO loss. Double ionization was found to be dominated by the knockout process with an onset of 20.9 ± 0.4 eV. The oscillator strength is significantly larger for energies above 26.6 ± 0.4 eV, corresponding to one electron being ejected from the Os3 center and one from the CO ligands. The cross section for double ionization was found to increase linearly up to 35 eV ionization energy, at which 40% of the generated ions are doubly charged.

  6. Lead content of calcium supplements.

    Science.gov (United States)

    Ross, E A; Szabo, N J; Tebbett, I R

    2000-09-20

    Substantial quantities of lead have been reported in some over-the-counter calcium supplement preparations, including not only bone-meal and dolomite, but also over-the-counter natural and refined calcium carbonate formulations. Examination of this issue is warranted given recent increases in physician recommendations for calcium supplements for prevention and treatment of osteoporosis. To determine the lead content of calcium supplements and to quantify the lead exposure from popular brands of calcium in dosages used for childhood recommended daily allowance, osteoporosis, and phosphate binding in dialysis patients. Analysis of lead content in 21 formulations of nonprescription calcium carbonate (including 7 natural [ie, oyster shell] and 14 refined), 1 brand of prescription-only calcium acetate, and 1 noncalcium synthetic phosphate binder conducted in March 2000. Lead content, assayed using electrothermal atomic absorption, expressed as micrograms of lead per 800 mg/d of elemental calcium, per 1500 mg/d of calcium, and for a range of dosages for patients with renal failure. Six microg/d of lead was considered the absolute dietary limit, with no more than 1 microg/d being the goal for supplements. Four of 7 natural products had measurable lead content, amounting to approximately 1 microg/d for 800 mg/d of calcium, between 1 and 2 microg/d for 1500 mg/d of calcium, and up to 10 microg/d for renal dosages. Four of the 14 refined products had similar lead content, including up to 3 microg/d of lead in osteoporosis calcium dosages and up to 20 microg/d in high renal dosages. No lead was detected in the calcium acetate or polymer products. Lead was present even in some brand name products from major pharmaceutical companies not of natural oyster shell derivation. Despite increasingly stringent limits of lead exposure, many calcium supplement formulations contain lead and thereby may pose an easily avoidable public health concern. JAMA. 2000;284:1425-1429.

  7. Effects of vanadium on different adenosinetriphosphatases and binding of 3H-labeled ouabain and calcium-45 to rat brain synaptosomes

    International Nuclear Information System (INIS)

    Mishra, S.K.; Osborn, R.L.; Desaiah, D.

    1981-01-01

    The effect of vanadium chloride on rat brain synaptosomal adenosinetriphosphatase (ATPase) activities was determined in vitro and in rats treated at 1 mg/kg and 10 mg/kg for 10 d. Additional experiments were conducted to determine the effect of vanadium chloride on binding of [ 3 H]ouabain and 45 Ca to rat brain synaptosomes. Na + + K + - and Ca 2+ -ATPase activities were inhibited significantly in a concentration-dependent manner by V in vitro. Mg 2+ -ATPase inhibition was neither dose-dependent nor significant except at 10 -5 M. Na + + K + -ATPase inhibition by V was more pronounced than that of other ATPases studied. Vanadium inhibited [ 3 H]ouabain binding to synaptosomes by 90% at 10 -3 M; the inhibition was concentration-dependent. Binding of 45 Ca was inhibited 50% at 10 -4 M; but concentration-dependent inhibition was not evident. Rats treated with vanadium chloride neither became myotonic nor showed any changes in ATPase activities or binding of [ 3 H]ouabain and 45 Ca to brain synaptosomes. Line-weaver-Burke plots of the in vitro inhibition of Na + + K + -ATPase and [ 3 H]ouabain binding revealed that (1) Na + + K + -ATPase activation by ATP was inhibited by V with an increase in K/sub m/ and a decrease in V/sub max/; (2) Na + activation was inhibited noncompetitively by V, as evidenced by a decrease in V/sub max/ and no change in K/sub m/; (3) K + activation was inhibited by V with a decrease in both V/sub max/ and K/sub m/; (4) noncompetitive inhibition of Mg 2+ -ATPase by V was observed; and (5) the kinetic behavior of [ 3 H]ouabain binding inhibition by V with respect to ATP and Na + activation was mixed and noncompetitive, respectively

  8. Inhibition by divalent metal ions of human histidine triad nucleotide binding protein1 (hHint1), a regulator of opioid analgesia and neuropathic pain.

    Science.gov (United States)

    Shah, Rachit; Chou, Tsui-Fen; Maize, Kimberly M; Strom, Alexander; Finzel, Barry C; Wagner, Carston R

    2017-09-23

    Human histidine triad nucleotide binding protein 1 (hHint1) is a purine nucleoside phosphoramidase and adenylate hydrolase that has emerged as a potential therapeutic target for the management of pain. However, the molecular mechanism of Hint1 in the signaling pathway has remained less clear. The role of metal ions in regulating postsynaptic transmission is well known, and the active site of hHint1 contains multiple histidines. Here we have investigated the effect of divalent metal ions (Cd 2+ , Cu 2+ , Mg 2+ , Mn 2+ , Ni 2+ , and Zn 2+ ) on the structural integrity and catalytic activity of hHint1. With the exception of Mg 2+ , all the divalent ions inhibited hHint1, the rank of order was found to be Cu 2+ >Zn 2+ >Cd 2+ ≥Ni 2+ >Mn 2+ based on their IC 50 and k in /K I values. A crystal structure of hHint1 with bound Cu 2+ is described to explain the competitive reversible inactivation of hHint1 by divalent cations. All the metal ions exhibited time- and concentration- dependent inhibition, with the rate of inactivation highly dependent on alterations of the C-terminus. With the exception of Cu 2+ ; restoration of inhibition was observed for all the metal ions after treatment with EDTA. Our studies reveal a loss in secondary structure and aggregation of hHint1 upon incubation with 10-fold excess of copper. Thus, hHint1 appears to be structurally sensitive to irreversible inactivation by copper, which may be of neurotoxicological and pharmacological significance. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Abnormal secretion and function of recombinant human factor VII as the result of modification to a calcium binding site caused by a 15-base pair insertion in the F7 gene.

    Science.gov (United States)

    Peyvandi, F; Carew, J A; Perry, D J; Hunault, M; Khanduri, U; Perkins, S J; Mannucci, P M; Bauer, K A

    2001-02-15

    A case of a novel mutation in the F7 gene that results in factor VII coagulant activity (VII:c) of less than 1% and VII antigen (VII:Ag) levels of 10% is presented. DNA analysis revealed a homozygous 15-base pair (bp) in-frame insertion-type mutation at nucleotide 10554. This insertion consisted of a duplication of residues leucine (L)213 to aspartic acid (D)217 (leucine, serine, glutamic acid, histidine, and aspartic acid), probably arising by slipped mispairing between 2 copies of a direct repeat (GCGAGCACGAC) separated by 4 bp. Molecular graphic analyses showed that the insertion is located at the surface of the catalytic domain in an exposed loop stabilized by extensive salt-bridge and hydrogen bond formation at which the calcium binding site is located. The mutation probably interferes with protein folding during VII biosynthesis and/or diminishes functional activity through the loss of calcium binding. In vitro expression studies demonstrated that the levels of VII:Ag in lysates of cells transfected with wild type VII (VIIWT) were equivalent to those with mutant type VII (VIIMT), but the level of secreted VIIMT was 5% to 10% that of VIIWT. Pulse chase studies demonstrated that VIIMT did not accumulate intracellularly, and studies with inhibitors of protein degradation showed that recombinant VIIMT was partially degraded in the pre-Golgi compartment. Accordingly, only small amounts of VIIMT with undetectable procoagulant activity were secreted into conditioned media. These results demonstrate that a combination of secretion and functional defects is the mechanism whereby this insertion causes VII deficiency.

  10. A novel Glycine soja cysteine proteinase inhibitor GsCPI14, interacting with the calcium/calmodulin-binding receptor-like kinase GsCBRLK, regulated plant tolerance to alkali stress.

    Science.gov (United States)

    Sun, Xiaoli; Yang, Shanshan; Sun, Mingzhe; Wang, Sunting; Ding, Xiaodong; Zhu, Dan; Ji, Wei; Cai, Hua; Zhao, Chaoyue; Wang, Xuedong; Zhu, Yanming

    2014-05-01

    It has been well demonstrated that cystatins regulated plant stress tolerance through inhibiting the cysteine proteinase activity under environmental stress. However, there was limited information about the role of cystatins in plant alkali stress response, especially in wild soybean. Here, in this study, we focused on the biological characterization of a novel Glycine soja cystatin protein GsCPI14, which interacted with the calcium/calmodulin-binding receptor-like kinase GsCBRLK and positively regulated plant alkali stress tolerance. The protein-protein interaction between GsCBRLK and GsCPI14 was confirmed by using split-ubiquitin based membrane yeast two-hybrid analysis and bimolecular fluorescence complementation assay. Expression of GsCPI14 was greatly induced by salt, ABA and alkali stress in G. soja, and GsCBRLK overexpression (OX) in Glycine max promoted the stress induction of GmCPI14 expression under stress conditions. Furthermore, we found that GsCPI14-eGFP fusion protein localized in the entire Arabidopsis protoplast and onion epidermal cell, and GsCPI14 showed ubiquitous expression in different tissues of G. soja. In addition, we gave evidence that the GST-GsCPI14 fusion protein inhibited the proteolytic activity of papain in vitro. At last, we demonstrated that OX of GsCPI14 in Arabidopsis promoted the seed germination under alkali stress, as evidenced by higher germination rates. GsCPI14 transgenic Arabidopsis seedlings also displayed better growth performance and physiological index under alkali stress. Taken together, results presented in this study demonstrated that the G. soja cysteine proteinase inhibitor GsCPI14 interacted with the calcium/calmodulin-binding receptor-like kinase GsCBRLK and regulated plant tolerance to alkali stress.

  11. Simple and cooperative electrostatic binding of amonium ions to phosphate-polyions: NMR, infrared and theoretical study

    Czech Academy of Sciences Publication Activity Database

    Kříž, Jaroslav; Dybal, Jiří

    2004-01-01

    Roč. 108, č. 26 (2004), s. 9306-9314 ISSN 1520-6106 R&D Projects: GA AV ČR KSK4050111 Institutional research plan: CEZ:AV0Z4050913 Keywords : cooperative interactions * electrostatic binding * hydrophobic interactions Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.834, year: 2004

  12. Formation of Mixed-Ligand Complexes of Pd2+ with Nucleoside 5'-Monophosphates and Some Metal-Ion-Binding Nucleoside Surrogates

    Directory of Open Access Journals (Sweden)

    Oleg Golubev

    2014-10-01

    Full Text Available Formation of mixed-ligand Pd2+ complexes between canonical nucleoside 5'-monophosphates and five metal-ion-binding nucleoside analogs has been studied by 1H-NMR spectroscopy to test the ability of these nucleoside surrogates to discriminate between unmodified nucleobases by Pd2+-mediated base pairing. The nucleoside analogs studied included 2,6-bis(3,5-dimethylpyrazol-1-yl-, 2,6-bis(1-methylhydrazinyl- and 6-(3,5-dimethylpyrazol-1-yl-substituted 9-(β-d-ribofuranosylpurines 1–3, and 2,4-bis(3,5-dimethylpyrazol-1-yl- and 2,4-bis(1-methylhydrazinyl-substituted 5-(β-d-ribofuranosyl-pyrimidines 4–5. Among these, the purine derivatives 1-3 bound Pd2+ much more tightly than the pyrimidine derivatives 4, 5 despite apparently